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Techno Duck
Joined: 12 Nov 2002
Posts: 212
Location: Long Island, New York
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 Posted: Wed Nov 26, 2008 3:30 am Post subject: |
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| 333pg333 wrote: | I'm a little confused how it's running a twin cam head with only one cam wheel?...or am I missing something?
Thanks for sharing all the photos. Less that 2000lbs must be so responsive. |
The exhaust cam is driven by a chain between the two cams. This is how all the 16v motors were setup from the factory, and also how the Variocam adjusted timing on the 968 engine.
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1987 Zermatt Silver Porsche 924S <-- Sold in Nov. '04
1987 Guards Red Porsche 944 <-- Sold in Jan. '08
1988 Guards Red Porsche 951 <-- Das Boost |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Wed Nov 26, 2008 3:40 am Post subject: |
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Is that an axle driven alternator I see there????
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erstwhile owner of just about every 924 variant ever made |
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emoore924
Joined: 13 Apr 2004
Posts: 2822
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| Posted: Wed Nov 26, 2008 3:51 am Post subject: |
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I think this is the best post *ever* on 924.org
That is one incredible piece of kit. |
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emoore924
Joined: 13 Apr 2004
Posts: 2822
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| Posted: Wed Nov 26, 2008 4:09 am Post subject: |
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Oh, and THIS is my 924th post. What better place.
Yay me. |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Wed Nov 26, 2008 4:46 am Post subject: |
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Yeah, and in 7 more, you'll have to move on to some other platform 
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erstwhile owner of just about every 924 variant ever made |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Wed Nov 26, 2008 5:04 am Post subject: |
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I have another question: for all of the custom fabrication that went into the GTRs, why in the world did they not implement a double wishbone front steering arrangement??? Was there some provision in the rules that prevented that?
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erstwhile owner of just about every 924 variant ever made |
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924RACR
Joined: 29 Jul 2001
Posts: 9076
Location: Royal Oak, MI, USA
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| Posted: Wed Nov 26, 2008 6:04 am Post subject: |
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Kelly Moss did engineer one. I'm sure the rules for some series did prevent it though.
I think Scott's 933 had a KMR double-wishbone setup.
Yes, that's a axle-driven alternator.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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333pg333
Joined: 08 Oct 2007
Posts: 2
Location: Sydney, Australia
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| Posted: Wed Nov 26, 2008 11:24 pm Post subject: |
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| Techno Duck wrote: | | 333pg333 wrote: | I'm a little confused how it's running a twin cam head with only one cam wheel?...or am I missing something?
Thanks for sharing all the photos. Less that 2000lbs must be so responsive. |
The exhaust cam is driven by a chain between the two cams. This is how all the 16v motors were setup from the factory, and also how the Variocam adjusted timing on the 968 engine. |
Yeah I realised what I'd written and edited it but you grabbed it too early. I was thinking about some twin cam heads I've seen with two cam wheels in the front, but of course these were modified. Whoops.
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3.0L turbo 951 w lots of extras. |
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Scott Sanda
Joined: 10 Jan 2006
Posts: 68
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| Posted: Thu Nov 27, 2008 4:24 am Post subject: |
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It is axle driven. When I bought it, it was a total loss system with no alternator. When we put in the FI, we needed a little more juice, plus, I run it in some night races with HSR, and need to power the lights. We did the same thing on my Dprod car, which was total loss originally.
I don't know why the front suspension isn't double wishbone. My guess is, as has already been stated, it was rules driven. Remember, the 924 GTRs, with the exception of this one and one Fabcar built were all full tub cars. Mine isn't actually a full tube chassis, it has the original rockers, A&b pillars, roof and some other sections that are integral to the structure.
The 944 GTRs are double A arm front and rear.
The whole cam deal was confusing to me as well, until I saw how it works. We aren't using the variocam system. The consensus is it is to complicated and fragile for racing. |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Thu Nov 27, 2008 4:37 am Post subject: |
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| Scott Sanda wrote: | | It is axle driven. |
Any chance of getting a photo of the actual arrangement that drives the alternator? I've been scouring the 'net for photos of how this was done on the D-prods and haven't been able to find any photos that clearly show how the pulley was mounted to the axle assembly. In other words, was it just a CV end that had the belt grooves machined into it, or was it some sort of pulley that was affixed to the CV. I have a round block of alu that I am intending to put onto a lathe and make a pulley for bolting to the inner CV assembly, but I'd like to see how this was done "back in the day".
Good tip on the 944 GTR double wishbone setups, I'll look into that. Thanks!
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erstwhile owner of just about every 924 variant ever made |
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Scott Sanda
Joined: 10 Jan 2006
Posts: 68
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| Posted: Thu Nov 27, 2008 5:19 am Post subject: |
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I can't find any pics that show it, but I'll take some and post them.
Essentially it is a pulley over the CV joint, but I'm not sure off the top of my head how it is attached. |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Thu Nov 27, 2008 8:56 am Post subject: |
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| ideola wrote: | | Scott Sanda wrote: | | It is axle driven. |
Any chance of getting a photo of the actual arrangement that drives the alternator? I've been scouring the 'net for photos of how this was done on the D-prods and haven't been able to find any photos that clearly show how the pulley was mounted to the axle assembly. In other words, was it just a CV end that had the belt grooves machined into it, or was it some sort of pulley that was affixed to the CV. I have a round block of alu that I am intending to put onto a lathe and make a pulley for bolting to the inner CV assembly, but I'd like to see how this was done "back in the day".
Good tip on the 944 GTR double wishbone setups, I'll look into that. Thanks! |
Uh, forgive me for asking, but why does it matter? I'd say build the pulley, install it and get on with life. It seems to me that you've got bigger fish to fry in relation to your UWB project.
Personally, if I were running the race teams "back in the day" and having this solution worked up, I'd use a separate pulley to cut down on the need to ensure all of the spare transaxles have a groove cut into the output flange. The pulley doesn't need to be very thick so the difference in width isn't much. Plus you can tailor the diameter and offset of the pulley to meet packaging needs as well as allowing the alternator to spin at the proper RPM.
If you cut a groove in the output flange, you'd have to make sure all of the spare transaxles are machined the same way or swap output drive flanges every time you change a transaxle. In the heat of battle this could cause the repair to take much longer than necessary.
Just my $0.02
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Thu Nov 27, 2008 9:20 am Post subject: |
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| fiat22turbo wrote: | Uh, forgive me for asking, but why does it matter?
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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Chrenan
Joined: 15 Jan 2003
Posts: 3903
Location: Canada
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| Posted: Thu Nov 27, 2008 9:39 am Post subject: |
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| Rasta Monsta wrote: | | fiat22turbo wrote: | Uh, forgive me for asking, but why does it matter?
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The first rule of UWB Club is you never question UWB Club.
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1987 951 - M193 Version for Japan |
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fiat22turbo
Joined: 18 Jan 2006
Posts: 4040
Location: Portland, OR
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| Posted: Thu Nov 27, 2008 10:01 am Post subject: |
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| Rasta Monsta wrote: | | fiat22turbo wrote: | Uh, forgive me for asking, but why does it matter?
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you're evil.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose) |
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