I have a friend looking to put a set of L92 heads and a L76 intake on a stock bore LS1/LS6 block. The plan is to use the 4" bore head gaskets. (yes we know the bores do not match)

He has fuel rails and injectors to use. Is there an reason this won't work? Any possible consequences? Just curious.

Thanks in advance for the assist.

 

 

I think i read an article in engine masters where they did that but it was on an LSX block. They had great success doing it. I will see if i can find the article.

 

Good luck trying to open the valves when the heads are bolted on the block.

 

No no no no no no no no no....... Tell him to get get a LQ4/9 iron block yes yes yes yes yes.......

 

If he already bought the heads he wasted his money, time to sell them.. they don't fit.

 

the l92 heads need a minimum of a 4.00 bore. if he puts those heads on and tries to run the engine the you'll have a great excuse to buy new heads.

 

The reason they wont fit is because the huge valves wil not clear the pistion walls.

There is no fix for this. also in a sense your trying to slap big block headers on a small block engine, even if you found a way to make it work which you wont I doubt if you would see much performance gain from it. it might even lower compression.

those heads are ment for 4th gen engines only. hope he has not gotten them yet, if so its time to sell or trade for some good ls6 heads.

 

I'll buy them if the $$$$ is right and scrap my 383 plans,,, I haven't bought anything yet but was gonna use some of my current stuff in the 383 for a budget build....

 

Ok, I'm curious. I've read lot's of people say that this combo will not clear at all, but has anybody tried to measure the clearance and see how close it really is? If you think about this, the difference in bore diameter between an LS1 and a 6.0L engine is 0.100, meaning the cylinder wall is only 0.050 closer on an LS1 than a 6.0L.

I can't suggest this is a good idea, as I imagine that shrouding to be a bit of an issue, but will these physically fit? Radially, the difference in clearance between a 2.16 valve and a 2.00 valve is 0.080. I found this picture in a thread on cutting valve reliefs to illustrate where the valve is in relation to the cylinder wall (thanks to LS1Formulation!)



Thoughts?

 

Im all ears

 

Bingo!!

 

I'm not 100% on this so I won't say yes or no. What I will say if he's stuck on trying this have him instal light checker springs to manually test the valve movement to see if anything hits. Then check piston to valve clearance. Also you will lose compression. It'll be like 9.4:1 without any milling and on stock pistons. Again everyone says it won't work but I don't know of anyone who has physically tried. Good luck and let us know.

 

you can find those 6L motors for cheap as **** at junkyards. ive even seen soem go local, complete down to the pan with wiring harness for 1200 bucks. im sure theres been cheaper as well.

why has no one tried it? well, as said by someone else on here "because the math wont allow it to work, so why bother"

 

If you are anywere near futral i have a brand new set of L92 bare heads sitting there for $380.

 

need min. of 4.00 bore to run 2.16 l92 heads.

 

I have a thought... you're on the right track. Why, specifically, will this not work? I get it... the width of the valves (they're huge), as they open, must be wider than 4.0" Is that it? Are we going on what GM says (that they won't work, not that they don't fit) or has someone put a caliper on it and actually checked?

If that is the only thing, what's stopping us from having new valve seats installed and running smaller valves? I know, money. But there go your clearance issues and your shrouding issues. You'll give up some intake flow, but it's not the end of the world.

The only other problem I can foresee (other than some new rockers, etc) is that the actual combustion chamber will be too wide. I run a 317 head on my 3.905" LS1 and that's made for a 4" bore. The L92 will work on a 4" bore. If the combustion chamber is still too wide, will milling the heads shrink the width of the chamber enough to make it work?

RLD and Mast Motorsports both sell a "small bore" L92 head. The Mast unit is crazy expensive while the RLD is a little more affordable. I think they both start with the bare GM head, and not their own casting. They got it done somehow, so it can't be impossible.

Everyone goes into "no mode" when you talk about putting L92 heads on a 3.9" bore. Some people don't want to add 80+ lbs to their car with an iron block, even if they get it for free... and some people (like me) don't want to replace their perfectly good forged LS1 shortblock that they spent 4 paychecks on three years ago.

A little good 'ole fashioned American ingenuity can probably solve this problem!!


EDIT: one more thing - the L92 valves are farther apart than the LS1/LS6/LQ4/LSetc valves.

 

a 4.00+ bore engine will use up the head more than a 3.9 bore, and will bring more cid capacity with it, its a win-win. imo
dont have to neccesarily a iron block for l92 heads, can use ls2,ls3 or l92 alum. blocks.

 

Agreed, the larger block is a win-win, but the only affordable block out there that's big enough is the heavy iron block. The LS2, LS3 and L92 blocks are still pretty expensive and not nearly as plentiful as the iron blocks. For guys that have big bucks tied up in a forged LS1/LS6 block, it's a tough sale.

As posted above, the clearance has to be close! Going from the 3.9" bore to a 4.0" bore is a difference of .05" on each side!!

 

Use an AFR205/215 or a TFS215 and leave the L92/3/7 head stuff to the larger bore and bigger motors.