Pistons/Cylinders 71 911t 2.2l

sebastianroher · 02-18-2015, 07:22 PM

Hi everyone, I've almost completed the teardown on my 71t motor and one the pistons is frozen inside the cylinder. Likely rusted to the inside of the cylinder due to the 30 years of inactivity. Anyways, I found a set of p/c's on ebay for around 1400, they are JE forged pistons and aluminum cylinders. I was wondering if anyone has used these p/c's and what they thought of them?

Porsche 911 84mm Je Piston Cylinder Kit 2 2 2 4 | eBay

Thanks,
Sebastian Roher

doswald · doswald's Garage

Sebastian, when I had the machine work done for my 71T, I was advised to stay away from the AA cylinders. I ended up boring the iron T cylinders to 85 mm and installing JE 9.5:1 pistons. Used iron cylinders are readily available.

dho

sebastianroher · 02-19-2015, 06:49 PM

Quote:

Originally Posted by doswald

Sebastian, when I had the machine work done for my 71T, I was advised to stay away from the AA cylinders. I ended up boring the iron T cylinders to 85 mm and installing JE 9.5:1 pistons. Used iron cylinders are readily available.

dho

What was the reason they gave for steering clear of those cylinders?

doswald · doswald's Garage

Inconsistent quality.

dho

sebastianroher · 03-03-2015, 12:07 PM

Quote:

Originally Posted by doswald

Inconsistent quality.

dho

What set did you end up going with? I think I'm going to go with JE for the high compression pistons but I'm unsure on my cylinder choice.. Everything is so damn expensive..

doswald · doswald's Garage

Sebastian, I used the original T iron cylinders, bored out to 85 mm. They are readily available used. I replaced the pistons with JE 9.5:1 pistons.

dho

mcaterino · 03-03-2015, 05:06 PM

I did exactly what doswald did. Runs great.

Mike

Lapkritis · Lapkritis's Garage

Any luck the removing the offending cylinder/piston? If the engine is on a stand, I would suggest rotating so the cylinder is on top and then soaking from above with pb blaster. Use a brush to clear any debris from the two of piston/cylinder to let the PB work. If you're in no rush, let it set as long as needed. I prefer to use wood blocks for driving softer metal. I've seen frozen engines clean up surprisingly well once freed and honed. There's an outside chance you'll get lucky still.

sebastianroher · 03-03-2015, 08:22 PM

Quote:

Originally Posted by Lapkritis

Any luck the removing the offending cylinder/piston? If the engine is on a stand, I would suggest rotating so the cylinder is on top and then soaking from above with pb blaster. Use a brush to clear any debris from the two of piston/cylinder to let the PB work. If you're in no rush, let it set as long as needed. I prefer to use wood blocks for driving softer metal. I've seen frozen engines clean up surprisingly well once freed and honed. There's an outside chance you'll get lucky still.

Alas, she was stuck REALLY good and the shop cut the cylinder... We tried mystery oil, kroil, etc. Let it sit, but NOTHING.. I believe there is a picture on my thread of the cut cylinder? If not, it may be on my build thread I have on earlyS... Any leads on 90mm cyl?

R,
Sebastian

sebastianroher · 03-03-2015, 08:25 PM

1971 911t

Lapkritis · Lapkritis's Garage

Ah, tough break there.

You might try the classifieds here on Pelican for a single cylinder/piston. There are a lot of folks here with piles of spare parts.

Best of luck,
Andrew

sebastianroher · 03-04-2015, 11:10 AM

Can these cylinders be bored out to accept a 90mm piston? I'm trying to do a 2.5 spec race motor

tharbert · tharbert's Garage

You have, if original, 84mm P/C's. You can go up to 86mm without machining the spigots. From what I understand, if you don' t have a 7R case, don't other. Talk to Henry at Supertec about P/C options. I found new Mahles too expensive and good used is very hard to find now. Henry had some palatable alternatives.

tharbert · tharbert's Garage

BTW, I'm building a 2.5 with a 70.4mm throw crank and 86mm p/c's...

dennisO · 03-04-2015, 02:03 PM

What kind of gas do you run with the 9.5 compression pistons? Any issues with the lower octane fuels? If you run zeniths, did you change the jetting?

Thanks,
Dennis

sebastianroher · 03-04-2015, 05:15 PM

Quote:

Originally Posted by tharbert

You have, if original, 84mm P/C's. You can go up to 86mm without machining the spigots. From what I understand, if you don' t have a 7R case, don't other. Talk to Henry at Supertec about P/C options. I found new Mahles too expensive and good used is very hard to find now. Henry had some palatable alternatives.

Tharbert, I am planning on doing 90mm so I'm sending the case out to Ollies to get the spigots machined. Probably going to get the case shuffle pinned as well.. I have a laundry list for them so that's where most of my budget is going. New pistons and cylinders are like 4600 (Nickies+JE pistons) that is EXTREMELY expensive (currently out of the reach of a mere mortal such as myself) What are the options I can go as far as p/c's? Don't want to put Chinese crap in my engine. I'll contact Henry and see what he recommends. I may just get my cylinders bored but I have to purchase one as we had to cut a cylinder to get the piston out.

sebastianroher · 03-04-2015, 05:18 PM

Quote:

Originally Posted by dennisO

What kind of gas do you run with the 9.5 compression pistons? Any issues with the lower octane fuels? If you run zeniths, did you change the jetting?

Thanks,
Dennis

Dennis, I hope we can get away with using high octane gas... I don't want to build a motor that can't run off of pump gas... Currently exploring options other than zeniths.. I've got a few leads on webers but everyone I come across are in the 2k range and by the time you do a rebuild, put in what you want, etc. PMO is looking like a viable option, but is quite expensive as well ($3400)... Time to take out a second mortgage?