BigRich954RR

iTrader: (1)

I side with you on getting the most for your buck But when your at the limits some time saving a few bucks could cost you alot more later

BigRich954RR

iTrader: (1)

Some of the logical conversation is wrong nothing will change that.

I was a auto mech then started going to school for auto design. now ME Degree ive worked on USMC crap. I work with NASA on a internships program and a little with Lock. Ive study all kinds of stuff

BUT NONE OF THAT HELP FIGURE out when L92 heads would lift. What did is when my buddy car lifted them at 865hp 925 TQ.

A few people have cracked the heads couple on this site. My buddy truck semi cracked the heads and burn the deck of the block costing more money but was with spray not FI

Im done with this topic it has gone off

LS9 heads start off with better Alum and design= stronger
LS7 seem to have a stronger casting too
ls3 havnt playing with enough
l92 seem to be the weak ones

108dragon

iTrader: (5)

Just curious to see if you had anything productive to add here. You obviously know what you are doing. Other than telling others that they don't know what they're doing, why not share your experience?
Asking you what you were running, why, and how it was holding up was an honest question. Wasn't trying to be a smart ***.

Texas_WS6

iTrader: (9)

Great, I have the dreaded L92 heads. Scruw it, I have the engine in place, and the GT88 turbo build almost finished, I will just have to see for myself when and if they crap out.

What I do not understand is everyone says they will "lift" and basicaly blow head gaskets, right? My question is how is that the heads fault? Seams more like a clamping issue to me. I am not trying to stir the pot just looking for info here.

I plan to puch my build until I make at least 800rwhp, if I have issues due to the heads, I will post my results. Do not expect any results back for a while, I am still at least 2 months away from being done.

108dragon

iTrader: (5)

As NicD so elequently pointed out, the limit I've pushed a set of these heads to is a little over 800hp. I've laid out that there is a difference in castings. Does anyone here know what the limitations of the LS3/LS7 casting actually are for FI application?
The answer to this question would reveal exactly when the point "saving a few bucks now could cost you a lot more later." And at the same time, would reveal how far we could safely push these stock performance heads. Not trying to be a smart ***. Just asking the same question I have been all along, and also getting a coherent answer for the OP.

BigRich954RR

iTrader: (1)

Your close but if you got them all ready run them. your not going for crazy power.

The deck of the cylinder head will bow in the middle causing the leak not the bolts failing

BigRich954RR

iTrader: (1)

Thats what makes it so hard. One car may lift the heads at 850 one at 800 another at 950.

We have to know every little detail to find out at what point the head will be issues ive seen them start at 850 ive seen them crack at little over 800 but with spray and was hot so it was really work to get there.

Makes head lift easier TURBOS/ HEAVY WEIGHT/ HOTTER TEMP at equal power/

S0 a 1000HP 8k supercharger car might not lift the heads where a 800HP turbo will. Because how the PSI in the cylinder builds.

Same thing how a light turbo 800hp car wont lift where a 800hp heavy will its how the load is

Ive been seeing issues around 850 so there where i feel the Avg strength is but it will change on comb.

Pushing part close to the limit cost more. I lifted a head and slowly hydro a motor Killing my whole engine. I Didnt know the head was lifting till i took the motor apart and saw where it was. Which was just enough to not know it was doing it and ran fine then one day it let go in a sec

108dragon

iTrader: (5)

OMG!!! Not someone actually supporting what I've been trying to say all along?!!!
Now all we have to do is find out WHERE the "line in the sand" is for these castings and we will have done a service for the rest of the LS1Tech.com members and this thread won't have been a total waste.
Texas_WS6 may be correct. The lifting issue may not have as much to do with the heads themselves as it has to do with clamping pressures.. or because these heads do not have as many fasteners as other heads purposely designed for higher performance, more fasteners per cylinder to distribute higher torque values overall without warping.. possible?
So ok.. we have one set of L92 (I assume) heads lift at 865hp, 925tq. My LS3 heads stayed in the game at hard 800+. Barring differences in castings and if the failure was actually due to the heads, the standing capacity seems to be between 800hp and 865hp. The more infomation and REAL feed back we can add to this, the clearer the picture will be. Wouldn't you agree?
Texas_WS6- I appreciate the feedback. If the OP hasn't given up on this thread, I'm sure he will appreciate it too.

108dragon

iTrader: (5)

So do you think the better materials of the LS7 or LS9 head, in your professional opinion, might actually safely hang with 800-1000hp FI? Would better fasteners and gaskets help increase the longevity in this application as well?
Personally, I like the newer head design because it utilizes the (4"+) extra cylinder width and chamber space for more valve without shrouding.
Play devil's advocate for a second, BigRich. What would you do if you were Texas_WS6, had to use the L92 heads (financial reasons, or whatever), and needed them to live on an 800hp+ FI engine? What would you do to increase the chances of success with them?

Texas_WS6

iTrader: (9)

I do not personaly know anyone doing this to the LS engines, I thought about going that route last year when I started real heavily building my engine but did not try it, has anyone went "old school" and oringed the LS engines? I wonder if doing this (assuming you can) would raise the ablity of these and or all the ls heads? Basicaly do you think there would be a positive benifit to doing so?

OUTLAWZ RACING

iTrader: (9)

There is no budget in F.I builds. L92 heads are ok from what I read and have been told by a number of builders. Keep in mind none of the builders tried to sell me anything. The one thing I kept hearing is "thicker deck is better." I dont have a fancy degree in anything all I got is my hard earn dollar and that out weighs most things. Common sense should come into play on choosing parts. The higher price **** is always not the best ****. If they guy wants to use l92 heads more power to him. I have a set of patriots stg 3 317 heads on my z paid 1300 dollars for them new from gunnar. People told me that they where crap heads and said I wont make power. I was told to buy some tfs or afr by a vendor that is out of busniess now and he dident even take the time to hear my goals and what I wanted to spend, But I opted to do what I wanted to do. That was 3 years ago same heads same springs and so on numbers in the sig and thats on a rearmount. My point is **** will break, **** wont give you the numbers you want, Try to listen to people that try to help and not be so quick to sell you some ****. If the op wants some l92 heads and that is what fits his budget then have at it. Im not jumping sides at all, But myself, I like to listen to people that build these type of cars on a daily basis. I know some vendors are tired of me lol but its a learning curve. just my .2

BigRich954RR

iTrader: (1)

Yea ive seen a few ls7 and one ls9 taken up and hold alot higher.

I was factoring head studs with all heads and the best gaskets. after you switch to studs its never leaks by the studs you can see where the head flexs its not by the bolts its in the middle. The thinner alum deck flexs up and cause the leak. Ive seen in the thinner deck where they cracks off at the stud. The spray car the head crank in the chamber where its thin middle close to exhaust side.

IF he has the heads already keep them. Give up a few hp for lower timing. Try not to push alot of timing near max TQ with a Turbo car.

Switch to a slower burning fuel so you make more power over all on the down stroke. Then having a higher peak pressure.

There other things to do to make them last or hold more power but that runs into alot more money which it would be better to just buy better heads anyways

BigRich954RR

iTrader: (1)

The 317 head are almost the same as the 243 heads. Which were proven to hold more power then the L92 already.

Fireball

iTrader: (21)

Shawn did that with mine...double o-ringed...We've pushed north of 1700 hp thru my 4-bolt setup and it still is sealed up good, though with ETP castings...not OEM

108dragon

iTrader: (5)

OK then. What is the concensus of the failure point on the L92 heads? What exactly is the FI limit for use with these heads? People are saying they are "weak", but what exactly is the point of failure with them par application?

themailman

iTrader: (12)

I think the guys that have found out the hard way have already told us what the saftey margin range is: 700-850rwhp.
I have a few thousand in my L92's. Hand ported, O-ringed etc. Will the o-ringed heads and block make it last longer?
Who knows. I hope it helps. It sure cost enough.

Will they last at 16# of boost on my GT4788 build. Who knows. Everyone really concerned has probably already made the investment into these heads, and most of us don't have $3500 to make a turn this late into our projects.
Do I want more than 750rwhp? Yes. Am I willing to risk everything to see a bigger number? Only time will tell.

I thank all of you guys for your info, questions and answers. The problem is that some of us will keep asking the same question until we get the answer "we" want. I know these heads are not as good as the ETP LS7 heads or many many others. But when I started building this thing in January, they were the ****. Being a pioneer in this game is very costly and time consuming. If I could go back in time, I would have bought better heads with a better deck. But I can't. So now all I can say is THANK YOU to all the guys who broke these heads and hurt motors in the processes of finding out where that line is.
I really don't want to spend another year and another $15,000 proving Vee8 and Shawn and others wrong at my own expense.

That line in the sand is your bank account and common scence.

I hope this helps someone.

pwrtrip75

iTrader: (8)

Dont keep repeating the retard statement of the decade.

108dragon

iTrader: (5)

I know that was directed toward me. So allow my reply:
I just had a lengthy pm conversation with Fireball, the moderator who replied here earlier. He and I both ponder the validity of cutting into an already questionably thin l92 deck to o ring it. In short, to improve the sealing, you may have further compromised structural integrity. But at least you can provide us some solid data when you push your combo.
Fireball is running o rings, but with a more solidly designed ETP casting. I would suppose that barring "official" testing this should satisfy both queries from yourself and Texas_WS6. But it never answered my question.
And I am not asking the same question until I get the answer I want. I ask the same question until I get an answer that doesn't deter from the subject at hand. I asked where the breaking point of L92 heads are in FI application. And we get stories of a buddy's buddy's car. At best, nameless individuals who cannot be contacted for more specific information. Or people talking about the 1500+hp they made with aftermarket heads or they'd never use the L92's to begin with. And then there are the guys with the L92's who haven't even run them yet to tell us what to expect.... WHY are you upset? You already sunk "a few thousand" into your L92's. You, of all people in this thread, should want a solid, charted, answer to my question.
The issue here is not proving Veee8, Shawn, and BigRich wrong. I agree with thier professional assessments that the aftermarket heads are better in a max effort FI engine. I want to know exactly where on the powerline and FI line that the L92/LS3/LS7 heads absolutley require upgrade to aftermarket to prevent failure. I'd be content with 800-850rwhp. So if that is the safe limit, then I'm happy with these heads. ...but can you, with all the he-said-she-said information, say without reservation that this is absolute?

BigRich954RR

iTrader: (1)

That what i keep trying to explain there is no line to to draw in the sand. We cant pick the HP number of 923 hp will lift l92 heads there to may different thing that cause a head to lift.

We could draw a line of 5250 psi of cylinder pressure will lift a head. Till some one want to cut up a block to make a presssure test rig no ones going to know. Also knowing what Cylinder Psi the head lifts still will only get you close to the Hp Rating the head will lift at for the same reason there to many factors making up the max PSI in the cylinder

EX.slower burning C16 fuel will make 800 HP at a lower max cylinder pressure then 800hp on faster burning pump fuel. So a head will stay on one 800 hp engine but not the other just because of the slower fuel used.

108dragon

iTrader: (5)

I know GM did this testing with both thier single cylinder test engine and in Beta testing (pre production release) on all thier engines. I'm trying to find thier results on the LS9. This series of engine tests would be closest to what we are doing here and would provide the most accurate information as it applies to forced induction application. If I can scare it up, I'll post it here. I'm hoping GM doesn't consider it proprietary information...