tyler durden

I am new to Porsches, my background is with BMWs and Audis... But I am looking at a C4 for my next purchase and am curious if the C4 is able to handle high amount of horsepower. Back in the day, I owned a 1991 325IX, and due to a weak transfer case, they are unable to handle more than 200hp safely. Does the C4 have any issues with high power engine modifications?

tbennett017

What kind of power are you talking about? Stock they put out originally about 248, and the C4 system is pretty free of issues... They rarely come up as problems here on Rennlist. Mine has 200K and is virtually trouble free.

It's a slippery slope when you start trading $ for power... Let us know how far you want to go and then we can react to your ideas...

tyler durden

Would the stock transmission/diff of a C4 be safe with 300 NA hp?

KaiB

Know you're a bit new to these cars, but how would you propose to go about getting 300 n/a horsepower?

This can get a bit pricey; how do you intend to use the car?

vasculardoc

Especially considering that 250hp in a C4 is still a LOT of fun !!????? And 300hp is going to cost a lot $$$$$$

evoderby

Hi Tyler, transmission are generally rated at a maximum torque figure rather than maximum horsepower. Tuning towards 285-300 N/A HP is indeed easy enough and will in no way increase torque enough to get you into trouble with C4 reliability.

Having said so, is there a particular reason you're looking at 4wd? The C4 is both heavier and suffers from additional drivetrain loss making it a much slower and less nimble car than the C2 version (compare 0-200 km/h times). It can also be quite understeery....

velocitylover

Do you own a C-4?
Heavier ? - yes but some of them much less ('89 didn't have air bags, dual mass flywheel, etc)
Much slower? - Not in a street situation and not in a foul weather condition (street or track) and defind "much slower"
0-60 accelaration is actually equal or faster, 0-200 km/h? - need to look into it, but they are not drag racing cars and never meant to be, understeer is very easily corrected (just look for info here...)
Definitely more sure footed while on the edge...

psiegel

I had my C4 modified (Protomotive Stage 2 Turbo) and it has about 450 HP. I had this done at 145,000 miles. My C4 now has 205,000 miles and there has been no problems, other then normal stuff. But specifically nothing with the transmission. As I understand the 964 can handle twice the HP without modifications.
Hope this helps.
Peter

evoderby

Hi Rob,

No I don't own a C-4. I have driven a few in my time and although they're absolutely fine I couldn't help but notice the effect of the 100 Kg's extra weight in the way the car behaves. I also feel 4wd turn in is less nimble than the C2 counterpart.

Here's a link with some performance stats:

http://www.porsche964.co.uk/technical/performance.htm

BTW on Autobahns and the Ring 100-200 km/h acceleration does play a role, especially since we're talking about multiple seconds difference....nothing to do with (not) being a drag car.

As said the C4 is a fine automobile, however since the OP is already talking about tuning it I just questioned his reasoning behind choosing C4 since a C2 to me is the more logical choice when outright performance is your ambition.

Rgds,

Harald

tyler durden

Perfect. Thank you all for your help.

GarC

Ultimas use G50 transmissions and these have significantly more bhp/torque than a 964.

In 1987, the G50 gearbox was installed into the Carrera 3.2 911. This transmission used Borg-Warner syncromesh instead of the Porsche-design balk-ring system to improve the shift quality and lessen the effort required to change gears, especially from a stop. These gearboxes were rated at 221 ft/lbs of torque. The G50’s have been utilized with several variations of gearing and speeds. The 993 series was the first 911 offered with a 6-speed version of the G50 design. These later units also introduced significantly improved clutch cooling.

Other versions of the basic design, called the G50/52 series, were used in the 3.3 C2 Turbo and 3.6 C2 Turbo cars. These transmissions also have stronger differentials and cases and a type of Limited Slip differential that locks 20% under power and near 100 % on the overrun to minimize trailing-throttle oversteer. All of the G50 cars use the 240mm clutch size introduced on the earlier Turbo cars and they are now hydraulically actuated.

Source: http://www.ultima-gtr.info/utips.htm#Transmission

elbeee964

Pete, are you getting that 450 in Silverthorne, or is was that a sea level quote/measurement bump of 250?
(Me --> general ignorance of whether turbos eradicate, or just lower, altitude power loss.)

Marc Shaw

My C4, at 2850 lbs, weighs less than a C2.

But is is hardly a stock C4.

Marc

psiegel

Lonnie
The 450 was at sea level. I have no idea what it is up here at 9700 feet but what i can tell you is that the turbo spins up a lot slower at altitude. As you can imagine its a large turbo and since there is no "air in the air" it doesn't throw you in the back of the seat until about 3900 rpm. At sea level you feel it at about 2700 rpm. That's a big difference, but how that equates to HP as i mentioned, i don't know. Because it takes longer to spin up, does that mean there is less HP? I do know that an N.A. car at 9,700 feet looses around 40% of its HP. That's actually why i had the C4 turbo'd in the first place as i was tired of having the subaru sti's kick my *** going up Vail pass. That doesn't happen any more, LOL.