I was getting ready to upgrade my stock pistons to a set of high compression forged pistons when my buddy who use to build circle track engines all day everyday said I should look into doing a offset grind set up first to get a little more out of it. I was wondering if anybody new of good set up that would work with a set of off the shelf pistons. The price of custom pistons makes it not worth doing . I was kind of planning on upgradding my rods anyway along with the pistons so I figure it couldn't hurt to look into it

 

The problem with doing that is the crank is only heat treated to a cartain depth. Dont know exactly how much that is, but the journal will lose its wear resistance because of the metal being softer. You could offset grind it to 1.88 (Honda rod journal) and have it cryoed. But you would have to buy rods. For that much trouble you could go forged. Its prolly not worth the headache.

 

nooooooooooooooooooooooooooooooooooooooooooooooooo ooooooooooooooooooo not forged!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:d

 

If you offset grind the crankshaft you have to worry about deck height. Where are your pistons going to be at top dead center?

On a small block Chevy the pistons are usually around .025" in the hole. If you offset grind the crankshaft you can gain .018" stroke. This leaves the pistons around .007" in the hole. With the right head gasket it makes it easier to get the proper quench. However you only gain around 2 cubic inch if that depending on the bore.

Doing this on an LS1 is a different ball game. You need to do the math and and throughly check things out.

 

nooooooooooooooooooo not forged!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

On the Gen I motors they have been offset grinding cast cranks for years. The first 383,s were arrived at by taking a 400 cast crank main down from 2.65 to 2.45 if I remember right. I dont see why you couldnt offset grind the rod journal as long as you take the appropriate amount off the flats of the piston to get the deck height right also requires the use of a small journal connecting rod. Check into Speed-o-Motive, maybe Crankshaft Specialties, Chrome a shaft etc, dont remember who,s still in business. Maybe the radius is different though? call one of the shops mentioned aboved.

 

Offset grinding the old SBC cranks is an old 'cheater trick' to eek out a tiny amount of power by a slight increase in stroke, cubic inches, and compression. Usually in various stock type racing classes that don't allow much deviation from stock engine specs... sometimes being physically restricted, sometimes just visually.
With such obvious restrictions, and the lackluster power potential of stock SBC combinations (mediocre compression, relatively short strokes, small runner volumes), racers would look for every advantage they could implement without blatantly breaking the rules. Hence, this mathmatical manipulation through just re-machining the existing stock crank.
The power increase from this was probably never astounding, maybe noticeable on an engine dyno, and possibly (with proper gearing, fueling, and tuning) just enough of an 'edge' to make one's combo superior over another's, but only a worthwhile endeavor under such relatively strict class rules and limiting factors relating to the use of only stock components. I don't think trying to save money was ever a consideration.
I can't imagine it would be worth the time or trouble for building a LSx combo. With the LS1's longer 3.62" stroke, improved compression and combustion efficiency through better quench/closer tolerances, and obviously excellent cylinder head potential... the physical 'small block' penalty in this case is the LS1's 3.90" bore. If you are planning on using your stock crank, but getting new (affordable) pistons and rods, I would consider looking into a LS2 or LS3 (or 4.00" iron) block and concentrate on gaining power and cubes through increasing bore size. This will help unshroud the valves for better airflow, and still be able to use a readily available off-the-shelf piston.

 

Who does this Sevice in the Houston area?

 

If you read this whole thread you would see that there are more minuses than pluses for minimal results. Nobody does it in the LS world.

 

I’ve done it in the past with great success

 

How much displacement did you gain? What did you do to heat treat the crank?

 

I could see doing this for class racing but that would be the only reason, It's cheaper and you have better option going with an off the shelf stroker kit.

 

Pete's Crank Grinding and Repair. His shop is around 1960 and Jones Rd.

Be forewarned though, he may turn it down if you take him a stock LS crank. You would need to have the journals turned down to a Honda size or similar.

 

As said, these days it's not worth the effort unless you're building within some restrictions, or get a KILLER deal on some billet crank. Back in the day when stroker cranks were exotic and expensive, it was a good budget way to gain a few cubes and some torque. These days, when you can get a cast stroker crank for opening a bank account because it's cheaper than a toaster (yeah, showing my age), it's not worth the hassle. Heat treating being only .030-.060 (depending) would require a retreat. That cost alone would run what a cast stroker does. Then you get into the fact that it's hard to find a GOOD crank grinder, and you won't know he did a shoddy job until it's home and paid for..........it's just not worth the cost or grief.

 

Bad idea. For the cost vs power gain and the lack of strength the crank will have after I wouldnt. Turn the motor a couple hundred rpm more and it will make more power doing that.