Loss of relibility with the 89.5mm piston?

[Steven]

I have the 440 sleeve in my cylinder now and it needs a rebuild.

Is there any great drawback to running the 89.5mm piston. I know it takes .020 metal (.010/side) out of the sleeve but does this hurt anything? I dont want to resleave if I dont have to.

I don't know is this is pertinant, but the compression ratio will be between 11.5 and 12:1, I just haven't decided yet.

[Steven]

bump...

[Steven]

ok, ho-hum... I'll answer my own post because I called LA sleeve today.

I got a woman on the phone who had to ask. She returned to the phone and said its no problem in a very non-shalont way.

Needless to say, I wasn't convinced. I asked to speak with whomever she asked and she obliged.

A guy came to the phone and gave me the same non-shalont monotone answer and added that the sleeve was designed to take up to a 90mm piston.

So needless to say, I'm not convined but I'm going to try it anyway.

It will be interusting to feel the bottom end of a true 440 with 11.5:1 compression.

Steve

[sleeveslave]

Did you ask what the OD dimension for the body and step of the sleeve is? The only way to know for sure that the information given is correct is to have those dimensions so you can determine wall thickness at 89.5 or 90mm.


Northwest Sleeve
Tech Staff

[Steven]

No I didn't, but I did remind them that this sleeve is tapered at the bottom so it will fit in the case. They still said it would be fine.

I'm not worried about the sleeve in the cylinder, its the thinner part of the sleeve that sits in the case that I'm worried about. I can measrue its wall thickness and post it.

What, in your opinion is a minimum safe all thickness for this coller?

Thanks

[Steven]

If a piston is labled 89.5mm for its diameter, then how does that relate to the piston's circumfurence?

I was playing with some formulas to try to figure out how much metal is removed from the sleeve going from an 89mm to an 89.5mm.

I calculated that the curcumfurance only grows by about .005mm. I don't trust my figures though.

Can anyone explain and clarify?

[deansfastway]

Yeah steven thats your next bore size and I think theres only one more left Your math is all jacked or you dont understand ,I gotta go potty now . Good Luck

[Steven]

The diameter increases by .5mm, I know that but how does that relate to circumfurance?

[sleeveslave]

Steven:

Every manufacturer probably has different but similar OD specs on this sleeve--especially if it is stepped for case clearance. Going back to the dimensions from the early big bore sleeves they made, the step od was 3.600".

At 89.5, your wall would be .038; at 90mm, .028. If the od of the step on your sleeve is 3.600 or less, we would disagree with the statement the sleeve was designed to accept up to the 90mm piston.

Northwest Sleeve
Tech Staff

Hmmm its getting interesting now isnt it steve.

I had gone thru this when recently rebuilding mine (again :( ) and it had the original IMS-JE kit (88.5mm) and I was upping the piston to a true 89mm and the sleeve did come into question.

After talking to the same great guy at LA sleeve who said everything was ok I decided to do some checking around. What I found was that there was plenty of sleeve for the 89mm and that things could get a little thin on the next over bore.

What I had decided was that for now I would re use the old sleeve but would consider changing it out to a non taper and open up the cases in the future, but LA did claim that this sleeve would be OK for the 89.5 as they tols steve.

Sorry but I couldnt find the sleeve thickness or od of the taper now but will post it if I find the #'s.

[Steven]

Thanks, fellas.

So sleeveslave, do I have enough wall clearance for the 89.5mm piston @ .038? You clearly said the 90mm piston would be pushing it, but what about the 89.5? Can I get away with it?

Thanks, Steve.

[sleeveslave]

Steve:

I would love to be able to predict what the outcome would be for you if you go to 89.5 on a sleeve with 3.600 step od. I can't. You might find a truck load of luck and have no problem; on the other hand, if you somehow bump, hit, crack or split that step and it breaks off, stop and think about the damage it could do beyond the cylinder bore.

I know it doesn't seem like .010/side makes all that much difference as you contemplate how far to bore it out, but you can't help but weaken that area of the sleeve with every pass of the boring bar you make.

We clearly state that our sleeve is designed for 88 - 89mm pistons. I have every confidence that it would stand up to the larger pistons because of differences in our material from that of our competitors. But that doesn't mean that I would endorse it's use at those larger sizes.

In our view, if you want to run 89.5 and up pistons the sleeve body should be at least 3.730", with no step and the cases bored. This is just our opinion.

Good Luck.

Northwest Sleeve
Tech Staff