If I have a set of 243 heads with stage one porting with 2.00" (stock valve
size) verses an identical set with 2.O2" and 1.57" exhaust how much app,
horsepower to the wheels difference would there be.
346 ls1 with 224 cam,ls6 intake,kooks long tubes and high flow cats,and
a good dyno tune.

The reason I am asking is a machine shop I talked to said that It would not
be worth it to install the 2.02" etc valves . He said the horsepower difference
would not make the work worth the money. I don't think I believe him.
A friend of mine says that it would be about 20 hp at the wheels. What do you
guys think?

 

Your machine shop is correct. 2.0 valves on stock cubes is plenty. A 2.02 valve will only flow maybe 10cfm more than stock 2.0.

 

So how much horse power do you think is 10 cfm worth? This seems interesting on what people think 10 cfm is worth.

 

A 10 cfm increase with everything else perfect and in the upper rpm ranges can produce 2.57 hp per cylinder, so times 8 would be 20.56 hp flywheel.

I agree with your machine shop.

 

With the 2.02 valves, you'll gain a little more intake flow at high rpm, maybe 5-10 hp. The heavier valve might limit your redline a bit. Looking at your signature mods, I probably would not worry about stepping up to a larger valve.

 

Im kind of in the same situation, I can't decide if I should use stock valves or have TEA put the 2.04int 1.575 ext valves in. Also should I get turned down ls3 valves or just have TEA put the manley valves in. What are the power benefits of the 2.04 vs the 2.00 and when does shrouding start to become a issue?

 

PREDATOR-Z, I'd love to get your input on CND'd 243 heads. I know AI uses stock sized valves with both their 226cc and 232cc programs and TEA uses larger valves in their Stage 2 ported heads. I looked at the flow numbers and the TEA heads flow better, but what is your opinion on which of the two is better? I've seen many of your threads with great results from AI heads. I guess I'm asking is there going to be much HP/TQ difference between the TEA Stage 2 heaeds and the AI 232cc heads?

 

The only way to truly answer that is to flow them back to back under same conditions.
Both are good products.
Personally I'm a fan of light moving valve-train, meaning light valves, retainers and beehives. (Perhaps part of the reason I've no issues controlling harsh ramps at reasonable rpms)