macined 94mm barrels to 90.5mm

jakriz · Post by **jakriz** » Sun Jun 16, 2002 1:07 am

I was wondering if anyone is running or has any experience with machined down 94mm barrels to fit into 90.5mm bore in the case. Its to save me splitting the case again which I've just put back together, & also to keep a little more meat in the case.
regards
Jak Rizzo
Downunder http://www.porscheclub.org.au/images/ga ... perbug.jpg

bottle fed bug · Post by **bottle fed bug** » Sun Jun 16, 2002 12:50 pm

I do not think that you can turn 94 barrels do to fit into 90.5 and if you can it would be very thin and not safe

Frozen in AK · Post by **Frozen in AK** » Sun Jun 16, 2002 12:57 pm

If you want more displacement without splitting the case you should probably get a set of 92's, but they aren't great either. They should fit the same case bore and head bore too, but they have thinner walls which causes blow-by at the heads and can also allow them to distort easier too. Best way is to bite the bullet and tear it down for the machine work to get the 94's.

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Jesse McCormack

jakriz · Post by **jakriz** » Sun Jun 16, 2002 1:02 pm

Thanks guys, its just that I was told that there a few shops in the states that already sell the barrels machined, I think that Rimco was one of them, or is this not true?
Jak

Tate · Post by **Tate** » Sun Jun 16, 2002 1:05 pm

Actually, yes. Rimco does this. There are a few guys on the CLF who have motors built like this with no problems. The only place where it is thin is where it goes into the case, no real strength issues, and some believe it is better because you don't bore the holes in the case so close to the studs. I was looking at doing the same thing and got positive responses from people who are already doing it.

rcb78 · Post by **rcb78** » Sun Jun 16, 2002 2:46 pm

Only negative things I've heard are from those who haven't tried it for themselves. Those who are running them say they've had no problems. --Ryan

Barry · Post by **Barry** » Sun Jun 16, 2002 3:20 pm

Ryan

Do you know if Mikey went ahead and got a set of those? - he said he was

Eaallred · Post by **Eaallred** » Sun Jun 16, 2002 4:05 pm

One of the guys running 94's like this, is goes by the name "Bugly" up in Washington state. He's running them hard in a bus. He was actually the first person I heard of having this done, and still has had no problems.

Like Ryan said, the only negative I've heard is from people that haven't done it yet. So far, the track record is good for them.

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Eric
64 Bug
64 Bus

rcb78 · Post by **rcb78** » Sun Jun 16, 2002 5:15 pm

Good to see familiar faces while our board is under the knife.
Barry, not sure about Mikey. I don't think he had made up his mind yet before the board went down, and haven't heard from most of the guys since. I only recognize a few names over here. Maybe they'll catch on a start posting here untill Supe gets things worked out. --Ryan

bayareathrasher · Post by **bayareathrasher** » Sun Jun 16, 2002 5:28 pm

hey dude im here, just not posting that much. im suffering withdrawls since the SBO! is down, but yeah i dont recognize that many handles overhere

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John Bradley - MASSIVE Apprentice
Raby's Aircooled Technology
www.aircooledtechnology.com

James2 · Post by **James2** » Sun Jun 16, 2002 6:43 pm

I think boring the block is a better option, but if you don't want to split the case, the machined barrels work.

The barrel is going to be REAL thin about 1 mm or .040 of an inch.

Mikey · Post by **Mikey** » Sun Jun 16, 2002 11:04 pm

Hey Guys, Good to see ya around while the super forums are down.
Barry, I have not purchased Pistons yet, But I will be getting a regular set from Aircooled.net.
The case that I am getting has 8mm case savers so I still have room to Bore the case.
But for those of you that are thinking of getting ones with turned down skirts, Id say go for it.
Remember that it's going to cost the same to machine the barrles as it will cost to machine the case. but it definaltey makes things easy if you don't want to split the case.
Later Guys.
Mike (when is SBO forums open again???)

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Driver found VW

Bruce2 · Post by **Bruce2** » Sun Jun 16, 2002 11:54 pm

Sounds like you don't have enough time to do it right, but one day in the future you'll have all the time in the world to do it over again.
I had a 78x90 engine that the PO had built with non-standard case bore and turned down cylinders. It will technically work. Mine had a wall thickness of 0.75mm, and lived over 80k miles before the crank broke and took out the P&Cs. The annoying thing is that I had to bore the case for the second time in its hi-perf life. If you turn the cyls down, when you need a single, you will have to dick around getting one turned. All because you are too lazy to do it right the first time.

jakriz · Post by **jakriz** » Mon Jun 17, 2002 3:56 am

How thin are 92mm barrels then? surely they must be close in width to a turned down 94mm barrel?
Jak

Searoy · Post by **Searoy** » Mon Jun 17, 2002 8:29 am

Most guys who say no f-in way on doing it this way misunderstand, not that any of you guys do. I just want to clear it up for any lurkers.

We are not considering boring our 90.5mm barrels for 94mm pistons they way that they do for 92. 92s are possible the worst piston choice ever and doing that for 94s would be much worse.

Instead we are suggesting that 94mm barrels be machined at the base, where they fit into the head. Strength is not an issue down there so the neither the case nor the cylinder strength is compromised. Not all the exposed area of the cylinder is machined, nor is the section that fits into the head, so cylinder wall thickness in and around the combustion area is the same as stock.

Some racers have done similar things with 96mm pistons for Type 1 cars. Super thin, but hell, it's a race car.

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*** Teach a Man to Fish ***
Darth Searoy

"I tend to lean toward a tighter gap and a
looser skirt....a little slap never hurt." -- Joe of the West