Clever exhaust

[robo]

http://www.impulsengine.com/how/header.shtml

Some cleverness about exhausts, worth a read.

Bob

[Davey]

Frankly I think that is mostly over egged rubbish! "Must be used with synchronised valve timing" What? They haven't even matched the lengths of the primary tubes! Lots of pseudo techy words on that site but mostly meaningless in my humble opinion.

D.

[robo]

There must be something in it because F1 have been doing the stepped ring exhaust thing for a few years now.

Bob

[Davey]

Have a close look at an F1 exhaust system and you will find that all the primaries are the same length. Yes a properly designed and "tuned" exhaust system can help deliver slightly more power just like the inlet tract length can affect power delivery but it has to be matched to the speed at which you want the power to arrive. This exhaust manifold is poor by comparison, by not having equal length primary tubes the different cylinders would get different amounts of reduced pressure to pull the fresh charge in. That's never going to be good for overall power production.

F1 intakes/engines/exhausts are designed as a whole to get the max out of every piece. They are designed to produce their power at extremely high revs and all components are designed to work together to achieve absolutely maximum horsepower.

D.

[Davey]

Having had a proper look at that website I can only come to the conclusion that its either a joke or aimed at gullible people with more money than sense or knowledge.

D.

[robo]

I wont comment on the primary length issue or the any of the other technical blurb. What they are saying is that a smaller primary coupled to the stepped collector tube will increase the exiting exhaust speed. That in turn with some trickery on the valve timing will net an increase in power by partly pulling the intake charge before slamming the exhaust valve shut which causes a ramming effect. I think....... Bottom line is the stepped exhaust system is on all the top race cars now nascar,F1 and bikes etc.

Edit this is a head spin on the subject http://www.performanceforums.com/for...-67265439.html

Bob

[Davey]

Only works properly when coupled with head work, new cams etc,etc,etc, look at the rest of the website, they sell it as a package. The exhaust manifold is a tiny part of the equation and probably accounts for less than 2% of the power output. Whem its that marginal primary collector lengths being equal count for at least 50% of the benefit of the extractor manifold's benefit so to not use equal length primaries is actually going to give negative results.

They can't even use proper scientific language, there is no such thing as negative pressure, pressure is simply a measurement of load acting on a surface. A total vacuum is actually zero pressure, therefore there is no such thing as -8psi (a figure they quote in their website). 0(zero) pounds per square inch is absolute vacuum, i.e. no pressure!

D.

[wylliezx9r]

Seems like their using the theory that "bullshit baffles brains"

[Davey]

Originally Posted by wylliezx9r

Seems like their using the theory that "bullshit baffles brains"

I reckon so. Look at their extensivelist of dealers.

D.

[robo]

Originally Posted by Davey

Only works properly when coupled with head work, new cams etc,etc,etc, look at the rest of the website, they sell it as a package. The exhaust manifold is a tiny part of the equation and probably accounts for less than 2% of the power output. Whem its that marginal primary collector lengths being equal count for at least 50% of the benefit of the extractor manifold's benefit so to not use equal length primaries is actually going to give negative results.

They can't even use proper scientific language, there is no such thing as negative pressure, pressure is simply a measurement of load acting on a surface. A total vacuum is actually zero pressure, therefore there is no such thing as -8psi (a figure they quote in their website). 0(zero) pounds per square inch is absolute vacuum, i.e. no pressure!

D.

You are right in part Honda tested some headers like these on the dyno and found 3hp with no engine mods so the gains are small. No one is going to re-invent the wheel here but the difference between a 1965 2ltr engines hp and the modern day version has been doubled and made up over many years of tiny bits like this. So if you are in the throws of knocking up some headers is it not worth pushing out the boat and grabbing that 3hp? If you were a race team you would be crazy to ignore it.

Bob