Cylinders -- some questions

[Matt Holcomb]

Last night we slid the cylinders off and separated the pistons from the rods.

Cylinder #6 is cracked! The crack runs down one of the stud holes; the fins have cracked, too. Can this cylinder be welded, or is it toast? I suspect the cost to repair it would be more than the cost to replace it.

Also, cylinders #3 and #5 have a couple of fins with small segments that have snapped off. Do they need to be repaired/replaced?


Matt Holcomb
1974 911 Carrera 2.7 Euro-spec
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[This message has been edited by Matt Holcomb (edited 08-08-2001).]

[Roland Kunz]

Hello

Can you make some pictures ?

Well I suguest to junk them anyhow as welding will cost more then new ones.

Grüsse

[Matt Holcomb]

Roland, I'll have some pictures soon.

Just to clarify, the cylinder lining isn't cracked, just the third (outer) layer which the cooling fins are attached to.

The guy who's going to reassemble most of the motor seems to think that we can re-use this cylinder.

If anyone is interested, the cylinders are 89mm, not 92mm! Yep, they're custom cylinders, and they've been made from cast iron!

Interesting, eh?


Matt Holcomb
1974 911 Carrera 2.7 Euro-spec
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[peter]

Hi Matt.

The cylinders you have must be 80 or 84 mm T cylinders that have been bored up to 89 mm. You might consider to get a set of T cylinders and get some of then bored up to match the others. I dont know what i would cost you, but putting an engine back together with bad parts would ruin my night sleep. Good luck with the engine project.

MVH Peter

[CamB]

Hmmm

I am gonna bump this back to the top and ask a couple of conceptual questions.

{idiot mode on}

The last post here mentions boring out 't' cylinders. I haven't looked at mine too closely (in other words, all I have done is look from the outside only, while on the engine). How much can these things be bored out? I mean, if Matt's old cylinders were bored from 80 or 84mm to 89mm that is a lot of material on the floor in the machine shop.

I also remember "Iris" has 3.0 cylinders bored and sleeved to 3.2. From memory this means going up from 95mm to 98mm, plus however much got bored out for the sleeve? Once again, it seems like a lot of material being taken off.

So, the question is, are my cylinders good for anything? Anyone who has ever driven a 2.0T will tell you they aren't exactly a high power engine. Mine has E cams (according to the PO's PO) and is still relatively gutless...

It might go better with RS size pistons (2.5 litre), or Matt's pistons above, but I am poor, so not only would I need to talk Matt into cheap pistons, but would need to find cheap cylinders.

By the way, Matt, I haven't seen what you are doing to your old cylinders to reuse them for the new pistons - the JE ones. You only mention they are ovoid - does that mean you will have them bored to 90mm from the custom 89mm they are at the moment.

{Idiot mode off - end of stupid questions}

I guess I need some educating here... I have asked some stuff I really ought to know the answer to...

Thanks

Cam

------------------
Cameron Baudinet
1975 911S (in bits)
1969 911T

[This message has been edited by CamB (edited 09-04-2001).]

[rvanderpyl]

EBS has JE Pistons, 81MM for bored 2.0 liter and 85 mm for bored 2.2 liter Biral cylinders. That's about as much as they recommend taking off, Matt's must have been sleeved to go that big.

A set costs $995.00 and boring/honing costs $300 a set. You can get any compression you want so you could bump your T motor up to S compression for a reasonable power boost.

Robert

[john walker's workshop]

i've seen a lot of cracks in sleeved cylinders. especially on race motors. so i don't use them unless the customer signs a waiver leaving me not responsible. i'd trash them. trouble is the thinner it gets, the more it's tendency to go oval. there's also little support for the sleeve. either buy big bore, or go stock nikasil cylinders with J&E pistons to fit.

[This message has been edited by john walker's workshop (edited 09-04-2001).]

[CamB]

Or go 3.0 or 3.2...

The car is hardly original anyway.

So it seems you can edge a couple of mm or so, but not lots? And then, as JW said, you get into a higher chance (or shorter time?) to ovoidness?

Thanks for opinions/help.

Cam

[Matt Holcomb]

Originally posted by CamB:
By the way, Matt, I haven't seen what you are doing to your old cylinders to reuse them for the new pistons - the JE ones. You only mention they are
ovoid - does that mean you will have them bored to 90mm from the custom 89mm they are at the moment

Cam,

I've decided against retaining the cast-iron cylinders. Actually, my wrench, John Gregory, talked me out of it -- he thinks a set of (used) 90mm Nikasil cylinders is a much better long-term prospect for these new 90mm JE pistons I've ordered, and when John says something like that, then it's usually prudent to do exactly what he says!

So, I've got the 89mm ARIAS pistons and now the ovoid cylinders sitting in a plastic tub in the laundry ...


Matt Holcomb
1974 911 Carrera 2.7 Euro-spec
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