LT1 Intake flow numbers?
Le Mans Master
Joined: Jul 2000
Posts: 5,012
Likes: 5
From: OKC OK
I've seen some flow bench #s and graph from a stock LT4 intake vs a ported/welded LT4 intake. I think the ported/welded LT4 intake only flowed something like 260cfm...pretty sad considering how good a well ported LT4 head flows (290-300cfm) 
Le Mans Master
Joined: Jul 2000
Posts: 5,012
Likes: 5
From: OKC OK
Originally Posted by Nathan Plemons
I think it is generally accepted that the LT1 manifold isn't a restriction
The short runners also suck for makin' tq
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Agreed, but if you're making something like a 409 stroker you don't need to worry about the intake to make torque, you rely on the extra stroke to do that for you. Even in the large strokers people still use the stock LT1 intake with very good success. Maybe it has something to do with the fact that there aren't many aftermarket options out there, but at least part of it is that the intake is pretty damn good to start with.
There are a few forum members here with 400+ cube LT1's. You might ask them. Unfortunately their names escape me currently.
There are a few forum members here with 400+ cube LT1's. You might ask them. Unfortunately their names escape me currently.
Le Mans Master
Joined: Jul 2000
Posts: 5,012
Likes: 5
From: OKC OK
I'm with you, but the problem (although not huge) is w/ a 350-355ci motor you don't get good tq. Then w/ a stroker you don't get enough plenum volume to support the extra cubes. I don't think it really becomes a issue until you're going all out.
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
I don't know a lot about engine dynamics and how plenum volume really affects anything, but it seems to me from a logical standpoint that volume would really be less important than efficiency.
If you have a large volume that may be nice for dumping a lot of air into the engine very quickly on a burst demand, but what if it can't refill itself quickly? I think it goes back to that thread I posted about MAP pressures. As long as the MAP stays as close to ambient pressure as possible, you should be alright. Afterall, once the throttle blades are all the way open the plenum might as well be exposed to the atmosphere. In this case it would be beneficial to have little if any restriction into the intake.
If you have a large volume that may be nice for dumping a lot of air into the engine very quickly on a burst demand, but what if it can't refill itself quickly? I think it goes back to that thread I posted about MAP pressures. As long as the MAP stays as close to ambient pressure as possible, you should be alright. Afterall, once the throttle blades are all the way open the plenum might as well be exposed to the atmosphere. In this case it would be beneficial to have little if any restriction into the intake.
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Thread Starter
Pro
Joined: Apr 2003
Posts: 552
Likes: 13
From: Oz
Thanks guys, i didn't think there were any numbers published anywhere...
It seems that the general concensus is that they can make good power...
I'm about to begin modifying one to work on a 406...
It seems that the general concensus is that they can make good power...
I'm about to begin modifying one to work on a 406...
