Question about 4.1 Block

[geetee]

I purchased 4.1L 291 block. I took it a machine shop to get it cleaned up. They said the cylinders would clean up at 20 or 30 over. My question is do they make pistons that size. It might sound like a stupid question but I'm new to the buicks.

 

[hotairgnx548]

I purchased 4.1L 291 block. I took it a machine shop to get it cleaned up. They said the cylinders would clean up at 20 or 30 over. My question is do they make pistons that size. It might sound like a stupid question but I'm new to the buicks.

You need to get in touch with Mike Litch or Earl Brown on this site. For many years the only piston was the hypers and they are not good for racing. The one I had ran 11.30's hot air set up. John

 

[Nick Micale]

It would be best if you work with your engine builder to source the pistons and rings.

Bore as small as possible, and we find 4.0" bore and larger will get you a proper piston and ring package.

Also, you need to decide on the compression ratio you want so the dish in the piston is compatible with the block and heads.

Over the many years and builds of 4.1 turbo engines, we have a "selection" of custom pistons from the 2 major manufacturers we use.

You would not be happy after spending big bucks to find out pistons/rings would not work out for your block? We completely machine and prep the block before we order pistons.

We had a customer order a complete rotating assembly for a 4.1 build, and it would not work in his 4.1 block. Fortunately we had a few other 4.1 builds going through the shop at the time so we were able to work it out for him.

 

[earlbrown]

Here's what I've came up with the last couple years...

http://turbobuick.com/forums/threads/whos-building-an-engine-this-winter.419495/

I'm in the same boat as you are. After building my 4.1 with hypers (and cracking two of them on one of the first test drives), I decided to make a cost effective piston.

What REALLY sucks is my car starting losing a hole and pulsing oil out of the PS breather 3 days ago... Looks like I didn't get my pistons in fast enough!

Here's a thread where I was crowdsoursing just in case I missed an idea....

http://turbobuick.com/forums/threads/what-would-be-a-dream-piston-for-the-average-build.395533/

 

[geetee]

Thanks guys!!! I appreciate the feedback. I'll do what Nick suggested and let the engine builder figure it out.

 

[Undercover87T]

First version of my 4.1 had a stock crank, rods, and .030 hypers. The hypers were the thing I was worried about the most and limited how much i could push the combo. Hard to find rings in that bore size too. 4in bore is a SBC size and lots of options available. Depends what you want to do with it but if your going to push it, do it once and get forged parts.

 

[Ttype6]

My short block is still on the engine stand waiting to accept my heads. I went with a 3.625 stoke with 6.350 rods and 4" diameter pistons and purchased it all from Dave at turbo Buick Performance. Your only choice is a custom made piston. You can see that these are very robust. They're made from 2618 material. That's as good as it gets.

 

[geetee]

The block looks great, pistons too. Looking for an engine builder in my area NJ. Hope to start the build around March of next year.

 

[David Husek]

The block looks great, pistons too. Looking for an engine builder in my area NJ. Hope to start the build around March of next year.

Contact me when you are ready. I am located on long island and can build the engine for you. I can supply you with everything you need to build the engine.complete

David