Timed the Z

[Manteuffel]

Hi all!
I did this very same thing last year with my AP-22 accelerometer. My brother also records the runs from the cockpit on videotape as well, to make sure the times from the accelerometer are correct. So, here are the results:

*All runs (last year and today's where done with about 1/2 tank and my brother on the car.) Car weights 3097lbs with ~1/2 tank, I weight 172lbs, brother weights 130lbs So the weight we set on the meter is 1545 kg. or 3399 lbs.*

-Last October (2002), my best 0-60 mph was 4.54 secs, power peak was recorded at 49 mph, 357 hp SAE corrected. This, from what I've read on the web page is exceptionally accurate to what stock cars are pulling. So, I'll assume the AP-22's price tag is for a reason.

-Today, my best 0-60 was 4.72 secs, the horsepower peak at 50 mph was 372 hp, SAE corrected. (No mods, all I've done is opened the airbox a bit, installed AMSOIL foam airfilter and replaced all the fluids to AMSOIL as well.)

372 hp is not too bad. But...

So, most of the runs from 0-60 we did today were 4.98, 5.12, 4.83, 4.91.... the 0-30 mph is what kills me: 2.3-2.7 secs in the 0-30 mph when I've seen ppl pull the AWESOME 0-30 mph in 1.6, 1.7 secs. You guys ROCK!
My question is, how on earth do you keep the Zbeast from spinning the wheels?

After giving up trying to get under the 4.54 again, we went to do 30-80 mph runs. Why? Because we have a good video that measures the AMG E55 doing it in 4.82 (counted the frames and at 29.98 fps, we divided the total fram count between the needle at 30 mph and 80 mph by the fps and thats how he got it.)
For those in the accuracy squad, well, we have about 25 0-60mph runs and 5 30-80mphs runs on tape where the speedometer is centered dead on the camera. The difference between the AP-22 and the video is on the 0.0x difference. So, I think it works pretty good.

Anyways, so we set out to get a good 30-80 mph, faster than the AMG boat did on the video and after several tries on the range of 4.98s, 5.2s, 5.0s, I fnally did it:

-Best from 30-80 mph was 4.69 secs, and the amazing thing is that the car peaked max power at the same spot as before, 50 mph, but this time it showed 393 hp SAE corrected. Same day, same car, same settings same everything. Amazing!
393 at the wheels plus ~12 percent is about 440 hp at the crank. My question now is, giving the dead on accuracy the AP-22 meter has, could this be possible?

Any help, suggestions, ideas, comments... will be greatly appreciated!

Thanks!

G.

[EnzoM]

Very interesting. Did it get cooler over the course of your runs? Was your car idling for a long time before your earlier runs?

It is really amazing that we keep mentioning the E55 in our forum posts. I am going to schedule a test drive just to see if it is really the beast it is reported to be.

[Manteuffel]

Hi EnzoM, thanks for posting back!
I was beginning to think this was another dead post.

The procedure is very simple. There is 2 lane highway with a traffic light crossing. The street that crosses ends about 50 meters in one end, so noone can come from there. I cross the highway, get the Z in the side where nobody comes. Wait until the highway light closes. I get in the highway: there is nobody on the highway for at least 1km ahead. So, I brake, stop the car, recalibrate the accelerometer and off I go. Then I turn onto the service road to get back to the starting point. Then repeat another run. It takes about 5-10 minutes to get back to the starting point.
The car idles for 1 min or so before the light turns red.
Regarding cooler: The oil temps since I use AMSOIL is at the 185 degrees line most of the time. It moves a tad up when gunning it, say 19x. I should get the oil temp from the DIC, but since I am in competitive driving, I cannot see it when it matters.
From my data I've recorded, I can see why the E55 does so well: It is not due to the 469 hp at all, it is because of the autoshift.
Their autoshift can change gears in 0.2 secs. Me shifting gears usually takes 0.6-0.8 secs to shift.
Half a second difference without power can make all the difference.
The E55 has only 1 shift between 30-80 mph, Z has three.
Now, I don't like AMGs, I don't like MB, I don't plan on owning one and I do plan on blowing its doors off.

Let me know.

G.

P.S. I don't do quarter miles on the public roads because doing 116 mph in a 55 mph road is too scary for me. 80s are breaking the law, but not DEMOLISHING the law.

[Penforhire]

Lower rear tire pressure to get more traction (at 1/4 mile tracks we use low-20's PSI). Raise front pressure for less rolling resistance (40+ PSI at track).

Not sure the speedometer method is reasonable due to speedo error (both absolute error and lag probably repeat okay but you haven't measured them).

[Manteuffel]

Thanks Penforhire.
I never used the speedo while making a run. I set the HUD with the RPMs only so I can see the shift message well.
To achieve speed I go by the gears: To do 0-60 I go all the way to redline in 2nd. To do 30-80 I'll go all the way to 3rd gear (or almost)
The tape we used it to verify what we were getting on the accelerometer was more or less correct. If the accelerometer reads 4.83, the camera frames will show the time to be 4.8someting. It is usually a bit more than the accelerometer. You're correct about the lag.
The good news is that I only use the camera to verify that 4.69 secs on the 30-80 mph was not a 8.32 sec in the speedo, or a 2.34 second run for that matter. To test the accuracy of the accelerometer, my brother and I prepared a good speed test a year ago for it: we tested 40, 60, 80 and 100 mph speeds from a dead stop.
What we did is stop the car, calibrate, accelerate at normal rates to 40 mph on the HUD. The hud doesn't have the analog speedo lag. We tested all these four speeds and the results on the accelerometer had errors on the low 0.x range. So, if HUD read 60mph, the speed on the accelerometer will read 59.8. So, I am not sure if the error is actually on the speedo or in the accelerometer. But if speedo is showing 60 and accelerometer is showing 59.8, I will have to asume I an going at 60 mph. Maybe I am wrong.

I might invest some cash on a real GPS based accelerometer. But those are too expensive for just a couple of runs every once in a while.

So, to achieve good run times on the 0-60s I need to deflate the rear tires to get better traction. That's very interesting. I had no clue about that! It makes perfect sense too. I will give it a shot this weekend and see what the results are.
The other thing I've been practicing on my MX-6 since last weekend is clutchless shitfing. Mr. Heinricy was the responsible for the advertised GM 3.9 secs on the Z06, using with this type of 'clutchless' shifting.
I've already noticed it is very hard to master, but I can see why shifting is lightingfast. Need more practice, tho.
It is amazing how the gear stick shifts effortless when RPMs match the shift point. amazing. BTW, any good advice on clutchless shifting? I am all ears.

G.