ebaker

I've been trying to figure a correction for running uphill. It takes 74250 ft.lbs. of energy to lift a 3712.5 pound car 20 feet. 1 HP is 550 ft.lbs/sec. On a 9 second acceleration run 20 ft. uphill it would calculate 74250 ft,lbs/9 sec =8250ftlbs/sec = 15 HP extra would be needed. If you're running downhill it would be like 15 extra road HP. I don't know how much difference in 60 - 130 time 15 HP will make.

Bill S.

Beware of a velocity drift error in the AX-22. You can see this error if your shift points don't match the speed you expect. See the graph below for two runs in my CS. Both were done with identical calibrations and procedures.

As you can see, the shift timing is correct in both runs, but the AX-22 drifted after the second shift in the bottom run. So, although both #3 shifts occurred at nearly the same time, the bottom graph made it look like I was going much faster for 60 to 130.

I don't know what sets off the drift, but it can start half-way through a run. It may be a mechanical problem or software bug. Hopefully the manufacturer can fix it.

NineMeister

OK, I promised Jean that I would post results from 9m tuned cars as and when they were available. Unfortunately the weather in the UK for the last few weeks has been pretty useless for testing, so here is the first of 2 runs measured by one of my customers in Germany using his new driftbox, the actual 60-130 time is 10.18 seconds. The car in question is a LHD G50 930 with turbo 2 bumpers, teardrop mirrors and turbo S rear spoiler, all up weight including driver as tested was around 1450kg.

Obviously this is a 2nd/3rd/4th gear run with average 0.4s gearchanges, but the obvious question is: How much real power has it got?

I naturally know the specification and also know what hp our dyno measured, but rather than giving you all the answers I thought it would be better if the power was deduced from the performance figures. All I will say is that the core engine is a stock 3.3 lump with 964 cams, once I have your best shots I'll let you have more details. Good luck with your calculations!

Konstantin

let me guess around 440 FWHP

Konstantin

Jean

Bill

I am not sure I understand the difference between both files but if you send me the raw data I can check what happened. I have never had any wrong readings with my runs, nor 99% of the files that I get, other than when people are bench racing that is

Colin, thanks for the data. My estimate is this car has 400 Porsche HP, if it is stock weight (1,290Kgs). The question is, how do we know the chassis dyno readings are accurate?

Konstantin, this car does the runs in 2-3-4 unlike the 3-4-5 of the 993 so I believe it benefits from better torque from 60-130mph..

JBL930

Hi Jean, my car weighed 1381kg with a full tank of fuel, i weigh around 90kg so that makes my 930 with me in it 1470kg

What does a 930 fuel tank hold? Lets say 80ltrs of fuel at 750g per litre which makes a full tank aproximately 60kg. The only real weight saving from stock is no aircon and rear wiper delete, oh and after market headers.
Lets assume Colins man has deleted similar bits from his car, only had half a tank of fuel and weighs a bit less, surely it would still be around 1430kg?

Jean

The weight I mentioned is the factory posted weight if I am not mistaken, and my estimate is based on that weight without driver.

Greg A

What's wrong with using the weight stated above?

Greg A

TB993tt

450PS @ 1.1 bar? -the 100-200kph is excellent at 8.85s

NineMeister

OK, so our 1450kg car (with aircon and heavy electric seats) is 0.8 second faster than a car you confirm has 480hp, so am I missing something other than the loss of power through the 993 4wd system? Does this equate to 100hp when it is not being driven??

Toby, you have run your car in 2wd & 4wd mode, what is the difference in your 60-130 time with the same engine (assuming traction was not a problem)?

TB993tt

Unfortunately I didn't have the reliable measuring devices when I was in 4WD

I have always guestimated ~40hp gain/loss when losing/adding 4wd based on a ~500hp starting #.

The Lightweight 965 Turbo S was tested at 1400kg test weight. It has Porsche 381PS and was timed 100-200kph at 9.5s - hence my 450PS guess at yours - I thought was erring on the generous side

Jean

Colin seems like what you are missing is that you are comparing a 2900ish. lbs car (factory specs) to a 3550 car (factory specs) Other than the 2WD vs 4WD impact. I don't have my references with me, that is from memory but I think these are the quoted weights for these cars..or are they the weights with driver?

NineMeister

The car was weighed on the day it was tested at 1450kg ~= 3200lbs which is within 10% of the weight of a stock turbo. Should I get the customer to run the car again with one of his fat friends in the passenger seat?

I'm not here for an argument Jean, but what is the point in quoting factory specs for weight since all the data we are collating is for modified cars? All I am looking for is a realistic extimate of the power of this vehicle in comparison to other cars of similar power that have been tested in the same way, hence Toby's comparison to the Turbo S seems to be the most valid as the weights are within 50kg, although the 100-200kmph time seems to be the more of a measure. Given the 61 pages of posts do we not have another 2wd car around 1400-1500kg tested weighr that runs a similar time?

Jean

Colin,I am not here to argue either. Funny you quote me on some previous run to disqualify my estimates yet you say you are not arguing.

Anyway, here is my logic concerning this specific comparison, which I think is rather irrelevant when comparing such different cars.....taking your numbers for the 930,

Similar power to weight ratio for both cars at 400HP and 480HP with drivers.

Now check out the gear changes of Woodster. He lost at least 0.3-0.4 seconds vs the 930 run. Now add the 4WD loss and you have two cars with similar performance based on similar weight/hp ratios.
Forgive me if the 996TT you quoted me for was more like 470HP and this 930 more like 410HP! This is not an exact science, and I am not Einstein. But certainly there is not much difference.

The point in quoting factory weights is because the 930 is stock and the 996TT you quoted is also stock, typically cars are lighter when modified, not heavier than stock . They can certainly be both heavier by 50Kgs when running vs factory numbers( excluding drivers), no issue.

JBL930

My car isn't stock, no aircon, lighter headers, no rear wiper, and even with no fuel in it would weigh at least 1320kg. These are facts, period! The factory figures are clearly wrong.