I have the opportunity to get a 4.00 crank at a great price new. My car only has the mods in my sig and is an a4.

It is also a cast crank but this will not be sprayed or taken to the track so I think I will be alright. Heads are unported and will be for some time. Thinking of getting a small cam and not revving over 5.8k. So what else would I need besides the crank? I know there are people that replace every little thing but if I could get away with just the crank that would be nice.

 

Your gonna need more than that. Probably need shorter rods and will have to have new pistons. That's assuming a 4" stroke can be clearanced to clear the pan rails and it will clear the cam.

 

Dont think it would be worth it to run stock heads and a small cam w/ a 4" crank. You will see a lot better power gains by using a slightly bigger cam and leaving the crank alone.

 

4.00 inch or 400 (3.75") crank? Figure atleast 2500$ to get the lower end built to run a 3.75" crank amd nearly 3 times that amount to run a 4.00" crank in an LT1 block, if it will even fit in the first place. A 4.00" crank requires major clearancing of the block. Limited choice of rods, custom pistons small base circle cam, oil pan etc. Most of the small blocks running 4.00" cranks have blocks with raised cam journals because its so much stroke it hits the camshaft. Plus to make the most out of that large of an engine, you'll need a killer set of heads, like AFR 210s. You'll be over 10000$ in no time.

 

See thats the thing, from what it sounds like he just wants to put the crank in, no heads, small cam. Way more work/money/time than its worth, the gains will be minimal if anything.

 

Ya will need an early SBC block and all the changes to change the car over to conventional cooling or an after market block.
Ya hit water with a 3.875 crank or the bottom of the cyls are so thin it will crack.Some people hit water with a 3.750(383) crank.

 

I wonder if a partial blockfill would help with the bottomend clearancing but that still leaves you will the other issues. As noted too the motor would suck with stock heads. People REALLY need to learn that heads are more important to power than bottomend. If you only have the money for one do the heads first every time.

 

Bad idea.

Rich