what would you rev it up to

[slakjaw]

ok
i am wondering what is a safe redline for this motor i was thinking nothing past 6500 but thought i would ask

it started as a 2.2 T
now it is in a 7R case
new P&C JE&byral 9.9:1,, .020 oversize
same T crank and rods, recently reconditioned and balanced
Solex cams
new valves and springs
ports opend up to 36mm S style

i had the windage/breathing mod done to the case anyone know if this actually helps like BA says in his book.
I wanted to change to an S counter weighted crank but the telephone co laid me off and i ran into money issues, I was kind of worried that the T crank may not be as strong as and could cause problems if i were to rev it up too much.

the pistons were balanced too


Thanks
Kyle
71 911

[silverc4s]

If you used the stock rods and rod bolts, I would stay below 6800 rpm. The T crank is not necessarily weaker (it's still forged), it just has no large counterweights, so it may have more natural vibration than the fully counterweighted one.

Your top end is as revvable as any factory version, just the overall strength and durability on the bottom to look out for.

Where is the HP peak for the Solex cams? It is not real high, as I recall, so that's a plus. Sounds like you have a nice engine, how does it run??? Did you add an external oil cooler? What oil are you using?..

[cegerer]

I've got basically the same motor, except for 90mm RS pistons and 70,000 miles. I take it up to 7300 RPM almost every time I drive it! -- Curt

[Chuck Moreland]

I have a similar t to S spec motor. I turn 7300 and haven't had any problems.

I have S cams. Your Solex may run out of steam at the top end, so you may not benefit from revving that high.

[dtw]

I've got a similar question, perhaps it will provide some contrast/comparison on the original question from Kyle.

-9.5:1 JE 2.4 pistons
-4R case, E crank
-GE60 cams
-std rod bolts and case studs - I can still upgrade but would prefer not to.

I can dial in my own redline to keep me honest with the ignition I've got. Where should I set it?

[zuffenhausen]

Originally posted by silverc4s
The T crank is not necessarily weaker (it's still forged), it just has no large counterweights

According to BA, the T crank is cast, not forged, but the real problem is with the lack of counterweights and that causes vibration at high RPMs. It's not an "instant destruction" problem, it's a longevity problem (I've actually seen vintage racing engines built with the T crank, but they don't have to last long). At high RPM, the T crank will beat the main bearings and will surely exacerbate the out-of-round problem of the main bearing saddles of magnesium crankcases. For the sake of longevity in a street engine, I'd keep it below 6800RPM. Remember, the T engines had a mild cam that didn't make any power up there anyway.

As for you, dtw, set that rev limiter at 7000RPM until you get familiar with the car and the powerband of that GE60 cam. If you find that the engine power hasn't started to drop by 7000, you can bump it a couple hundred RPM.

-zuff

[Plavan]

We have been using T cranks in our race motors for a long time without any problems. The benefit of the T crank is that it revs up much faster which is good for racing. We are by no means big money racing, so we do not want disposable motors. We freshen them up every year or 2 with new bearings (around 50 -60 hours) We even had one motor go to 94 hours with a T crank without a rebuild! We keep these motors at 7300 -7400 RPM. Just make sure you have very good oil cooling.

[silverc4s]

Whatever Bruce A. has to say about the crankshafts, the Porsche spec books say ALL 911 cranks are forged, and I believe the spec books are accurate.
The T cranks are very revvable, IF the rest of your bottom end is strong enough...raceware rod bolts, shuffle pins, external oil cooler, etc...

[J P Stein]

The Solex cams in my motor pull well up to redline......varible depending on what chip is in the MSD.....7100 or 7300. I take both to an AX. Usually start out with the 7100. The 7300 goes in if needed. Haven't got the guts to put the 7500 chip in there.

It's really stout from 4k to 7K.
I'm sure it falls off somewhat above 7K but, when you're trying to stretch 2nd gear out for that last few feet, who cares?

[Matt Smith]

Just in case anyone was interested or unaware, in 1972 the T's got the same crank (and with a different space cam, MFI ) as the E as S.

Thus producing the ultimate early car bargain.

[michel richard]

I have a stock 2.2 E that I have taken to 7500 in 2nd gear without breakng anything, 1,000 miles after a complete rebuild. Absolutely no damage. I've taken it to 7,000 numerous times.

My wrench says he has taken his 2.2 S to 8,000 but he believes he got valve float there, again, nothing broken.

HTH

Michel Richard

[tobluforu]

My 72, T crank, e cams is snappy as all hell. I have brought it up tp 6900. But, it is only good to about 6400. Anything after that is almost useless. Better to shift around 6400. I run the hell out of my car. Total miles on crank=179,000. Got I hope I didn't just jinx myself.

[slakjaw]

thanks for all your replies to this post

the motor will prolly give me a few of those instant ear to ear smile ,fast runs to 7000

ill try to keep that to a minimum though,, HA

its about 90% done at the moment i am gonna try and post some pics one of these days

again thanks for the replies

LATE
Kyle
71 911

[dtw]

zuff-

I believe you've got a non-counterweight T crank in your garage. Why not head out there and take a look at it. There may be some visible clues as to whether or not it is forged.

-dtw

[Plavan]

All Porsche cranks are forged. I have 3 "T" cranks in my garage on my shelf.