well, i will be doin my head/cam swap soon, also putting on stronger timing chain and a pulley. my bottom end will be staying stock. i see a lot of people running the "stage 2" size valves on stock bottom end which are usually 2.02"/1.57"....i was thinking of running 2.05""/1.60, which is basically considered a 2.5 or even stage 3 head. since i will be staying with stock bottom end, bore/stroke, stock compression, as well as naturally aspirated, will these be too big for me, or is it fine to put a high flowing head like this on a stock bottom end??

 

These are the same size valves that MTI uses in their premium stage 2 heads. Give them a call they can give you the info you are looking for.

 

I just spoke with Brad @ Forcefed High Perf.

I too am considering heads. However, i have a mild cam ( TR220/220 .553 .553 112+4) & all bolt on's, LS6 intake etc....

I too was considering the Stage 2 LS6 205 160's.

Brad listened and talked me into a 5.3 head with the 202 157.
He said this would be perfect for what i do which is daily drive my 2000 Z28. I also have the A4 with a Yank 3500.

He stated to me that with a good tune i could easily see @ least 400 hp.

Don't know, we'll see.

Good luck.

 

thats what i have on my heads....

and mine were to go on a 383....

2.05-1.60 rev
230cc int
89cc ex
64cc 10.6:1 CR

and made 400rwhp with a baby cam!

 

Sweet!

Very impressive. I need some heads!

 

2.08/1.60 here, completely stock bottom end, w/cut pistons.

 

i dont doubt that people are running this setup, im just wondering if its worth it on a stock bottom end. i would think, depending on runner size, going too big on valves would actually decrease velocity. i think ill be sticking with a 2.02/1.57" setup....maybe ill lower compression to 59cc being that im going with a 5.3 head.

im just under 400 rwhp with a 224, bolt ons and true duals and stock heads. i will probably be going with a little bit bigger cam, but i do wanna keep the lsa at 114 for idle quality...though my 224 is on a 112. tsp said they would custom grind the torquer for me on a 114 lsa.....anyone know of any negative effects having a wider lsa on a big cam like that would have??

 

Valve size doesnt matter...its cfm@lift..thats what you need to ask
my 2.055/1.60s are sitting on the shelf because my 2.02/1.57s outflow them across the board...

 

I have chimed in on this type of post before, but the way i see it, valve size should be dictated by bowl size and the shape and geometry relation ship of the 2. Most LS1 style ports cant support 2.05" and larger valves when scrutinized in this way. 6.0 and LS6 heads can support large valves, as far as losing velocity with bigger valves, i dont see it that way. Larger valves expose bowl and port to more pressure drop than smaller valves can. This keeps air flow thru port more active in cylinder filling situation. Proof of LS6 style large valve results can be seen with S.A.M. Project car flowing in the 350cfm range, not too shabby.