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What's the horsepower difference between US and Euro spec
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CÚdric  



Joined: 27 Aug 2004
Posts: 2077
Location: Sweden

PostPosted: Mon Jan 11, 2021 9:58 pm    Post subject: Reply with quote

Fifty50Plus wrote:
We are allowed to use the 924 Turbo tail but not the 944 version. I also retained the front engine undertray to aid in cooling but don't think it does much else.
SCCA does not appreciate Porsches winning any races since Porsche does not provide sponsorship to Corporate SCCA HQ unlike Mazda, Nissan, Toyota, BMW, and a few others. In the '80s, I was dominating D-Prod with a 911 at a realistic weight. In 2000, I started building a 2.4 911 based on it finally being approved for Improved Touring at 2200 lbs (factory weight). When the club heard that I was building another Porsche, they changed the rules and added 300 lbs to the minimum weight before I even hit the track. Datsun 240Zs were the dominant car (Nissan giving money to the club office) at 2300 lbs. After I finally got my car built and dialed in, I was 1/2 sec slower than the winning Datsuns. The 300 lbs SCCA gave me made a big difference in my lap times.
So I sold the 911 and built my first 924 after seeing what Vaughan Scott did with his car at Road Atlanta (long track, heavy braking needed). It's a great car but could use a few more horses on the shorter tracks.


Thats a weird way to write rules, i havent seen those type of rules in our world of racing, where rules in general arent car specifi, more built on technical parameters.

yeah the standard undertray probably give you some aero benefits, would not expect any cooling improvements to talk about, though a larger and smoother undertray would be nice. A friend of mine tried with and without the standard one and got higher oil temps on track with it on, he have an external cooler added now anyway, which i guess you have.

Are everything else on the body supposed to be untouched? Decreasing the radiator opening is often a very efficient way for reducing drag for example. Or a 924gt/944 flush windscreen, smaller mirrors etc
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Tue Jan 12, 2021 4:36 am    Post subject: Reply with quote

SCCA lumped all the 924s on one page of the rule book so we can pick and choose best options (LSD, vented brakes, rear tail, either gearbox) but the weight was selected by a "committee" (probably after looking to see which MFRs paid money to the club and which didn't). The other major rue is "If it doesn't say you can, you can't". There is a global engine prep section that pretty much says you must use stock parts without lightening or modifications except for balance; no porting but any exhaust is okay. Suspension is free but can't be substituted (can't put coil overs on the rear for the 924).
Aero wise, I've got a small 935 style rear view mirror. We are not allowed any other body mods.
I raced BMW 2002s in the same class in the past and had more horsepower but the body shape and frontal area limited the max velocity on longer tracks.
All in all, I like racing the 924 and cost wise it's similar to the BMW, cheaper than the Alfas, more expensive than the Hondas and VWs and more reliable than all of the others.
If SCCA lowered the weight, there would probably be a bunch more 924s showing up on the grid since the racers would pay more attention to the lap times being posted.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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Karlio  



Joined: 17 Nov 2019
Posts: 15
Location: UK

PostPosted: Tue Jan 12, 2021 9:10 am    Post subject: Reply with quote

Blimey, why would you race in that series, that is some serious disadvantage. 2495lbs equates to 1132kg here. Dry(ish) weight of our cars is around 930kg/2050kg,add chubby driver, and a bit of fuel I get in at around 1020kg post race.
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1138
Location: Washington DC area

PostPosted: Tue Jan 12, 2021 9:53 am    Post subject: Reply with quote

It is a competitive class...we usually have 10-15 cars in our class and we run with another class that has almost as many. As much as I bitch about it, I was the series champion in 2018 and 2019 - 2020 was a bust. I just keep getting honked off with the lack of SCCA respect for Porsches. The only trophy they keep giving us is lead.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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anthonimartini  



Joined: 17 Feb 2020
Posts: 28
Location: portland oregon

PostPosted: Tue Jan 12, 2021 1:50 pm    Post subject: Reply with quote

hey fifty50, you seem quite knowledgeable. would you happen to know if the early 944 pedal assembly is the same as 1980 931? im converting my 77 to a snailshell trans using the rear torsion assembly, torque tube and bellhousing/clutch from the 931. im going to bolt all that up to my 95hp lump while i rebuild the 931 engine using a td04 turbo. im unsure of what exactly i need to order to adapt my cable clutch parts to use the hydraulic stuff.
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87 924S
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morghen  



Joined: 21 Jan 2005
Posts: 8274
Location: Romania

PostPosted: Tue Jan 12, 2021 7:02 pm    Post subject: Reply with quote

I did a similar upgrade a long time ago, the 944 clutch pedal sub-assembly can be fitted to the 924 in order to run the 931 bellhousing and hydraulic clutch.
The brake pedal and accelerator pedal can be kept from the 924.
However you need to drill the firewall for the bolts holding the master cylinder, and while you are there you really have to build a reinforcement sheet of metal that doubles the firewall in the area holding the master cylinder, otherwise it will crack and obviously cause the clutch to not work properly and then quickly destroy your precious snailshell.

For the conversion you need:

-931 bellhousing complete with slave cyl and hydraulic line.
-931 master cyl complete with reservoir and hoses.
-931/944 clutch pedal assembly (bolts on to the 924 body).
-firewall brace plate, i made my own(after firewall cracked) but you can either make your own or buy one from only944.
My brace plate was considerably smaller than the one from only944(did not go under the brake booster) and it held fine.
I made it out of 3mm thick Aluminium.

https://www.only944.com/partscatalog/only/firewallbrace/
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safe  



Joined: 18 Mar 2017
Posts: 210
Location: Sweden

PostPosted: Tue Jan 12, 2021 7:58 pm    Post subject: Reply with quote

Fifty50Plus wrote:
The only trophy they keep giving us is lead.


Thats a trophy in it self!

I would put a proud sticker on the car stating how much ballast lead that is added so they can pass!
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Porsche 924 -79 NA, under EFI and turbo conversion
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anthonimartini  



Joined: 17 Feb 2020
Posts: 28
Location: portland oregon

PostPosted: Wed Jan 13, 2021 4:47 pm    Post subject: Reply with quote

thanks morghen! the pedal box was the last thing i needed! cant wait to get the LSD equipped G31 in my car!
im going to build a flange to mount a garret t3 to the stock NA manifold and run the 931 WUR with the 77 cis system just as an experiment, my 77 engine is in great health so i think it might actually work out pretty well. hell i might even just drive that setup for a while if it is fast enough and reliable. if not the the 931 engine will be ready pretty quickly. im going to use 88mm VW flattops with that and planned on also building an adapter flange to mount the garret to the 931 manifold.
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87 924S
77 924 Safari (931 swap)
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