Roamer

WOW!!

I did not check the board last night but I am truly surprised by the response and incredible experience available here, thanks to all! A special thanks to Steve for his expert input! Martin, I have your article stuffed into my 101 projects book already!

In response to many of your comments, one, I have no intention on dragging the car, last night I got eaten alive by a Z06, as expected. What I did not like was when we got to the twisties my inablity to take my exit speed advantage out on him. I would catch him in braking and out accelerate him (on his tail) of the corner but his throttle response was incredible and he would literally 'jump' away from me only to be caught at the next corner.

The goal that I have is to have that same instant throttle response that maintains that jump out of the corner and makes guys in cars like the Z06 catch me at the end of the straight where I can outbrake them again.

From the posts, I think I will be looking at a 3.6 conversion after I get the rest of the car and the driver up to the capabilities of the new motor.

On the suspension front, just an off topic, how low can you drop a 911 (realistically) for street use and without cutting fenders, assuming 17" wheels having similar outside diameters to stock.

Thanks again and keep it coming!

Marc
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

Ed Bighi

The Z06's are tough to pass on the track. I get by them, but it takes some serious effort on my part since they handle a lot better than vipers. What I find is their weak spot on a track are in braking, since that is where I catch up to them, and like every front engine car out there, sweepers, hairpins or any other turn that goes around 180 degrees. But they are quick in a straight line. Not 930 with K27 and other tricks quick, but very quick.

Bill Verburg

You, will be very pleased with the 3.6 swap, even though the hp #s may not be spectacular, the torque makes it a very streetable package. I agree with Steve W. 100% about the gearing, there are other cheaper ways of getting favorable gearing besides redoing the transmission internals. Keep the final drive ratio down to improve the apparant internal trans spreads.

• keep the rear tire diameter down, I wish that a 275/35x17 were available, but its not AFAIK, so stick to 255/40 or 265/40x17 for a bit smaller rolling radius at the expense of ultimate cornering power
• another possibility is 7:31 r/p vs 8:31 stock, this will really wake the engine up around town, but also be ARPITA on the interstate, there are also reliability concerns with the 7:31, the elevated engine speed on the highway can be alleviated somewhat with the aforementioned 275/40 rear tires

As far as ride height mine was at 25 3/8" at the front(this is where the problem will be, if any) with 205/55x16 and went to 25 3/4" with 235/45x17.

Steve Weiner-Rennsport Systems

Hi Marc:

Glad I could offer something constructive for you,..

Coupla quick points for you,.....

1) The limitations on lowering any 911 are dictated by shock travel. Its very easy to lower one "by eye", and have 1" or less of shock travel which is not enough.
Depending upon what you wish to do, you might need RSR rear shocks (2" shorter) and either RSR struts or have your spindles raised 19mm (Bilstein only).

2) There are several ways to do a close-ratio transmission but don't go the cheap route. The early 7:31 ring 7 pinion will not handle the 3.6 torque for long and at $ 1800 + labor (12 hours), this isn't cheap. Stick with your stock R&P, do this once and do it right. Change 2nd through 5th gears,...this makes a HUGE difference. Don't forget an LSD if yours doesn't have one.

I know that a properly done 3.6 in your car and close-ratio tranny will close the gap on those ZO6's for you and provide what you are looking for,...

George 911-V8

I have read all the above post on 1/4 mile times and hp. I do a little of both myself. I agree to disagree with some of the post so far. I have a good pca track in my area along with a drag strip all in one. I have seen the kelly moss supercars turn 1.14 laps. I have seen all the high dollar purist big money turbos as well on the same track. I have seen vipers,Z06 vettes,928's and 944 all race around the same track. I have to say 300hp without a turbo will cost and WIIL BREAK not if but when. I was once in the same boat as you. I was wanting to go fast at the same time keep it street driven. After putting the project on paper and consulting with the best minds in porsche racing Pete at andial and Jeff at kelly moss. I came to the fact that unless you spend about 30-40k on just a motor you could only make about 450-500hp period. Thats twin turbo 3.8 on kill. I have a professional race background. I race so I know what it takes to go fast. I went a whole different route for my hp than the normal porsche owner would do. With the help of jeff at kelly moss we put in a 550hp small block chevy with 300hp shot of the giggle gas if needed. I have a 915 gearbox, but I have all porsche rsr race parts in it. I spent about 4K on just the gearbox to handle the power and torque the small block makes. At 3000 rpm the motor makes 330hp. I also have a kevlar rsr clutch and pressure plate. The small block weighs 100 lbs less than the porsche motor. A good friend of mine Daniel thats works at the local porsche dealer myself along with jeff stone owner of kelly moss put the swamp monster on scales to set the car up for track duty. Jeff said it weighed in better that most track 993tt. The swamp monster weighed in at 49.1% up front 50.8% in the rear 3167 with me in it. I think that unless you have like some of the others have said big pockets leave it stock and have fun. Take a de class and learn how to drive it. Drag racing without a lot of r&d will cost you time lots of broken parts and most of all a broken heart looking at the time slip. good luck
<a href="http://pws.prserv.net/4play/911chevy/index.html" target="_blank">THE SWAMP MONSTER</a>

Bill Verburg

Steve, So what's the estimated cost to regear, say a 915/67 and what ratios would you recommend for use behind oh, say a 3.6?

Roamer

George, thanks for the thoughts, I was waiting for someone to mention sbc swap. While not a purist I do want to keep it all Porsche. I am leaning toward a 3.6 swap which is spiritually similar to what you have suggested, larger displacement higher hp naturally aspirated engine. Since I am not trying to compete with 'prepared' supercars, I don't feel I need that much power. Frankly 300-350 would be enough for my needs on the street/track without braking the bank or the engine.

Before settling on a 911 I was very seriously considering dropping in a highly modified 302 into a 240z, real light, real fast. In the end time and economics dictated otherwise.

Also, I don't know about that weight comparision, 911 engines are made of relatively light alloys versus the all iron block (and heads?) of a sbc which weighs in at around 450 lbs from my recollection. I have a hard time believing the Porsche engine alone weighs more than 450.

Thanks for the input!

t.p.

George runs a "Bow-Tie" block, which is aluminum and expensive. Not your typical 350.

Steve Weiner-Rennsport Systems

[quote]Originally posted by Bill Verburg:
<strong>Steve, So what's the estimated cost to regear, say a 915/67 and what ratios would you recommend for use behind oh, say a 3.6?</strong><hr></blockquote>

Hi Bill:

Depending upon whose gears you use, you'll pay anywhere from $ 525 to 625/gearset. We charge 8 hours of shop time to redo a 915 and any differential work is extra, of course.

Gear ratio choices really depend upon many factors such as engine RPM range, rear tire diameter and what kind of top speed and cruise RPM you want. If you have upgraded valve springs, retainers, and rod bolts, along with a proper chip, you can take advantage of the stock 3.6's breathing capabilities to 7000 RPM. RS cams will do even better.

Each person wants something different so its not a one-size-fits-all kind of thing,...

adrial

Rich glickel?
Figured you'd respond to this...
anyway He has a 3.6L engine swap and laid down 260RWHP with SSI's and some internal goodies...care to share rich?
Awfully close to your 320hp goal if ya ask me...

JackOlsen

Lots of great advice here. I think the 3.6 makes the most sense, personally -- but that should come as no surprise. I've mated one to a close-ratio box, with B&B headers (SSI's are too restrictive for a 3.6), 80% limited slip, 930 brakes, etc. I'd guess I'm putting out maybe 260 hp, but on the track I don't feel a need for any more power. Thom Fitzpatrick's 3.6 swap does 0-60 in 4.7 seconds (I've never tested mine). And in some recent controlled (and repeated) tests, my car was faster from 60-140 than a 996. I think it makes a good argument for the swap. (It won't land you on the perfect-world numbers of 300 hp and 2000 pounds, but it will get you very close, if you're willing to cut the weight.)

Also, assuming you're tracking the car, pay a lot of attention to your suspension settings and use drop links, not just spacers, to correct your steering geometry if you lower the car. Also, 29mm bars are not going to be enough. I'd suggest 22/30 or 22/31. And if your racing/classification plans allow it, consider getting 8x10x17 wheels made, so you can fit 245/275 tires under those Carrera flares.

Roamer

Okay, now which motor . . .

I studied Paul Frere's book last night and Steve's web site. It appears that my best bet may be to go with a 92-94 3.6 and enlarge it to a 3.8 with RSR cams + chip. While the Varioram engines seem nice they are $2k extra (according to Dr. Timmins) and I think the money could be better spent on properly preparing the earlier 3.6.

In addition, what can be done to beef up the 915. I know that this tranny was based on the racing tranny from the 917 so why do I often hear fears over torque limitations. I know you can't ham-fist it, but since I don't drive that way I am not concerned but I would like to keep the tranny (in one piece) with any upgrade I choose.

Also, I also studied the build of my 3.2 as deliniated by Paul and am wondering what all the fear is over a low-boost supercharger. It appears that the bearings, crank, and cylinder heads are of similar construction to a turbo. If you only talk 5-6 lbs of boost with an intercooler to keep temps down, will this really put the engine in jeapordy?

Marc
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Bill Verburg

I think that you have done a good analysis of the engines. If no further mods are in the cards then the 993 variram is the way to go, I also like the 95 993 for a stock install(because of the hyd lifters). If further mods are planned then the late 964 w plastic intakes are good starting points. As I am planning my winter projects along theses lines here's my tentative plan(wish list) for the engine($ issues may affect this a lot);

• Mahle 11.3 piston/cylinder set for 3.8 liter
• ARP rod bolts
• Eibach sport valve springs w Ti retainers
• Web Cam 993 ss cams
• Unichip

As far as the trans, I used the 76 915 mg case for many years with no issues, I finally swithched to a 915/67 european trans with the stock euro cooler mostly for the lsd and the taller 5th gear. I am considering regearing 2,3,4 but am on the fence on that issue. I will also use a shorter(265/40 instead of 275/40) rear tire in the future to get better gearing in 1st, I will give up a little ultimate cornering grip for the more advantageous 1st gear.

It would be interesting to hear others comments on these issues though.

nate

[quote] In addition, what can be done to beef up the 915. <hr></blockquote>

Talk about a great thread! One more question for the mix: is it possible to transplant a 993 motor and six speed into an earlier 911? I love my 911, but I've always felt the slow shifts of the 915 tranny was the one weak point in the driveability of the car. Anyone with experience in this area?

Steve Weiner-Rennsport Systems

Hi Nate:

Well sir,.....anything is possible. All it takes is money and sometimes, lots of it.

The 6-speed G50 is a large beast and rather heavy. To install that into an earlier car would require major surgery to create a new transmission tunnel, fabricate a front tranny mounting system, remove the torsion bar tube and replace with a G-50 one, and fabricate some driveshafts for the adaptation.

Then, you'd need to install the hydraulic clutch setup and a G50 shifter/linkage.

In short, the gains do not even come close to the huge expenses. Although the 5-speed G50 is shorter and slightly easier to do, neither conversion is easy and certainly not cheap.

For Bill V:

From a performance POV, its more cost-effective to do your close-ratio transmission than an engine uprade. The bang-for-the-buck is FAR greater with gears, than more power. Save those engine $$$$ until you NEED to go inside that thing.