911SC 3.0 Rebuild and Upgrade

[Ryan_Cunningham]

I purchased a 1981 SC back in May and absolutely love it. It’s seen far more use than my hotrod 1972 T with it essentially being my daily, plus I can take my two monkeys and wife around in it! With that said, it consumes about a quart of oil every 600 miles so it seems a refresh is due, which is corroborated by my mechanic having looked it over.

Now I considered simply just rebuilding it and leaving it stock, but I really enjoy this car and would love to get around 250-275hp. I was told it’d be roughly $15k for just a rebuild and in order to hit somewhere around the numbers I’m looking for I’d be all in for $30-35k.

Parts and options we discussed are listed below:

EFI - Bitzracing, X-Factory, Clewett being some options
GE80 camshafts
98mm Mahle pistons
74.4mm crank and 23mm wrist pins
Heads port and polish
Bore case
J&B dual plug distributor

I know this might not be the most efficient use of funds, some might argue sell it and buy a car with the upgrades you already want, but with the addition of an IROC front and RS rear bumper, she’ll look exactly as I want.

So what am I missing? I plan on taking time off work to assist with all the tear down, reassembly, and reinstall and finishing Dempsey’s “Porsche 911 Engines” and Anderson’s “Porsche 911 Performance Handbook” before the process commences.

Any recommendations? And I have read the “3.0 to 275hp” thread three times!

Thanks!

[Dpmulvan]

Your not going to get 275hp out of a 3.0.

[ahh911]

Heads up, your oil consumption is 65% of the average oil consumption specified in the Porsche published technical specifications including later revisions. Here is the 1981 revision of the technical spec.

Your oil consumption is not cause for rebuild, with alusil cylinder most likely, you are in a very strong position to continue almost indefinitely without rate of consumption increasing.

Unless you see smoke coming out the back on decel, I'd look for other reasons to have a rebuild.

[pocv0]

I agree with the above posts. Do a leak down and compression check, and if all is within normal range just drive it ! No way you will get 270hp out of a 3.0 unless you increase CR and run race headers and exhaust. You're in CA , the CARB police will be all over you.

[pocv0]

Add HP to the '72. You can do whatever you want on that one, it's smog exempt , plus add rear seats for the monkeys.

[Ryan_Cunningham]

Originally Posted by ahh911

Heads up, your oil consumption is 65% of the average oil consumption specified in the Porsche published technical specifications including later revisions. Here is the 1981 revision of the technical spec.

Your oil consumption is not cause for rebuild, with alusil cylinder most likely, you are in a very strong position to continue almost indefinitely without rate of consumption increasing.

Unless you see smoke coming out the back on decel, I'd look for other reasons to have a rebuild.

Thanks for the input. I thought I read in one of my publications that 1 quart per 600 miles was the limit, I appreciate the correction. No smoke on decel, but quite a bit on every start after its sat for 24 hours.

Originally Posted by pocv0

I agree with the above posts. Do a leak down and compression check, and if all is within normal range just drive it ! No way you will get 270hp out of a 3.0 unless you increase CR and run race headers and exhaust. You're in CA , the CARB police will be all over you.

Valid. I'll have those completed.

Originally Posted by pocv0

Add HP to the '72. You can do whatever you want on that one, it's smog exempt , plus add rear seats for the monkeys.

It's got 400hp, a full cage and no sound deadening, so not really friendly for the family. But it sounds like its best to just keep my 81 stock and spend that money more wisely on the 72.

Thanks all for the advice.

[jac1976]

“…so it seems a refresh is due, which is corroborated by my mechanic having looked it over…”

Might ask your mechanic how he arrived at his conclusion. If you didn’t explicitly ask to rebuild, he seems pretty willing to tear into what you’ve represented here as a healthy motor.

[ahh911]

If you're looking to re-build, then broken head studs will probably be the reason. That would be a fortunate scenario in my opinion, it likely means the engine has never been disassembled.

I had 2 headstuds broken when purchased, rebuilt it myself and decided that putting a well running engine back together and enjoying the power band as it left the factory was what made most sense. Certainly giving up low end torque would be out of the question for me then and now, but I've been reading about the M1 cams. Ian C, claims it provides the factory low end torque with some high end extension with some fueling tweaks. Looking back, that would have been the best choice. Initially I'd run the stock cis up to factory redline with the m1 until I'd learn how to operate the cis, then start playing with the fueling once everything was well in hand. The cam would presumably be waiting for me to catch up to it. Too late now.

Phil

[jess p]

Rather then seek HP, look for weight reduction. Lots of threads on here on the way to go.

[shoooo32]

Bumping to 3.4, port/polish, EFI and cams would yield 275hp easily if tuned correctly.

I'd avoid the weight reduction aspect for a daily. You already have a '72 hotrod; keep the impact bumpers and interior (sound deadening). I'd focus on torque over an outright HP figure. Power under the curve makes the car better in traffic.

[Ryan_Cunningham]

I'm looking at other options, I don't want the 81 to be a super lightweight outlaw, maybe more of an in-law to quote a buddy.

Going to look at a 3.6 Varioram this afternoon which might be best to increase power and keep the streetable aspect of the car. Not in a rush but I do appreciate all the opinions.

[PeteKz]

Like pocv0 wrote, since you already have a 1972 hotrod, throw your fun money at that one. If money is not a big deal and you want more oomph out of the 1981, then "there's no replacement for displacement." A 3.6 Varioram probably is the best of all options. Just be sure to get the whole package, from the ECM and wiring harness all the way to the exhaust tips. You will satisfy both your right foot and the CARB nannies. Any attempt to get to 275 HP based on a 3.0 case and crank will require a much hotter cam, which almost certainly will cause you grief at smog check time. It will also make the car less satisfying on the street.

[pkabush]

I agree with the others. Check headstands and do a LD test and drive it.
That said, Id prefer a hopped up 3.0 over a 3.6
Although both are expensive endeavors rebuilding the original 3.0 would be cheaper, better ROI and more fun IMO
Minor thread derail question. Can you please post pics and specs of the 400HP 72

[Ryan_Cunningham]

Originally Posted by pkabush

I agree with the others. Check headstands and do a LD test and drive it.
That said, Id prefer a hopped up 3.0 over a 3.6
Although both are expensive endeavors rebuilding the original 3.0 would be cheaper, better ROI and more fun IMO
Minor thread derail question. Can you please post pics and specs of the 400HP 72

I imagine it might turn some off due to its engine - SBC. But I am debating potentially a water cooled 911 engine in the future.

996T brakes
12 point cage
930LSD
Coilover suspension
11/13” wide wheels F/R

[Ryan_Cunningham]

If I were to purchase the engine below, anyone have a rough parts list of additional items I'd need to make it work in my SC? I've read through countless SC to Varioram conversion threads, and know that there use to be kits available, but having a hard time finding a source listing everything to make it function properly.

Porsche 993 Varioram Engine 3.8 litre

[Axel84]

you would need a standalone EFI system I guess, 915 flywheel conversion from patrick motorsports, powersteering delete and some other bits and bobs....

3.6 or 3.8 in a G body is the way =D

[hughc]

Originally Posted by Ryan_Cunningham

Thanks for the input. I thought I read in one of my publications that 1 quart per 600 miles was the limit, I appreciate the correction. No smoke on decel, but quite a bit on every start after its sat for 24 hours.

FWIW I was occasionally having a puff of blue smoke when starting from cold. It didn't always happen but when it did it concerned me a bit. I decided to live with it.
At some point, app 2yrs ago I decided to add one 600ml bottle of Lubro Moly Mos2 at each oil change and can say that I've not noticed any blue smoke at start up.
I'm not saying it's related but I thought I should point it out to you.
I currently have 210K mi and I'm using (leaking) app 1 L per 1000 mi.

[Ryan_Cunningham]

Originally Posted by hughc

FWIW I was occasionally having a puff of blue smoke when starting from cold. It didn't always happen but when it did it concerned me a bit. I decided to live with it.
At some point, app 2yrs ago I decided to add one 600ml bottle of Lubro Moly Mos2 at each oil change and can say that I've not noticed any blue smoke at start up.
I'm not saying it's related but I thought I should point it out to you.
I currently have 210K mi and I'm using (leaking) app 1 L per 1000 mi.

Thanks Hughc, I've been monitoring the consumption and it has actually been better than I initially reported. Suppose I was just worried. With that said, I think I made a mistake in looking at a transplant - Now I can't get it off my mind. And it'd be a fun challenge to undertake on a car that I plan on keeping as long as I can currently contemplate especially since I'll be moving to only working three days a week this summer.