SharkSkin

Looks like there's something to be said for retaining the flappy....

drnick

where are some 0-60 or 1/4 mile times from the centrifugal guys??

cmon tim, dynos are great and all but to be truly representiative a comparison should be done with the same machine at least. besides which how can you compare a dynograph to a 0-60 time??

who cares about bloody dynographs anyway?! pick up a popular car mag in any store and see for yourself... no dynos anywhere, just times from 0 to 60 to 100 and back.

so what if someone puts a dyno up with a million bhp, or even 7-800 (aka kelly moss) - how does that car drive, or does it even move (what happened to kelly moss car?)

nobody is sending their engines out to kelly moss to build up because there is little evidence that it moves. if you send your engine to devek you may expect to achieve something like their white car, which has surpassed 200mph - murcielago teritory, if you add a twin screw you equal 996 turbo performance. what do you get with a murph kit - we know that it is very well engineered and functions - what about the driving preformance?

hacker-pschorr

On 1/4 times - unless the cars are side by side, same tires, weight, fuel etc... it's never going to be apple's to apple's. Then you still have the driver factor that plays the biggest part.

To say there are no dyno's anywhere is 100% false. Most major car mags have started to dyno aftermarket tuner cars and posting results. The super car challenge (not sure who does it every year) has a dyno run part of the contest. Reason why you don't see new factory cars on a dyno is more of a legal issue. It was either R&T or C&D that dyno's a bunch of american iron few years ago. Didn't go over well with the big boys since the results where NOT what they wanted posted. Fact remains the dyno is the ONLY way to get consistent results.

On Kelly Moss - A friend of mine has worked there for years. I had a chat with him about the 928 GTR a few months ago. The car is at Kelly-Moss, the reason for the car not moving or showing up anywhere is not the car's fault or it's design. More of an issue with the owner and KM. The car is basically done and ready for the track, but most likely won't any time soon- that's the most I should really share.
To bring up that car on a 1/4 argument is silly. That car is not designed for drag racing, never was and hopefully never will be setup to do so. That car is an unlimited design with no budget, probably expecting a rebuild every season (just my guess on that part).

Carl Fausett

Gosh Andy - it'd be easier to take a 32v 928 to a drag race track IF I OWNED ONE. All my 928's are 16v cars. Best I could do with a customers car was dyno it b4 and after.

I like to think that is a little better reference line than 1/4 mile times. With a dyno, tire grip, wheel hop, quality of the launch - don't exist. The dynos are even tempoerature, humidity and altitude compensated.

Your hookup and launch from a standing start time in SoCal on a 90 deg day (warm track) with your tires is going to be completely different than our launch in WI on a 60 deg day. Hell, - the driver alone, (clutching, shifting) throws a variable in here that makes comparison worthless.

At least, on a dyno, we are talking about the engine only - and not the driver, the hook-up, the tires, the track conditions.... etc.

But, I have others who have asked me for my 1/4 mile times too (for what their worth) and, if it makes you happy, next summer I'll take my street legal SC CIS track car down to Morton Grove, IL (the closest 1/4 mi track to me, about 3 hours away) and have at it... on one condition: you gotta take down that sentence on your website that says "home of the most powerful street legal 928" - until you post a dyno chart better than Tim's, Jim Page's, Todd's, or Lag's.

Hey! Lag and Tim and Jim and Todd and others in the GLOC - lets plan a date next spring/summer and all go to the 1/4 mile drags at the same time! That should make for some great video! I'll host it!

hacker-pschorr

Don't forget about WIR in Kaukauna (Appleton) should be closer. They do weekly open drags in the summer. I have no idea about the quality of the place.

I'll come along and do what I do best - take pictures.

fasttech

hacker, is your km friend doug by any chance.

hacker-pschorr

fasttech - I sent you an e-mail.

Jim_H

I hope Andy, Tim and Carl don't take the pissing match any further. You are all great contributors and each kit has it's own niche. I know you guys are competitors but don't forget you are also the point men for making these cars 'true' super cars and for that my hats off to all three of you.

mspiegle

It says:
"The world’s quickest supercharged street driven 928"

This implies a 0-60 or 1/4mi time for a 928 that is primarily driven on the street. Not a dyno chart.

While the CS guys do get props for having the highest HP dyno charts, you can't keep making excuses for NOT giving up some 0-60 and 1/4mi times. You should at least come to the table with something, then add your disclaimer. I know you can obtain a gtech that will get 0-60 times for less than $50. If you do indeed claim better 0-60 times and better 1/4mi times, i'm sure Andy will tell me to remove the statement from the website (and then work on reclaiming the title ).

mspiegle

I have one other question, does anyone know why all of the Dyno charts have a little dip at 3750rpm?

The 3 charts on Tim's site have the dip and so does Andy's. I noticed that mine has no such dip, and neither does Shane's. What is this dip, and is it S4 specific?

Carl Fausett

mspiegle - "implies a 1/4 mile time"? No it doesn't. It SAYS "The world’s quickest supercharged street driven 928" which implies the street driven car with the most power (IMHO). Its a matter of interpretation.

oh, whatever.

And, mspiegle - I am not aware of any dodging or excuses for not going to a drag strip. I am a road racer and drag strips do not interest me. Never have.
Drag racing a Porsche is like trying to run a funny car at Le Mans. Who would do that?

A comparison of dyno charts is a much better way to compare two engine's output - one in CA and one in WI - for all of these reasons I posted befroe:
Jim H is right to remind us, and I have said it before... there is more than "one way" to add HP and Fun to the 928. Stroker, Turbo, SuperC, they all work if designed and built right.

I wasn't picking hard on Andy's site - just poking fun at his enthusiasm a tad.
I remember when my eldest son showed me the first draft of the 928 Motorsports website - he had somthing on there like "Home of the worlds only 928 Supercharger kit".

I appreciated his enthuisiasm, but I made him take it down. It wasn't true. Albrect in Austria had kits, F.A.S.T. had kits.

Then I remember Tim Murphy's site that came after mine - and it said somthing like "home of the only complete 928 supercharger kit" and I ribbed him about that till he changed it. I know how easy it is to get caught up in your own hyperbole.

I offer these two anecdotes to Andy in an effort to explain that I understand how things like that get put oin websites - but unsubstantiated claims and exagerration cheapen your product and others belief in it.

Old & New

Today on the F-A-S-Tonline.com website:

"The world's first and only supplier for complete 928 supercharger kits."

"3-5-02: FAST NOW HOLDS 5.0L 928 RECORD DYNO! 480RWHP/520RWTQ ON PUMP GAS, STOCK EXHAUST"

They need an update...

Z

Not sure where that .5 second figure came from, but as the cars get faster in the 1/4 mile the advantage becomes greater for the automatic transmission car. The automatics will shift faster and won't have the same interruption in power delivery to the ground like the manuals do during shifts. As the cars get faster, there are more shifts that have to be completed during the 1/4 mile. Each shift gives the automatic another advantage point. That's one of the reasons the majority of fast drag cars have automatics.

Since I'm sure there's going to be at least somebody that's going to have a hard time accepting this, I'll give an example that shows this pretty clearly. There are actually several points than can be clearly shown by the following charts. They're G-Tech charts showing 1/4 mile runs of my automatic transmission '88 928S4 and a manual transmission '01 Mustang Cobra. The black line is my run, and the red line is the Cobra's.

The accelleration vs time chart shows that I have greater acceleration right off the line up to about .8 seconds. That's at least in part due to the torque multiplication of the torque converter in the automatic transmission. The Cobra also has an acceleration peak right off the line due to it launching at about 1,900 RPM. The Cobra's peak doesn't increase as steeply, and it drops off faster than the torque multiplication of the torque converter with my automatic, and my just flooring it from a 750 RPM idle as shown in the RPM vs time chart though.

During first gear, from about .8 seconds to about 3.6 seconds the Cobra's accelerating harder, at least in part because of the lower rear gearing of his car, but then he has to shift. The big dip in acceleration for him that's centered at 4 seconds is what happens with a manual transmission during an upshift. In comparison you can see that my automatic maintains a much higher level of acceleration during the shift that occurs for me at about 4.6 seconds. That type of drop in acceleration during the shift happens with all conventional manual transmissions. It is physically impossible for them to maintain the level of acceleration that an automatic can during the shift. The Cobra is again accelerating at a greater rate when actually in second gear than I am, but his acceleration is decreasing faster than mine in that gear. Then he has to shift again, and he once again has the big drop in acceleration during the shift.

The numbers at the top of the charts show that I had a better 60' time, a better 330' time, a better time and higher trap speed in the 1/8 mile, a better 1,000' time, and a better 0-60mph time. The reason my 1/4 mile results were slightly worse than his is because I quit before the 1/4 mile point was reached. The chart shows I stopped accelerating and started braking at about 12.4 seconds, which is about 1.2 seconds before I reached the 1/4 mile point.

Even though his car was actually accelerating at a greater rate when actually in gear, the difference wasn't enough to overcome the big drops in his acceleration that occur during the shift with the manual transmission. The distance vs time chart shows my car being ahead at all times until I got off the gas.

In the acceleration vs time chart, you can see the two distinct humps in the acceleration of my car at 2.0 and 3.0 seconds, caused by the two humps of the 928's torque curve. You never see those two humps anywhere except for there in first gear. That's because after you shift, the RPMs never drop that low ever again. Any increase in torque below about 4,100 RPM would be of absolutely no use whatsoever after first gear, because during maximum acceleration the engine never gets down that low in the RPM range ever again after first gear. If you're talking about second gear, it's even higher. The RPMs never get below about 4,600 RPM in the chart in second gear. People have talked about torque increases starting at 3k RPM. That 3k RPM is reached in about 1.7 seconds in my normally aspirated, stock heads, stock cams, 5.0 liter, automatic transmission, 2.20 rear gearing, 3,600lbs+, '88 928S4. In a more powerful or lighter car it would occur in even less time. The speed vs time chart shows that at 1.7 seconds my car is going less than 25mph. After that 25mph, any torque increase at 3k RPM will be completely worthless because I'll never be at 3k ever again. *IF* I had the traction to use an increase of torque at 3k RPM in first gear, I'd have better acceleration at 25mph. I'm much more interested in the large region of speed between 25mph and 58mph in first gear, and all of what happens in second gear, third gear, and fourth gear. I've been in some of the centrifugal supercharged cars on a number of occasions. More torque below 25mph than that is the absolute last thing I'd want, even if I had the bigger, stickier tires on my car that those cars had. The above is all with being an S4 with the 2.20 rear gearing. The lower gearing (higher numerically) that some of the other year and model 928s have makes any low end RPM torque increase end at an even lower mph speed, and you also never see it again once you shift out of first. When driving hard or at maximum acceleration, ask yourself if you spend more time at full throttle with the engine at 3k RPM or at 4k+ RPM. That should help make any power increase choices you're considering easier to make.









I have a drag racing simulation software program. To come up with a chart of estimated results for a 1/4 mile run, rear wheel dyno results for the entire operating RPM range are input. Besides that, it requires the weight of the vehicle as it's run, the wheelbase, whether front or rear wheel drive, the percentage of weight over the drive wheels, the vehicle frontal area, drag coefficient, whether it's a street engine, track engine, or race engine, engine displacement, transmission type, number and ratio of the transmission gears, stall speed of the torque converter if it's an automatic, rear drive gear ratio, diameter, width, growth factor, traction coefficient, and type of tires, what the engine redline is, what the shift points are for each gear, the shift time, the launch RPM, the staging rollout distance, temperature, barometric pressure, humidity, altitude, and wind speed. Changing any one of those factors will change the simulated 1/4 mile results. Magazines test what are at least supposed to be totally stock, as new off the showroom floor vehicles, and the results can still vary by a good margin from one test to another. There are a lot of ways to get significantly better 1/4 mile results without ever even opening the hood of the car. Even a bracket racer car built from the ground up, with the sole goal of running the most consistent 1/4 mile times possible, will have times that vary even on the same track and same day. If someone with a trick new power increasing product removed 1,000lbs of weight from their 928, put on drag slicks, and ran it at sea level on a 0 degree day, would those 1/4 mile results really tell the owner of a stock weight 928, with street tires, on a hot day in Denver anything much about what that new power increasing product would do on his car? Put the two cars on a dyno and you'd have a much better chance of getting a realistic comparison of how much, if any, difference in power there was due to the product.

wjk_glynn

Interesting thread... from what I've gleaned that there are currently 3 (three) 928 SC kit vendors as follows:

http://www.murf928.com/ (and http://www.928motorsports.com/ is a reseller?)
http://www.f-a-s-tonline.com/
http://www.928supermodel.com/

If I missed anyone, can somebody correct me?

In addition, can someone post links to the turbo-kit suppliers for the 928 (which was alluded to in an earlier post)?

Thanks.

Karl.

Jim_H

OOPS, 928 Motorsports, Quick Carls Co. I don't know how involved F A S T is anymore. I would consider the Big 3 of Superchargers to be
Andy, Murph & Carl.