Muffler delete with FI?
Thread Starter
Instructor
Joined: Jun 2016
Posts: 229
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From: Rochester NY
Muffler delete with FI?
so i dropped my mufflers off my supercharged 05 and when driving to the muffler shop to get a quote on straight pipes i noticed it wasnt as quick as it usually is. Is this due to back pressure? will the back pressure issues be solved when i put the straight pipes on or will i need to retune to adjust for the back pressure? Thanks in advance!
Le Mans Master
Joined: Mar 2001
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From: Omaha
2020 Corvette of the Year Finalist (performance mods)
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Wow, that has to be insanely bad drone when driving the car with no rear exhaust section. Anyway, I would guess that your tune is going to be off with no rear exhaust (especially if you were tuned with stock mufflers), and personally I would not be going WOT with it in that state. You could potentially be moving enough extra air that it's causing a lean state, which could lead to detonation/knock, which would lead to timing being retarded. Detonation on a forced induction motor is really bad, and should be avoided if at all possible. Another possibility is that running without the rear exhaust is causing enough noise/vibration to fool the knock sensor into thinking their is detonation, and again retarding timing.
Thread Starter
Instructor
Joined: Jun 2016
Posts: 229
Likes: 3
From: Rochester NY
Wow, that has to be insanely bad drone when driving the car with no rear exhaust section. Anyway, I would guess that your tune is going to be off with no rear exhaust (especially if you were tuned with stock mufflers), and personally I would not be going WOT with it in that state. You could potentially be moving enough extra air that it's causing a lean state, which could lead to detonation/knock, which would lead to timing being retarded. Detonation on a forced induction motor is really bad, and should be avoided if at all possible. Another possibility is that running without the rear exhaust is causing enough noise/vibration to fool the knock sensor into thinking their is detonation, and again retarding timing.
Le Mans Master
Joined: Mar 2001
Posts: 8,475
Likes: 3,971
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
Mufflers alone should really make enough difference to need a retune. Getting rid of the mufflers completely for straight pipes may make enough difference to need an update. Going from stock manifolds to long tubes will definitely require an updated tune. If you're after power, mufflers to straight pipes is going to be less than stock manifolds to long tubes, especially on an 05 (LS2). If you can find a set of LS7 exhaust manifolds, they will flow a lot better than the LS2/3 manifolds for not a lot of money.
Thread Starter
Instructor
Joined: Jun 2016
Posts: 229
Likes: 3
From: Rochester NY
Mufflers alone should really make enough difference to need a retune. Getting rid of the mufflers completely for straight pipes may make enough difference to need an update. Going from stock manifolds to long tubes will definitely require an updated tune. If you're after power, mufflers to straight pipes is going to be less than stock manifolds to long tubes, especially on an 05 (LS2). If you can find a set of LS7 exhaust manifolds, they will flow a lot better than the LS2/3 manifolds for not a lot of money.
Le Mans Master
Joined: Mar 2001
Posts: 8,475
Likes: 3,971
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
I'm at 672RWHP on a bone stock LS3 with LS7 exhaust manifolds and 11psi on a V3 Si. The LS7 manifolds flow really well, and I'm happy with them. Could I gain another 20HP? Probably, but it's not worth the cost differential.
Thread Starter
Instructor
Joined: Jun 2016
Posts: 229
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From: Rochester NY
oh very nice, im sitting at about 600 to the crank right now bone stock with the blower around 8psi, im looking to get around 600-650 to the wheels
Le Mans Master
Joined: Mar 2001
Posts: 8,475
Likes: 3,971
From: Omaha
2020 Corvette of the Year Finalist (performance mods)
C4 of Year Winner (performance mods) 2019
I gained 14HP from the LS7 manifolds when I was bone stock. Let me know what you gain when you put them on, would be nice to see how much they add to a blown car. 650RW should be fairly easy, do the LS7 manifolds, move one pulley size smaller on the blower for about 10-11psi and add methanol injection.
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