BlackWS666

iTrader: (31)

So i closed my season on a lean #7 cylinder, which made me tear into my engine sooner then expected. On inspection of my heads i noticed little cracks on the head between the valves. Im positive they werent there before installation. Im also switching around intake setup and have the chance to go to a rectangular port head. Ive searched for about a week now seeing no one really put a rectangular port head to the test of high boost. Many that see 10-12 psi, but im looking at 24-28 range. So who has put a LS3, LSA, LS9 head to the test? Would notice a power gain in the lower at lower boost levels with these heads? Or should i stick with my 317s?

Background on the car: 370, GT55-94, 25 psi average, E85, 1/2" ARP studs, LS9 gaskets . Current heads are hand hogged 317s that held up to over 75 20-28 psi passes, and probably hundreds of street pulls.

Louis

iTrader: (7)

The LSA and LS9 head would be much better than the 317s. Since you are setup for it, Id rock the LS9 because of the 1/2 head bolts. It will take a little machine work, but youll be happy with them.

We run 19-22 psi on the ZR1s with out issue and getting pretty crazy with the tuneup and water temps ( 25-27* timing and AFRs in the 13s on a road course)

Id stay FAR away from the 821 or 823 LS3 castings.

BlackWS666

iTrader: (31)

Thanks man, i was hoping someone could shead some light on this! Anyone else?

9sectruck

iTrader: (9)

I thought the 823 heads where the head of choice for boost, if not whats the casting number (5864 or something like that)

dudeman

iTrader: (43)

i think what he is getting at is they will lift before the lsa or ls9 heads.

does anyone know why this happens on the l92/ls3 heads compared to the 317s?

Louis

iTrader: (7)

Ill be cutting some heads apart tomorrow

The LSA and LS9 heads are also a much better material.

The 317 vs the LS3, I have not the slightest clue. I have one of those too, Ill cut apart.

stevieturbo

Often detonation will cause that.

PRAY HRD

iTrader: (119)

My future plans definitely have the lsa heads included in them and have for a bit now. Seems to be the best bang for the buck going at the moment. I thought i read there's a minimum bore required of either 4.00 or 4.030. Can you confirm that as well Louis?

Sales@Tick

iTrader: (3)

I wouldn't run the rectangle port stuff on anything under 4.065" personally, but that is only my opinion.

Louis

iTrader: (7)

It needs a minimum of a 4" bore. Yes, larger bore is optimal, but there is no issue with a 4".

Sales@Tick

iTrader: (3)

With boost or nitrous I agree 100%.

N/A is another story for another part of the forum....

Louis

iTrader: (7)

Totally agreed. Unshouding in any case is good, but if he already had a good shortblock, a little shrouding is still going to fair much much better over the cathedral setup.

PRAY HRD

iTrader: (119)

Great to hear! thanks guys.

miatainthe10s

I'm in for Louis's findings on cuttingthe heads apart.

IH8FORD

iTrader: (6)

I plan on using my 823 castings on a turbo set up. I have wanted to know what the deck thickness was compared to a 317 head myself.

IH8FORD

iTrader: (6)

Bump for results from the heads being cut apart

Louis

iTrader: (7)

I got the ls3s cut apart last night and Scoggin dickey delivered the LSA head yesterday. Probably have everything cut apart on Monday.

IH8FORD

iTrader: (6)

Sounds good.

Mightymike2000ss

iTrader: (4)

From the old beat to death L92 head threads seems like if you try and machine them to run 1/2" studs they break super easy under a decent amount of boost. I'm running standard diameter ARP studs and will see how far i can push my L92's with the GT-88

No Juice

iTrader: (11)

In for pics