409 is the largest or is there a 427? or bigger and why would someone want to use a 383 over a 409 besides costs?

 

reliability.... I saw a LT1 block in a local machine shop they we're clearencing it for a 396 build and it wasnt pretty, they had welded it up in many places where the castings were too thin because they went through them while clearencing it. I guess the engine wouldnt hold water without leaking into the oil pan. Sounds real reliable to me! I'm sure it partly had to do with the shop but still a forged 383 with a 200 shot should make anyone happy.

 

so what ur saying is that one shouldnt go higher then a 383?

 

I think it really has to do with the shop doing the work. I know of a couple of 408/409 LT1's running around here. It can be done but it's really pushing the limits. It all comes down to what the machine shop specializes in. If they know their way around an lt1, you're good to go.

 

The guys running 427 ci LS1 use the 6.0L iron block from GMC trucks and put in it a 4.0" stroke crank. I'm not sure about LT1 but 409 could be the limit for it.

 

383 is the sweet spot in terms of the cost/performance curve. There is a lot of variation in these castings. Sometimes you hit water even clearancing for a 383 (3.75" stroke). Other blocks have no problem with a 3.875" crank (396). You will almost certainly have a problem with a 4" stroke. Of course, some rods are much better than others for a stroker.

As far as bore goes, 30 or 40 over is the max without getting into sonic checking the bores, unless you are a gambler. I have seen even 30 over LT1's split a cylinder in a forced induction application.

Builinding a very large LT1's is either just for bragging rights (ie you really don't care how it runs or lasts) or would require the availability of a large number of blocks to check and experiment on. Not cost effective. The head choices are quite limited, so a big LT1 stroker makes very little addtional hp over a smaller motor.

Rich

How much do you want to pay the machine shop?

 

YOu could always sleave a block, not cheap to do every cylinder JUST to have a 414 (4.125" x 3.875") or 420 (4.155" x 3.875") or 434 (4.155" x 4.00") LT1....

Keep it at 383 and spend the money on the heads/intake/valvetrain/ECU rather than all the crap you have to do just for a few more cubes.

Bret

 

most people have no problem w/ a 383?

or the reliablity on those is also down the tube?

 

what about offset grinding the crank?or would you still have the clearance issues?

 

Well no need to offset grind since you can get the stroke you need without it.....

You could turn the rod journals down and run a physically smaller rod so it has less issues with the block.

Bret

 

so would you recomend to not stroke it?

 

383 small block Chevy's have been around for decades. It's a proven combo. 396 is also an option with the caveats noted. I prefer the 383.

Rich

 

Wouldn't it be cool if World Products or Dart Machinery would make a cast iron LT1 block that would take the 4.250 bore, then we could build 454" sb LT1s.

 

never gonna happen.....

Hell why people want HUGE cube LT1's is beyond me sometimes.... Get some heads to work on the things first, then spin the SOB faster with a better ECU setup and it will be much faster.

Bret

 

There goes my dream.

I always wanted a 409. I guess I'll just go with the hogged out heads instead and maybe a 383.