Adding punch to the Solstice GXP ?

[wspohn]

Originally Posted by Brazan GXP Do any of you that are running the GMPP tune also have a CAI installed?

My understanding is that the stock air intake is very effeicient and that there isn't appreciable power to be had with a stock or GMPP tuned engine - people do that mostly for looks and to increase the noise (although that always surprises me - that people would want more sucking sounds....)

[Brazan GXP]

Thanks wspohn. I really wondered if the stock intake restricted it to where it needed more air. I really am not interested in more noise,just the best performance within reason. I am thinking very seriously going with the GMPP tune. It sounds like a pretty good deal for 30 HP and 80 ft/lbs of torque.

[wspohn]

Originally Posted by Brazan GXP Thanks wspohn. I really wondered if the stock intake restricted it to where it needed more air. I really am not interested in more noise,just the best performance within reason. I am thinking very seriously going with the GMPP tune. It sounds like a pretty good deal for 30 HP and 80 ft/lbs of torque.

Best deal out there if you car about factory warranty. The torque is very evident.

If you want more power after that, look to low restriction CAT and exhaust system.

[Kappster]

Wspohn,
I read that you were designing your own exhaust system.
I am still trying to figure out what is the best set up. And according to this article. Your new custom system will not be helpful, Just louder.
Read this link I'm putting here and let me know what you think.
Auto Exhaust Science

Its from Super chevy.

[RedHead RedLine]

Originally Posted by Kappster Wspohn, I read that you were designing your own exhaust system. I am still trying to figure out what is the best set up. And according to this article. Your new custom system will not be helpful, Just louder. Read this link I'm putting here and let me know what you think. Auto Exhaust Science Its from Super chevy.

Almost none of that applies to turbos. -J

[wspohn]

Originally Posted by Kappster Wspohn, I read that you were designing your own exhaust system. I am still trying to figure out what is the best set up. And according to this article. Your new custom system will not be helpful, Just louder.

Not exactly.

I am doing a system that reduces back pressure and component weight, and have based it on the street race system from Solo, which is simply a 3" pipe splitting into a couple of 2.5" pipes with no mufflers. I am inserting resonators in the final 2.5" legs to reduce noise while maintaining (according to Solo) 97% of flow.



As for power results, first, realize that the article you referenced was talking about (as I understood it) peak power readings being a little better in a V8 system with a little back pressure. The Solstice has a hash of a system compared to NA cars - the gas has to make its way through the turbo unit, which presents significant resistance, then the CAT, which presents more, before getting to the stock muffler, which presents yet more resistance. We are talking about removing the last of those impediments to flow, only.

Companies such as Solo have done dyno tests of their systems compared with stock thats show significant improvements over stock (that fact that these readings will go away if you still have basic GM tuning is irrelevant for our purposes). They claim 27 BHP benefit from the Street Race system. If that is true (and if you don't think it is, take them to task, not me), then the fact that I am adding a small additional resistance in the form of a muffler might reduce that by a BHP or two, but I can certainly live with that for the sake of noise reduction.

I was originally thinking of using a combination of Magnaflow resonators and some tip resonators I have used in the past on other cars, but in talking with Jeff at Solo, he offered me a solution that is not sold or listed on their site, and it looks like it will do the trick quite nicely. I should have it on there in the next week or two and I'll report back with results.

[wspohn]

Originally Posted by RedHead RedLine Almost none of that applies to turbos. -J

Rats - you covered the same thing I did in one sentence!!

[Brazan GXP]

So how about if you removed some of the restriction in the exhaust system and then put on a less restrictive CAI? Then it seems to make sense to go with a CAI unless you just can't cram anymore past the turbo. Does this sound reasonable? Might as well if you are going with the gmpp tune to get all you can.

[Kappster]

OK. so this is the system you are Building?

[wspohn]

Originally Posted by Brazan GXP So how about if you removed some of the restriction in the exhaust system and then put on a less restrictive CAI? Then it seems to make sense to go with a CAI unless you just can't cram anymore past the turbo. Does this sound reasonable? Might as well if you are going with the gmpp tune to get all you can.

No - the CAI does little and the stock intake is NOT a restriction. If you want a CAI, by all means fit one, but don't think you are making any improvements in power, do it because you prefer the look or the noise.

The GXP power improvements are to be made downstream with the CAT and exhaust. Even if you fit a straight pipe exhaust, there is little point in getting a CAI.

[wspohn]

Originally Posted by Kappster OK. so this is the system you are Building?

Essentially the same, yes. Small differences between the Solo and RPI, including the fact that RPI never made a system for the Solstice (although some were made up using replacement tips) and GTS LE system bits - an expensive way to go given that it cost just under $1K.

Ironically, Werks blew the remaining stock out at the end of last year, before I owned a Sol, or I'd have probably been a buyer even at that price. The Gods must look out for poor coupe owners, though, because I got the Solo combo for about the same price as the Werks blow out price had been, and I like their workmanship.

[Kappster]

My understanding is that the solo is a RPI knock off.
Anyway about it, The point of that artical was that a glasspack acts like an extension of the header collector. But the resinator (an empty can) is a good thing.
I would think that the best bang for the buck would be to do away with the cat all together. and a free flow muffler.

[wspohn]

Originally Posted by Kappster My understanding is that the solo is a RPI knock off. Anyway about it, The point of that artical was that a glasspack acts like an extension of the header collector. But the resinator (an empty can) is a good thing. I would think that the best bang for the buck would be to do away with the cat all together. and a free flow muffler.

I don't think that is fair. There are only so many ways to get the gas out, and given that GXP owners, for the most part wish to retain the wtin outlets of the stock model for looks (even though it does nothing for power), the routing of the Solo street race was pretty much a given. To say it copied someone else would be like saying that anyone that builds a car with 4 wheels is copying the first one that did that. Remember also that Solo doesn't market that sort of system with mufflers in it - I had to drag them kicking and screaming into supplying me with what I wanted, which just happens to resemble the RPI solution.

I share your conclusion about the best thing being to eliminate the CAT, but where I live that is against the law.

[Kappster]

You've got me there. Not Fair..
Its illegal in Arizona too. But Is it not a fact that most of the high flow cats don't do the job of a OEM anyway?.That it would fail the test? too? I think through magnaflow you can buy A High Flow Cat.. but its over 400 bucks. And its supposed to pass.
All I know is I'm Just having fun here and trying to learn.. not make anyone mad. Exhaust is a science and we pay lots of money for things we dont understand.... Like oil.

[LiquidPT]

Originally Posted by wspohn I share your conclusion about the best thing being to eliminate the CAT, but where I live that is against the law.

Oh, it's illegal in the USA, too. All of it. Doesn't stop people from doing it. Pretty sure you'd still pass AirCare...