tylerdurden

I've been considering getting a 944 turbo and possibly stroking it to 2.8 or buying a high-mileage 2.5 turbo and replacing it with with a 3.0 liter turbo. Lately, however, I've been kind of swayed by reviews of the 968 CS. It had praise heaped on it like the 944 never seemed to (or other 968 models for that matter). Is the 968 that much different(better) than a 944? Further, how hard is it to take a 968 to 968 CS specs?

H Dog

Since January 2000 I've been researching my 944 Turbo project. To my mind, the hot setup would be to get a 944 Turbo (I have recently purchased an 86) and set it up to 968 Turbo S specification.

The 968 TS was, according to Autocar & Motor, a race car barely tamed for street use (the 968 Turbo RS was a Le Mans race car and is thus not streetable). Unfortunately, Porsche has no information regarding the 968 Turbo S, since only 14 were made, apparently by the Motorsports department. Thus, there is no record of these cars in dealership microfiches.

The 968 CS was hailed as the best handling production car by Autocar in 1993, beating even the then new BMW E36 M3. This makes it a natural goal for any 944/968 upgrade project (my last car was an E36 M3 3.2 liter). From the information I have, it appears that it differs from the 968 M030 only in that it is lighter by several kilos -- no A/C, lightweight seats, manual window lifts, etc.

I have been searching for a used 968 CS suspension while here in Germany, and so far no luck. From the dealer the parts cost over $3,000, so it would be far less expensive to simply buy an aftermarket coil over suspension and get springs and dampers which are set up roughly to the same spec as the CS. What these rates are exactly is not clear -- while it is clear that the 968 CS had 28 N/mm front springs (see my other post), the rear barrel springs are not known, nor are the front and rear damper rates (both bounce and rebound, fast and slow). For my project, which starts with a 23.5 mm torsion bar instead of the 968's 25.5 mm bar, I also need to know the motion rates or wheel rates of the rear torsion spring, but again, Porsche has been tight lipped about this information.

Therefore, I have changed my focus, and now am also looking at BMW E30 M3 suspension setups. These cars have essentially identical front and rear suspensions as the 924/944/968 series (the E36 cars come with a 5 link rear suspension which helps in bumpy corners, allowing stiffer rear springs while maintaining control). Because the E30 M3 was the most successful racing saloon of all time, emulating this suspension should produce very good results (i.e. results which do not require buying several sets of rear springs and hours of costly testing at the track).

Grassroots Motorsports have published articles in the past year regarding upgrading both a 944 and E30 M3 suspension, so I would recommend that you check these issues out.

tylerdurden

Thanks for the info! I've also toyed with the idea of putting a 3 liter M3 engine in an normal e36 and gutting it and working the engine over (SCC has their 3 liter making over 260 at the wheels!). Why did you choose to let the BMW go?

CBass

The Turbo S was a lightened Club Sport, that recieved a 951 cylinder head and turbo equipment. It had all the M030 stuff and big S4 brakes from the CS. Weighed about 2850 lbs.

Tom Pultz

[quote]Originally posted by CBass:
<strong>The Turbo S was a lightened Club Sport, that recieved a 951 cylinder head and turbo equipment. It had all the M030 stuff and big S4 brakes from the CS. Weighed about 2850 lbs.</strong><hr></blockquote>I don't think the 968 Turbo S used a 951 cylinder head because the water passages are different. It is my understanding that it used a modified head from the 2.7 liter NA engine since that head bolts to the 3 liter block without modifications.

Also, the Turbo S did not use the S4 brakes, but rather had the "big red" front and "little red" rear setup from the 911 3.6 Turbo.

Tom Pultz

[quote]Originally posted by H Dog:
<strong>Because the E30 M3 was the most successful racing saloon of all time, emulating this suspension should produce very good results</strong><hr></blockquote>I guess I don't get it. How would emulating the setup of a RACE CAR produce good results for a street car? Any E30 involved in any type of serious racing would certainly have used a much stiffer setup than stock.

When I was first thinking about modifying my suspension my goal was to duplicate the US 968 M030 setup. However, like you, I abandoned that idea and went with something of my own selection, which is somewhat stiffer and more expensive than the factory setup. I'm very happy with it.

CBass

They did actually use the entire top end from from a 951. There was a fair bit of custom work done, and it just ended up a 3L turbo.

I thought they used the S4 brakes though. Something to do with the 911 brakes being mounted backwards or something.

Infinite Fiberworks has fiberglass 968 body panels for not a lot of money, and a stroker 951 with M030 suspension is very close to 968 Turbo S mechanically... The fenders weigh something like 5 lbs each. Crazy.

Tom Pultz

[quote]Originally posted by CBass:
They did actually use the entire top end from a 951. There was a fair bit of custom work done, and it just ended up a 3L turbo.<hr></blockquote>This could be, but it's not what I've heard that others have done to try and duplicate the setup. Maybe a 968 Turbo S owner will verify how it was done.

[quote]I thought they used the S4 brakes though. Something to do with the 911 brakes being mounted backwards or something.<hr></blockquote>To use the big reds all that is required is swapping locations of the bleeder screws and cross-over tube. When you rotate the calipers from the front to the rear of the rotor, it makes them look like they are upside down, so you swap the parts.

CBass

Tom, you're the most knowledgeable guy I know about these brakes. I don't know what I'd do with out ya.

I've been talking to a lot of people about 968/S2 turbo conversions. If you can get the factory Mahle 7.5:1 pistons, you don't need much else(aside from the turbo, and custom manifolds, but thats easy), but they $2000 a set. For 4 of them.


Or, you can use Carrillo connecting rods, which are a little shorter than stock rods, and those drop the compression to around 7.5 or 8 to 1.

Or, you can get a cylinder sleeve and custom pistons.

This is if you want to keep the 16V head. I think I'm going to go with the Carrillo connecting rods,
the Jon Milledge barrel valve intake, custom turbo header(just pay a shop to use their mandrel), and probably a K27 turbo. Expensive, yes. Not as much as a "bolt on" supercharger, that you can only run 3 lbs through. I'm looking at 400hp and 400ftlbs at the wheels. In a 924 with a 968 lightweigh body shell. 2300 lbs. Crazy, huh?

Danno

If you build this monster, I'll come up to check it out!

CBass

Nah, I'll drive down there, it'll be more fun. Besides, I'll get to terrify the locals with my fire breathing Porsche

Danno

Did you check out the Oct. 2001 issue of European Car with the Vision Motorsports 968Turbo-powered 951?

CBass

Can't say I did. Where can I see it, or do I have to track down an issue?

I think a Turbo 968 motor is more at home in a 968 than in a 951...

Turbo Fanatic

I'll jump in here. I researched the 968 turbo back in 96-97. At that time after speaking to KMR,
and other sources, I was directed to Porsche Motorsports. Here is information I was able to get from them. Cylinder head is unique to car, water jacket same as 2.7 8 valve, but has cermamic liner in exhaust ports, Water jacket much larger than 2.5 turbo, hence exhaust port much smaller on 3.0 turbo head. Valves have same overall size except in stem area. The valve guides are the size of the 16valve heads. Thus the car has is own set of intake and exhaust valves. This could be remedied by installing 2.5 valve guides in the head. The pistons were represented to be 7.5:1 and were price to me at 795.00 each! Porsche Motorsports told me that the block, rods, and crank from normal 968 would work.
I picked up cylinder head new from KMR, but passed on the pistons, as at the time Andial was working on pistons and at 8 to 8.5:1 compression.
As my purpose was better driveability and more low end torque, I held out............... Now you guessed it, Porsche no longer supporting parts,
and no pistons yet from Mahle. Hopefully with a little help and luck my project may get jumpstarted again!
If you are interested here are pics of 968 turbo head next to 951 head.

CBass

You happen to be in luck my friend. For a mere $2000 you can get a set of Carrillo connecting rods that will allow you to use your factory pistons. Talk to Rob Dommes at Kokeln Racing Products

<a href="http://www.kokeln.com" target="_blank">www.kokeln.com</a>

There are many ways to do this swap, but the only big advantage I see to doing a 3L turbo conversion as opposed to a 951 stoker is the 16 valve head. No head, no 4 valves per cyl, no VVT, none of the goodies.

If you want good torque, get a stand alone ECU as well. Shop around for one you like the best. My advice is get a Motec M48, it has capacity for VVT, traction control and boost regulation.

For a good intake, check out Jon Milledge's shop, and ask if he'll make a barrel valve for your 968.

<a href="http://www.jmengines.com" target="_blank">www.jmengines.com</a>