I took the 90 down to DynoSport today to see if we gained anything with the new exhaust system. Here are the results:









I was a little dissapointed in that I was thinking 220 or even a little better rwhp but we gained 17 hp and 16 tq which is ok through the stock mufflers. As you can see the AFR got a little fatter so it was running richer. So I don't know at this point if the EGR delete is doing that or if the new exhaust system is. The first run was the best and the other 3 were less by around 3 to 4 hp and less tq also. He thought the anti knock might be kicking in maybe, thus retarding the spark a bit, but I have yet to hear it ping in any gear at any rpm.

The tuner said he could tune it to lean it out and shut off the ck engine light and change the fan temps etc for around 400 bucks including parts. Sounded a little high to me but I am new to the tuning deal.

The car runs great and sounds good to me, even better with GT cranked up on the way home.

So you got 17 HP for new exhaust? That's not too shabby. Did this include headers too?

TPiS headers into 3" cats into 2.5 inch X pipe on back to hook up to stock exhaust 2.25" into stock mufflers.

You see how this goes now? You are going to start scratching your head to see how to best open up the airflow into the system to take advantage of the free flowing exhaust.... I call it the snowball effect!

$400 for a dyno tune is pretty darn good. Mine cost a lot more than that.

A gain of 17RWHP is a huge amount for just exhaust.
Will

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I agree. I have been quoted $500-$600 around here, but part of that is welding a bung in for the wide band sensor.. Still $400 seems like a pretty good deal to me.

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Way ahead of you on that! That is next winters project. But then that's it, no more...........do you think roller rockers would help?

the egr delete is causing the rich mixture. if she gets leaned out a little i think you will find another 10 rwhp . next time you go to the dyno take your scann tool*if you have one ) and you can look for knock events right after each run. that the easiest way to tell

also it looks like you were right on on the pipe sizing as this test showed tq gain across the board . if the pipe size was too big you would have either a tq loss in the midrange or no gain .

You are well on your way of proving my theory... that proper intake and exhaust will give the L98 LT1 power levels.

17hp on JUST exhaust is nice. Remember, you have done nothing to the intake manifold.

My feeling is that they are each worth 20hp... but combined? It's like a 2 car draft at Daytona, and combined, I figure they are worth 50+ hp.

Now... Let's see if I am right!!!

17/16 rwhp/tq are very respectable numbers for a stock motor with only exhaust! You should be happy with that. I understand it's an obsession and you're always looking for more, but be realistic. Like Andy said - once that intake project is done, the exhaust will shine even more.

Great job getting the back to back dynos!

Also - is the 400 for just a chip tune, or for a full dyno tune? If it's for a dyno tune that's great.

Matthew

Nice gains across the curve!

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I don't know. What would a full dyno tune consist of? I will ask him if I have somemore info.

By the way I added up the money and it came to $1500 dollars for the system as it sits, not counting the EGR stuff that I bought that I decided to keep just in case I ever go back.

It was a little more than I predicted earlier but it always is.

The H.P. peaks at 4k on a stock motor. Looks like yours is at 4400 and stays up there from 42k to 46k.
Torque looks like it's peaked at about 3200 which is where the stock motor peaks.
So the H.P. curve moved up a bit and the #'s are higher,a good thing.
How do you like the sound?
Any SOTP improvement?

My picture did not show the whole RPM curve so I noticed that both hp and tq stayed up from 4600 to 5200 over the stock line (red line).

The sound is good for me and in the Dyno building under full song it sounded goooood! Seat of the pants is where I noticed it first but am always sceptecle of my evaluation since I spent the money I really want for it to feel like it. I do feel it is quicker and moves easier at all rpm stages.

me thinks bogus is right, when you get the intake done you might just see a 30 hp increase .my buddy had the exact same porting done on his zr1 same porter too . he only got 16 wrhp more than when it was stk .where as me allready having headers,exhaust, and reverse air cleaner .before corey started porting we hit his dyno car made 372 rwhp and 353 tq.after his porting car made 409.9 rwhp and 382.1 tq .which is about what corey sees when the car has headers . he said without the exhaust the inj housing and plenum porting cant really shine

I hope you are right. I want to get it done next winter.

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More than likely he would weld in a bung for a wideband 02, and be monitoring everything on a laptop, making changes as you go through multiple pulls to increase hp

Ok Marcus, time to do the intake!

You may want to run the LT1 conversion... that would be cool.

I wonder if this would clear the hood of a C4?

http://www.summitracing.com/parts/EDL-71373/

It might be worth a call to Edelbrock to find out.