Turbos

[ManDownUnder]

As I understand it - turbos, use a little more fuel - and give of HEAPS more power (i.e. the power added is dispoportionately higher than the fuel used...)

I assume the same is true of mechanical blower?

1) Is that the case...
2) If so, why don't all vehicle have 'em. It's good for power and good for the environment (smaller motors, same amount of power - works for me!)

Or am I working with false premises?
MDU

[FlyingDutchMan]

The theory behind turbos says that is true (higher compression blah de blah gives higher efficency), but in reality they use shite loads more fuel for the power they produce. A mechanical blower (supercharger?) is similar but doesn't suffer so much from turbo lag - i.e. you open up the throttle and it will give you the power right then and there... depending on the type of supercharger you've got of course. Some pump more air at low rpms, some need heaps of rpms. They're huge amounts of info out there, but in general a normally aspriated vehicle is more efficent, even if it produces less power. Anyway production turbo cars generally produce the same hp/litre as a sports bike (around 180 hp/litre).

[scumdog]

As I understand it - turbos, use a little more fuel - and give of HEAPS more power (i.e. the power added is dispoportionately higher than the fuel used...)

I assume the same is true of mechanical blower?

1) Is that the case...
2) If so, why don't all vehicle have 'em. It's good for power and good for the environment (smaller motors, same amount of power - works for me!)

Or am I working with false premises?
MDU

Things NOT good about turbos: they add weight, they take up room, they create lots of heat in a small area, they require lots of plumbing/wiring, they do not give much grunt until they 'spool-up' (turbo-lag), when under boost the engine takes a hammering - ergo need stronger components.

Thins NOT good about superchargers: same as turbos generally but also not so 'flexible' when it comes to where they can be located (mostly driven off the crankshaft), greater 'parasitic' loss of power (i.e. the s'charger takes 20hp to drive so to make 100hp at output shaf it has to put out 120hp at crank). One good thing about s'charging is there is no 'lag', it makes hp. straight away

My 2 cents worth

[ManDownUnder]

Thanks Dude. Kinda explains why it seemed wrong for all vehicles to be non boosted, but the performance stats suggested they should be (to me anyways...


MDU out!

[bugjuice]

The other problem with turbos is that when you've got it, you use it more, so you go thru more fuel anyway, just cos you spend half the time dickin around making the turbo spin up. From what I understand, the turbo is forcing more air into the engine, more fuel is added, thus creating your extra power boost. The turbo is driven from exhaust gases, so the exhaust has to be pumping out hard before the turbo spins up to compression, hense your turbo lag. To reduce the lag, you use a smaller turbo, but that's smaller power, hence 'twin turbos'. One is a smaller one to get off the lights, then they cut over to the larger one where the bigger turbo is more effective higher up the rev range. You can bodge this to be two big turbos on things like V6s etc. But turbos can often out-spin most engines, so the boost lasts and lasts most of the time.

Compressors (mercs call 'em Kompressor), super chargers, blowers etc, whatever you call 'em, work mechanically and often belt driven, so it works straight off as the engine spins up. These don't have any turbo lag. But they don't have much top end.

What I want to know, is given the theory of how both work, can they both be bolted to one engine? The supercharger will give you the boost off the lights, the turbo will give the power up the rev-range..

I'd love to fit a small turbo to my bike, not for the power increase, but just to hear the whoosh from it..

[vifferman]

Some truths there, and some untruths. Turbos use more fuel when being used because they're forcing more mixture through and creating more power. However, turboed vehicles often run lower compression ratios, so when they're being run below the range where the turbo kicks in, they are more economical than the same engine without a turbo.Turbos give 'free' power in a sense, in that because they're using exhaust gases to drive them, they're not sucking any power from the engine. As has been stated, superchargers suck lots of power as they are a mechanical compressor driven off the crankshaft. Some more sophisticated models are disconnected when the extra boost isn't required, thus not provided a penalty at lower throttle openings.

The lag can be gotten round by making the turbo impellor smaller, by using a 'twin-scroll' turbo, or by using two turbos, one which kicks in at lower revs, and another larger one that kicks in later.

The latest superchargers use a system that is driven by a 'magic fluid' that doesn't slip when under pressure, so that at low revs it slips, then locks up when revs (pressure) increase. Instead of gears or vanes, they use planetary rollers that multiply the input revs by 5 or 6 times. These are very effective on small engines like bikes, as they are compact and efficient.

[Ixion]

..

What I want to know, is given the theory of how both work, can they both be bolted to one engine? The supercharger will give you the boost off the lights, the turbo will give the power up the rev-range..

I'd love to fit a small turbo to my bike, not for the power increase, but just to hear the whoosh from it..

In theory yes. Some car maker did it but I can't remmeber who. I think maybe it wasn't a great success.

[scumdog]

I'd love to fit a small turbo to my bike, not for the power increase, but just to hear the whoosh from it..

Why bother, look up Trademe, Ebay and buy yourself a Suzuki XN85..... :niceone:

[TonyB]

One good thing with turbos is once spooled up they give you huge amounts of torque over a very wide rev range, so while the maximum power may not seem that great, the engine will pull like nobodys business from the moment the turbo kicks in, not just at the top of the rev range like a normally aspirated engine does. For instance the latest Legacy GT 2.0 turbo makes 205kW at 6400 rpm and peak torque is 343 Nm at 2400 rpm. While the Legacy 3.0R SpecB makes 180kW at 6600rpm and 297Nm at 4200rpm. So despite having a 50% bigger engine, the 3.0R SpecB makes less power, but more importantly, significantly less torque at much higher revs.

[Suney]

What I want to know, is given the theory of how both work, can they both be bolted to one engine? The supercharger will give you the boost off the lights, the turbo will give the power up the rev-range..
it..
In the ausie Hot4s magazine, there a red corolla sporting both turbo and supercharger, so it's definitely possible

[bungbung]

However, turboed vehicles often run lower compression ratios, so when they're being run below the range where the turbo kicks in, they are more economical than the same engine without a turbo.

Isn't that arse about face?

When operating in the off-boost situation, they are less efficient than the equivalent na engine running at a higher compression.

[bugjuice]

Why bother, look up Trademe, Ebay and buy yourself a Suzuki XN85..... :niceone:
cos it isn't sexy orange, and doesn't look menacing like mine does..
I just wanna hear some whoosh..
like this (http://www.superbike.co.uk/content/movies/30_1_4/gr_2_busa_turbo.wmv), but not as much power 499bhp (~12.7mb)

[TonyB]

Or how about this:
Current Ford XR6- 182kW @ 5000rpm, 380Nm @ 3250rpm
Current XR6 Turbo- 240kW @ 5250rpm, 450Nm @ 2000rpm
Current XR8- 260kW @ 5250rpm, 500Nm @ 4250rpm.....no wonder they feel so bloody peaky when you drive them- all the power and torque are at the top of the rev range. The XR6 Turbo is a much betterer car.

[scumdog]

Isn't that arse about face?

When operating in the off-boost situation, they are less efficient than the equivalent na engine running at a higher compression.

Dead right, a lot of the time the first bit of turbo boost is just getting the engine into thinking it's running at 11:1 comp instead of 8.5:1.
A hi-comp engine under lightish load is going to be more fuel efficient than a low-comp one under the same load i.e. will run a higher vacuum.

[chris]

What I want to know, is given the theory of how both work, can they both be bolted to one engine? The supercharger will give you the boost off the lights, the turbo will give the power up the rev-range..

The Lancia Delta S4 had both fitted during the heady days of Group B rally cars. I presume the turbo was fited to compensate for the superchargers inability to provide decent boost at high RPM.

Turbos do not necessarily have to suffer from lag. The newer ball bearing models tend to spool up much quicker and just about eliminate lag. The other way to eliminate lag, as the WRC cars use, is an anti lag system that injects and then ignites fuel directly in the exhaust system when the driver is off the throttle. Doersn't do much for the life of the turbo components though.

Superchargers are great, but my choice would be turbo.

[scumdog]

cos it isn't sexy orange, and doesn't look menacing like mine does..
I just wanna hear some whoosh..
like this (http://www.superbike.co.uk/content/movies/30_1_4/gr_2_busa_turbo.wmv), but not as much power 499bhp (~12.7mb)

I'm in contact with the TMIOA (Turbo Motocycles International Owners Association) and one member has taken his XN out to 836cc (normally 650) and his dyno reading is 118hp and 79.4ft/lb of torge, nothing to be sneezed at for a 22 year old bike eh?

[Jonty]

Dead right, a lot of the time the first bit of turbo boost is just getting the engine into thinking it's running at 11:1 comp instead of 8.5:1.
A hi-comp engine under lightish load is going to be more fuel efficient than a low-comp one under the same load i.e. will run a higher vacuum.

Interetsing post - sorry silly question scumdog, but what to the compression values mean? ie 11.1 vs 8.5.1. I realise one is a higher compression than the other but in terms of how it is calculated.

Cheers

[Ixion]

The Lancia Delta S4 had both fitted during the heady days of Group B rally cars..

I shoud'a known 'twould be Lancia !

[Ixion]

Dead right, a lot of the time the first bit of turbo boost is just getting the engine into thinking it's running at 11:1 comp instead of 8.5:1.
A hi-comp engine under lightish load is going to be more fuel efficient than a low-comp one under the same load i.e. will run a higher vacuum.

Hm, there's more than compression involved. There's things like valve and port sizes. They have more effect on consumption than comp ratio. (Low comp engines are usually good on fuel cos they also have small valves and ports).

Thing is, with a turbo you can have quite small inlet valves and ports (assuming the donk is designed for turbo from the start).

Cos the turbo can shove the mixture in through a (comparatively) small port happily enough. You've got heaps of boost pressure to force it in

Normally aspirated, all you've got to get the mixture in is the vacuum suck. So you need bigger valves (and/or lots of them) and big ports.

The big ports and valves are fuel inefficient at low revs (for lots of complicated technical reasons around air velocity and turbulence and such like). Meanwhile, the turbo, when running at low (non turbo) revs is very fuel efficient cos of those small valves and ports (May be pretty gutless at low revs mind you, until the turbo kicks in. But if you're the sort of person that runs a turbo you probably don't care about low rev performance)

[bugjuice]

I'm in contact with the TMIOA (Turbo Motocycles International Owners Association) and one member has taken his XN out to 836cc (normally 650) and his dyno reading is 118hp and 79.4ft/lb of torge, nothing to be sneezed at for a 22 year old bike eh?
most definately not!! Rebuild every few days...??


Thought the anti lag system fed the over boost from the waste gate back to the inlet of the turbo, to keep it spinning?

Lancia's rock. I want a Delta Integrale HP (the 200bhp+ version)

[ajturbo]

Why bother, look up Trademe, Ebay and buy yourself a Suzuki XN85..... :niceone:

or you could offer me a small fortune for mine!!!!

i would trade it on a TL1000s..........:Punk:

[scumdog]

Interetsing post - sorry silly question scumdog, but what to the compression values mean? ie 11.1 vs 8.5.1. I realise one is a higher compression than the other but in terms of how it is calculated.

Cheers

11 to 1 means the volume in each cylinder is 'squeezed' in effect into one eleventh the volume if you know what I mean i.e. when piston is at the bottom of its travel the cylinder has 11 times the volume it has when the piston is at top dead centre at the top of its travel..

A turbo 'fools' the engine into believing it is 'bigger' than it really is by cramming more air/fuel mixture into the engine than it could 'suck' into itself normally.

More air/fuel = more 'bang and energy released, that's why (all things being equal) a big engine puts out more grunt than a little engine.

Low-comp motor - not much compressing of the fuel/air mixture so less efficient burning of same i.e. a weak bang.

Hope the confusion is not too bad, maybe somebody more erudite than I can elucidate??

[Blackbird]

I used to run a Shorrock C750 vane supercharger on my drag bike and it produced huge no-lag torque from way down low. This characteristic can actually improve fuel consumption under normal road-going conditions on a car or bike. As Scumdog said, horsepower absorption is an issue and you have to match applications carefully. Physical size is a further issue. Both the vane and Rootes screw-type superchargers were also quite high maintenance through the drive train and vane bearings although the newer developments which Vifferman described may have improved this aspect.

Many years ago, there was a legendary road-going Bonneville in the UK called Ghengis Khan which was equipped with a Shorrock supercharger. Not only would it see off any other road-going vehicle, it would give most track bikes a good seeing to as well. This was presumably only on a straight line given that early Bonnies had a hinge in the frame. I should know, I owned one for a short time! :yes:

Geoff

[Lou Girardin]

Quoting peak torque figures is meaningless unless you can see the entire curve.
An engine with a lower peak torque may have an actual curve that starts sooner and is flatter than the other giving a much more flexible engine and one that'll accelerate harder in the real world. And regardless of how you do it, X amount of power requires X amount of fuel once you reach optimum volumetric and thermal efficiency.
And I'd rather hear supercharger scream than that asthmatic gasping that turbos do.

[bugjuice]

I think speedpro has some 80's 1000cc turbo thingy.. Saw it once, the turbo sit just under your left thigh, and the pipes go just a bit further out. That looked mental. Also looked like it'd handle like a boat and had similar brakes to match, but having never rode it etc, I could quite possibly be wrong.. Think it was a Kawa come to think of it, but probably wrong about that too..

[chickenfunkstar]

Dead right, a lot of the time the first bit of turbo boost is just getting the engine into thinking it's running at 11:1 comp instead of 8.5:1.
A hi-comp engine under lightish load is going to be more fuel efficient than a low-comp one under the same load i.e. will run a higher vacuum.


Is this approximatly the change in compression from when an engine is 'off boost' to when it is 'on boost'?
Is there any way to relate PSI of boost to the change in compression?

[chris]

The BMW turbo charged engine fitted to the Brabham F1 cars in the early eighties gave around 1500bhp in qualifying trim...........from a 1500cc four cylinder engine with a production car block!! 1000bhp per 1000cc aint bad.

[RiderInBlack]

Would increasing the O2 percentage, by say a bottle of pure 02 adding control amount to the carbies, increase an engine's output? Or is there to bigger risk of it causing the fuel to pre-ingnite? Could a dive bottle with air be used to increase the pressure pre-compression?

[Blackbird]

Doug,

This is what superchargers/turbochargers do by cramming in more air and fuel. Stuff like Nitrous Oxide and Nitromethane also do it. Can't remember my chemistry but I think Nitromethane liberates about 55% of its weight in O2. Extra power = extra heat and all that implies. Can't remember how many piston crowns I melted on the drag bike, not to mention splitting the crankcase!

Geoff

[Motu]

All these pros and cons go out the window with turbo diesels,they are a natural for turbo boost and it's a win/win situation all round - you don't need lower compression,you don't need more fuel,temps are cooler not higher,no strengthened parts...more power,more torque,less fuel consumption.Nearly every haulage truck,locomotive,ocean going vessel will have a turbo - it's for efficiency not power.2 stroke diesels like the Foden V12 ran twin blowers/twin turbos.

[TonyB]

Quoting peak torque figures is meaningless unless you can see the entire curve.
An engine with a lower peak torque may have an actual curve that starts sooner and is flatter than the other giving a much more flexible engine and one that'll accelerate harder in the real world. And regardless of how you do it, X amount of power requires X amount of fuel once you reach optimum volumetric and thermal efficiency.
And I'd rather hear supercharger scream than that asthmatic gasping that turbos do.
That's the point I'm trying to make- the turbo engines all make their peak torque at very low revs- much lower than the normally aspirated engines- yet the peak power is still near the red line. Therefore they have a good spread of torque and are more driveable than a normally aspirated engine (turbo lag aside). Drive an XR8 and an XR6 turbo back to back and you'll see what I mean. The XR8 needs lots of revs, whereas the XR6 turbo pulls very hard for very low down and just builds and builds as the revs rise. Why anyone would buy the XR8 after driving the turbo is beyond me.

[Jonty]

All these pros and cons go out the window with turbo diesels,they are a natural for turbo boost and it's a win/win situation all round - you don't need lower compression,you don't need more fuel,temps are cooler not higher,no strengthened parts...more power,more torque,less fuel consumption.Nearly every haulage truck,locomotive,ocean going vessel will have a turbo - it's for efficiency not power.2 stroke diesels like the Foden V12 ran twin blowers/twin turbos.

Agree - Although I notice only a few diesel tractors are turboed. I have a feeling it is to do with reliability factors in that turbos can be costly and have a habit of causing problems. Also, the turboed tractors I am familiar with have noticably better power output than the equivilent naturally aspirated machines.

Could all be in my imagination though :yes:

[Ixion]

All these pros and cons go out the window with turbo diesels,they are a natural for turbo boost and it's a win/win situation all round - you don't need lower compression,you don't need more fuel,temps are cooler not higher,no strengthened parts...more power,more torque,less fuel consumption.Nearly every haulage truck,locomotive,ocean going vessel will have a turbo - it's for efficiency not power.2 stroke diesels like the Foden V12 ran twin blowers/twin turbos.

Diesels is a whole different matter. Turbo on a diesel is a no brainer.

[Lou Girardin]

TonyB, peak power is always near the redline.
And I'd take issue with the better drivability statement. EG. the flat spot when the turbos change over on twin turbo Legacy's and Clarkson's test of a modded EVO 8 as an extreme example. There are some turbos that are hard to pick as turbos, but they're usually low boost examples. You'll never get the instant punch at zero revs that big cubes will give.

[Motu]

You'll never get the instant punch at zero revs that big cubes will give.

Or a supercharger - it's pretty hard to tell if you are driving a V8 or a supercharged V6 Commodore when you floor it off the line....if you are half deaf like me anyway....

[chris]

no strengthened parts

I thought most diesels ran stronger blocks and bottom ends than their petrol counterparts due to the much higher compression ratios.

[Ixion]

I thought most diesels ran stronger blocks and bottom ends than their petrol counterparts due to the much higher compression ratios.


I think Mr Motu meant that putting a turbo on a diesel didn't create any requirement for strengthing anything. Mainly because (as you note) diesels are already built stronger

[TonyB]

TonyB, peak power is always near the redline.
And I'd take issue with the better drivability statement. EG. the flat spot when the turbos change over on twin turbo Legacy's and Clarkson's test of a modded EVO 8 as an extreme example. There are some turbos that are hard to pick as turbos, but they're usually low boost examples. You'll never get the instant punch at zero revs that big cubes will give.
Sigh. At smoko I had a chat with one of my workmates. He gets to drive just about every new car that is test driven by his motor journalist mate. So he gets to drive a hell of a lot of cars. New cars. He confirmed what I am trying to say: once spooled up, a turbo car will make a lot of torque and therefore pull very hard all the way from say 2000rpm all the way to the peak power output. An Aussie V8 makes very little power down low. It all comes in a rush in the top half of the rev range. Infact, my mate said that when he has driven 5 or six speed manual SS, HSV, XR8 or FPV cars, and tried to roll on accelerate in a higher gear from lower revs, they simply bog down and "do nothing". When he has tried the same test in Legacy Turbos, WRX, EVO 4,5,6,7 etc etc etc they all push you back in the seat and accelerate. I also can confirm this having driven an old late 80's Mirage turbo, my dad's 90 Cefiro turbo, an 02 WRX, the bosses XR6 turbo and my own Legacy GT that ALL of these cars pull MUCH HARDER from low revs than my bosses ex VT SS and the BA XR8, and they continue to build in power right through the rev range*. Sure the XR8 has a killer rush at the end, but it doesn't do a whole lot down low. This is speaking from experience.

*Except my GT which does indeed have a flat spot as the turbo's change over. Infact, if your overtaking at around 100km/h in 4th up a steep hill, it can actually get to a point where it seems to get stuck in the middle between the primary and secondary turbo's...

So can you see what I am saying? Turbo charged engines have a much broader spread of torque and power than a conventional engine.

Edit: until such time as the turbo spools up, a big cube engine will shit all over a small turbo engine, so yeh for instant grunt big cubes are the go.... but then a good turbo with bearings etc spools up bloody quick..

[soundbeltfarm]

i wanted a super charger after watching mad max.
his car was was shit hot flick a switch and start and stop his charger whenever he wanted pity it dosnt work like that in real life.
maybe it does now though.
in 1995 me and a mate were going to import a used 350 chev super charged with a B&M mega blower for 10 grand. through a proper source.
but no one would insure us as we were pretty young.
not sure what it would be now.
but im not into the car thing anymore.

[HDTboy]

Sigh. At smoko I had a chat with one of my workmates. He gets to drive just about every new car that is test driven by his motor journalist mate. So he gets to drive a hell of a lot of cars. New cars. He confirmed what I am trying to say: once spooled up, a turbo car will make a lot of torque and therefore pull very hard all the way from say 2000rpm all the way to the peak power output. An Aussie V8 makes very little power down low. It all comes in a rush in the top half of the rev range. Infact, my mate said that when he has driven 5 or six speed manual SS, HSV, XR8 or FPV cars, and tried to roll on accelerate in a higher gear from lower revs, they simply bog down and "do nothing". When he has tried the same test in Legacy Turbos, WRX, EVO 4,5,6,7 etc etc etc they all push you back in the seat and accelerate. I also can confirm this having driven an old late 80's Mirage turbo, my dad's 90 Cefiro turbo, an 02 WRX, the bosses XR6 turbo and my own Legacy GT that ALL of these cars pull MUCH HARDER from low revs than my bosses ex VT SS and the BA XR8, and they continue to build in power right through the rev range*. Sure the XR8 has a killer rush at the end, but it doesn't do a whole lot down low. This is speaking from experience.

*Except my GT which does indeed have a flat spot as the turbo's change over. Infact, if your overtaking at around 100km/h in 4th up a steep hill, it can actually get to a point where it seems to get stuck in the middle between the primary and secondary turbo's...

So can you see what I am saying? Turbo charged engines have a much broader spread of torque and power than a conventional engine.

Edit: until such time as the turbo spools up, a big cube engine will shit all over a small turbo engine, so yeh for instant grunt big cubes are the go.... but then a good turbo with bearings etc spools up bloody quick..
I know from experience that a 170Kw naturally aspirated 330i has a lot smoother torque curve, and pulls harder and lower than my 165Kw turbo skyline
A4L XR6 turbo will pull hard anyway because it has 4L, the low down torque in these cars comes from big cubes, your GT legacy probably hsa a little turbo to get it moving.
The previous generation of aussie V8s made torque at lower revs than the latest ones, they've moved the powerband higher in the rev range

[chris]

Turbosupercharger

[Ixion]

I think Mr Motu meant that putting a turbo on a diesel didn't create any requirement for strengthing anything. Mainly because (as you note) diesels are already built stronger

hm. Strengthing. I like that word. Mr Hitcher, please add strengthing to the offical dictionary.

[Motu]

I know turbo pistons in the 4D56 Pajero are different than non turbo - but some use non turbo pistons because they are cheaper....and the total piece of crap motor will self destruct before the pistons do.The DOHC Turbo motor in my Charade was a thing of joy inside - the forged pistons made more noise than a 501 Maico but were strong as,a strengthening (long version of the choice word) bridge over the bottom end had 2 squirters to each piston and the head had a wide valve angle with 4 valves...it put out 100HP from 1000cc and were raced with 3 times the boost reliably.One of the best big grin cars I've driven.

[sedge]

The old MR2s came out with a supercharger and were pretty fast... HKS did a 'twincharger' kit that added a big pulley, big injectors, management computer and BIG turbo etc... So you got boost from idle via the SC and then when the turbo spooled up you got more.

Base kit was 300HP (they already had forged pistons and strong crank etc)

The kit was able to be used under warranty at this output :), most people who added it then let the turbo spool up to it's potential... 500HP+... Heh heh... What a nice little car, I always wanted one.

Oh yeah, 1600cc, reasonably light, mid engined, t-top, midnight blue - 500HP+ :)

One of these days I'll get one...

Sedge.

[dangerous]

What I want to know, is given the theory of how both work, can they both be bolted to one engine? The supercharger will give you the boost off the lights, the turbo will give the power up the rev-range..

Yeah mate trucks have used that theroy for years in OZ I was driving a V8 Kenworth that was a two stroker deisel with a supercharger and two turbos....... ohhhhh, wicked

I'd love to fit a small turbo to my bike, not for the power increase, but just to hear the whoosh from it..
Been there done that and its fuking awesome :ride:


Thought the anti lag system fed the over boost from the waste gate back to the inlet of the turbo, to keep it spinning?

pressure release or 'blow off' valves release the pressure from the manafold during a gear change which allows the turbo to spin freely.... other wise as the engine revs drop during the gear change so does the turbo.... it then has to wind up again ie: lag

[TonyB]

A4L XR6 turbo will pull hard anyway because it has 4L, the low down torque in these cars comes from big cubes, your GT legacy probably has a little turbo to get it moving.

the latest Legacy GT....343 Nm at 2400 rpm.
the Legacy 3.0R SpecB ....297Nm at 4200rpm.
Current Ford XR6....380Nm @ 3250rpm
Current XR6 Turbo....450Nm @ 2000rpm

The Legacy GT has one big turbo and 2 little litres
The 3.0R has 3 litres, no turbo
The XR6 has 4 litres, no turbo
The XR6T has 4 litres, one big turbo
You will notice that the 2 litre turbo GT makes nearly that same peak torque as the 4 litre XR6 at much lower revs.
The XR6T will stomp all over the 5 litre XR8 until they hit maybe 4500
What are you calling low revs? Idle to 2000? If thats the case I agree with you.

[dangerous]

Hell BJ dont mean to be stalking ya but heres another quote....

I think speedpro has some 80's 1000cc turbo thingy.. Saw it once, the turbo sit just under your left thigh, and the pipes go just a bit further out. That looked mental. Think it was a Kawa come to think of it, but probably wrong about that too..
Yeah baby that bike is a Kawa Z1TC a late 70's Z1 (speedpros is a McIntosh framed beast tho) which kawa nabed a few as they went out the back door and bolted a simple turbo kit up to they suck the fuel mix through the turbo cos they are a carbed motor.
Kawa in the 80's built the GPZ750zx turbo (see Death's profile) which was the fastest mother of all the turbos with Honda's CX650 right behind it, as with the suzuki XN they were injected the Yamaha XJ650 was the only other carbed turbo from the japs.

Heres a write up on the CX500Turbo (http://www.kiwibiker.co.nz/forums/showthread.php?t=2854) I had, all bikes should have one aye :Punk:

BTW turbos are better IMHO cos they use wast energy to make power were as superchargers use power to make power :yes:

[Jeremy]

They don't put turbos on all production cars for a number of reasons:

1) They cost money
2) A large part of their market buys cars to get from A to B so they don't need massive amounts of HP
3) They increase the amount of maintence and engine needs. The top of the line EVO8 is an extreme example. Can you afford having to go into the mechanic every 3000km?

Anyway for more performance it may be far easier just to put in a lower range gearbox that has more gears. It'll get you to your top speed faster, and I'd a hazard a guess that it'd use less fuel.

[bugjuice]

what's that little Suzuki Cappachino thing run on? Something like 700cc and a turbo.. 2 seater convertable thing.. looks like a micromachine for real..

[HDTboy]

They don't put turbos on all production cars for a number of reasons:

1) They cost money
2) A large part of their market buys cars to get from A to B so they don't need massive amounts of HP
3) They increase the amount of maintence and engine needs. The top of the line EVO8 is an extreme example. Can you afford having to go into the mechanic every 3000km?

Anyway for more performance it may be far easier just to put in a lower range gearbox that has more gears. It'll get you to your top speed faster, and I'd a hazard a guess that it'd use less fuel.
and weigh more, and not increase the volumetric efficency of the engine

[HDTboy]

what's that little Suzuki Cappachino thing run on? Something like 700cc and a turbo.. 2 seater convertable thing.. looks like a micromachine for real..
660cc turbo, don't know a hell of a lot about it other than that

[HDTboy]

The Legacy GT has one big turbo and 2 little litres
The 3.0R has 3 litres, no turbo
The XR6 has 4 litres, no turbo
The XR6T has 4 litres, one big turbo
You will notice that the 2 litre turbo GT makes nearly that same peak torque as the 4 litre XR6 at much lower revs.
The XR6T will stomp all over the 5 litre XR8 until they hit maybe 4500
What are you calling low revs? Idle to 2000? If thats the case I agree with you.
I was assuming you had a twin turbo legacy, sorry i was wrong in that
My idea of low revs is the bottom half of the tacho, which for most common cars would be 0-3000rpm give or take
Ball bearing turbos do reduce the lag quite a bit and probably play a part in the observations which you've made
XR6T should stomp all over a 5L! even if you multiply by 1.6 its effective capacity is 6.4L

[TonyB]

I was assuming you had a twin turbo legacy, sorry i was wrong in that
My idea of low revs is the bottom half of the tacho, which for most common cars would be 0-3000rpm give or take
Ball bearing turbos do reduce the lag quite a bit and probably play a part in the observations which you've made
Nah, I have the twin turbo one. But the numbers I posted are for the latest single turbo version. I agree that a bigger engine is the way to go in the very low end, but you tend to drive in the middle of the rev range (on the open road at least) and this is where aturbo shines.
Ball bearing turbo's make a huge difference- my old mans Cefiro used to go amazingly well, almost no discernable lag and it pulled around 2000rpm. Then one day the turbo died- he reckoned it was like driving a Morri 1100! He then discovered it had a non servicable ball bearing 'sports' turbo. He went for the cheaper rebuildable version. It ruined the car- big lag coupled with an auto is not much fun...

[HDTboy]

Nah, I have the twin turbo one. But the numbers I posted are for the latest single turbo version. I agree that a bigger engine is the way to go in the very low end, but you tend to drive in the middle of the rev range (on the open road at least) and this is where aturbo shines.
Ball bearing turbo's make a huge difference- my old mans Cefiro used to go amazingly well, almost no discernable lag and it pulled around 2000rpm. Then one day the turbo died- he reckoned it was like driving a Morri 1100! He then discovered it had a non servicable ball bearing 'sports' turbo. He went for the cheaper rebuildable version. It ruined the car- big lag coupled with an auto is not much fun...
Cefiro's don't come standard with a BB turbo, musta been fitted at some stage,
Here's a good article on the XR6T
http://autospeed.drive.com.au/cms/A_1613/article.html

[dangerous]

Yeah baby that bike is a Kawa Z1TC Kawa in the 80's built the GPZ750zx turbo (see Death's profile) which was the fastest mother of all the turbos with Honda's CX650 right behind it, as with the suzuki XN they were injected the Yamaha XJ650 was the only other carbed turbo from the japs.

Z1tc (Z1000)
http://www.turbomotorcycles.org/Images/Bike_s_z1rtc.jpg

ZX750 (GPZ750)
http://www.turbomotorcycles.org/Images/Bike_s_gpz750.jpg

XN85 (GS650)
http://www.turbomotorcycles.org/Images/Bike_s_xn85.jpg

XJ650 (XJ650)
http://www.turbomotorcycles.org/Images/Bike_s_xj650.jpg

CX650tc (also as a CX500tc)
http://www.turbomotorcycles.org/Images/Bike_s_cx650.jpg

[HDTboy]

Eww, yuck, carbys mixed with turbos

[dangerous]

for those that give a shit.........

http://www.z-power.co.uk/Images/Z1RTC.jpg

1978/1979 Z1-R TC
The relative poor sales of the standard Z1-R prompted Kawasaki America to team up with the AMERICAN TURBO-PAK Company to produce the Z1-R TURBO. Basically a standard bike with a turbo kit bolted on. No warranty was offered and a few hundred were sold in 1978 in the original silver blue colour. In 1979 a couple of hundred more were produced but this time the bike was painted in black with red, yellow and orange stripes. Very tacky and very seventies. Power output was quoted at anything between 100 and 145 bhp, depending on how much boost the rider dialed in. 160mph was available, on a bike which struggled handling the standard engine output. Performance was exciting, for all the wrong reasons!

[DEATH_INC.]

Jeez so much to cover....
Ball bearing turbo's don't reduce lag that much,it's the sizing that really matters.A normal turbo's shaft floats in oil,not much drag there.....
Anti lag is done by shifting the firing of usually one or two cylinders so they fire with the exhaust valve open , burning the fuel in the exhaust so the turbo thinks it's a jet engine(not really ,but it's the easiest way to explain it...)the other anti lag is yer normal blow off valve,crude but they help....
Turbo's are reliable nowadays,just look how many high k skylines etc are still running sweet.(btw the cefiro and skyline turbo's ARE ballbearing/ceramic turbos)
Lag isn't too bad with most stock setups,but I think what you're talking about is actual spool up rpm,not lag,they are different.
Turbo's do normally make power/torque at lower rpm,the old gpz for example made it's peak (hp)at 9000 i think where the n/a version made it at 11 or so....and the turbo made good useable power from about 3500rpm,where the n/a didn't really get going till about 6 or 7000.
Fuel consumption depends on use,mine will do 200k on a tank if I putt around,but I've also sucked it dry from full in about 100 (from south auck to halfway to wellsford!)
Turbo's aren't on everthing because of added costs in manufacturing,as I had it explained to me, if you build a 200hp engine you have to build all the components to handle 200hp for at least the warranty mileage,so it's often just easier to make it bigger(busa and zx 12 for example)as it will end up just as big and heavy anyway....(this is from a factory veiwpoint anyway...)
As pointed out ,a turbo is much more efficient than a charger,80% effiency as compared to about 50%,but the screw compressors blow all this out of the water with about 90% efficency,dunno why these aren't real popular....
HP...My 20 year old turbo with a measly 8 valves and 810cc runs over 200hp,pretty much what they're getting outta the thou's now,but I'm doing it under 10000rpm.
Anything I've missed?

[TonyB]

Lag isn't too bad with most stock setups,but I think what you're talking about is actual spool up rpm,not lag,they are different.
Turbo's do normally make power/torque at lower rpm,the old gpz for example made it's peak (hp)at 9000 i think where the n/a version made it at 11 or so....and the turbo made good useable power from about 3500rpm,where the n/a didn't really get going till about 6 or 7000.

At last, someone who understands me... I thought I was all alone in the world :niceone:

[Kickaha]

for those that give a shit.........

http://www.z-power.co.uk/Images/Z1RTC.jpg

1978/1979 Z1-R TC


And if a certain Mr Cotton stops dicking about we'll see one out on Pre82 racing this season :niceone:

[dangerous]

if you build a 200hp engine you have to build all the components to handle 200hp
Anything I've missed?
for example: the CX500 engine upgrades from naturaly aspraited to turbo charged (48hp - 82hp cx650 - 102hp) are smaller/stronger valves, very heavy clutch, semi drop forged con rods and toughened pistons, lowered compresion etc all adds to the cost.

Na you covered shit rather well :niceone:

[dangerous]

And if a certain Mr Cotton stops dicking about we'll see one out on Pre82 racing this season :niceone:
If hes too chicken shit too.............. then I'll bloody well do it :Punk:

[Motu]

Yeah,pretty good Death - another thing,turbos convert heat to energy,it's not gas pressure and flow,they don't work until they are given heat....that's why you do silly things like retard timing,lean out open the ex valve like you mention,this gives the heat to make the turbo work faster.

[RiderInBlack]

As pointed out ,a turbo is much more efficient than a charger,80% effiency as compared to about 50%,but the screw compressors blow all this out of the water with about 90% efficency,dunno why these aren't real popular....Just waving my ignorance around here but, what's a "screw compressor"?

[sAsLEX]

Just waving my ignorance around here but, what's a "screw compressor"?


What is a screw compressor and how does it work?

A screw compressor is a positive displacement machine that uses a pair of intermeshing rotors instead of a piston to produce compression. The rotors comprise of helical lobes affixed to a shaft. One rotor is called the male rotor and it will typically have four bulbous lobes*. The other rotor is the female rotor and this has valleys machined into it that match the curvature of the male lobes. Typically the female rotor will have six valleys*. This means that for one revolution of the male rotor, the female rotor will only turn through 240 deg. For the female rotor to complete one cycle, the male rotor will have to rotate 11/2 times.
from link (http://www.cashflo.co.uk/Screw.html)
http://www.power-technology.com/contractor_images/mayekawa/1_compressor.jpg

[RiderInBlack]

Cool! So what is their compression ratio? 1: 1 1/2, 1: (1 1/2)squared (1:2.25), or 1: (1 1/2)cubed (1: 3.375) taking that the rotation ratio is 1: 1 1/2?
Do they use up much power driving them?
Are they being used to supercharge combustion engines?

[pete376403]

A supercharger doesn't have any internal compression - it just takes a "packet" of air and pushes it to the other side - ie the air is delivered to a container (eg manifold, plenum, etc) which the engine draws air from. If the other side cannot use the air as fast as it is delivered then the air pressure will rise. The extra air allows extra fuel to be burned and this is where the power increase comes from.
Nitrous oxide is another form of supercharging - in this case, when the nitrous is heated, it releases oxygen, which is then available to burn extra fuel.
Adding oxygen on its own, without any additional fuel, is a recipie for instant super-lean condition, and the piston crowns will be found sprayed all over the crankshaft very soon after.

[Pixie]

Lag ,that is why turbo bikes are not very pleasant to ride.\

But the Peugeot Jet Force scooter is the first production supercharged two wheeler.125cc

[Pixie]

Do away with the piston engine bits and put a combustion chamber between the compressor and the tubine of a turbocharger.

Oh, sorry some guy called Frank Whittle says he's already tried it.

[Pixie]

All these pros and cons go out the window with turbo diesels,they are a natural for turbo boost and it's a win/win situation all round - you don't need lower compression,you don't need more fuel,temps are cooler not higher,no strengthened parts...more power,more torque,less fuel consumption.Nearly every haulage truck,locomotive,ocean going vessel will have a turbo - it's for efficiency not power.2 stroke diesels like the Foden V12 ran twin blowers/twin turbos.
The Napier Deltic was an intriguing design.
See who can figure this out:

18 cylinders
three crankshafts
36 pistons
no heads
two stroke
6 cylinders long

[bugjuice]

Do away with the piston engine bits and put a combustion chamber between the compressor and the tubine of a turbocharger.

Oh, sorry some guy called Frank Whittle says he's already tried it.
when you do away with the piston engine, it only leaves one giant 'turbo' (http://www.marineturbine.com/motorsports.asp) to get you movin..

[Pixie]

when you do away with the piston engine, it only leaves one giant 'turbo' (http://www.marineturbine.com/motorsports.asp) to get you movin..
I saw a test of this.The response is so poor that you have to throttle back three seconds before a corner to get off the power, and open up before you enter the corner inorder to accelerate out of it.
But it does run on diesel.

[TonyB]

That's because they used a fricken great helicopter turbine. I'd love to see a bike with a small purpose built turbine + gearbox.

[Motu]

Just waving my ignorance around here but, what's a "screw compressor"?

I used to work on compressors for a living,back then a mobile compressor like an Atlas-Copco would be a V4 reciprocating job with 2 large low pressure pistons feeding high pressure pistons,powered by a 6cyl Ford turbo engine - they were complicated to set up and we did various things with the 2 taps to load and unload the compressor to test valves etc...with both taps wide open it would be working at max to keep 100psi.I remember the first rotary screw that I worked on,it was powered by a Duetz aircooled diesel - starting with taps closed it would start with a blip and idle - that was it up to pressure...with taps wide open it would sit just above idle maintaining it's 100psi working pressure - fucking amaizing,and with a pump you could fit on the carrier of your bike.I remember some compressors were rotary vane,same as a Shorrocks blower - superchargers are just compressors after all.

[Ixion]

The Napier Deltic was an intriguing design.
See who can figure this out:

18 cylinders
three crankshafts
36 pistons
no heads
two stroke
6 cylinders long

Yeah that was a neat design. Fred Lanchester had something like that in the 1900's. It's always seemed wasteful to me, having cylinder heads. You apply all that force which could be used to make the wheel go round , to the cylinder head, then have to put in lots of strong bolts (and weight) to stop the force breaking things. In effect half the energy in each combustion cycle is completely wasted.

[Lou Girardin]

I used to work on compressors for a living,back then a mobile compressor like an Atlas-Copco would be a V4 reciprocating job with 2 large low pressure pistons feeding high pressure pistons,powered by a 6cyl Ford turbo engine - they were complicated to set up and we did various things with the 2 taps to load and unload the compressor to test valves etc...with both taps wide open it would be working at max to keep 100psi.I remember the first rotary screw that I worked on,it was powered by a Duetz aircooled diesel - starting with taps closed it would start with a blip and idle - that was it up to pressure...with taps wide open it would sit just above idle maintaining it's 100psi working pressure - fucking amaizing,and with a pump you could fit on the carrier of your bike.I remember some compressors were rotary vane,same as a Shorrocks blower - superchargers are just compressors after all.

As I understand them, Rootes blowers are not compressors, they are displacement pumps. There's no internal compression of the air they shift.

[Motu]

True of any pump Lou - you don't get pressure until you apply restriction,the Roots (no ''e'',that's Hillman you are thinking) blower is like a gear oil pump,a centrifical blower (used by the Yanks a lot,the Studebaker had them) is like a water pump.

pixie - I had a TS3 as my avatar once,but only know a delta from pictures.

[pete376403]

While we were discussing the TS3 and the Deltic a while back, I did a bit of research (bless the 'net). The Deltic was originally designed as a boat (navy torpedo boat) engine, where it would have recieved proper care and attention. When it was put into the BR locos, it was de-rated to compensate for the extended duty but was still over 2000 HP.

Later used in torpedo boats in Vietnam, two 3100 HP engines in an 80 foot boat would be quite a ride

http://www.ptfnasty.com/ptfDeltic.html

[ajturbo]

Z1tc (Z1000)



XN85 (GS650)
http://www.turbomotorcycles.org/Images/Bike_s_xn85.jpg



think this was the SEXIEST one of the lot!!!!:Punk:

[lukehyslop]

Most anti lag systems work by retarding the timing a huge amount (say 50 degrees) when the throttle is closed. The mixture is then ignited while the exhaust valves are open and the flame front goes straight into the exhaust powering the turbo. Obviously this will wear the turbo out in no time but eliminates lag.

[speedpro]

Nah, I have the twin turbo one. But the numbers I posted are for the latest single turbo version. I agree that a bigger engine is the way to go in the very low end, but you tend to drive in the middle of the rev range (on the open road at least) and this is where aturbo shines.
Ball bearing turbo's make a huge difference- my old mans Cefiro used to go amazingly well, almost no discernable lag and it pulled around 2000rpm. Then one day the turbo died- he reckoned it was like driving a Morri 1100! He then discovered it had a non servicable ball bearing 'sports' turbo. He went for the cheaper rebuildable version. It ruined the car- big lag coupled with an auto is not much fun...
My cefiro ceramic turbo shit itself, I found the exhaust turbine in the catalytic converter, and I'm reasonably sure a Morri 1100 would have blown it's doors off. It had very little turbo lag if any in real life. However the replacement turbo was a bit bigger but otherwise bolted straight on and lag was a real problem AND fuel consumption increased lots. This turbos ex outlet was 60mm across versus the old ones 50mm. Above 140kmh it was definitely faster but in situations like going up City Rd off Queen st it crawled because the engine speed wouldn't increase enough to flow the ex gas to spin the turbo and without the turbo spinning it didn't make enough power to spin the engine up. With the old one you could lay rubber all the way up the hill. Evidently "Diesel and Turbo" on Wairau Rd had never had a complaint before me. With the horrible restrictive ex manifold plus the turbo these engines (RB20DET) are never going to be powerful off-boost plus they are going to be inefficient due to the restriction in the exhaust.

[Motu]

The Napier Deltic was an intriguing design.
See who can figure this out:

18 cylinders
three crankshafts
36 pistons
no heads
two stroke
6 cylinders long
http://www.craftsmanshipmuseum.com/images/clen2.jpg http://www.craftsmanshipmuseum.com/images/clen1.jpg http://www.craftsmanshipmuseum.com/images/clen4.jpg http://www.craftsmanshipmuseum.com/images/clen30.jpg http://www.craftsmanshipmuseum.com/images/ClenSectionM.jpg

Um...yeah...um....if I only had time....

story of this engine (http://www.craftsmanshipmuseum.com/Tomlinson.htm)

[speedpro]

Also I ran my bike on a dyno when it was first built. It made 73KW at under 4000rpm. Later with bent exhaust valves (again) it made 175hp at <9000rpm and 105ft/lbs around 6000rpm. The valves were bent enough to make it REALLY hard to start. That's rear wheel horsepower.

[Coyote]

http://www.craftsmanshipmuseum.com/images/ClenSectionM.jpg

Um...yeah...um....if I only had time....

story of this engine (http://www.craftsmanshipmuseum.com/Tomlinson.htm)
Looks good, not sure how it works :confused:

[Ixion]

Looks good, not sure how it works :confused:

Actually quite simple in theory. Take 3 60degree two stroke V twins. Throw away the cylinder heads. Put the engines in a triangle so the tops of the bores are up aginst each other. Now the combustion space will be the space between the opposing pairs of pistons. now extend the idea lenthways so that the Vtwins become V 12's. You now have 36 cylinders and 36 pistons. Connect all the crankshafts together with gears. Light blue touch paper and stand well clear.

I do not want to think what the firing order would be.

[speedpro]

Neil Hintz (mince) has built a couple of uniflow 2stroke engines that appear to be using a similar principle. 2 cranks, 4 pistons. The first was a bucket motor, the later ones are meant for gyro copters. He did all the casting molds himself, primarily because he was told it couldn't be done. His later engine has enhancements and refinements that this one could use. That is one cool bit of engineering though.

[Jeremy]

Looks like a plain delta design to me. They use them on trains usually. Been a very long time since I've seen one though as the only time I was interested in trains was when I was 8 or so.

[pete376403]

Brit Rail used Deltics for a while but maintenance costs were too high. BR prefers things that can be fixed with sledge hammers. Perhaps Deltics (the real ones) were most recently used in Vietnam war era fast patrol boats - theres a link several posts back

[RiderInBlack]

:Offtopic: Thanks for the Deltics links guys:niceone: My Dad has really enjoy reading those sites. The big surprise for us was the Deltic History: Napier Heritage (http://www.ptfnasty.com/ptfDelticHist1.htm) page, which lead us to do a seach on Supermarine S6B Seaplane (1931) (http://www.sciencemuseum.org.uk/on-line/flight/flight/s6b.asp) and Schneider Trophy Aircraft (http://www.raf.mod.uk/history/schneider7.html). These were designed by Napier as well. Dad loves his planes and used to draw the Supermarine as a kid, so it was quite a kick for him to be able to read more about them on the net:niceone:
Who would have thought that this thread on Turbos would have lead Dad and I to the Supermarines:cool:
Thanks again guys:Punk:

OK back to Turbos