Power gains?

[mitchel63]

Long story but I am building up my green 2G again. I am keeping it a little more sleeper style and am currently running an EVO316G externally gated and dumped.....with stock exhaust. I am able to run 20psi and hold it all the way until redline. I have an RNR turboback on order but I really like lack of attention I get from everybody running stock exhaust. How much do you think the stock exhaust is/will be hurting me, keeping in mind the wastegate dump? And how will it effect me when I turn the boost up for the track....also if I cancel this exhaust order, that money would probably go to cams so I would be trying to move even more air through there. Thoughts?

Mitch

[mac214]

Just an idea, but I think RRE still sells their twin pipe tip that still looks pretty stock. With that on, you would be able to go 3" exhaust but maintain the stock appearance.

[mitchel63]

They do still sell that....it is just a magnaflow though, I could get it anywhere. That thought is in my head though...

[Bryan Savage]

Long story but I am building up my green 2G again. Gee Mitch. I thought maybe you'd have learned your lesson the first time around.

[mitchel63]

Or the 2nd.....

[confusionisbad]

If you want to keep the exhaust stock, what about an electronic cut out?

[mitchel63]

Does anybody have any opinions of whether or not JUST the exhaust actually needed by the turbo for say 40 lb/min could run through stock exhaust? Keeping in mind, the "waste" is going elsewhere.

[fusionsport]

I doubt in a very serious way you will make any sort of power through the stock exhaust. If you are looking to have a good sounding but high-flowing exhaust there are several options out there. We just had a 2G com in with a really quiet exhaust on it- in fact it sounds nearly stock but is a full 3" exhaust.

One thing though- unless you muffle the WG dump its not going to matter which exhaust you have, its going to be loud. I would think you would be better off simply doing a 3" exhuast to suit your budget/tastes and be done. I think you will still have the sleeper effect simply because with all the cat-back and muffler only people out there a good-sounding exhuast doesnt always mean a quick car.

[mitchel63]

Thank you for your reply.

It is more just the look, not so much the sound. My car appears totally stock from the outside, and I really like that. I have a 3in system on the way, maybe I will do baselines with the stock exhaust and then with the 3in and see how much of a change it is.....if it is worth it to me.

[Anne]

I don't think you'll "make" power with the stock exhaust but I don't think you'll "lose" it either. I also think that if you're holding boost with the stock set up, you might as well leave it.

[talontsi]

I don't think you'll "make" power with the stock exhaust but I don't think you'll "lose" it either. I also think that if you're holding boost with the stock set up, you might as well leave it.
I disagree. If you were to dyno your car right now, and then dyno your car with 3" exhaust, test pipe and a straight through muffler, you will see power gains, torque gains, better boost and throttle response and a LOT more flow.

With your stock exhaust, you may still be able to flow 40lbs/min, but you will be able to cut down on lag-time, increase throttle response, and gain some power at the least.

My 2 cents

J.P.

[Mirage]

Having a stock exhaust will only hurt response if it's the restriction.

If you're not flowing enough (highly doubtful) to take advantage of even a test pipe, then you won't see any gains.

If it's a restriction in ANY way, then you will see a difference.

IMO, go with a 2.5" with a resonator and a twin tip magnaflow muffler or at least the tip. On an Evo III, that's all that you will need and it will keep it quiet and stock looking.


Marcus

[v413nc3]

It changes boost response. The earlier you make boost the earlier you make power. Horsepower is a function of torque versus RPM. If you want absolute factory fit with a larger exhaust get a thermal and throw the different muffler on it.

[jmakado]

Stop being such a pussy. Every Geo has an exhaust now. No one is going to notice if your green POS has one too. And besides, if they don't notice that, they *might* see the huge Supra intercooler hanging out from under the bumper.

And, oh yeah, your car will suck if you leave the stocker on there. Too much restriction = slow green turd.

[mitchel63]

Stop being such a pussy. Every Geo has an exhaust now. No one is going to notice if your green POS has one too. And besides, if they don't notice that, they *might* see the huge Supra intercooler hanging out from under the bumper.

And, oh yeah, your car will suck if you leave the stocker on there. Too much restriction = slow green turd.


I am going to beat your ass on the course....

[Anne]

Stop being such a pussy. Every Geo has an exhaust now. No one is going to notice if your green POS has one too. And besides, if they don't notice that, they *might* see the huge Supra intercooler hanging out from under the bumper.

And, oh yeah, your car will suck if you leave the stocker on there. Too much restriction = slow green turd.

:claps: Jason cracks me up!

I would also like to note the fact that you're pretty much in constant boost and the wastegate is roaring the entire time! ALSO, I don't actually care either way as long as you keep the dirty exhaust off of my stuff in the garage.

[cotsi95]

I say go with the 3in tbe with a test pipe. Yeah you won't look "stock" anymore but you will gain more power and response and blah blah blah. But I would realy like to see the dyno of before the exhaust and after the exhaust!

[mitchel63]

I say go with the 3in tbe with a test pipe. Yeah you won't look "stock" anymore but you will gain more power and response and blah blah blah. But I would realy like to see the dyno of before the exhaust and after the exhaust!


I actually think I am going to do that.....more for shits and giggles than anything. My exhaust should be here next week so I guess I had better get on it. Last I heard, Triad, the AWD dyno in Loveland wanted $80 for a baseline. Hopefully, I can convince them that they are retarded because I don't really feel like going all the way to Mac for this....

[UnSpOkEnGiFt]

Did you ever get the chance to dyno and compare the two?? Just curious of what your results were.

[mitchel63]

Still waiting on my exhaust.....

I'm planning on doing it though.

[UnSpOkEnGiFt]

Ahh cool... I was just wanting to see the difference.

[sbiggi]

I just went from a 2.5" TBE (pressbent catback) with test pipe to my brothers 3" TBE Mandrel bent with test pipe.

1. It is way louder.
2. My 50 trim spools about 200-300 rpm sooner.
3. Didnt notice any power gains in my butt dyno, but the power does come on alot smoother.

But I dont have cams or intake manifold yet, and I'm not moving enough air to really need a full 3" yet.

-Seth

[v413nc3]

The earlier you make boost the more power you will eventually make. Horsepower is a function of torque and RPM.

[sbiggi]

The earlier you make boost the more power you will eventually make. Horsepower is a function of torque and RPM.

If I make the same amount of torque from 4500-7000 then there is no increase of HP from 4500-7000

If I made more torque earlier, then I would have more HP earlier, but 4500-7000 would remain the same given the above statement. For drag racing were I dont drop below 5000 rpm it wont make a difference.

[v413nc3]

Ahh yes, but for those of us running a large enough turbo you can make more up top by spooling the turbo earlier :) You're running a 50trim right? If that's correct as you get into a larger and larger turbo it will be more and more noticeable.

[mitchel63]

Okay....so I finally got my exhaust. I decided to skip the before and after baselines because I am poor. And white. That money could be better spent on an hour of tuning. I did however do before and after DSMlink logs. Boost was set to 16psi for the before pull. I changed nothing but 3inch turbo back exhaust from the stock exhaust. Boost did go up to 20psi after the exhaust was installed. DSMlink hp estimator showed a 90hp gain with the exhaust. Granted, this is far from completely accurate and 4psi of extra boost showed up, but I am more than convinced it was holding me back dramatically. My knock issues magically disappeared too!

[Hal]

Just compare the airflow in the before and after logs. That will give you a much more accurate measurment.

The DSMLink HP estimator requires accurate vehicle info.

All it does is calculate power required to move x amount of weight a known distance, in a certain amount of time.

But variables such as up hill/down hill roads can have a pronounced effect.

Hal

[mitchel63]

Yeah....I'm just too lazy. It was about 6lbs/min.

[jmakado]

Uhm....yeah, I told you so. Oh yeah, with the knock, I told you so again. Just throwing that out there.

[mitchel63]

Uhm....yeah, I told you so. Oh yeah, with the knock, I told you so again. Just throwing that out there.


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