rpm vs speed graph
05-09-2008, 05:59 AM
#5
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I don't know the speeds that each gear gives, but i can say that hitting the rev limiter in 3rd doesn't quite give you 130mph, it's close though. I was doing some 60-130mph runs with an AX22 data logger to post on the 993 turbo forum, pulling from 2nd gear and hoping to have only one shift into 3rd, i hit roughly 126mph at 6800-7000rpm when the limiter kicked in, the tires were maybe half worn.
I guess with a fresh pair of tires on standard 16" rims, 7000prm will give you as near as damn it 130mph. Is 4th really good for a theoretical 205mph?
The speeds i've posted above are true GPS speeds, not reading off the clock, on the 60-130mph run the clock was showing around 140mph which is WAY off the true figure.
I guess with a fresh pair of tires on standard 16" rims, 7000prm will give you as near as damn it 130mph. Is 4th really good for a theoretical 205mph?
The speeds i've posted above are true GPS speeds, not reading off the clock, on the 60-130mph run the clock was showing around 140mph which is WAY off the true figure.
05-09-2008, 06:50 AM
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I've scanned the graphs from the owners manual, are these figures worked out from the gearing and radius of the wheel, or are they speedometer readings?
This first graph would say that 7000rpm should yield around 135mph+, I can say matter of fact that isn't true. However, it does show that 4th is easily good for 200mph before 7000rpm! Does anyone have the same "Owners Manual" graph from the 89 5 speed, or the 964t?
This first graph would say that 7000rpm should yield around 135mph+, I can say matter of fact that isn't true. However, it does show that 4th is easily good for 200mph before 7000rpm! Does anyone have the same "Owners Manual" graph from the 89 5 speed, or the 964t?
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05-09-2008, 08:56 AM
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I didn't look at the graph above properly, it actually looks like 130mph in 3rd comes up at 6700rpm which may be correct with fresh tires. In 4th gear it looks like 180mph comes up at 6400rpm, which would make 200mph only achievable at 7111rpm on stock 16" wheels, so 7000rpm will only net you around 197mph.
What size wheels would you need to fit to reach 200mph, at say 6500rpm?
What size wheels would you need to fit to reach 200mph, at say 6500rpm?
05-09-2008, 10:41 AM
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Download this , it is what I used , along with actual data, to determine potential new gear ratios.
http://www.1barsystems.com/930/ThrustVsSpeedwInstr.xls
This data pretty much matches my actual data from the track, which I'll try to post later (when I have more time). The only thing you need to do, if you are running a stock 930 box, is enter the tire diameter.
I plugged mine in at 25.6.
Brian
http://www.1barsystems.com/930/ThrustVsSpeedwInstr.xls
This data pretty much matches my actual data from the track, which I'll try to post later (when I have more time). The only thing you need to do, if you are running a stock 930 box, is enter the tire diameter.
I plugged mine in at 25.6.
Brian
How's the shakedown testing been going? Hope all's well.
05-09-2008, 01:41 PM
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Brian, that's great thanks! So the final drive ring and pinion on a stock 930 is 4.22? It looks like i will need a tire diameter of 27.5" or more to get 200mph at 6500rpm. I know bugger all about wheel and tire sizes, it's something i haven't yet got my head round, is a tire diameter of 27.5" or more even possible for a 930? Would it be a 17" wheel or 18" wheel, and what profile tire would be needed for each wheel, if it's even possible that is.
Hi Jim, things are going slowly with the car, It's getting on my **** to be honest, it'd better be ready soon or i can see me going a bit nuts, hope you're well mate, you coming to the 24hrs?
Hi Jim, things are going slowly with the car, It's getting on my **** to be honest, it'd better be ready soon or i can see me going a bit nuts, hope you're well mate, you coming to the 24hrs?
05-09-2008, 02:15 PM
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So far that's the plan, but I might be right in the middle of recovering from some knee surgery depending on how fast I can push the docs to do it. Go in this Tuesday for a MRI, 4 - 5 days after that I go back to hear the plan and the schedule. You'd think we're working a Shuttle launch as long as this is taking.
05-09-2008, 02:40 PM
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JBL930:
Dude, its gonna take a LONG straightaway for you to get to 200mph in a 930. Even then aero may prevent it. At VIR, here in thes States, the backstraight is 4200ft long, and I barely reach 150mph, and that's in a 2500lb car with 441RWHP.
Its gonna take a LONG straight my man to push one of these bad boys to 200mph...
Another thing to consider is the stock 4th gear we have. For instance, when I shift out of 3rd I'm at approx 132 (if I recall), and I'm only hitting say 147 on average, and I'm normally in 4th for an average of 7.2 seconds. So if it took me 7.2 seconds to climb 15mph, its gonna take a much longer amount of time to reach 200 because once you break over 150, your gain in speed starts dropping off - big time.
Brian
Dude, its gonna take a LONG straightaway for you to get to 200mph in a 930. Even then aero may prevent it. At VIR, here in thes States, the backstraight is 4200ft long, and I barely reach 150mph, and that's in a 2500lb car with 441RWHP.
Its gonna take a LONG straight my man to push one of these bad boys to 200mph...
Another thing to consider is the stock 4th gear we have. For instance, when I shift out of 3rd I'm at approx 132 (if I recall), and I'm only hitting say 147 on average, and I'm normally in 4th for an average of 7.2 seconds. So if it took me 7.2 seconds to climb 15mph, its gonna take a much longer amount of time to reach 200 because once you break over 150, your gain in speed starts dropping off - big time.
Brian