Technical Turbo exhaust design theory by Garrett.

[TurboCinqy1250]

Size does matter.

A little while ago I tested my cinq with and with exhaust. Only 1 meter of 2" pipe

Difference:

Red with (fully open exhaust with only 2x76 Novitec DTM End.
Black Without. ( only a piece of pipe ending right under my handbrake)

So this is what I tried

First you get a can opener (or grinding tool)
[imghttp://members.lycos.nl/turbocinqy/forums/HT-Novitecedit.jpg[/img]

Than you discover that the inner pipe is tiny as H*ll

Than you will buy a bigger tube and drill 360 holes in it (or buy perfor plate and fold it around a tube and weld it :bang: )

The tiny tube was the last piece of pipe. With a amazing size of 27mm.
The perfor pipe was 40mm And the new one 60mm.

Than u buy some new steelwool and put it all back together with some old dampingwool. And replace it under the car.

Conclusion. Without is better but still got 8 WHP more than before and a lot more of torque and much earlier. (turbo spins sooner and)

And now you can see that a N/A exhaust (for 54BHP) isn't suitable for a 100BHP car or more cause the turbo gets to much back pressure

 

[GeX]

Than you will buy a bigger tube and drill 360 holes in it (or buy perfor plate and fold it around a tube and weld it :bang: )

Could you not have purchased perforated tube? At work we get it in various sizes made with both stainless and mild steel.

That design of back box is very similar to the Janspeed Subaru ones we have just done. I know that the box entry and exit holes were different sizes. IIRC 52mm one side and 70mm the other. A piece perf ran through it with some packing. The perf had a cone shaped TIG'ed to one end to allow for the size increase. I am guessing this is the gradual increase in sizes that are advised in the first post of this thread.

 

[arseofbox]

IIRC 52mm one side and 70mm the other. A piece perf ran through it with some packing. The perf had a cone shaped TIG'ed to one end to allow for the size increase. I am guessing this is the gradual increase in sizes that are advised in the first post of this thread.

Venturi tube Styleé? Yep. makes pressure differences more gradual. Good thing to have

 

[smokeme]

All that theory is correct, but that's where it ends THEORY

In real life the turbo won't run without backpressure for long since the much higher pressure on the intake side will place a large strees on the oil seals and eventually force the oil out the exhaust, just ask any coupe or Punto GT/UT owner

Large bore exhausts are good with some aftermarket turbos that come prepared to take the extra abuse but the stock units will fail rather quickly, in my experience with various turbos they last almost half of the normal lifetime

Most people agree with me including Garrett so i've no ideia where that info comes from, just check out the warnings that comes with some new turbos "Do not run turbocharger without exhaust for extended amounts of time"

But as i say to each they're own

 

[arc]

what size bore exhaust would you suggest for a 1242 low boost turbo smokeme?

 

[J333EVO]

All that theory is correct, but that's where it ends THEORY

Most people agree with me including Garrett so i've no ideia where that info comes from, just check out the warnings that comes with some new turbos "Do not run turbocharger without exhaust for extended amounts of time"

But as i say to each they're own

Errrrr, the theory was written by Garrett, so are you contradicting yourself or Garrett or what, if not what exactly are you trying to say cos its leads no where

 

[arc]

think he's just pointing out the differences between theory and practice?

 

[J333EVO]

think he's just pointing out the differences between theory and practice?

Yeah but in so doing he quotes Garrett when it was a flaming Garrett engineer that wrote it, so kinda contradicts himself if you follow.

 

[arc]

but first guy was talking only about theory..