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3.5" down pipe?

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Old 12-14-2003, 03:34 PM
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Default 3.5" down pipe?

How much power can I make through a 427 C5R in a corvette with a t-76 Q and a 3.5" down pipe. Can I make 700rwhp with the 3.5" downpipe?
Old 12-14-2003, 04:48 PM
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why not just go 4 inch down pipe?
Old 12-14-2003, 05:01 PM
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I can only fit 3.5 without notching the frame!!
Old 12-14-2003, 05:42 PM
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Originally Posted by torchz06
How much power can I make through a 427 C5R in a corvette with a t-76 Q and a 3.5" down pipe. Can I make 700rwhp with the 3.5" downpipe?

My LT1 is at 760rwhp @19psi with an Innovative GT80, 3.5in downpipe and exhaust, through the original muffler and tailpipes. (muffler opened up for 3.5in intermediate pipe).

So, yes, 700rwhp is no problem for a 3.5 downpipe, but IMO, the exhaust side of a T-76 Q is going to be a bit restrictive on a 427.
Old 12-14-2003, 06:17 PM
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Originally Posted by INTMD8
My LT1 is at 760rwhp @19psi with an Innovative GT80, 3.5in downpipe and exhaust, through the original muffler and tailpipes. (muffler opened up for 3.5in intermediate pipe).

So, yes, 700rwhp is no problem for a 3.5 downpipe, but IMO, the exhaust side of a T-76 Q is going to be a bit restrictive on a 427.

What do you think would be the best turbo?
Old 12-14-2003, 10:52 PM
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Hell rob did 800hp with a 3in DP so a 3.5in should be good for at least 900-1000hp your E/I pressure ratio will just get higher the more power you make.
Old 12-14-2003, 10:55 PM
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Originally Posted by torchz06
What do you think would be the best turbo?
We keep telling you that you need a T88 for that motor.
Old 12-14-2003, 11:08 PM
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Originally Posted by MYTURBOT/A
We keep telling you that you need a T88 for that motor.
yep yep yep

Old 12-14-2003, 11:54 PM
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I would get a T88 for a 346ci.. That would help me with getting traction b4 the real HIT!!!!
Old 12-15-2003, 10:04 AM
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like said above the exit for that 76 is not even 3" anyway... you have a lot more exhaust than a 346 has to move out through the turbo.
Old 12-15-2003, 03:50 PM
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T88 *drools* and im with vince, I'd do a t-88 on a 346 too! lol
Old 12-15-2003, 06:57 PM
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Torched...give me a call. I have a C5 single turbo kit for sale: T71 GTQ, BB, big FMIC, 3" DP. Currently making 580/580 @ 12psi on stock cubes. The T71 is rated at 880fwhp.

Phone: 248-842-3309
Old 12-15-2003, 10:16 PM
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Being a 427, not 346...thus t88 is what I'd use...judging by the maps I've played with lately..that would be fairly efficient depending on the rest of you set-up. Get that air pump pumpin'.
Old 12-16-2003, 09:55 PM
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Twin,

This is definitely the bigger is better crowd.

I'd like to make a couple of points: The GTQ T71 is rated to 880fwhp. Its efficient in the 600 - 650rwhp range. Beyond that, I believe you are going to be testing the limits of the pcm and fuel systems currently available for the C5. I haven't seen anyone running higher than 50lb injectors on a C5 and fuel pump setups that I have seen are good to 800fwhp (racetronix and boost-a-pump). If one wanted more power a GTS T76 is good for about 1100fwhp. No one in a C5 is going to come close to needing/using more than that. The current offerings for tranny's and rear diffs. have trouble handling anything north of 600rwhp. Last point of discussion: having a T71 under the hood of C5, I cant see a big frame turbo fitting. My "little" T71 is a tight fit. If I am correct, the T74/T76 are all in the same family and are therefore sized comparatively close. I think it would be difficult to fit a T88 in a C5 engine bay. I'm interested to hear some of the other "experienced" turbos guys views on this.
Old 12-16-2003, 10:44 PM
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Originally Posted by Earl H
Twin,

This is definitely the bigger is better crowd.

I'd like to make a couple of points: The GTQ T71 is rated to 880fwhp. Its efficient in the 600 - 650rwhp range. Beyond that, I believe you are going to be testing the limits of the pcm and fuel systems currently available for the C5. I haven't seen anyone running higher than 50lb injectors on a C5 and fuel pump setups that I have seen are good to 800fwhp (racetronix and boost-a-pump). If one wanted more power a GTS T76 is good for about 1100fwhp. No one in a C5 is going to come close to needing/using more than that. The current offerings for tranny's and rear diffs. have trouble handling anything north of 600rwhp. Last point of discussion: having a T71 under the hood of C5, I cant see a big frame turbo fitting. My "little" T71 is a tight fit. If I am correct, the T74/T76 are all in the same family and are therefore sized comparatively close. I think it would be difficult to fit a T88 in a C5 engine bay. I'm interested to hear some of the other "experienced" turbos guys views on this.

HP rating for turbos are nice to talk about, but usually people concerned about efficiency don't build a combination with the intent of maxing out a turbo. If someone has the money to build a turbo 427, there's no reason to limit yourself to the limitations of a stock pcm. (unless you're Harlan )

IMO, a twin turbo setup is probably the best option for a C5 with a 427 in terms of packaging and efficiency. A 427 with the proper turbo(s), could probably do around 80lbs/min @1 bar. If a PT76 GTS compressor map is similar to my Innovative GT80, than it's going to be around 2bar @80lbs/min near peak efficiency. It's just not a good match IMO.
Old 12-17-2003, 01:29 AM
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Earl

We've discussed this setup already...

https://ls1tech.com/forums/forced-induction/119170-what-size-turbo-427-a.html

See that for reasons and recommendations.

And the new GTQ wheels do seem to be flowing closer to the next size up older wheels. But if you look, he's looking for 700rwhp max on a 427. Kind of wierd combo for it if you ask me, but that's what he wants.

And we all know how much power the y-car driveline eats compared to the F-car. So he's probably looking closer to 850 at the flywheel to get there.
Old 12-17-2003, 10:21 AM
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Hey Harlan do expect any problems with all that heat right below your hood. The resason I ask is I'm looking at a similiar kit for the C5 with turbos mounted quite similiar to yours. Do you think that setup could withstand 25mins. of roadracing.
Old 12-19-2003, 05:39 AM
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Originally Posted by DetroitZ
Hey Harlan do expect any problems with all that heat right below your hood. The resason I ask is I'm looking at a similiar kit for the C5 with turbos mounted quite similiar to yours. Do you think that setup could withstand 25mins. of roadracing.
What hood?

With a view like that, he better keep it exposed for oohs and ahhs!

Just kidding!



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