Just wanted to know who has acomplished over 400ci in an lt1?

*If so what did you use for internals?
*Largest stroke beofre piston to valve clearance problems?
*How much did it cost you after everything is said and done? *What is the largest bore on an lt1 before the cylinder walls get to thin?
*Is it worth it?

Thanks fo the input,
Tony Semper Fi

 

421ci has been done many times, 409ci being "routine'. 4.030x4"

the 421s I have seen, one was a 4.125 stroke, the other was a 4.090x4".


I think you wil be dissapointed with all the money you spend, hassle you go through, for the little performance boost over a 396. if you want cubes, but a real motor in it(SBC) and go 434+cubes all day long

 

Most people will agree that a 396 is the way to go if you are staying with an LT1 block.

if you are gonna swap a gen 1 SBC in, might as well go 572

 

Tony: this comes up a lot, you might want to try a search. I will give you my take on it.

If you want a really big cube small block, ditch the LT1 and get a Bowtie or Dart Gen I block. It will cost more in the end but will give much better results. The largest I would think of going in an LT1 is 421 (4.125"/4.030"). You could get a couple of more ci out of more overbore at the risk of getting lots of bore distortion or even cylinder cracking due to the thin walls. Frankly, a 4" stroke (408ci) is a lot easier in terms of big end-cam clearance.

FWIW, changing the stroke does not change the position of the piston at TDC. A rod/piston combo with the correct compression height is used to place the piston correctly in the bore.

Cost depends on the parts used. My new stroker is a "379": 3.75" stroke with a 4.010" bore. I wanted thick cylinder walls to stand up to juice+boost, so the block will be partially filled. I didn't want huge hassles clearancing for the long stroke, so went with the 3.75". Cost? About $4,000 for the compete rotating assy, somewhere north of $1.5K for the block (including costs to buy and install steel 4-bolt main caps, fill and purchase the block, etc.). We are going to assemble it ourselves, but even with this being "free" labor it should come to ~$7,500-8,000 for the complete shortblock with reusing the water pump, Opti, oil pan and pump, etc. off of the old motor.

You could do it for a lot less, depending on the parts chosen. But if you going really big cube, it wouldn't be the time to scrimp. I thought about a 408 but felt that the money spent to gain that extra 30ci was best spent elsewhere. A 421 would be off the scale on $$/perforamnce gained.

Rich Krause

 

There is a guy around here that put an LT-1 intake and l98 head's on a 406SBC.
it ran awsome and it really went fast.
he spent $3,500 to build it and got 480hp & 560ftlb Torque at fly wheel.run's on 93octane.
he get's 17mpg beating it around daily he get's 11-13mpg racing on the AVE. But he said drive it nice and it will get 21mpg highway and 19 mpg city witch is awsome.
He had a 6 spd manaul and 3.73 gear's.
he put some 16inch wheel's on it tran some 235/55R16's on the front and some 295/50r16's on the rear lowered it some.
He zip's around the avenue every summer with it.
car is all Black with florecent flame's it's of them see it once never forget car's.his got old school exhaust tho.
shortie header's and 2.25" pipe Glass pack's ,true dual's stainless exhaust.
I thought it was kinda of a restsrictive exhaust for the engine.
But he claim's he Did it some he wouldn't blow it up, it would restricted the flow after a certain RPM so he couldn't over rev it.
so he is only uses like 85% of the engine power so he can be plenty fast and still get along engine life But if you ahev seen him drive it. he drive's it on the week end's, I'm not so sure on the longevity of it but he has been running it up there 4 year's now.