Is there hp to be gained by modifying exhaust to 3 inch?

[nig3]

Actually what im asking is that if i where to replace the entire DP back section with 3'' mandrel bent exhaust would i get mo power? right now i have a CS DP and mid pipe only with stock exhaust. i noticed that the rear portion of the stock exhaust past the back suspension is 3'' or close to it already but the mid section is all crushed bent 2.5''. Is it worth it going 3'' all the way on a modded MS3, whats your thoughts???

 

[nig3]

anyone have dynos of before and after 3'' exhaust , maybe????

 

[drledford93]

I was just reading a post by autoxer (I think that's his name) who had done the dp + rp along with a 3" straight pipe and had issues with his AFRs. He said he gained power (butt dyno), but if he can quantify it, I don't know.

FYI, I had a cat-back 3" straight pipe on my '99 eclipse gsx and it made a HUGE difference. From my experience, at least 10-15 hp. Plus, spool up was much faster. FWIW, both exhausts were the the same diameter stock...

Daniel

 

[Aaron@JSC]

I was just reading a post by autoxer (I think that's his name) who had done the dp + rp along with a 3" straight pipe and had issues with his AFRs. He said he gained power (butt dyno), but if he can quantify it, I don't know.

FYI, I had a cat-back 3" straight pipe on my '99 eclipse gsx and it made a HUGE difference. From my experience, at least 10-15 hp. Plus, spool up was much faster. FWIW, both exhausts were the the same diameter stock...

Daniel

that doesn't make any sense that he would have problems with his AFRs. The exhaust post DP is simply a routing system/sound deadender.

 

[drledford93]

I'm not sure why, but I know he said he had to bump up to a larger fuel pump or injectors...not sure which.

BTW, I think his moniker is autoxracer.

Daniel

 

[Aaron@JSC]

I'm not sure why, but I know he said he had to bump up to a larger fuel pump or injectors...not sure which.

BTW, I think his moniker is autoxracer.

Daniel

its possible that a more free flowing exhaust had an effect on the turbo spool and boost causing the car to require more fuel for the added boost and maxing out the fuel pump. Thats the only thing that would make sense, but is more an effect of the wastegate reaching its limit rather than an effect of the exhaust size.

 

[Oxymoron]

Actually what im asking is that if i where to replace the entire DP back section with 3'' mandrel bent exhaust would i get mo power? right now i have a CS DP and mid pipe only with stock exhaust. i noticed that the rear portion of the stock exhaust past the back suspension is 3'' or close to it already but the mid section is all crushed bent 2.5''. Is it worth it going 3'' all the way on a modded MS3, whats your thoughts???

Ive read multiple times on here that cbe only adds like 5ish whp. not cost affective for $600 or more. for power that money could be best served elsewhere. cbe is more for noise on our cars.

 

[drledford93]

Instead of getting a $600+ cbe, just get a 3" straight pipe. It's just as effective, more free flowing, and doesn't sound bad at all! Even my wife loved the sound of my eclipse--and she is by no means a car chic.

Daniel

 

[ericrapp]

its possible that a more free flowing exhaust had an effect on the turbo spool and boost causing the car to require more fuel for the added boost and maxing out the fuel pump. Thats the only thing that would make sense, but is more an effect of the wastegate reaching its limit rather than an effect of the exhaust size.

exactly. the lack of restrictions make the turbo very happy to spin. open it up on the front side with intercooler and intakes. Well then,natural boost increases as does the air moving through maf. Internal temps come down and lots of horse power becomes available with tuning. Just bolting on this stuff was dramatic. not 5-15 horsepower much more. But you will need to gain control of your ecu or have one of the tuners do it. No dyno so don't hate I am not making any claims, just saying after installing less restrictive parts the car flew but, it will need a tuning to get the most out of it as some folks have found out. like me.

 

[ericrapp]

The wastegate could become the issue drledford93. As the ecu now sees that the natural boost will increase due to lack of restrictions causing increased flow. which the stock ecu does not tolerate. so nig3 if you can compensate for more flow somehow, open her up!