LT1TA

iTrader: (17)

408 twin turbo, cr about 9.3:1
cam is a 236/240 640/620 115+4


Here is the issue, I am thinking about changing my turbo setup. I currently have unported 317s with valvetrain upgrades. vic jr and fast 92 tb.

I am only interested in stock l92 heads as I am not trying to invest money into the heads when i have other areas of concern and a very recently limited budget. I will likely sell the entire top end and put it towards the l92 swap, but I need to be sure this is going to be worth the money and time.

I know the 317 heads have an i/e% of 73% efficiency and the l92 has about 65%. But even with the more efficiency out of the 317, the l92 flows more which will give me more power advantage then the exhaust issue will cost me. So that part i'm leaning towards the square port.

Being that the l92 has so much more intake flow than exhaust, is the lift on the cam going to aid that problem more or am I reading the cam specs wrong?

Thanks in advance.

Jimbo1367

IF you go forward with the L92 heads, remember that you have the heavier valve on top of the boost. I'd work on fixing the boost leaks 1st as mentioned in your signature.

one fast zo6

iTrader: (490)

You just need a after market cathedral head IMHO

LT1TA

iTrader: (17)

Yes, the boost leaks wont be a problem. I'm making a whole new kit. if i can find an aftermarket cathedral for the right price i may go that route. mainly because the thin decks of the l92 worry me. I don't think my 317s will get me to a happy point like a ls3 topend would.

5.3-on-steroids

iTrader: (3)

Just get lsa heads

LT1TA

iTrader: (17)

thats good timing, i'm actually looking at a set right now.

LT1TA

iTrader: (17)

im so indecisive. Last night I was pending sales with new lsa heads, some like new ls3 heads or some tfs 235s. I went with the tfs heads. Just going to take a little longer to finish the build but there is a lot of peace of mind and power gains by the decision imo.