Exhaust help - performance

[skini]

What do you think is the best exhaust system for 172 ph1? I am not thinking about which manufacturer is the best but which principle works best on that engine(for performance on street)?

Concrete question:
Which is better on 172 engine:
60mm bore system, no cat, aftermarket backbox.

or

60mm bore system, no cat, aftermarket middle silencer and backbox.

Does middle silencer reduces performance?

 

[Fred@BTM]

loud is power on F4R engines is my opinion and my experience

2.5 inch (63.5mm) all the way through

 

[skini]

Do you think there would be some difference between 60mm or 63.5mm system Fred?
So no middle silencer you think?

 

[Fred@BTM]

do you care how loud it is?

we pinched the 2.5inch (63mm) from suspersprint, they also did a 70mm system which was incredible!

 

[skini]

Loud is ok, just don't wanna to be stupidly loud.
As i see on your website you use middle silencer for road exhaust system and on race you don't? Is there any difference in performance/bhp between those two systems Fred?

 

[Fred@BTM]

yeah there is, but not massive, hardly noticable if i'm honest, the tailpipe on our road system is a lot smaller diameter Vs the race tail pipe

think what happens if you put your thumb over a hose pipe

 

[skini]

Yes i see your point.
And can you tell me what is the tailpipe diameter on your road system and what on race system?

 

[Fred@BTM]

i will have to check tomorrow for you

 

[skini]

Please do if you can.
Thank you

 

[Teleturbie]

Can someone in the know please explain what kind of function backpressure exactly has (i.e. what it does with escaping exhaustgasses) and how it effects power/torque.

I always hear that less backpressure = more bhp, but once my exhaust broke (just before the cat), so it had no restrictions whatever and it was definetely waaay down on power. So to me it seems that backpressure is more then just a bad side-effect of cats/bafflers.

 

[skini]

Have you maybe checked Fred?

 

[Fred@BTM]

as i explained above, 182's seem to suffer a huge power loss if there is a leak from the exhaust manifold or cat joints

the stuff i've written above would explain it because the gas is escaping through the leaks upsets the "continuous gas flow"

skini i'm just about to leave for work now (been in london all morning)

 

[Gaz_]

Can someone in the know please explain what kind of function backpressure exactly has (i.e. what it does with escaping exhaustgasses) and how it effects power/torque.

I always hear that less backpressure = more bhp, but once my exhaust broke (just before the cat), so it had no restrictions whatever and it was definetely waaay down on power. So to me it seems that backpressure is more then just a bad side-effect of cats/bafflers.

Too big pipe work can lose you power. You need some back pressure on a N/A car. Its not so important on a turbo charged engine.