What the most you can bore on a LT1 block
whats the biggest stroke you can go with
I want a ton of comp.
please help

 

I suppose I'd only feel safe with .040 but I'm pretty sure you could do .060 and I believe a 4.00" crank will fit with block work, if not a 3.875 crank

 

Do not use bore to gain displacment, the displacement gains will be so minimal and the thin spots in the cylinders really not worth it, plus if anything should happen and it need refreshing there will be nothing left to hone and it would be time for a new block with new clearancing. I know a couple of LT1 Impala guys have gotten 408.xx so they can call it a 409(think old muscle cart era) even as cool as that sounds in a car like that and the guys spending BIG money on engines only a couple of those have been done because all it is good for is bragging rights, think they even had to check a few blocks just to find enough meat to bore. A lot of guys looking to make real power even stay away from 396s because those can place the rings so high in the piston that if you have problems with a power adder you are nearly assured of breaking a ring landing.

 

I have a question for you. How much are you willing to spend here?

 

What's "comp"? Compression? Has little to do with the bore or the stroke.

There's at least one individual who used to post here who did two different versions of a "421" cubic inch engine on the LT1 block.... one with a 4.030" bore on a 4.125" stroke, and one with a 4.090" bore on a 4.00" stroke. To get to the 4.090" bore, he used a hand selected block, did a sonic check on all the cylinder walls, and recentered the bores to maximize the thickness on the thrust side.

There is another individual who posts here that has done a "427" with a sleeved 4.120" bore and a 4.00" stroke.

A shop used to sell (and others may still sell) "409" (4.030" bore x 4.00" stroke) short and long block packages

All of those combos require a high level of expertise, and extensive effort at clearancing. Not for a limited budget or the mechanically challenged.

 

I've seen Lingenfelter reciepes for a 409 with a .100 over bore on a LT1 before. But dont base your build off how much you think you can overbore something. Thats a reciepe for nothing but disaster.

 

Ok thanks
does anyone know where i can buy a LT1 409 shortblock.
Is a 4.00 and 4.125 stroke considered to be a BBC crank

 

Do you understand how much money you'll have to spend on the top end to feed air to a 409 cubic inch motor properly? You need to plan a combo out, not just start buying parts. If you've already done so, disregard.

 

When I see you ask a question like that, it makes me wonder if you really understand what you are asking. The LT1 is a "small block Chevy" (SBC), and just because you bore and/or stroke it, it doesn't magically become a "big block Chevy" (BBC). You can build a 396, 427 or 454 with the correct SBC block, and you can build a 396, 427 or 454 starting with a BBC block, but the SBC will always be a small block with an SBC crank, and a BBC will always be a big block with a BBC crank.

 

I totally understand!
I just havent a SBC crank as big as a 4.125 in jegs

 

Then how would you plan to put a BBC crank in an SBC block, with different cylinder bore spacing and different journal spacing?

 

Callies offers a 4.000" Racemaster and a 4.000" Dragonslayer for the LT1.

As for bore size, I never got larger than 4.030 without checking the block. To be honest I have only ever done two at .060 over and the performance numbers weren't enough for me to consider the idea again. A 383 can be made to be pretty damn mean and still keep a lot of integrity in the block.

Both are non-stocking parts and pricey, but if this is your goal I would reccomend either of those crankshafts.

What are your power/performance goals for this package? Are you after cubic inch just for the sake of having it or do you have a certain goal in mind?

 

Where can I find a SBC 4.125 stroke crank
I need a lot of cubic inches

 

Nick:

There's a guy that posts as "airflowdevelop" who claims he routinely builds 427ci LT1's with 4.120" bores on unsleeved LT1 blocks. Made the claim on the Advanced Tech forum, when a couple of us claimed anything over 4.060" was a crap shoot. Yet he claims he sells them all the time to people in the middle-east.

Might want to check this thread - his posts are near the end (Page 2):

http://web.camaross.com/forums/showt...ighlight=Saudi

 

Why is it so important for you to have a lot of cubes? You can build a forced induction 350 motor and get more power out of it. Maybe if you let everyone in on your plans we could help you a little more instead of just saying you need a lot of cubic inches.