Most of the threads I've looked up on building a 400+ ci LT1 indicate that they are not worth the additional $$$. I'm not seriously considering doing this, but what is involved in re-sleeving an LT1 block? Where would I go to have it done?

 

the problem with it comes into not resleeving it, since there are no sleeves in it. What happens when you build a 400+ci LT1 is the stroke gets too long. I was going to build a 408 but compression height on the piston would be less than 1" which is way to small. It would have put the ring pack right over the piston pin, causing it to not seal. So the biggest combo you can feasibly do to a LT1 block would be a 396. If you want big cubes, go get a little M block that has a taller deck height and then put a 4" crank in it and have it bored to 4.125" and then put some big heads on it and go get a Mini-Ram modified to fit those. Then atleast it'll 'look' like and LT1....

Chris

 

There are clearance issues with very long strokes as well as the problem of short compression height for the pistons. In any case, power potential does not increase linearly with displacement for a stroker as the bore size limits valve size. peak revs will also be limited as the stroke gets longer, unless the very best parts are used.

Rich

 

There are a couple of documented 421ci LT1's but there is no indication how long they lasted. Combos were: 4.030" bore x 4.125" stroke and 4.090" bore X 4.000" stroke. As noted above, getting a long stroke in isn't easy, and going .090 on overbore is next to impossible, without a block that is cast correctly and a lot of work to recenter the bores to put the meat on the thrust side. Hardly worth it.

One of the performance shops offers a 409ci LT1 shortblock.

There's at least on member on cz28.com that has sleeved an LT1 and gone to 4.120" bore x 4.000" stroke for 427ci. You might want to do a "search" here on Advanced Tech, where sleeving the LT1 has been discussed previously.

EDIT: The member with the 427ci LT1 is "chad g69", or something like that. Odd thing is, after going to all the work to get the cubes, he dropped a HOT cam in it.

 

Ok . . . now that is kinda dumb. Although, a motor that size probably can't get enough air from LT1 heads anyway; it was probably a torque monster.

 

depends on the heads used...if you get the big AFR's you'll probably be ok. But the AFR 215's would probably be a little too big, depending on the cam. With the right cam you could use all of that head and go pretty fast...again if the motor holds.

chris

 

http://web.camaross.com/forums/showt...light=sleeving

Read the thread. Sleeving an LT1 is a waste. What it boils down to is that if you're serious about making big power out of a big cube smallblock, money isn't an object anyway - so go GEN1, get some nice GEN1 heads, and ACCEL or FAST EFI.

 

I think it's fairly clear that a 3.75" or at most a 3.875" stroke is the practical maximum for a stock block. A 4" stroke is likely to interfere with the cam and require some work to clear. More than 4" would seem impossible without either raised cam bores (ie not a stock block) or a special cam and rod prep. As far as the bore, going 30 over is fine, and 40 over can also be done with a resonable expectation of cylinders with adequate wall thickness for NA. Beyond that, exotic inspection (ultrasonic) and machine work like Fred alluded to becomes needed and you have to ask "is it worth it" in the context of LT1 heads. I'd say no, it isn't. If you aren't going to use LT1 heads, then ditch the LT1 block and go for it with a Dart or Rocket block. These can be had with the cam raised 0.391" and made as big as 454ci (4.125" stroke with a 4.190" bore). Just bring $$$.

Rich

 

Phil the owner of CXI a now defunked shop in Houston(due to a bad record), had a 421ci LT4 in his 95 vette, he also had a rather large shot of nitrous(400-500shot supposedly). He had dyno sheets to prove the power, and the mph when he ran it in the 1/4. He even daily drove the car occasionaly, but he had quite a few problems with it(mostly with the rest of the drivetrain holding up to the power). His car was featured in Corvette magazine a few years back, It had the car on the cover with "1000hp daily driver" or something of the like as the title.

 

I looked into Sleeving all the holes in a LT1. It can be done BUT it does get cost prohibitive. So I re-engineered every thing to go in a SBC Gen-I block and use a stock PCM

It was NOT very hard BTW

 

Do you use a distributor in place of the opti? You just turn off the spark side of the computer?

 

the stuff I designed kept the Opti in place. Althogh a Distributor can easily be used with this system as in the current thread in the forum