Thinking of going to l92 heads on my lq4.
My lq4 currently has stock 317 heads, 226/230 @600. 112+4 with a tbss intake and 90mm tb.

Thinking of going to L92 heads and l92 truck intake and milling the heads .030.

What u guys think??

 

You will also want a new cam that will favor the exhaust a little more with the L92's.

IMO if you are doing a head swap, and changing all that other stuff, you might as well stick with the cathedral heads and get something that will outperform the L92's.

Seems like a lot of hassle for not a ton of gain for that swap IMO.

 

Have you calc'd out the compression ratio with those dished LQ4 pistons? Seems like even if you milled the heads .030 the compression wouldn't be that great. I milled some L92's .030 and paired them up with some flat top pistons and got 11.3:1 so with a dished piston I think you'd be lucky to get 10:1.

Mike

 

If your going boost YES the L92s are worth it, otherwise dont even bother getting them. Stay with 317s.

 

Milling them .040 will put you at a 64cc chamber. I had a cam that I was told was a bad cam 244/248 .612/.615 112+2 for l92 heads and I went 10.64 in an extended cab truck in my old 10.6:1 compression motor. New motor is 11.8:1 compression and has a cam for these heads. 251/267 .623/.623 115+6 and I only gained 20hp..

So saying you have to have cam for these heads to work is irrelevant IMO.

I wouldn't hesitate to swap to these heads.

 

IMO L92 heads in a 4" bore shroud the valves ( hence why they are in a 4.065" bore). Stick to some ported cathedral heads.

 

glad this thread came up, I have a brand new rec port TBSS intake kicking around and just bought a LQ4
was debating on either putting my 799s on or getting a set of L92s
hope this thread makes up my mind

 

Your going to spend over twice as much on a ported set of heads than going with l92 heads to make the same power..
On my old 370 I picked up 45 hp going from 243 heads milled .030 to l92 heads with a cam that's supposively not for l92 heads.

 

The L92 heads do come in 4" bore application stock. LY6 etc.

peace
Hog

 

If your intake has rectangular ports then you must have a L92 truck intake, not a TBSS intake. To my knowledge TBSS's never came with rectangular port heads, only cathedral style.

Mike