whiskey52

i'm looking for opinions and research facts on how to plan an engine upgrade for my '81 SC. she is almost exclusively a track car running DE's and autoX. lots of suspension work completed, turbo brakes and NT01 tires make me very competitive in the turns but lack the pull on the straights. about 175k miles on a stock 3.0 with no rebuild (about 150 hp at the wheels). it pulls strong and does not leak (well almost none) nor burn excessive oil (about a qt / DE weekend). i want a low maintenance motor with about 235-275 hp at the wheels on premium gas. i'm considering a '95-'97 3.6 but looking to those with much more experience to point me in the right direction. much thanks in advance

clutch-monkey

hi i currently have a bog standard 964 3.6 in my '78 SC, in it's present state (after 4 years of track work and tarmac rally..) it still puts out a smooth 200rwhp.
given that it is completely standard i imagine a few go fast bits on a fresh engine would easily net you the power you are after (well, the 235rwhp threshold anyway) without adversely affecting maintenance.
that's just my experience, hope it helps.

edit; fyi the previous owner (who did the conversion) stated that the most marked improvement after the conversion was the increase in torque, loved it.

Ed Hughes

Your HP request at the rear wheels is going to be tough. A 993 V-ram engine could hit the low end, but 275 at the wheels? Your in blower territory, or high compression/large displacement/non-stock intake and expen$ive.

The transplant is the easiest route, and possibly the "cheapest", but that comes at risk. I know someone who went this route, only to have an internal problem in the motor surface. His "bargain" HP fix turned into a $25K plus endeavour.

High HP 911 motors are expensive, no matter which way you go.

Ed Hughes

PS- Lightening the car is the least expensive way to better HP/weight ratio, which is really what you want. You also get the benefit of a more agile car.

SCOTITUDE

the ultimate formula for an SC track car is a 993 3.6 and a strict diet. the diet will show more results than the new motor. both together will get you the results you think your gonna get with 275rwhp. if u dont have the bankroll of 8-9g for a 3.6 there are other options that will give you minor bumps in performance. First id gut it and add fg where you can. thats gotta be the basis for any improvement in p/w ratio. cant go wrong with a lighter car. then carbs, cams, pistons, regear tranny, ring/pinion.
your plight is where im sittin right now. Would love the 3.6, wallet says no.
I did the gut, fg and carbs last year. HUGE difference. now im lookin at HC pistons and cams. if i can starve the family maybe some tranny work. and lastly to get another 100 lbs outta the car.

whiskey52

thanks guys. looks like my initial hp hopes may be a little aggressive. i'm trying to get a better idea of the differences between the 964 and 993 3.6 motors. i plan to keep / rebuild the 915 tranny adding an LSD and possibly changing gear ratios a little (depends on hp and torque). i am on a budget but will save up thru 2011. i've stripped the interior, will add roll cage this winter. last corner balance weight was 2468. hope to get another 200 lb out somewhere. i'm looking for a very reliable, low maintenance motor with solid performance. i've seen a lot of headaches with carbs and the 3.0 (though very good performance too). the 3.0 has really spoiled me re: realiability. will the 964 or 993 offer the better long term results? thanks!

Ed Hughes

One never knows on reliability. That's why I posted of one transplant I know of that went very bad. You buy a used engine, you don't necessarily know what you're getting. Ideally, if you got one that was running and that you could hear and check compression, etc, you're in better shape for starters. A good 993 engine is as low maintenance as they come. 964 a bit less so.

race911

Where do you stand relative to the stock class SCs and 3.2L cars club racing? Pretty amazing what they can do with a "stock" engine, running about 2700lbs.

Another data point out here are the PRC Spec 911s. Not all of them are the mythical "$100K build." My friend's 3.0 w/ carbs is about 260HP at the crank, stock cams and pistons. Running right at 2400 lbs (w/ driver) and torsion bars on RA1s, the median for the class is only a couple seconds slower than what I'm doing in a more-than-RS-spec 993, and about equal to my old RSA stock class racer.

Now if your goal is just to haul *** down the straight, yeah, proceed to a nice, torquey 3.6/3.8.

Steve Weiner-Rennsport Systems

Do you have stock gears? I would sure address that before undertaking engine modifications and/or changes.

The VERY first thing I ask my clientel when discussing engine upgrades is, "Whats your budget to do this?". That, after all, frames whats going to be possible to do.

If you need 235-275 RWHP, then you need a 3.6 or 3.8, depending on your budget.

Lots of options,...

MUSSBERGER

If its a dedicated track car that won't be turned into a stock class race car just strip the bitch and when the motor lets you know its time then............

SCOTITUDE

i yanked off the cis and plopped on Weber 40's. simple swap and i have had zero issues, no fiddling or hiccups whatsoever. even comvinced some other friends to follow suit. they all happy
stripped im down to 2200, and i still have to replace the hood and tail with fg, and the stock battery is going bye bye. theres another 100 lbs, so if your at 2400 you have more to go. another 300 lbs.

SCOTITUDE

really? can you elaborate on that? how is he getting that hp with only a carb swap? im a stock 3.0 case with 40's on top. 9.5 je's on last rebuild. i dont think im anywhere near 260hp. help me as i'm about to plink down cash for hc pistons and cams.

Steve Weiner-Rennsport Systems

Thats accurate, depending on how the engine is assembled (and exhaust of course),....

whiskey52

steve, the tranny is stock but will be rebuilt with the engine change. any help on new gear ratios is appreciated. i've got a line on an LSD from an '84 turbo that i think fits. right now the gears seem a little tall to me. 3rd is a workhorse from 40-90 mph but i'm often waiting for the motor to spin up coming out of corners. 4th tops out at 120 and thats about when i hit the braking zone on tracks around here (central NC). the new light weight flywheel and stage 1 clutch have helped a little. will a bigger motor compensate enuff for the gears? do you have a recommendation. i understand the 915 has a bunch of options

MUSSBERGER

http://www.buckley-racing.com/products.html

Here's your gear change.