Exhaust Question

[someonestolecc]

Gday,

I have a quick question about my exhaust that I searched for, and since noone has a car that was put together as dodgily as mine I don't think it's ever come up.

Currently I have a sr20, aftermarket turbo hooked up to a x-force HKS copy dumppipe (the short style) that goes to a front pipe that goes into a cat. It then proceeds to a cannon muffler before depositing black crap all over the rear of the car.

The other day BHDave and I found that from the x-force dumppipe, which has a 2.5" outlet (quite possibly even 2") goes into a 3" pipe that has been squashed together and welded to a 2" flange. It then goes into a 3" high flow cat (I assume), and into my xforce copy cannon which has a 3" inlet but steps down in the middle to 2.5" into a 4.5" tip.

I had always assumed the whole thing from turbo to tip was 3".

I went to the exhaust shop last Saturday to ask them to chop the 2" flange from my front pipe and put on a 3" one - they said there would be little point doing that because my front pipe outlet is so small. They suggested they could cut the flange from the dump pipe and the flange from the front pipe, then put 3" flanges on both.

My turbo is a t518z 10cm (I think). I would assume that the outlet on it is 2.5" and the best case scenario would be that it travel to a 3" front pipe with the seperate wastegate runner connecting back into the main pipe just before the cat... so the front and dump pipe would be one.

For the $50 they were going to charge me to put on a new flange I would have been happy if the dump pipe was 3" outlet and then going into a true 3" pipe, not a squashed 3" pipe with a 2" flange welded on it.

Do you guys think it's better to get a new frontpipe? I'm currently a little down on power and I think one of the things contributing would be the exhaust stepping down from turbo>2.5" (dump pipe)>2" (the offending flange)>3"(the pipe)>2.5"(the cannon).

The other half solution is do what they said and replace both flanges with 3" one. Atleast that way the turbo would go into the dump pipe then into the 3" flanged pipe... but really is there any point if the dumppipe itself is smaller than 3"?

I also have a 'tuned length' stainless steel manifold.

Help what do I do!?! :hellpisd:

[hks12]

I used to have a hks cope dump on my 180, has an hks 2530 on it but dicided to change it because it was not 3" got an Flyn 3" dump frount pipe in one seen to go better with this pipe but have not had it dynoed yet.

[R31Nismoid]

make it 3" all the way and you'll notice the difference.

having it change often will cause all sorts of turbulence and backpressure

[Sydneykid]

How about cutting the HKS copy split dump just before the split pipes rejoin. Then weld a 3" pipe to the turbine outlet pipe that goes all the way to the cat. Also extend the wastegate pipe so that it joins more than 400 mm away from the turbine.

[someonestolecc]

Thanks for the replies guys.

S-Kid - that's what they suggest but I think they were going to charge me about $160.. which .. might be fair but I'm not sure if it's worth the money. Is it?

[Wazz]

by the sounds of it i'd just get a custom complete turbo back exhaust done but thats me... i hate dodgy exhausts

and yes there will be a bit of a difference between 2.5 n 3inch specialy if the pipe is chaning sizes all the time