911SC rebuild thoughts

[toddu]

I have an '81SC that I'm planning to send the motor out for rebuild this fall. I'm looking for some ideas of what to do with it. I could go tried and true 3.2SS, etc. Just getting some other ideas.

I currently have 46 PMOs and SSIs (neither on currently on the car).

Planning/counting on new P&Cs, but my builder has a ton of used stuff available (think most of it is 962 stuff actually) so that should not be too spendy.

Car is weekend toy, DE's planned.

Anyway, looking for ideas.

Todd

[jess p]

I am in the same situation,but the engine is an 82 and out of the car. I have
many new cis parts and would enjoy a little more power. I am told that by
backdating to ssi exhaust and higher compression pistons for 30-50 hp.
I'd like to go to carbs as I have some 40mm webers,different cams and
pistons but with that the emissions station and I wouldn't get along.

[G450X]

You might try the general 911 forum for more response, and search any mod you might consider for some feedback.

I am in the same boat with my '82 and I am doing an old fashioned hop up:

1) Max Moritz P&C's 9:3:1 (single plug)
2) early SC large port heads
3) early CIS to match the head ports and early distributor
4) 964 cams
5) SSI's M&K 2/1 (already installed)
6) possibly a 7:31 R&P and 5th gear swap for the 915

I am budget constrained or I'd consider some sort of EFI, but that will be on the future mod list.

I'm not sure of your budget (most SC guys are budget conscious), if money is no object I'd call a good builder and let funding dictate the level of modification.

Keep us updated, I always like to hear real world feedback and there are quite a few SC owners out there that are waiting for a rebuild.

My '82 is at 165k+, but runs pretty good so I almost feel guilty rebuilding it. I guess I really want a bit more power and the low redline (mine seems to run out of breath around 5.5k rpm) drives me nuts - it just starts sounding good then falls off cam!

[j911brick]

Originally Posted by G450X

You might try the general 911 forum for more response, and search any mod you might consider for some feedback.

I am in the same boat with my '82 and I am doing an old fashioned hop up:

1) Max Moritz P&C's 9:3:1 (single plug)
2) early SC large port heads
3) early CIS to match the head ports and early distributor
4) 964 cams
5) SSI's M&K 2/1 (already installed)
6) possibly a 7:31 R&P and 5th gear swap for the 915

Are the max Moritz P/Cs still available? Why not just port your OE heads. You can make them flow better than large port heads. Also: I'm not a big fan of the 7/31. It leave the lower gears too short. If your going to do fifth anyway, just do 3rd and 4th as well ad set it up ust how you need it.

[Targa Time]

Being you already have the Carbs and SSI's you have already covered 1/4 of your parts and machining costs. It's all of those "while your in there" costs that add up.

A 3.2SS is a fun quick motor but by todays standard certainly is not FAST!

By the way my rebuild cost a bit more that anticipated. I was surprised at how fast all those little unexpected items added up. Once again those "while your in there costs".

[bullethole]

just to give you a data point. I just did a rebuild of a motor for my race car. Kept it at 3.0 because of class rules (if i went to a 3.2SS i would have had to add additional ballast to stay in GT5S, which would have negated some of the HP gains). Did twin plug, 10.5:1 compression (JE pistions, with replated mahle cylinders (mainly because neither the nickies or the JB Racing steel lined cylinders were available (8 weeks minimum for them to get parts in). Upgraded rods to pauters, web cam 100/102 profile (new billet - switched to the bolt style camshaft vs the "big nut") With the machine work (twin plug, head reconditioning) etc, all the misc parts, gaskets etc my parts bill was a little short of 8K (included new chains, ramps, lots of new hardware bits). With my wasted spark ignition, and 3.2L intake EFI with MS, I'm hoping for 230hp at the rear wheels (my former mechanic in TX thinks this should be achievable, as he did a similar motor for a RSR clone (carbed and distributor based, but a more aggressive cam profile) that is getting 240 at the rear wheels).

[toddu]

I'm on the fence for twin-plug. I'd like to future-proof the motor a bit, but that is a $$$$ pill to swallow. No real inexpensive way to do it. The other parts I was able to sit on the sidelines and wait for a good deal to come up. Twin plug bits don't come up very often however (would lean towards a dizzy rather than crank fire). Going to my builder in the next couple of weeks to talk about options.

Todd

[G450X]

Originally Posted by j911brick

Are the max Moritz P/Cs still available? Why not just port your OE heads. You can make them flow better than large port heads. Also: I'm not a big fan of the 7/31. It leave the lower gears too short. If your going to do fifth anyway, just do 3rd and 4th as well ad set it up ust how you need it.

I found the Max Moritz set in good used condition. I checked on new ones, which can be ordered, and they were around $5k.

It all boils down to money. I found a good low mile 7:31 R&P and 29:22 5th for less than one GT gear set (a little over $600). I feel like the stock 1st in my SC is too low already - I usually go low rpm in 2nd and try to avoid using 1st. I know it will be a stump puller 1st , but 2nd through 4th should be perfect, and 5th (with the swap) bearable. I don't run too fast on the road these days anyway. This is a fun car, not a daily driver. I love to shift, and from what I've read a 2nd, 3rd, & 4th with the swap are nice. I have a spare hybrid (mag/alum) 915 I plan to modify - If I hate it, the original 915 goes back in.

I found a good set of early heads for $500.00. I can sell my small port ones to offset the cost a bit.

Of course if I had unlimited funds, I'd use all new GT transmission custom gears with a new R&P & LSD - I could easily drop $10k+ in the 915!!

I would also drop in a built 3.6 ($25k+??)

Fortunately, I have a wife and kids to support - for example, the kids braces cost over $10k (so far) and they take precedent over the hobby car.

Health care (and things like the kitchen remodel for the wife) keep my fun car on a budget. It's actually kind of a fun challenge to gather all the parts (almost 3 years to find the MM P&C's) and send them to (for me it will be JW in Seattle) a proper builder to work his magic. I plan on pulling and stripping the engine to save a bit on labor.

I have a mildly modified e46 M3 if I want go faster and in more comfort, but that little SC is a blast - it just needs a bit more power and a fresh build to make it all come together....

[winders]

I don't like the 7:31 for a street/track car either. It's okay for an autocross only car. Even 2nd gear will be used sparingly on the big track with a 7:31.

Of course, another downside is that the 7:31 is a little weak for the engine you are putting together.

Scott

[j911brick]

Originally Posted by winders

I don't like the 7:31 for a street/track car either. It's okay for an autocross only car. Even 2nd gear will be used sparingly on the big track with a 7:31.

Of course, another downside is that the 7:31 is a little weak for the engine you are putting together.

Scott

Glad someone else mentioned the 7.31 as being weak. I've seen them blow up in stock SCs.

[Sboxin]

What you could do is drill/machine the heads now for the second plug while the heads are off and not wire it up this time around. Then you would be ready to go for the next time you open the engine or just change cams and chip.

Regards,

[G450X]

I didn't mean to hijack this thread, I offered what my future build will be and that maybe I would attempt a 7:31 R&P swap with a higher 5th for the highway.

The 7:31 R&P swap seems to have stirred the pot a bit, and I appreciate the feedback.

The 7:31 certainly seems to have two camps going for it, roughly 50% for and 50% against (from the threads I read through). Most of the negative comments seem to stem from durability with a beefed up engine. I will be very happy if my build makes 210+/- H.P., and I am leaning on a build/tune that slightly takes away from low end torque and adds a higher red-line for more high rpm power. I think torque is the greater enemy of the 915 and I plan to keep that figure manageable.

I do plan on upgrades like an internal one piece bearing carrier and reinforced side cover with a 930 bearing as well (maybe an internal gate shift to prevent a wrong shift). I have a hybrid (mag front with steel bearing inserts/alum final drive) '77 915 which I plan to build. The only negative I heard is a weaker 2nd gear on the pre-'78 915 - not sure what to do about that other than swap internals from a later 915). I may consider a cooler/spray bar set-up like Wevo offers.

I think proper use is the key. I know it's not a drag car and will never attempt drag starts, or anything that would add extra stress/torque to the drive train. Rarly8 made a 5 speed 915 survive for many years behind a high H.P. turbo 911.....

I will keep the stock box and swap it back if it does not suit me. I also plan on a backdate and diet to drop at least 150 pounds of unnecessary weight.

Since it was suggested, does anybody know what 2nd, 3rd, and 4th gear choices are available for a 915 in used form (to be affordable) that would make for a nice 8:31 R&P 915 to add more punch? My 7:31 R&P is in really nice shape, and I would actually like to see it go back in an early 915 since they seem to be hard to come by these days and '72/'73 911's are bringing top dollar...