rare bird

I have a recent set of absolute speed 5.3 stg 2 heads w/2.055 int. valve. The intake & exhaust runner volume was supposed to be 218 & 79 cc's respectively. What I found after cc'ing was 232 & 87 cc's consistently. This seams to be a bit large for a stock displacement ls1 to me. Has anyone checked their heads or ran them on their car or maybe even dynoed?

Bowtieman4life

iTrader: (1)

Holy ****. Call Jay and point out what you found. Maybe he sent you the wrong ones.

KGSloan

were these the cnc'ed heads?

i've got a set of the cnc'ed heads. ran them for about 6k miles. i didn't ever check them out but probably will now since the motor blew up and the heads are off anyways. my results wern't what i was expecting to say the least

rare bird

yes these were the cnc'ed ones.

rare bird

I did call Jay, he told me he was porting these heads more like the Lingenfelter heads, I just don't know why he didn't tell me ahead of time. It just seems like I would be loosing port velocity. He says the Lingenfelter heads make a lot of power.

bigdsz

iTrader: (1)

What are the casting numbers on the heads? What are the flow numbers that you were supplied with?

rare bird

These are 862 castings.
.100=70cc, .200=148, .300=204, .400=258, .500=294, .600=312 (int #'s)

bigdsz

iTrader: (1)

I got a set of 5.3's from Jay about 3 weeks ago and they have the same 862 casting numbers.My flow numbers are nearly identical to yours. Did you recently get your heads and were you told by Jay to use the 7.350 push rods instead of the 7.40's?

I understand you concern about velocity, however I must say AS reputation has been excellent and now that the heads are being CNC'd uniformity should be better. It is odd that the runner volume would be increased without letting customers know. I hope the end result is that we all get the performance numbers we're looking for. Jay certainly would not compromise head quality just for the sake of CNCing and increased quantity, that would be a recipe for disaster.

rare bird

Yes, I got my heads shortly before you, but I have 7.40 pushrods, but you may be running the taller springs, therefore a taller valve which would call for a shoter pushrod. I'm using comp 918 springs which does'nt require altered valve lengths. What cam are you using?

bigdsz

iTrader: (1)

I've been running a Comp 216/220 .525/.532 for the past 2 years, however I'm going to go to a Comp 224/224 .563/? 112lsa or TR224/224 .561/? 112lsa.

On the new heads I've got dual springs supposedly the 978's although they might be the 977's, I'll have my shop check. You'll do fine with the 918's, the guy doing my install thinks I'm nuts for going with the duals and not the 918's.

I still don't understand the theory on the 7.350 push rods. I've got the 11/1 CR and an after market cam that has a smaller base circle, so I should be taking a longer PR. The only thing I can figure is that the valve seats or the back sides of the valves has been cut.

Anyway like I said before. I hope we can make the power we're looking for.

Mike K.

At least you know that at 232 cc's that the heads have actually been ported, it does kinda suck though if you were led to believe otherwise. That said I'm sure you will still have enough velocity to make good power with those flow numbers even with the larger runner.

Cary@Perf-Induction

iTrader: (1)

I SEE EVERYDAY SOMEONE ADVERTISING SMALL RUNNER HEADS WITH THE BIG NUMBERS, 232-235 IS PROBABLY MOST COMMON AMONG ALL THE HEAD PORTERS. UNLESS YOU LEAVE THE ROCKER BOSS IN THE PORT AND ONLY DO A VALVE JOB YOUR GOING TO BE 220 PLUS. STAGE THIS, STAGE THAT 205, 225 THIS OR THAT, THERE IS NOT A WHOLE LOOTA DIFFERENCE BETWEEN ALL OF THEM. iF YOU DON'T GET THE VALVE JOB RIGHT OR PUT THE RIGHT VALVE IN IT, 205 DOESNT MATTER ANY MORE THAN 225. EVEN ON A STOCK LS1, IF YOU DO NOT OPEN UP THE RUNNER TO 230 CC, THEY DON'T CARRY OUT UP TOP AS WELL. EVEN AT 235 CC, LS1 CROSS SECTIONAL AREA IS STILL SMALL. THE QUESTION IS DOES ANYONE KNOW WHAT A STOCK LS1 INTAKE PORT VOLUME IS????

Tony Mamo @ AFR

iTrader: (13)

LS1 Castings 201 cc's

LS6 Castings 211 cc's

Bowtieman4life

iTrader: (1)

His website is still claiming between 209 and 215 cc. If you haven't installed them you can alway let Jay know your concerns and send them back. Personally I think 232 is huge.

rare bird

I have a totally stock set of ls1 heads at home that I will check & let you know. One thing I do know, the GMPP/Lingenfelter LS6 heads have a 250 cc int. runner but still have the 2.00 valve, but I cannot attest to what kind of low end torque these heads make. Perhaps the smaller valve creates the needed velocity.

rare bird

I checked my stock LS1 heads and got the exact same as Tony, 201 cc's. Just for illustration purposes the diff between 201 and 232 cc's is roughly 1 ouce in a measuring cup. You tell me; is that a lot for a stock displacement motor? You're looking at 13.5% more volume.

PREDATOR-Z

IMO for a small cam, yes, those heads are overkill.
The longer the duration the bigger the charge with the big valves.
With big runners like that a stroker would benefit more.

bigdsz

iTrader: (1)

I just checked my AS 5.3's intake runners ~240cc and exhaust ~90. Does this mean that some how velocity will be hurt on the small cube engine? I mean some people are running ported LS6 heads on 346 cu.in. engines.

CHRISPY

I have seen absolute heads in the high 230 range as well. (236cc intake port volume)

Certain people questioned what I saw but it was right there in front of me

JS

iTrader: (4)

My Cartek LS6 S2X's are in the 220cc range.....