Formula 5 question?

[jasonu]

Fuckin hell, there's enough rule arguments on these things to keep Biggles happy for years.

Note to self, unsubscribe as soon as someone brings a rule into question...Even if it's me.

That someone sure as hell won't be the MNZ!

[50bucketracer]

The std GPR50 has a 14mm carb, max power at 10K revs, the Metra has a 19mm carb and 12K revs.
Im sure it starts as a std engine, but if the Forza 155 pit bike was considered unsuitable because its a competition engine/machine I find it hard to believe that this Metrakit bike can be considered legal. If someone bought a Metrakit rolling chassis and then fitted a Derbi 50 fitted thats fine, but thats not what has happened here is it? It's been bought as a purpose built race bike and is sold as such. What next? a TZ250 is ok for F3 because a TZR250 Kocinski rep is based on the same thing?

Sorry for the lag; just catching up with postings on this forum & I see some crossed wires here.

There were 2 versions of the Metrakit 50 when the bike in question was manufactured. One had a race modified motor with different cylinder, big carb etc & made a claimed 19hp. The other had a bog standard Derbi 50 motor with standard cylinder, standard 13mm carb, standard ignition etc & made a real 10hp. They may have changed the spec in 2011, but that was the deal in 2004. The bike for sale is the standard engined version, exactly as you say - a Metrakit race chassis fitted with a standard Derbi 50 engine. Check it out if you want.

Even in that 10hp form with 12" wheels it was fast enough that with a 13 year old rider it lead the 2008 F5 GP ahead of Mark Lattimer, F5 Dave & myself. Just a pity that a brake problem prevented it finishing the race...

[RMS eng]

Sorry for the lag; just catching up with postings on this forum & I see some crossed wires here.

There were 2 versions of the Metrakit 50 when the bike in question was manufactured. One had a race modified motor with different cylinder, big carb etc & made a claimed 19hp. The other had a bog standard Derbi 50 motor with standard cylinder, standard 13mm carb, standard ignition etc & made a real 10hp. They may have changed the spec in 2011, but that was the deal in 2004. The bike for sale is the standard engined version, exactly as you say - a Metrakit race chassis fitted with a standard Derbi 50 engine. Check it out if you want.

Even in that 10hp form with 12" wheels it was fast enough that with a 13 year old rider it lead the 2008 F5 GP ahead of Mark Lattimer, F5 Dave & myself. Just a pity that a brake problem prevented it finishing the race...

just a side note,Marks GP winning Aprilia 50 may be for sale if any one is after a fast 50 race bike.

[Henk]

Could be keen. Let me know as and when. Seem to be building up an F5 collection at the moment

[Dutchee]

Could be keen. Let me know as and when. Seem to be building up an F5 collection at the moment

No dear, I have my F5 bike, you have my reject parts to sort out into a "running" F5 bike. See the difference. I'm not cursing my mechanic, I'm having fun.

[husaberg]

No need for fancy computers, anti lag can be made with an small fuel pump, a diesel injector, and a micro switch on your clutch lever. If ya wanted to get fancy you could put a timer on it so it only pulses a certain amount of time each pull of the clutch, to save having a foot long flame out the pipe when your waiting for the flag.

Boost control is easily controlled with a pneumatic waste gate actuator, and just as easily made to be adjustable.

The lag is not really the problem I am referring too although it will be a real issue with a supercharger designed for at beat an engine 6x the size.
Any kind of anti lag will not get around this simple problem size. Whilst it may be possible to get it to spool up, it will still have an incredibly peaky power curve.
Where as a supercharged engine with a Rootes style blower will be user friendly and have no issues to deal with lubrication either.

[Drew]

The lag is not really the problem I am referring too although it will be a real issue with a supercharger designed for at beat an engine 6x the size.
Any kind of anti lag will not get around this simple problem size. Whilst it may be possible to get it to spool up, it will still have an incredibly peaky power curve.
Where as a supercharged engine with a Rootes style blower will be user friendly and have no issues to deal with lubrication either.

Anti lag goes on a turbo, a supercharger doesn't need it because it is always spinning. It is true that a turbo is peaky in it's power delivery, which is why I say to run both. Supercharger to get things moving, turbo to create power up high.

Lubrication isn't really fuck all to worry about, it's dead simple most of the time.

It's all time consuming to build and engineer though, so I've got a better idea. N.O.S! It's cheap, it's fuckin easy, and it's readily available.

[Gigglebutton]

Use the Nos before the turbo spools up = no lag

[grantnz]

I rection one could also find the smallest turbo available (I've seen a tiny one on a diesel generator) and turn down the turbine and impeller. One could then make inserts to go in the housing and make it all match up again.

Bah, May work, may not. All just un-academic musings until someone wastes a whole pile of coin on it that would probably be better spent elsewhere.

Watch for some interesting developments if I ever win lotto.

javascript:

http://www.ebay.com/itm/110695313833...84.m1438.l2649

Heres one for you...

[husaberg]

Sorry if this sounds like a sermon It is not meant to. I enjoy your give it a go spirit. Or as it may be, give it a go after spirits.

This is not about scoring points it is just about getting some basics established.

Anti lag goes on a turbo,

Anti lag is not is not solving the problem. While it may help a little. The problem is the turbo designed for an engine 6-9 times the size. With more cylinders.
Anti lag is to do that lessen lag of a slightly oversize or trimed turbo not a hugely 6-9 times oversized turbo. you may get away with 3-4 times 6-9 is asking a bit much.

For instance this turbo



http://www.ebay.com/itm/110695313833...84.m1438.l2649
posted above is designed for a 660 cc 3 cylinder and i believe it was also used on a cx500 turbo possibly. It has been used on a lot of bikes but is not likely to be effective on a 100cc engine without significant mods.

It is true that a turbo is peaky in it's power delivery

A correct size and trimmed turbo will have a nice flat power curve. With the waste gate controlling over boost.
A rootes blower achieves a fixed rate of delivery say 300cc (Aisin AMR300) it will provide 300cc per revolution, IE a fixed rate of boost regardless of speed.IE 1.5 atmospheres above base for a 100cc engine if driven at half engine speed. About 22psi with is possible with legal fuel plus water injection high quality engine internals and effective intercooling more boost is possible with a more efficient blower or turbo.
Not all superchargers are Rootes style. the are also vane, screw and some common ones are centrifugal like a turbo.http://victorylibrary.com/supercharg...r-choices3.htm
but their design is not 2x the boost a twice the revs. like people seem to think they have a real curve biased to the top end
ie In general, centrifugal superchargers or turbo's produce boost in direct proportion to their displacement per revolution, and the square of their rotational speed

Yes a waste gate can control this.
On a adequately sized application not a problem. but it will do nothing on this application. As the turbo is over sized rather than undersized.

which is why I say to run both. Supercharger to get things moving, turbo to create power up high..

A superturbo



would be a great idea but they are still to large and complex and heavy. An overriding electromagnetic clutch also used on the MR2 would make it easy.
This set up was available on the Nissan march mircocar in the early 80s. But and its a big But.
It used the same size turbo and supercharged that is being talked about here but on a engine 9x the size.

Lubrication isn't really fuck all to worry about, it's dead simple most of the time.

Unless of course you have low pressure lube system like pretty much all the bikes that are bucket size or legal. the turbo needs decent pressure and cool clean oil.

As well the engine if it was to produce 40-45hp will need a 40-45 hp cooling system. It will need to be water cooled if it was to survive on petrol and more than just short bursts.

so I've got a better idea. N.O.S! It's cheap, it's fuckin easy, and it's readily available.

NO2 is great and easy it is also illegal i thought it would be sweet but lost a chocolate fish with Jason on it. The party poopers at the MNZ already ruled it illegal.

http://www.mnz.co.nz/newsDetail.aspx...rticleID=28927

It is fun and cheap though. A real giggle as it were..

http://www.nitrous.info/motorcycle-nitrous-injection-system.htm

http://www.nitrous.info/nitrous-faq.htm

[Drew]

I'm a bit gutted that NO2 isn't allowed. It's no different to turbo or supercharging in essence.

You are obviously well versed in turbo technology dude, but I think you are also over thinking it. I know a bit about chucking a turbo on a motor it doesn't belong on, I've done it once or twice. And lots of people who have taken it further.

There are tiny turbo's out there, and it is quite possible to make them smaller to accommodate the smaller engine displacement.

The engineering is extensive for sure, and the limiting factor in my opinion.

[speedpro]

One of the things you can do to increase the rate of spool-up is to plumb in a volume between the manifold and the wastegate actuator with a small bleed controller. This causes delay in actuating the waste gate as the volume takes time to fill through the bleed so the pressure at the actuator stays low for longer and the wastegate stays closed for longer allowing maximum gas flow "through" the turbo. This also has the added advantage if the motor is already making power but off boost that you will get a momentary over-boost when you open the throttle. I played with this on a Nissan Gazelle with an RB20DET and it worked real good. With the bleed controller I machined up I could easily control the momentary overboost and max boost as well. The Gazelle only ran 5lbs stock but was quite happy with 11lbs on the dyno and the gas analyzer.

With even the smallest turbo though I don't think it's going to be an issue as getting any boost will be a problem on a bucket engine.

As stated also if the turbo suits the engine the power curve will be huge and flat if all is well, and by winding in the waste gate for more peak boost it will also have an effect on spool-up and off-peak boost available as wastegates creep open bleeding off gas before peak boost value is reached which slows spool-up. I ran 19psi in my big bike at Taupo once and it pulled noticeably more boost at various revs lower down when the throttle was opened.

[nudemetalz]

It's amazing what has come out of this thread after my original O/P of 100cc four-strokes

[Drew]

It's amazing what has come out of this thread after my original O/P of 100cc four-strokes

I raised the turbo question to find out if it could be done to a 100cc bike. Kinda got out of control.

[husaberg]

It's amazing what has come out of this thread after my original O/P of 100cc four-strokes

The same old arguments. Sorry

One of the things you can do to increase the rate of spool-up is to plumb in a volume between the manifold and the wastegate actuator with a small bleed controller. This causes delay in actuating the waste gate as the volume takes time to fill through the bleed so the pressure at the actuator stays low for longer and the wastegate stays closed for longer allowing maximum gas flow "through" the turbo. This also has the added advantage if the motor is already making power but off boost that you will get a momentary over-boost when you open the throttle. I played with this on a Nissan Gazelle with an RB20DET and it worked real good. With the bleed controller I machined up I could easily control the momentary overboost and max boost as well. The Gazelle only ran 5lbs stock but was quite happy with 11lbs on the dyno and the gas analyzer.

With even the smallest turbo though I don't think it's going to be an issue as getting any boost will be a problem on a bucket engine.

As stated also if the turbo suits the engine the power curve will be huge and flat if all is well, and by winding in the waste gate for more peak boost it will also have an effect on spool-up and off-peak boost available as wastegates creep open bleeding off gas before peak boost value is reached which slows spool-up. I ran 19psi in my big bike at Taupo once and it pulled noticeably more boost at various revs lower down when the throttle was opened.

Yes thats what i was trying to explain to Drew was that the turbo has to be sized to the engine and it is asking a bit much for a turbo designed for instance for a 7 liter diesel to work great on a 1300cc escort for instance. Anti lag or not.

With the bit you brought up waste gate creep is now commonly controlled with a electronic boost controller with a blow off valve to control transient throttle conditions as most performance engine now do. You can make one your self quite easily if you are keen on the soldering and so on.They were commonly based on debounce circuits from memory.
The bleed into a chamber kind of intrigues me?
Or are you just talking of a plain air bleed to fool the factory set limit? oh i see you mean this.http://autospeed.com/cms/A_107770/article.html i had never seen it before.


On the previous page i posted some useful links that explains a lot in common terms.
The victory library and the Autospeed pages are well worth a look for anyone contemplating forced induction.

http://victorylibrary.com/supercharger/super-carb6.htm
http://autospeed.com/cms/A_1931/article.html
http://autospeed.com/cms/A_110294/article.html
http://autospeed.com/cms/A_110213/article.html
http://autospeed.com/cms/A_108651/article.html