3.0 16V engine mods, etc

[Thom]

3 clutches? Your KEP1 is too soft, try the KEP2

The 8V has too much torque in the low and mid range, the 16V delivers power more smoothly and on a wider upper range, allowing transmission components to digest the torque in a non-destructive manner, if that makes sense.

[Tom]

3 clutches? Your KEP1 is too soft, try the KEP2

The 8V has too much torque in the low and mid range, the 16V delivers power more smoothly and on a wider upper range, allowing transmission components to digest the torque in a non-destructive manner, if that makes sense.

KEP I with cup disk has been working great for me. I tried other clutches before finally discovering KEP, and am now a believer in KEP. The other clutches used stock pressure plates with the fulcrum point moved, with more aggressive disks. The South Bend set up was next best, but nothing was as factory smooth as the KEP/Cup combo.

To you point about power delivery, I blew one tranny in second gear right when that torque would hit all at once like a cannon. It's not a sound I'd ever like to hear again!

[blade7]

I remember reading years ago, that second gear is usually the one that takes the most punishment. Often as soon as drivers get out of first, they find some traction and then hoof it.

[Thom]

I was not able to increase the boost up to 30 psi but to 23 psi "only" as traction becomes an issue in 4th gear. Keeping the right foot down whilst feeling the back end lighting up with tyres on the edge of traction all the way up to 120 mph through 4th gear requires some concentration.
Some key results :
100-150 kph (62-93 mph) in 2.5 s, in 3rd gear
100-200 kph (62-124 mph) in 6 s, through 3rd/4th gear
The peak injector duty cycle observed was 80%, still with the 1200cc units. Some online power calculators suggest interesting figures for the engine peak power.

The difference in performance between 18 and 23 psi is impressive. The turbo kicks in much harder at higher boost levels. I get boost spikes to ~27 psi around 4000 rpm that I find difficult to control, but the engine does not knock even then. The intercooler seems to be working more as inlet temp through 3rd and 4th is 12°C above ambient, which I think is still ok, as I used to see between 25 and 30°C above ambient at 18 psi "only" with the SFR Stage 2 intercooler.

It should be interesting to see how much the fresher air of the colder seasons affects performance and traction further.

Tuning the engine on the dyno will be definitely needed, if perhaps only for the sake of science as I would make no use of more power considering how traction becomes a problem and I am not keen to fit bigger wheels and tyres. The transmission is probably already working hard enough.

[Tom]

I was not able to increase the boost up to 30 psi but to 23 psi "only" as traction becomes an issue in 4th gear. Keeping the right foot down whilst feeling the back end lighting up with tyres on the edge of traction all the way up to 120 mph through 4th gear seems requires some concentration.
Some key results :
100-150 kph (62-93 mph) in 2.5 s, in 3rd gear
100-200 kph (62-124 mph) in 6 s, through 3rd/4th gear
The peak injector duty cycle observed was 80%, still with the 1200cc units. Some online power calculators suggest interesting figures for the engine peak power.

The difference in performance between 18 and 23 psi is impressive. The turbo kicks in much harder at higher boost levels. I get boost spikes to ~27 psi around 4000 rpm that I find difficult to control, but the engine does not knock even then. The intercooler seems to be working more as inlet temp through 3rd and 4th is 12°C above ambient, which I think is still ok, as I used to see between 25 and 30°C above ambient at 18 psi "only" with the SFR Stage 2 intercooler.

It should be interesting to see how much the fresher air of the colder seasons affects performance and traction further.

Tuning the engine on the dyno will be definitely needed, if perhaps only for the sake of science as I would make no use of more power considering how traction becomes a problem and I am not keen to fit bigger wheels and tyres. The transmission is probably already working hard enough.

That's awesome! I suspect you are a few hundred HP north of my motor, and I've already gotten to the point where I felt it had as much power as everything else can handle without a lot more work -- so can't imagine how explosive your car must feel. 12°C above ambient for the intercooler is fantastic compared to the logs I did many years ago. I can't find that data right now, but even with the (now-removed) SFR front mount intercooler, I was seeing multiples of that after 3 or 4 full boost runs. I've need tempted to finally get a Dragy -- mostly for the 992TTS -- but that might be a useful tool for you too.

[Thom]

Well, the car is on 17" wheels in the stock 968 wheel/tyre sizes and Michelin Pilot Sports, so nothing too exotic. Yours on the stock slimmy 16" sizes I guess must have been a real handful in comparison!

The 12°C gradient should probably be taken with a grain of salt as at such high speeds on the road I ran out of room too quickly to keep accelerating hard and long enough to reach the possible soaking point of the intercooler, but the logs show that inlet temp comes down reasonably quickly once getting off the throttle. For sure that intercooler is not a waste of space, and I have not even made any ducting yet, which I am sure will help further.

Yes, a dragy or a similar device may be handy, as the figures mentioned are deduced from the data logged, for what they are worth.

[blade7]

That's awesome! I suspect you are a few hundred HP north of my motor, and I've already gotten to the point where I felt it had as much power as everything else can handle without a lot more work --

There does come a point where the driver running out of talent, or the car running out of traction, makes any more power pretty pointless.

[Thom]

I agree. When even big black brakes feel like they're on their knees then it's perhaps time to call it a day as far as the HP race is concerned.

My initial goal with the 16V engine was to get rid of the obnoxious wall at 6000 rpm of the 8V engine which was getting really long in the tooth. I can't deny that the 16V engine has some lag down low that the 8V did not have, or perhaps the 16V engine is actually faster off boost than the 8V engine but the transition with full power is so mesmerising that the gap between low end and top end feels huge. It just cannot compare with the breathless 8V engine. That "lag" then is a truly insignificant trade off compared with what the top end feels like. This short moment when you floor the throttle at 3000 rpm and prepare for the boom that occurs shortly before 4000 rpm is like a half-relaxed moment in the eye of the cyclone awaiting the switch to hyperspace, not too dissimilar to that short moment in Star Wars in the Falcon Millenium before stars all go like straight lines and the ship eventually explodes straight away and you are not too sure anymore if the rear tyres are still motivated entertaining any discussion with the pavement.

I cannot help but put the blame on Porsche themselves who delivered a crappy half-finished 8V engine that did not even remotely do justice to the ability of the chassis. I have been playing with Ferraris in the last years and one thing I reckon is that Porsche do not have a clue on how to make genuinely brilliant engines on their mainstream cars, at least on the other side of a Carrera GT. Or rather they certainly do know, but deliberately hold off to satisfy the clueless masses of mainstream consumers who cannot drive properly. The only good thing about all that is that the 951 remains one of the best kept secrets in the world of performance cars and needs "only" about 30k€ to get its ticket to the motoring hall of fame up there with 400hp leaf spring Cobras that made the legend.

[Tom]

My guess is that it was business guys and not the engineers who held the 944 back. But it was also a different era, when most cars had meager power. The 944 Turbo was actually the fastest car sold in the US by some reports, for a short while before the Testarossa arrived. As for brilliant engines, my 992TTS is fairly astonishing, although in classic Porsche form, the car seems to get more out of its 640hp than you'd normally expect. And it has a plastic oil pan and an 'integrated dry-sump" according to the marketing department (known as "not a dry sump" to the engineers), so there's that. But still, the overall car is pretty amazing to me. In its heyday, my 951 probably had a higher peak g-force when the boost hit, but from any point A to any point B, the 992TTS will get there faster than anything I've ever driven. The 951 will always have a special place in my heart though -- its a very special car.

[blade7]

Old car not silly fast, but good fun to drive. New car silly fast, but not such good fun to drive. Unless you're Lewis Hamilton ( or kidding yourself that you are) .