924Board.org

bass gt · Posted: Sat Jul 08, 2006 8:18 am Post subject: In Gear Speeds

Guy's,

A quick question if i may. What's the max speed in 1st gear for a 931? Reason i ask is i am setting up my launch control, and as i have no speedo, your help would be great.

Thanks,

Steve

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

This file from the FAQ might help you:

http://www.924.org/Downloads/PorscheTrans1.xls

If you want to know the top speed at a desired shift point in RPMs, you'll need to adjust the cell references in the speed table on the bottom right to reference the 931 transmission column in the top table. Let me know if you need help, I can make the adjustments to the file and email it to you, I have had plenty of experience with Excel.

If you just want to know the top speeds, it is already in the file in the orange bottom part of the top table. A 931 with the Dogleg tranny maxes out at 23mph in 1st, with the Audi box it is 25mph in 1st.
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1987 951 - M193 Version for Japan

bass gt · Posted: Sat Jul 08, 2006 8:34 am Post subject:

Thanks

Khal · Posted: Sat Jul 08, 2006 8:38 am Post subject:

OK, you knew it'd happen... I disagree!

Actually, I'm not a 100% sure, but 23mph just doesn't sound quite right. I know they're low-geared but 23mph is only 37km/h, which is way too low, IIRC. The top table in the file you linked shows a top speed of 41mph in 2nd and 121mph in 5th, both of which I know are just plain wrong!

The table on the bottom of the page shows a top speed of 32mph and 53mph in 1st and 2nd repectively at 6,500rpm, which seems much more like it...

I re-read your post... so you have to adjust the table to the required rpm's. Now I get it... I think?
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'80 924 Turbo

bass gt · Posted: Sat Jul 08, 2006 8:45 am Post subject:

So any advance on 32? Going once.....going twice............

Khal · Posted: Sat Jul 08, 2006 8:48 am Post subject:

Nah, just me being dumb. I think I get what the spreadsheet is about, it has to be adjusted.

But it's definitely closer to 32mph. Certainly not 23mph..?
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'80 924 Turbo

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Sorry, my bad, my explanation above was muddled to say the least.

First thing you want to do is make sure that the cells in the spreadsheet for "Tire Width", "Tire Hgt" and "Rim Size" are correct for your car. Leaving these cells at the default setting, and adjusting the "Enter RPM to upshift" to 6500 (redline for 931?), you get a max of 30mph in 1st with the dogleg tranny, and with the Audi box it is 32mph in 1st.

Hopefully that makes more sense, sorry for the error.
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1987 951 - M193 Version for Japan

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

sorry for the stupid question...but "Tire Hgt" is that.. 205 / 60 / 15 ,bold value ???

and if so...why is it in percentage?
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Supercharger and EFI kits
https://www.the924.com

tux · Joined: 02 Jul 2006 Posts: 133 Location: Nottingham UK

OutOfTheBox · Joined: 31 Mar 2006 Posts: 434

60kmph

37mph

RIPDOTCOM · Posted: Sun Jul 09, 2006 11:16 pm Post subject:

Optimal accelleration shift points are as follow. This is from an actual dyno test.

1st= 32mph @ 6600Rpm
2nd= 56Mph @ 6310RPM
3rd= 79mph@ 6070RPM
4th= 109Mph@ 6350RPM

This is for a 1980 model 931