Smaller Header Pipes

[FlyingDutchMan]

No - read the whole thread. For a start the engine shown is in a dyno room - no ram effect there. Further F1 regs state there has to be a hole in the back of the airbox to prevent air pressure build up. Mind you, BMW are proably a cut above your average backyard mechanic so don't be surprised if you can't duplicate their figures

I did, and this was part of it:
(I think that these are things that they're not allowed to do).

1.12 Supercharging :
Increasing the weight of the charge of the fuel/air mixture in the combustion chamber (over the weight induced by normal atmospheric pressure, ram effect and dynamic effects in the intake and/or exhaust system) by any means whatsoever. The injection of fuel under pressure is not considered to be supercharging.

So they are allowed to increase the air intake by using a RAM air setup, intake and exhaust tuning and pumping fuel into it. They're not allowed to use intercoolers or other such flash gadgetry.

But point taken with the bench test...

[WINJA]

When the intake valve shuts, nothing more can enter that engine.
I guess you're referring to intake charge inertia, which is used to increase cylinder filling. But it doesn't achieve 100% plus.

WHAT ABOUT AT BDC IS THERE STILL IN RUSH, REALLY I HAD NO IDEA WHAT THE DUDE WAS TALKING ABOUT , ALL I KNOW HIS HE BUILT GOOD ENGINES

[Coyote]

"The louder the pipe, the more power it has" - Straight from the Homies mouth. Thought he was bullshitting, sadly he wasn't

[Drew]

"The louder the pipe, the more power it has" - Straight from the Homies mouth. Thought he was bullshitting, sadly he wasn't

Not how it works. In theory, the more gas that escape from the exhaust, the more power you can extract, but you have to play with all the other variables, this is a can of worms you might want to study for a degree in engineering befor you open.
I think you should check the headers for restictors, gut the pipe, and jet the carbs.
If you start fucking with the rest of it, you could go backwards, and unless you got a spare bike, that leaves you kinda screwed.

[DEATH_INC.]

Making headers is great fun,have a go.....
If you look at motu's formulas you'll see that size is relevant to both bore and stroke,and rpm.Length is only relevant to rpm.....But I've found these formulas don't really work for bikes,you'll often end up with a length of 15" or less......
Smaller will give more low rpm grunt at the expense of top end and of course vice versa.
Start with the stock sizes,make one set 1 pipe size smaller,and an inch or so longer and make another set 1 size bigger and an inch or so shorter.Try making the smaller set 4>2>1 too,it tends to add more midrange.Make your tail pipe about 1 1/2 times the size of your headers and use a straight through muffler.
If you have pipe expanders you can make slip joints under the engine and add different lengths in too.
Outta interest I've found around 28" long seems to work on 750's and thous etc.I prefer 4>1 myself,but then I always chase top end.....
I've also seen a study in a cage mag where they experimented with backpressure,as the rumour has been that some actually helps a bit,but they found to the contrary,as any backpressure they introduced made a definate reduction in power.

[RiderInBlack]

Doesn't Yammy's have the Exup thingy in the pipes/collector that is suppose to boose the power?
How does that work and could it be applied here?

Just curious.

[WINJA]

Doesn't Yammy's have the Exup thingy in the pipes/collector that is suppose to boose the power?
How does that work and could it be applied here?

Just curious.

WORKS BETTER WITHOUT IT ON MODERN BIKES , THE ZX10 R1 CBR1000 AND GSXR1000 ALL HAVE THEM BUT YOU TAKE THEM OFF TO GET REAL POWER, THEY ARE THERE FOR NOISE TEST I RECKON , I GOT INSTRUCTIONS FROM YOSHIMURA ON HOW TO REMOVE MINE , AND FUCK IS IT BETTER , EVEN THE MECHANIC WHO JUST RODE IT RECENTLY SAID IT WAS FUCKEN GOOD

[FlyingDutchMan]

I've been thinking of making adjustable length headers. Have the 4-1 at quite a short distance from the engine, then have 'slider' bits that go inside them and can extend out. So at low revs it'll be all the way out & long, and as you rev it up the go in further & get shorter. Still haven't quite managed to work out how to make them move magically yet though. Would be wicked to have a wide powerband.

[Ixion]

I've been thinking of making adjustable length headers. Have the 4-1 at quite a short distance from the engine, then have 'slider' bits that go inside them and can extend out. So at low revs it'll be all the way out & long, and as you rev it up the go in further & get shorter. Still haven't quite managed to work out how to make them move magically yet though. Would be wicked to have a wide powerband.

Ferrari did this on one of their V12 F1 engines. More practically I think some racing gokart engines use the same idea

[Drew]

Looks like I am the only one who thinks, fucking with a 250 seems a lot like throwing money away.
Having said that, once I get an idea on how to get more power out of anything, (including my generator motor,) I can't be talked out of it, hence my falcon is getting a pair of hair driers, (turbos for those not up with the lingo).
So give it a go, at the end of the day, as long as you don't hack up the stock bits, they can go back on.
Have fun, and be sure to post the results

[Motu]

Making headers is great fun,have a go.....
If you look at motu's formulas you'll see that size is relevant to both bore and stroke,and rpm.Length is only relevant to rpm.....But I've found these formulas don't really work for bikes,you'll often end up with a length of 15" or less......
Smaller will give more low rpm grunt at the expense of top end and of course vice versa.

I forgot to mention,although it was in the link to the other thread...double the result for a good length for a bike,catch the wave next time round.I also have the formula for intake length.Most of this stuff was done in the 40s and 50s on car systems,we have come along way since then,but I haven't seen any formulas for modern day engines.You can actualy hear a good exhaust when you get it right.

All the advances in modern times have been combustion chamber design,port design and cam profile - not cam timing.If you look at cam timing figures for engines say pre 70s and compare them to the engines we have today the modern engines have almost lawnmower camshafts...it's how they open them that has changed,and then how the gases flow through ports,around valves etc.

[FlyingDutchMan]

Looks like I am the only one who thinks, fucking with a 250 seems a lot like throwing money away.
Having said that, once I get an idea on how to get more power out of anything, (including my generator motor,) I can't be talked out of it, hence my falcon is getting a pair of hair driers, (turbos for those not up with the lingo).
So give it a go, at the end of the day, as long as you don't hack up the stock bits, they can go back on.
Have fun, and be sure to post the results

Perhaps it is throwing money away, but producing more power and actually being able to use most of it most of the time has more use than 500bhp on a 'busa. And it'd be a great project to play around with (just like FI). Planning on getting a new bike (CBR600) in the next year, and turning the wee cibby into a full out project mobile.

[John]

Looks like I am the only one who thinks, fucking with a 250 seems a lot like throwing money away.
Having said that, once I get an idea on how to get more power out of anything, (including my generator motor,) I can't be talked out of it, hence my falcon is getting a pair of hair driers, (turbos for those not up with the lingo).
So give it a go, at the end of the day, as long as you don't hack up the stock bits, they can go back on.
Have fun, and be sure to post the results

Yea but your normal, people like to be different - if they didnt then think what the world would be....

[speedpro]

I've been thinking of making adjustable length headers. Have the 4-1 at quite a short distance from the engine, then have 'slider' bits that go inside them and can extend out. So at low revs it'll be all the way out & long, and as you rev it up the go in further & get shorter. Still haven't quite managed to work out how to make them move magically yet though. Would be wicked to have a wide powerband.

It's been done on a bucket sort of. It had a rear cone within the rear cone. The inner cone was moved by a push/pull cable hooked up to something like a powervalve controller. It worked quite well. The same bucket had the stinger exiting out the side of the centre section. 2-strokes of course but the idea is the same - vary the tuned length.

[DEATH_INC.]

I forgot to mention,although it was in the link to the other thread...double the result for a good length for a bike,catch the wave next time round.I also have the formula for intake length.Most of this stuff was done in the 40s and 50s on car systems,we have come along way since then,but I haven't seen any formulas for modern day engines.You can actualy hear a good exhaust when you get it right.

All the advances in modern times have been combustion chamber design,port design and cam profile - not cam timing.If you look at cam timing figures for engines say pre 70s and compare them to the engines we have today the modern engines have almost lawnmower camshafts...it's how they open them that has changed,and then how the gases flow through ports,around valves etc.

Funny,the formula I normally use comes from a '67 car mag......Yeah,doubling the length does bring it pretty close,and I guess once you calculate the cam timing into it you'd prolly be pretty bloody close....
Lorcan,the guy that runs the Turbo site I go on,had his cams reprofiled by a mate who worked on formula 1 engines (lotus I think),same timing,just a different profile,with very good results.Like you say they're always getting better...
Can you send me a copy of the intake length calculations?I've never found a decent one.....