Seeing what the boost limit is on 4 bolt heads with course arp head studs and ls9 head gaskets before any head gasket issue. I plan on runing a 6.0 iron block

 

It depends on the power adder, the fuel, the tune, the heads used, a lot of stuff. The "safe" consensus is 18-20lbs Blower, and 22-24lbs Turbo.

 

What about after upgrading to larger diameter studs? I think I have heard of a few going 12mm?

 

i pushed 20lbs for a while stock 243s then pumped it to 23.4 on the dyno was a stock
l33 motor. Blew a piston heads where fine never lifted. Plan on 25-28lbs on the built 5.3 iron block and afr 210s.

 

1/2" Inch head studs help, but O-Ringing is better.

 

Good thread here on this

http://www.yellowbullet.com/forum/sh...d.php?t=307824

 

Factory heads hold a lot of boost specially the lsa /ls9 castings.

the shorter the stroke and the narrower the piston diameter the more boost allowance you will have with the OEM cylinder block and heads.

Worse heads for boost are Dart pro1 ls1/ls2 with 4" stroke they lift like an elevator, ouch Dart!

Something to consider is how and what lifts; what happens the head lifts between studs, not the stud stretching as must people think when conversation is brought up about the subject.

Fact; ARP studs will hold a lot more boost than must heads and cylinder blocks ever will.

Another misconception is the block, aluminum blocks lifts just like the head
by stretching upwards at the stud area which is really the reverse of what happens with the head.
When the block stretches up, the block area between the studs looses it's head gasket pressure leak starts there, will remain till you change head gasket but will come back as soon is boosted beyond casting capability, (this means will keep happening)

Those why some of us prefer cast iron blocks for boost, however a 4.6 and 5.3 liter motor will take a lot more for longer due to smaller piston diameter which don't load the heads and block to their limit as soon.

Here's how to know whether block is stretching or head is lifting;

If leak appears above the head gasket or between gasket and head and the lower area of gasket is clean, THE HEAD IS LIFTING.

If leak "or black exhaust path trace" is at lower area of head gasket only, THE BLOCK IS STRETCHING UP at stud area, (not the stud) If stud lifts black exhaust path will surround area immediately around stud, I personally NEVER seen this.

If you have boosted enough to encounter all the limits then;

You would know that's possible to stretch the block and lift the head all at the same time when black exhaust path marks are present both above and below on head gasket.

The head usually lifts at outer area rite in the middle between studs sense the LS engine heads tapered-out on the out side away from best structural area which is the inner and center of head where taller structural valve cover and rocker area is.

The piston cylinder positions outside the center of head placing combustion chamber outside the center tours heads weak end, other weakening factor for LS head is the spark plug hole at heads weakest taper area and center between studs, presence of the spark plug does not help at all either, it gladly lifts up for the ride.

This next fact may be surprising but happened to me so how I know, inner side of head lifts as well with enough boost though not as prom as the out side, I seen leaking tours the center as well.

So why 6 bolts heads and blocks, the inner or six bolt is very important as well when you want to make sure.

Hopefully these goes to save some active soul some work and $ as well as unnecessary expending on 1/2 inch or 12 MM studs and help clear the air as to what lifts, why and how.

If this is all blah blah to nobody same is lacking enough tools, cash, will and wisdom even with enough beer.

 

No easy generic answer.

What form of boost, what heads, what fuel, what compression etc etc ?

Push the CR, Push poor quality fuel, Push boost, Push timing limits and you may see problems long before a well tuned and built setup.

I've run 20psi+ for many years and never had a HG problem that wasnt caused by detonation which was my own fault. And that was only twice.
Once the meth failed, the other I ran the car with other problems when I knew I shouldnt.

More recently Ive seen as high as 30psi...although that was an accident lol...still everything is holding together fine, same engine for past 4 years or so.

 

My turbo setup has seen 20psi stock 6.0 317 heads ls9 gaskets china studs

 

My buddy has a Silverado Ext Cab 416ci LQ9 w/ PT94mm and the Dart heads. Standard ARP bolts and no oring. Has been 9.36 @ 147 at 4500#'s. That's like 1200 rwhp. He beats the tar out of that truck. Heads stay on good.

Lots of head lifting has to do with the tune.


Turned down a little for the street. Skip past the first run, he didn't break boost. Beating up on a GTR.

 

I didn't know the DARTs had a bad rap either. I ran a 418 with them and an S88 to 18psi 975rwhp with no issues.

 

I broke 2 set of dart heads. They are not the best casting but the tune is the real issue even for me at the time

 

24 psi here with stock LY6 heads, Ls9 gaskets
ARPs torqued to 95ftlbs

no coolant pushed

 

stock 317 heads, arp standard studs, ls9 gaskets, large frame turbo pushing 23lbs at 18 degrees of timing

 

I know several with standard factory style heads pushing 30psi on 6.0 blocks with just standard arp studs. Makin upwards of 1100ish. No problems. Before I'd drill a block for half inch studs id do the ca arps. Keep your block and head material and still have same strength.

 

Whats CA arp's?

 

Custom age 625+ ARP's

Ultra studs.

 

Here is a link to them. You will see why few people run them in your average turbo builds when you see the price.

http://www.coloradospeed.com/arp-cyl...6-p-24550.html

 

Boost doesn't mean anything, neither does HP

Cylinder pressure (tq) is what is driving the head off.

control where and how torque is delivered and you are in good shape

Most problems stem from tuning issues whether it be detonation which creates insane cylinder pressure or it be boost delivery and timing

 

Start with two flat surfaces.

Have the block decked and the heads milled.

Avoiding pressure spikes induced by detonation would be a higher priority than running $1K studs in my book.