bigfatls6

iTrader: (34)

IM looking for a set of heads to use on my stock bottom end ls6 and was wondering if a 208 valve would be too large for the stock ls6 bore? I know its pushing it but would the 208 valves cause problems?

Sales4@Texas-Speed

iTrader: (4)

Yes the 2.08" valve is a little large for a stock cube motor. Not only will it cut p to v drastically just because of size, but it will also kill low end power because of how big it is. The stock motor just can't utilize a valve that big.

02*C5

iTrader: (1)

2.02/1.60 the largest you can go with stock LS1/LS6 bore

SweetS10V8

iTrader: (4)

Ive run 2.08s in a stock 5.7L before, although it was in an set of ETP 225cc heads that have a rolled valve angle. They made great power.....

butler

I am running afr 225's with the 2.08 valves with no issues. It's in a 383 3.905 bore. ms3 cam. plenty of clearance though low end torque may suffer I can't tell. 470 rwhp through an auto with 4200 stall.

Damian

iTrader: (89)

Any of the best head porters will tell you a 2.08 is too big for a 346ci. In most cases the job can get done with stock valves. I've made 460rwhp with stock valves before.

QCK57

So guys they do fit 2.08 in 346ci set up.
However with a high lift combo you will have clearance issues?


The issue is low down power dramatically effected?

batboy

iTrader: (6)

Even if you do squeeze 2.08" valves in there, there would be so much valve shrouding it would not be worth it.

That's not true. Trick Flow 215 heads are designed for LS1 bore and they have 2.04" intake valves.

Sales2@Texas-speed

iTrader: (5)

Lift has very little to do with the piston to valve clearance. The low lift duration numbers are far more important, along with lobe centerlines.

As stated, a 2.08" valve, while it will clear the bore, will be severely shrouded on a 3.898-3.908" bore.

JakeFusion

iTrader: (7)

2.02 is not the biggest you can fit.

Most aftermarket heads have larger valves than this... including the AFR 225 small bore.

Most ported heads use a 2.04" or 2.055" valve for the stock bore LS1. But you can make great power with the stock 2.00" valve as Ai generally takes this approach.

Stock valves are lighter than standard stainless aftermarket and that makes valve control a little easier. With a 2.08" valve, you have a heavy valve that requires more spring to control. And more spring puts more stress on guides, pushrods, and lifters.

Piston-to-valve clearance is the issue as well as shrouding as has been said before.

You can run it, but you better check clearance before you run it.

wildcamaro

iTrader: (15)

I would think those monster valves would kill you intake port velocity which costs power.

yonerhottlt1

iTrader: (21)

I personally wouldn't run anything over a 2.04 intake valve with the standard LS1 bore.

KCS

iTrader: (20)

2.08" is fine for a stock LS1 bore, some people have actually gone bigger successfully.

Look at it this way, a 2.08" valve is roughly 53% of a 3.898" bore. A 2.165" valve is 54% of a 4" bore, and I don't see people having too many issues with L92 heads on a stock bore LQ9. If I remember correctly, some of the highest horsepower LS1's are using hollow stem LS3 valves turned down to 2.08".

QCK57

Guys what my prediciment is....

347 standard bore built motor, ported 241.
Drag car only!

I am moving to a larger cubed motor late next year.

However i need to upgrade heads, so i got a deal on some All Pro heads, 6 bolt.
Just not sure what is the biggest valve that will fit in this 3.9 bore.
If they will fit?
but not as efficent?

I can live with until i get my new short block.

wilfredes

Any of the best head porters will tell you a 2.08 is too big for a 346ci.

batboy

iTrader: (6)

Buy the heads and put them on the shelf until you get a bigger bore short block. I would not run them on a stock cube LS1.

J Glen

It actually has nothing to do with PTV clearance. When the valve is at max lift the piston is at the bottom of the piston chamber.

Sales@Tick

iTrader: (3)

This X2.

I prefer stock valves really, but if you have to go aftermarket use a 2.02-2.04" intake hollow stem valve.

Also when TEA turns down a LS3 valve, 9/10 it's turned down to 2.04 like Chris1313 is using.

CATDIESEL

im running a stock short block with 2.08 intakes..... im not sure if it is the fastest set of heads out there but i have been running them for 30k miles or so and unless the cobra has a ken belle it will hold its own!

therabidweasel

iTrader: (5)

For a point of reference Mamo uses 2.055 on his ported AFRs. The man has some tricks up his sleeve though.