bandit0220

I think he was talking to Jason on that one Shawn.

Humar you should be able to do 12:1 easily I personally am doing 12.26 to 1 on crappy 91 octane with zero detonation an max timing in the 26 range runs like a scalded dog.

kumar75150

no I was speaking to Jason

He laughed at 35 but you have gained 31 before.

bandit0220

I have yet to see a "REAL" 600 rwhp car with just bolt ons maybe a solid lifter cam would help but some of the so called "we made 600+ rwhp with heads and cam" are just needing a little more QM "quality management"

bandit0220

That was "WITH" milling jason was laughing at 35rwhp from porting alone

Randy@RaginRacin

Oh Ok. No problem. Glad we got that straight.

kumar75150

edit: nevermind. did a search and it seems like most people think the stock valves are fine for NA applications

since you guys are here, do you replace the valves on ls7 heads when going with a big cam? intake and exhaust valves?

im thinking a 245/260ish cam and milled heads to 12:1

i better get near 580 at least

bandit0220

stock valves here and working beautifully I think the stock valves are pretty nice already no need to upgrade just yet at least IMHO

Randy@RaginRacin

We haven't had any valve failures, but I did get some pictures of a failed exhaust valve a few days ago. Destroyed the motor.

dfinke23

^
I have seen that happen before, 3 times on modded cars and heard of it once on a stock setup. I upgraded my valves. Since my warranty is void, and my budget is not unlimited, I wanted to be as safe as possible.

kumar75150

ouch

Gannet

What did you do to get to that number? How much mill and what gasket? And did you have to notch pistons for valve clearance?

DSteck

I'll try to get some data on porting vs. porting and milling. I currently have stock heads that have been ported on the exhaust side only with only a few thousandths taken off to clean up the mating surface. Once my car is back from the clutch replacement, I'll try to jump on the dyno again before pulling my heads again. I am going to yank my heads in an effort to fix a ticking noise that I'm tired of hearing (I've narrowed it down to a lifter, because it's a half engine speed sound and I've replaced every other component). When I do, I'm probably going to have them cut down by 0.035" and switch to thinner Cometic gaskets. After that, I'll try to dyno again. I have a number from when it was cam only, but it was a poor tune (only did 542rwhp peak on a Dyno Dynamics). This is all with a QM600 cam.

Now if Jason would just supply the world with an LS7 intake manifold that can keep up...

I doubt you'd have to do anything to the pistons... they have valve reliefs already.

0C_Williams@RPM

Bandit,

The pictures shown in this thread are from an engine in my shop - dropped the head off a sodium filled exhaust and it's not the first one that I've seen. The original installer may have contributed to the failure but no clear evidence is left.

Be careful though, as there are problems with these valves and though it appears to me that the issue is at a failure rate compared to the rocker needle bearings, it's a costly one.

Charlie

J HEBERT

Shawn, that motor is not bad, me fix.... A lil' welding on the head, a sleeve, some JB-weld and a file, and she will be ready to spray

0C_Williams@RPM

I'm going to generalize here and back it up with data sheets when I get time, which won't be until later in the week.

Intake Ports

Flow numbers on the the stock heads (using a radius plate) peak at .550 lift and ~350 CFM - by .600 lift they head south in a hurry and at .700 lift the turbulence is deafening. However, attach the stock intake manifold and even though the CFM drops by 30 points the curve becomes stable past .625 lift before dropping like a rock.

Our ported heads, same radius plate as above, peak past .650 lift ~390 CFM and with our ported intake attached carry ~375 plus CFM past .800 lift - no turbulence. Not much loss with a ported intake.

Those numbers are repeatable and given any free time this week I'll post a video of them on the flow bench. BTW, it's a combination of the CNC work and the valve work that contribute to the gains.

Exhaust Ports

Flow numbers on the the stock heads (using a 1 7/8" pipe) peak at .550 lift and ~245 CFM - by .600 lift the numbers start to fall and by .650 they are past being over.

Our ported heads, same pipe as above, peak past .650 lift ~280 CFM and carry that flow to .750 lift.


Summary & Notes

► Intake and exhaust ports can be substantially improved upon but the ultimate HP gains are a result of a "complete package" just not a single part. As an example: The right cam, adjusted DCR and an intake system capable of evacuating the manifold will show huge gains while a less than optimized package will fail.

► Gains in CFM are a result in both porting work and valve & valve seat work.

► For comparison -peak CFM numbers alone are no more relevent than only peak HP numbers - Area under the curve is the king and our CFM gains are across the board, verified by independent shops like WCCH.

► All test information derived from our standard SF600 bench

0C_Williams@RPM

Replace the exhaust valves. I'm in the process of changing over several completed projects for safety sake myself.

If you don't have a local source for the work we can do it for $375, two day turn-around. Price includes:


► Disassemble and hot tank & inspection
► Serdi Valve seat work (exhaust)
► New SS Exhaust Valves
► New valve seals
► Reassembled

J HEBERT

Shawn called me about that engine last week, and I asked about the valve locks and the rocker bearing assembly. He said "Dude, everything is still on the valve...the head of the exh. valve came off!" Just then I got a warm fuzzy over the fact I run heavy-azz stainless exh. valves in the ETPs. !st thing I thought when I heard about this was rocker arm bearing failure. Do a search on the 6.2 vvt used in the caddys and such, as it pertains to stock valve heads breaking off and destroying the motor. I know where 3 of 'em are sitting just feet from one another RIGHT now.

I have 5k in my heads alone It seems that for reliabilitys sake, a head/cam pkg. using reliable valves (whos mass works w/ cam profile at high rpms) would easily be worth the extra $ for peace of mind alone.....

0C_Williams@RPM

The stainless valves weigh in at 94 grams not significantly heavier than the intake and - easily controlled by the spring kits available.

bandit0220

Ok Ill take this one step further William you know I have nothing but love for ya and I run a very precise package, I have your intake, 92mm throttle body, milled stock heads, extreme springs, 1 7/8s stepped to 2in american racing longtubes, etc etc. Ok I have said william knows his stuff I will make ya the same deal, as well as I will pay to have the exhaust valves replaced at the same time for safetys sake. I am game to do this in fact its hard not to justify having you do it with the results the intake got. So what ya got to lose from what i can see nothing but you got everything to gain

dfinke23

I have an RPM intake on the way, in fact, it's the one featured in all of Charlie's pics. If you can test and confirm 20+ hp from just porting and then comfirm another 25-30 hp from milling, I'm in. As of right now, I'm in the mill only/save $$$$ mode.