4.1 pistons for 4" bore??

[charlief1]

Does anyone have a part # or manufacturer that makes a 4 inch bore piston for the 4.1 block?

[1chance]

summit H471C

[49-blues]

the 471s are hyper cast pistons-can be brittle , I have a forged set of Ross 4.00" pistons for a striker combo for $300. Shipped that I'm not going to be using

[Nick Micale]

Originally Posted by 49-blues

the 471s are hyper cast pistons-can be brittle , I have a forged set of Ross 4.00" pistons for a stroker combo for $300. Shipped that I'm not going to be using

If they are new, as in never installed, send me the complete spec sheet on them. If they are like what we need, can use them, thanks.

[49-blues]

Nick- they are new-i know the comp height is 1.200"-i can get the rest of the specs on thursday-they re up at my garage. i also have a brand new set of Diamonds 4.00" bore with a 1.640" comp height- not sure what combination of stroke and rod length you would need for these and there are 8 diamonds in total. also looking for $300. shipped for these also. The original post should have read "stroker combo" not striker.

[Nick Micale]

OK no rush, thanks, just get me the spec sheet on the Ross pistons as we do use them as well as CP.

[wickedtt]

Originally Posted by charlief1

Does anyone have a part # or manufacturer that makes a 4 inch bore piston for the 4.1 block?

Forged J E pistons
Piston P/N 271718.
Pins 940-2750-16-51S
Rings J100F1-4000-5

[charlief1]

Let's try this again. What's a striker combo? And what I've been thinking is there a simple replacement piston that's for an engine with a 4" bore that would be able to go into the 4.1 bored to 4"? I was thinking that I would use a 3.0 rod (6.33") instead of the stock rod. Kinda like using a 6" rod in a 350 chevy. Increasing power levels and allowing a different rotating mass.

[getchasum]

Originally Posted by charlief1

Let's try this again. What's a striker combo? And what I've been thinking is there a simple replacement piston that's for an engine with a 4" bore that would be able to go into the 4.1 bored to 4"? I was thinking that I would use a 3.0 rod (6.33") instead of the stock rod. Kinda like using a 6" rod in a 350 chevy. Increasing power levels and allowing a different rotating mass.

Charlie, Webber has an off the shelf Wiseco for the 4.1, I'm thinking it's .035 over which would give you a 4" bore. I wish other vendors carried something off the shelf in a J&E....there is a demand.

[charlief1]

Thanks getchasum. I've been doing some homework on my idea. The stock piston compression height is 1.825.(3.8 or 4.1) A .125 over 283 piston has the same height which is a 302 chevy. The 300 ford inline is the same as well. If you substitute the 3.0L rod your pch changes to 1.53 which is the same as a sbc 350. You can check out the findings here.
United Engine and Machine Co.
They have some interesting calculators you can use to see what you want as far as a piston. Since I'm not planning to do a 10 sec or faster car I'm thinking about the 3.0 rods for better power. After all changing to a 6" rod in a sbc does give better power due to the change in the rotating mass and rod to stroke ratio change. My biggest question is whether the 3.0 rod is strong enough to hold up to a turbo. Does anyone know anything about them? I'm not planning a whole lot of boost in this thing but cam, ported heads and adjustable boost is a must. I'm looking for a fun car that sees the track once in a while, not a trailer queen.

[ijames]

Dave Williams proposed this as a possibility (the 3.0 rod/chevy piston) at least 12 years ago on the old gnttype mailing list. Someone posted a picture of a 3.0 rod somewhere several years ago and it looked a lot thinner and weaker to the eye than the 3.8 turbo rod. I don't know anyone who has actually built a 4.1 this way.

[49-blues]

wickett- whats the horsepower rating on those je pins?

[wickedtt]

I have no idea on HP rating but their Forged J E'S so I would think they could take a real good beating

I all for $699.00 + shipping
Forged J E pistons
Piston P/N 271718.
Pins 940-2750-16-51S
Rings J100F1-4000-5

[ATEURV8]

I too have been hoarding a set of 3.0 rods and a 4.1 block for years. I keep thinking about it and have never got to building it yet. I guess I am waiting for someone else to do it first!

I dont think the 3.0 rods are much different than the 3.8 rods as far as a visual check of the "beefiness" goes. I thought a good set of rod bolts and see what happens. I don't want to make huge power either. so I thought about hypers. but I guess I never thought about small block pistons in the sense of cost (i.e. cheap forged) before either. Hummmm......

[49-blues]

Nick the specs on the Ross pistons are: 4.00" bore , 1.205 comp height , .927 pin dia , 2.500" pin length , 100M # 67045A .The pin does not go into the bottom ringland. Just pistons- no pins or locks.

[Nick Micale]

Originally Posted by 49-blues

Nick the specs on the Ross pistons are: 4.00" bore , 1.205 comp height , .927 pin dia , 2.500" pin length , 100M # 67045A .The pin does not go into the bottom ringland. Just pistons- no pins or locks.

If the "#67045A" is the job number, we can check with Ross and see if these have the same specs we use as the ring land thickness and other items need to be within our requirements, thanks.

[Nick Micale]

Originally Posted by charlief1

Does anyone have a part # or manufacturer that makes a 4 inch bore piston for the 4.1 block?

I just want to comment on pistons for 4.1's. Since there never was a production 4.1 built for a turbo application, the replacement pistons were never available from the factory or aftermarket.

We have done many 4.1 turbo engines, and only use a custom piston with the proper ring lands, dish CC, pin location and other specs.

Having rebuilt some customer's engines, we have found the off-the-shelf pistons do "work", but performance is compromised especially if other machining is not done to compensate.

For a street build, the pistons available probably will do fine. For a performance build, they may not perform to expectation, or may not be as durable.

Most all of our engines have custom pistons, built to our specs by both CP and Ross. Explaining to the customer that when spending thousands of $$$$ on an engine build, getting the extra few $$ to get the best piston available is usually easy.

Just to verify our turbo Buick engine experience, we have 12 builds currently in process [most from out of state] including 2 TA blocks, 2 stage II, 1 stage I and the rest 109 blocks. At this rate, we will reach our grand total of 500 Buick engines built by the end of the year.

Oh, turn around time is usually 6-8 weeks depending on parts and special needs since we do ALL machining in-house. Our best time was 5 days for a GNX re-build!

[charlief1]

Ateurv8, if you have a camera and a set of calipers post a pic and some differences in size at locations on the rod. I'd be interested in seeing the diff myself.

[49-blues]

Nick that 500 milestone is very impressive.

[ATEURV8]

I will but I won't be back home till Sunday the 3rd. If I don't post it soon after that, stay on me! I tend to have a short memory!!

What were we talkin about???

[49-blues]

Nick-that number should be the job number its scatched into each piston.