So in another thread, the following flow numbers were posted for LE3 LT4 heads:
and these for LE3 LT1 heads:
Consider a basically stock 350 LT1 with a decent exhaust that will let these heads breathe.

Say you had a custom cam ground for each set of heads with the only goal being all out power. What differences would you expect to see in the HP curve for these heads? (max HP, location of peak, shape, etc.)

Second question: what if the cams were ground primarily for street manners and emissions, and secondly for power. What differences would you expect to see now?

 

There have been more than a few threads covering this subject in some detail. Here's a link to one that explains what I use http://web.camaross.com/forums/showt...4&page=5&pp=15

and here's a link to a thread that will provide you with even more viewpoints on the subject http://web.camaross.com/forums/showt...light=Mindgame

There may be 30+ hp difference between the two heads mentioned if airflow were the only thing that mattered.

-Mindgame

 

The flow #'s are kinda important but the more important thing is the LT4's larger MCA and runner volume that allows a bigger cubic inch ro make HP to a higher RPM. An LT1 can only be opened up to a 2.05-2.1" MCA and have a 205-210 cc intake port. The LT4's can be opend up to a 2.4" MCA and have a 220 cc intake port so with the right cubic inch and RPM, you would see some gains.

On a mild set up, the extra runner volume and larger MCA is not useful and will actually hurt the way the car accelerates in the low and mid range even though a small dyno gain might be seen ayt high RPM.

A 6500 (or less) RPM 350 will be fine with the (fully ported) LT1 haeds. The LT4's would not show much gain in my opinion. If we are talking about a 6500 or 6800 RPM 383/396, there would probably be 15-20 HP (or more maybe) in the LT4 heads ove the LT1's.

If we are talking an emission cam in a 350, we are realistically looking at a 6000-6200 RPM shift point and the LT1 castings can handle that with no problem. I doubt if the LT4's would be any better on that set up. Even if it "dynoed" 3-5 HP better at 6200 RPM, If the car is equipped with 3.42 gaers, the car would be faster with properly done LT1 castings. It would probably still be better with a 4.11 and 3000 stall if we are talking an emissions cam.


Lloyd Elliott
972-617-5671
Eportworks.com

 

Thanks Lloyd!

 

I trust the MCA represents 'average (mean) cross sectional area'? It would appear so. I occasionally have difficulty deciphering one letter abbreviations. Maybe I'm just more accustomed to CSA.

 

MCA = Minimum Cross Sectional Area

 

I felt someone breathing down my neck.
For whatever reason (in my mind), those figures just 'seemed'.... large for minimum.

 

They are larger than most LT1 heads but when you are needing more area, you can find it if you look hard enough. You have more walls to grind on than most take advantage of.

Lloyd Elliott