slownova73

iTrader: (31)

ive searched and searched, didnt really find an answer.

My combo is a Turbo iron block 347, with 317 heads, forged internals- stock crank. bottom end is all together except the cam, that is the next step.

What i am curious to know is whats the limits on cam size for the 317 heads? mine have a valvejob, as stated by the seller when i bought them, otherwise they are stock. i do plan on going custom cam, as it isnt much more $$ than an off the shelfer. HP goal is maybe 800 on motor, 700-750 rwhp.

Thanks.

Nitroused383

iTrader: (10)

Depends a lot on; what turbo, single or twins, what intake, compression ratio and how much rpm?

slownova73

iTrader: (31)

pt78-pt88, single, edelbrock vic jr or LS6, around 9:1, 6500

Fbodyjunkie06

iTrader: (10)

Are you asking about PTV clearance?

slownova73

iTrader: (31)

well, i guess i kinda am, just wanting to know what the flow limits are basically, i know my duration needs to be in the 230's, and LSA in the wider area like 113-115, i have .600 lift valve springs.

SATAN

iTrader: (2)

I thought I read on here somewhere that the flow on the stock unported 317 heads peaked out at anything over .550" lift? I can't remember though. I will see if I can find what I am trying to remember.

EDIT: This is what I found over on Theturboforums.com. According to this, It appears that anything over .500" on the intake side does not gain you much. The exhaust side can still see some gains over .500" though.


Casting Number 317, 035
Head: 2001+ LQ4 and LQ9 6.0 Liter Truck
Material: Aluminimum
Part Number:
12562317 -LQ4
12572317 -LQ9
12572035 -LQ9
Combustion Chamber Volume: 71.06cc
Compression Ratio: 10:1 LQ9 Flat top pistons
Compression Ratio: 9.6:1 LQ4 Dish piston
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

Stock Head Flow Numbers
Chamber 71.06cc----0.100---0.200--0.300--0.400--0.500--0.550--0.600
Intake 210cc-----------66-----142-----196---228----236---238-----240
Exhaust 75cc----------59-----104-----137---155----167---173-----177

Fbodyjunkie06

iTrader: (10)

If your doing a custom cam a blanket statement saying your duration needs to be in the 230's isn't gonna be 100% true. It could end up being there, but the valve events are more important. The way your question sounded it made it seem like you wanted to know what the biggest duration cam you could put in without having to little of ptv clearance.

If they are box stock 317's (meaning the ports are stock) then I wouldn't go over .600" lift as there is no need and spring life will go down. A good beehive should be able to do what you want.

slownova73

iTrader: (31)

so having a little port work done would benefit everywhere, so its worth the money.

I really didnt have a specific question, but all of this has helped out tremendously!

Fbodyjunkie06

iTrader: (10)

For sure, the LS heads seem to really shine with a little port work and if the valves have already had a little work on the seat then I don't see why they wouldn't flow in the 280-300cfm area as long as the port work is half decent.

slownova73

iTrader: (31)

Good deal, i guess its time to go visit H.E.D for a quote.

winters97gt

I run a comp 232/244 on a 118+2 LSA on my 402 with 317 heads. With 12.5 pounds of boost on my Novi 1500, I make 825rwhp/755rwtq. It drives so much better than a similar cam on a 113 LSA(had one). The only way to know that it has a cam, is that I have BB bullet mufflers, and the cubes help a little bit. I chose the cam against the advice of a few people including who assembled the motor. I wanted a cam that had a good powerband, but did not shake at idle.

Nitroused383

iTrader: (10)

Well thats pretty vague as the turbine of a pt78 is different than a pt88 thus requiring a different EVC point and rpm range. Same thing with the vic jr vs LS6, complete different cam profiles and rpm range. Just because a head stalls at .500" lift doesn't mean there is no benefit to having a cam with more lift, more area under the curve. There are some formulas for Lift / Diameter ratio and with a 2" intake valve .600-.620" lift is a good area. A good port job / valve job will help stabilize / increase head flow above .600" lift but remember our engines don't operate at 28" of water.

slownova73

iTrader: (31)

i understand i have alot of variables hence i still havent made a definite decision on a turbo,intake yet, i know i need that information to make a cam choice as well, but money is also a major factor on my components as well, i would like to have a vic jr. and a PT78. i know the PT88 will be a little slower to spool with my cubes from what ive read thus far, but i have a better understanding of the heads and my future combo now.