2.5 Buschur catted exhaust ok with 20g or do I need more?

[4gfun]

Some of you have me thinking about a 20g while I am at it. I was wondering how much of a restriction my existing 2.5 inch exhaust would be. I imagine that a 2.5 inch exhaust might be ok or even ideal with the 16g family but was wondering if putting a 20g on there would make me regret not having a 3 inch exhaust.

I would already have the expense and time into a fuel pump and injectors to upgrade to a 20g, really not looking to add to it especially since exhausts are more expensive on a GVR-4.

Thanks

 

[talon2gbuyer]

the 2.5 exhaust would be a hamper to your set up. Turbo systems work best if the exhaust gasses can exit the engine and clear the car as soon as possible. If you have a smaller piping set up your going to create back-pressure (which is good on an N/A car because it requires back-pressure for the engine to function at efficiency) because the exhaust gasses cannot escape quickly enough, and will probably effect how your turbo will run. Standard size piping for a turbo exhaust is 3''. If you have spent a ton of money upping your fuel system and air/fuel delivery, but are keeping the 2.5 inch piping then you should have just left the fuel system stock. Open up the exhaust to 3'' and you'll notice a pretty big difference.

 

[4gfun]

Thanks for your thoughts. Gotta disagree with you here. I don't think running a 2.5 exhaust is too big a deal for the 16g family. You mention a stock fuel delivery system for running e.g. stock fuel pump and injectors because I am not running a 3 inch exhaust?

I have heard that a 2.5 inch setup has seen 600hp on a DSM and with a 16g I would not be looking at much more than half that. I agree with the facts that you have presented concerning bigger being better in a Turbo setup and a little backpressure on an NA setup but I think the idea of not bothering at all with anything because I have a 2.5 inch exhaust is extreme.

You have me worried. Even more so if I have read your post correctly. If a 2.5 inch exhaust costs me a few horsepower on a 16g then I am ok with that....but to not bother upgrading my fuel system as a result?

Now talking 20g, I would imagine that it would be a bigger deal but just wasn't sure how much a bigger deal.

Maybe I misunderstood your post.

the 2.5 exhaust would be a hamper to your set up. Turbo systems work best if the exhaust gasses can exit the engine and clear the car as soon as possible. If you have a smaller piping set up your going to create back-pressure (which is good on an N/A car because it requires back-pressure for the engine to function at efficiency) because the exhaust gasses cannot escape quickly enough, and will probably effect how your turbo will run. Standard size piping for a turbo exhaust is 3''. If you have spent a ton of money upping your fuel system and air/fuel delivery, but are keeping the 2.5 inch piping then you should have just left the fuel system stock. Open up the exhaust to 3'' and you'll notice a pretty big difference.

 

[talon2gbuyer]

Ok, maybe i put a little too much info into the post, but where have you seen a DSM throw down 600whp on a 2.5'' exhaust piping? I'm not calling you out on it, i have just personally never seen any track car (600whp sounds like just that..) running on such a small diameter plumbing. Your going to run into longer spool time with the 2.5 inch piping, and also less power. If you switch to the 3'' you'll notice a shorter spool time and an increase in power output. Check out the thread below, it gives some good pro's and con's. although its made for the 420a platform, any turbo system will react the same way.

http://www.dsmtuners.com/forums/420a-bolt-tech/318433-2-5-3-piping-exhaust-after-turbo-build.html

 

[91stocker]

I personally wouldnt worry about it right now. When it comes time to squeeze every ounce of power out of your 20g set up then id consider it.

 

[clipto]

I was able to test this exact theory. Now the buscher 2.5 exhausts is nice but after switching to a custom 3 inch turbo back exhaust anywhere from 20-30psi on my friends 20g was a huge difference. Now you might be ok with the 2.5 inch exhaust and definitely wanna drop the cat or get high flow cat. But main reason is why get 2.5 when you can just go 3 inch.

 

[91stocker]

But main reason is why get 2.5 when you can just go 3 inch.

O, he hasnt bought the exhaust yet? Disregard by previous post.

 

[talon2gbuyer]

Yea, for the price you really cant beat it. Its gonna cost you the same either way :/

 

[4gfun]

Very complete guys...thanks. Yeah it's already been in place since I got the car. Would you go as far a citing this as another reason to not get a 20g at this time? Willing to bet that the huge power increase will not be nearly as evident on the 16g....

600HP....read that somewhere in a search at some time....who knows...could be BS...

 

[clipto]

Well I can tell u my friend made 350whp at 20psi on his 20g with a lot of bugs and boost leaks. Now that everything dialed in I can tell u that between my evo 3 16g and his 20g both at 30 psi it is a good race. Obviously there are variables as I am fwd and auto he is and and 5 speed so that should give you an idea.

O, he hasnt bought the exhaust yet? Disregard by previous post.

Might be my had he said existing 2.5 exhaust so if he has 2.5 exhaust already just leave it for now or sell it and buy a 3 inch. Its really up to you what you wanna do both work great.

 

[4gfun]

Thanks...that gives me PLENTY to go on! How are you running 30psi on your E316g? E-85/meth/etc?

Could always go with a cutout on my 2.5 inch at some point to help.

Well I can tell u my friend made 350whp at 20psi on his 20g with a lot of bugs and boost leaks. Now that everything dialed in I can tell u that between my evo 3 16g and his 20g both at 30 psi it is a good race. Obviously there are variables as I am fwd and auto he is and and 5 speed so that should give you an idea.



Might be my had he said existing 2.5 exhaust so if he has 2.5 exhaust already just leave it for now or sell it and buy a 3 inch. Its really up to you what you wanna do both work great.