Boricua944:

OK, cop a chill and we'll try to get this sorted out.

First off, the topic was about launching a 951, which automatically got the attention of us "boost heads."

Second, "launching" typically infers that some form of straight line standing start contest is involved.

However, to answer your actual question, its the gearing, and the gearing was chosen to give the best over all performance for the car's intended purpose.

For running on a road course you don't need a "tall" first gear or a "beefy" diff like you need for running on a drag strip. What you do need is a 1st gear that will get you moving, and 2nd through 5th gears that give you a good power band for the turns and max top end speed for the straights.

Since you have an NA, one item that might help with driveability (particularly when starting from a standing stop like at a traffic light) is a round throttle cam.

The stock throttle cam has a rather pronounced "flat spot," which requires (IMHO) way too much accelerator peddle travel. A round throttle cam won't give you any more power, but it will make the throttle more linear and easier to control.

As for answering your friend's questions about why a 944 doesn't "launch" very well, tell them straight up that a 944 is a SPORTS CAR, and as such is not designed for "launching." If they don't like that answer then there is nothing else to say.

The 944 is however, one of the best balanced and "sorted" cars for driving on the road or on the track.

 

Well, 0-60 times are more indicative of the launch technique and traction while 1/4-mile times and speed are more about the actual power. There was only a single article for the TurboS I've found that actually tested a car at 13.5s to 1/4-mile and it was a non-stock car with lower R&P (S2?) that limited top-speed to 148mph. The lower-gearing definitely helps in acceleration. They said that the 0-60 5.5s time matched another previous TurboS test even with an extra shift due to the lower gearing; so that car was definitely faster than a stock TurboS. Unfortunately, a lot of other articles have quoted the performance figures of this non-stock car.

From averaging all the articles I can find these figures are more realistic:

Turbo
0-60: 6.1 - 6.3s
1/4: 14.4-14.7s @ 88-91mph
top-speed: 155mph

TurboS
0-60: 5.7 - 5.9s
1/4: 13.9-14.3s @ 98-103mph
top-speed: 162mph

Travis's Turbo (in video)
0-60: 4.7 - 4.9s
1/4: 13.2-13.5s @ 115-123mph
top-speed: 172mph+ (redlines 5th gear)

On that video I posted, we used a Gtech for the numbers. The times are accurate, but the MPH at the end of teh 1/4 is usually off by 5-10mph due to the calculated instant MPH at the end rather than an average over the last 50-ft or so like a drag-strip.

FWIW, I think the 951 can work fine as a drag-car. It just requires more difficult launch technique than a V8-automatic (more skill?). However, it WILL require more maintenance in clutches and CV-joints. Rage2 was replacing his CV joints every, what... 4-6 weeks? And a clutch job in a MustangGT costs $500; what does a 951 cost? Even if the 951 is just as reliable as a GT and needs a clutch only once a year, that's still a dramatic difference in maintenance costs.

"How well do 951's run with 911's on the track is it no contest or can they keep up?"

Depends upon the track and which 911 you're talking about. My 951 RacerX website has articles comparing a 951S vs. a 930 where a TurboS beats a 930 by 2-seconds a lap at Willow Springs. That's over 1/2 a football field ahead per lap. In stock trim, it's comparable to a stock 964 Carrera, maybe a 964 Turbo, slightly faster than a 993, about even with a 993 Carrera4S, definitely not as fast as a 933 TwinTurbo. Haven't matched up with any 996s or GT2s yet, so I'd have no idea.

 

NA's launch just fine, thank you, if you're talking about getting through the gates of an autoX course in a competitive time. But, as many have posted here, there's a bit of price to pay with CV's and clutches designed for dynamic track performance rather than hole shots. I don't get the sense that I'm tearing up my ride to launch at about 4,000 rpm with a smooth, brisk release of the clutch. I get a little wheel spin in the left rear that usually hooks up before the pull for second.

A Cheaspeake PCA bud with a 924S who also autocrosses at the Cumberland Airport was not so lucky though. He's a bit more of charger than I am and was getting big time wheel hop in his first two launches last June (probably dumping the clutch at about 5K). The third start of the day ended with a quick bang and a silent drift through the start lights. Pinion went bye-byes in no uncertain terms.

 

What does the 6th gear on the 968's help do?

 

"Pinion went bye-byes in no uncertain terms."

What kind of tyres was he running? Did the tranny look like this afterwards?



Now imagine dumping in over twice the power and torque, that's gonna be tough on trannies...

"What does the 6th gear on the 968's help do?"

Not much on an NA, great for a 951 if you want close-ratio gearing for track-racing. Take a look at the gearing ratios on my 951 RacerX website. The 968 has close to identical gearing in 1st through 4th as an '82-87 944NA. Just that it breaks up that big jump to 5th into two separate gears. Compared to an 88+ 924S/944/944S, it adds one more top-gear 6th.

Compared to a 951 tranny, it places 6 gears in tighter spacing than the 951's 5 gears. This is great for track-racing to keep the engine in the powerband. The 6th gear in the 968 is actually lower than 5th in a 951 tranny. But those who've used it on the street have mentioned that the need for more frequent shifting is annoying. I'm actually going in the opposite direciton, adding a taller 5th to my 951. That way, no more redlining 5th!

 

Qualifications mean naught... I've been a Distinguished Expert since I was 15, nationally ranked in the top 5 with 3 different weapons before the age of 21 and invited to audition for the olympic team.

My 300lb, somewhat out of shape 60y/o father can run 20 feet before I can get my .45 from my side (in my hand, condition 1 ~ NOT in a holster) to on target and a round fired. Not looking at accuracy here either ~ I was shooting at a full sized target (that wasn't moving) at about 10 meters. My dad's a bit faster with the pistol (IDPA competitor for many years), and I can easily make it 20 feet under the same conditions. Closer to 25' when he's holstered with an OWB quick draw and we never bothered with trying from his concealed position.

Feel free to get a friend and try it... You might be shocked at how far an average person can get in the time it takes you to draw, aim and fire. Anyone with basic knife training (which isn't hard to get/learn ~ IMHO easier to learn than keeping a pistol shot on target) can and will screw up a gunman within 15'.

It's all a moot point in my book as I use my head to keep me from such situations. I still carry a G21, knife and tactical light with me everywhere I go... each tool has it's time and place. I've never needed to draw a firearm ~ ever.

Sorry for dragging this so OT, it's just a pet peeve hearing that Stupid saying.

 

Yes, that's exactly what it looked like! Tires were nothing special. Old Dunlops on OE Phone dials. And yes, it must get dicey when you double the power...makes smaller, finer fod faster????? Are the beefed up Turbo S boxes significantly less at risk for this kind of failure?

 

The 6th gear is higher than the 951s final gear, checking in at 0.780 as opposed to the 951's 0.829. Interestingly, the good 'ol n/a has the HIGHEST high gear drive ratio at 0.730 (I love my n/a!) The difference in top speeds differs due to final drive ratios - 3.889 for the n/a, 3.375 for the 951, and 3.780 for the 968. As such, the single BIGGEST advantage to the 6-speed is not theoretical top-end, it's more gears to go through, probably due to the powerband dynamics of the 3.0L engine. I haven't seen 'em but I suspect the 3.0L caps out for torque & h.p. a lot sooner than the 2.5L or 2.5L turbo. As such, it makes sense to have more gears available to keep that engine "down low" where it makes best power - but this is a bit of conjecture on my part. . .

The other thing is that the n/a cars run out of power WAY before they run out of RPM / gearing. They'd be good candidates even in 951s but for the weaker pinions. A GREAT project would be to swap the 0.730 n/a high gear into a 968 trans or even a 951 trans (with the stronger pinion). I may eventually do this with the Callaway car, since I'll be taking far greater advantage of the n/a high gear with the huge amount of additional power I'll have to play with. . .

 

Dammit Danno, you beat me.

FWIW I got most of those #'s from your site anyway. . .

 

Don't leave out the "forgotten advantage" gear box. The 87-88 944 S box is a hybrid with the NA's 3.89 final drive ratio but with a .830 fifth and the first four ratios from the 951 tranny. Great for NA track and autoX as you get 10% or so more time in each gear before you hit rev limiter.

 

The 13.5sec 1/4 mile that Excellence quoted is the factory time, which has never been duplicated for a bone stock car to the best of my knowledge.

The factory normally underestimates the cars, so who knows whats going on here...

 

Maybe late, but dont forget the taller gearing our cars have. Thats the sometimes funny thing about the little Hondas, theyre into third as were finishing first/half through second sometimes.

 

Ummm most hondas (civic / integra) have tall gearing, hell they rev to 9.5-10K as well!

I dont believe a stock Turbo could do 13.5 unless it had drag tyres and had a professional at the wheel.

 

6 speeds are over-rated.

Want a better set of gears? Custom gear ratios are still cheaper than swapping in a 968 6-speed.

Heck, even on a track you won't need a 6th. Most tracks I've been to don't even need a 5th speed.

Only real reason to have a six-speed is fuel efficiency.

Just my $0.42,
-Z.

 

Not exactly right, a little understanding is missing about the ratio of the 6th gear there I think. If you dont get into the 968 6th on a track, then its a tiny little track with no significant straight.

Check out Powerhaus II for custom ratios and a strnger R&P early next year...

If you want shorter gears, a shorter 3-4 make for a good improvement... I plan to do this next year as I would see most of fourth out on the 1/4. And the stock 5th for the straights...