This is true, but, how i think.

Ptissshhhhhh turbo and DV

or
BRAAAAAAAAAAAAAAAAAAAHHHHBBAAA BRRAAAAAAAAHHHHHHHHHH pop pop :D or Throttle Bodies.

Unltimatly though, the turbo should always have the outright best performance :(

quote:

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Originally posted by MikeH
Wish i had a turbo.... i think they are just fundamentally better in all respects :)

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Wish i had a turbo.... i think they are just fundamentally better in all respects :)

yeah cos back pressure on a turbo slows the turbo down.

yeah theres alot of crap involved with exhausts. Turbos can go large (3") and not be excessively loud coz the turbo itself acts as a muffler.

But there is also considerations about gas velocity. Hot air moves quicker than cold air. By going overly large on an N/A car results in the exhaust gases cooling early in the system. Having the right sized pipe keeps things hot n moving quickly aiding combustion chamber scavenging. U'll also notice that alot of systems purposly put a slight restriction after the cat to create a heat build up which makes the cat work better

As above.

Also, different size exhaust bores can determin the overall power of the car. I can't remember which way round it it, but its something like, the smaller the exhaust bore, the better lower end torque/performance the car will have, the larger the bore, the more top end performance the car will have.

Also, a turbo'd car works differently. You want to get the exhaust gases away fromt eh turbo as quickly as possible hence most turbo bores are usually bigger.

its all got to do with the combustion chamber. If ur familiar with the 4stroke cycle (1.suck/intake, 2.squeeze/compression, 3.bang/ignition, 4.blow/exhaust) u'll get what i mean.

As the motor goes from the exhaust cycle back to the intake cycle (the top of the piston stroke) there is a thing called 'overlap' caused by the fundamental design of the camshaft.

During this period of 'overlap' the exhaust valves are about to close the intake valves are beginning to open (both intake/exhaust are partially open). Without any backpressure in the exhaust system, the new air/fuel mix will simply pass thru the motor during the overlap... meaning less air/fuel mix in the combustion chamber for the next cycle.

So having backpressure helps keep more of the flamable stuff in so u get a bigger bang.. more power.

Well, thats the technical BS behind it :thumbs:

[Edited on 17-09-2003 by OzzySRi]

[Edited on 17-09-2003 by OzzySRi]

if u have no back pressure u will get more bhp at higher revs but fuck all power down at the bottom. i think :)

dont no exactly but i do no it overfuels without it

Just always wondered.