924Board.org

Guest · Posted: Tue Jul 17, 2001 7:18 am Post subject:

From: Wayne d
Email: wdeblaker@hot.rr.com
Date: 17 Jul 2001
Time: 07:18:16

Vaughan I dont know all the particulars about your race car,but hear in texas when its 105 degrees f and you cant touch the pavement with your bare skin,minor problems with your cooling system will leave you stranded.on the slight chance that you have missed some thing I'll touch on the things that might help.1 of the things that caught my attention when I was checking out your website was a picture of your disasembled engine and the bright orange rust in the coolant passages,If you haven't flushed the system spacifically for rust and corrosion you should. 2 the gasket under the hood that seperates the engine bay from the ac intake should be removed if its still there,this will allow engie bay heat to escape out past the wipers and improve air flow through the radiator,the air rushing through your radiator generates high pressure under the hood and the air flowing over the hood has low pressure creating lift.it might help reduce lift a little. a turbo hood might be better.fender vents like on a stingray are prolly not legal. 3 some times on old radiators the thin metal that run perpendicular to the water channels loose thier bond reducing cooling surface area and efficiency, a little oven cleaner might help get grime out of cracks and crevices. 4 deleting heater hot water control valve so heater runs full out( personal preference,what are you willing to suffer.)5 replace conter wieght springs in the distributer, worn out springs will allow your timing to advance too far too soon,causing a run hot problem. and the vacuum thingy at the base of the distributer if not fairly new,should be replaced.after years of baking the rubber diaphram can leak causing slow response and not reach full advance.6 If you deleted your e.g.r. system you should consider putting it back,the cis was calibrated to run at or close to 14.?-1 ratio with it installed,just make up a few restrictor plates 1/8 1/4 1/2 3/4 of original diameter and see what works. 7 too late for this one but next time you rebuild your engine have them check for residual casting sand in the coolant passages .some times things arent cleaned as well as they could be( even germans have a bad day) 8 use carb cleaner to chech for vacuum leaks, it has a profound effect on idle speed. haynes says to retorque head bolts every 5k miles ? mostly basic stuff but I thought approching august, others might find this info helpful,an ounce of prevention and all that

Guest · Posted: Tue Jul 17, 2001 10:58 am Post subject:

From: Rick Martinez
Email: ricomartinez@yahoo.com
Date: 17 Jul 2001
Time: 10:58:11

Wayne, I have a question about #5. Where can you get the proper replacement springs and vacuum advance/retard for our cars?

Guest · Posted: Tue Jul 17, 2001 1:45 pm Post subject:

From: Vaughan
Email: vscott77@nospam.hotmail.com
Date: 17 Jul 2001
Time: 13:45:42

Excellent points all, but I am 99% sure the problem was due to an inadequate replacement water pump belt. It was glazed on inspection at the end of the first day, and side-by-side comparison with the old one showed a smaller cross-section.

Naturally, we swapped the old one in. After 1 track session, it loosened up and the car ran hot. Not surprising. We re-tightened it real good. The alternator was then cocked at an angle. No surprise, I hate those alternator bushings. It then cooled fine, ran nicely with the old belt back in. Then I pulled off the grid, did my cooling lap... car's still cool, great, I can finally race! Halfway through the first lap, the belt flung off on track in a repeat of Race 2 practice/qualifying earlier this year, and I had to park it.

Lessons learned: stock alternator bushings suck. I'm redesigning my car to use solid metal-to-metal contacts in all points for the alternator mounting, so that I can tension the belt as desired without losing my belt. #2: belt dimensions are critical, as are sources. I'm getting my next ones from a more trusted source.

I'm also going to take some time off to build some more power into the motor - no point fighting this hard to go this slow!

Vaughan

Guest · Posted: Tue Jul 17, 2001 6:17 pm Post subject:

From: Rick Martinez
Email: ricomartinez@yahoo.com
Date: 17 Jul 2001
Time: 18:17:41

Vaughan, why don't you just ditch the alternator and go total loss on the electrical system? Or does that break the rules?

Guest · Posted: Tue Jul 17, 2001 8:36 pm Post subject:

From: Lars
Email: l_porsche@hotmail.com
Date: 17 Jul 2001
Time: 20:36:53

...and run a generator in the trunk of of deisal fluid? hmmmm.....?!?!?!?!

*confused*

Guest · Posted: Tue Jul 17, 2001 11:12 pm Post subject:

From: AznDrgn
Email: dy15@yahoo.com
Date: 17 Jul 2001
Time: 23:12:05

You need the alternator, the engine will not run without it.

Guest · Posted: Wed Jul 18, 2001 12:55 am Post subject:

From: wayne d
Email: wdeblaker@hot.rr.com
Date: 18 Jul 2001
Time: 00:55:51

as I have posted hear before I do not know that much about the 924,and Im not even sure these electronic ignitions have counter weight springs. Im a yankee transplanted to texas, and have had some difficuty adjusting to this climate, personally and as it relates to my cars.last august had a crash course in what can cause a car to over heat. I was passing on the info that the locals hear told me to check. I left 1 out as it didnt apply to 924,carb vacuum ports clogged with carbon turning off everything that is vacuum assisted.

Guest · Posted: Wed Jul 18, 2001 4:01 am Post subject:

From: Rick Martinez
Email: ricomartinez@yahoo.com
Date: 18 Jul 2001
Time: 04:01:15

Uhh...Lars, AznDrgn, many race vehicles run a total loss electrical system straight off the battery. This is recharged later. It saves weight and drag on the engine (alternator is removed).
Haven't you ever heard of someone limping home on the battery after the alternator has failed?

Guest · Posted: Wed Jul 18, 2001 6:37 am Post subject:

From: wayne d
Email: wdeblaker@hot.rr.com
Date: 18 Jul 2001
Time: 06:37:49

um no I can not, but you already new that. turns out 924 has hall effect trigger.however crane cams has an upgrade to a optical trigger for you racer types
.
http://www.cranecams.com/ignition/appsp.htm

Guest · Posted: Wed Jul 18, 2001 7:57 am Post subject:

From: Vaughan
Email: vscott77@nospam.hotmail.com
Date: 18 Jul 2001
Time: 07:57:54

This is quite true; but yes, it's not legal in my class. It would also leave me with no ability to tension the waterpump belt without re-engineering something.

Another thing that's done is to use a very small alternator, like a motorcycle one...

Guest · Posted: Wed Jul 18, 2001 10:47 am Post subject:

From: Lars
Email: l_porsche@hotmail.com
Date: 18 Jul 2001
Time: 10:47:46

so you need a special baterry? because on a regular battery, after an hour of driving it your battery ain't gonna be supplying much power to the coil!
I bet these batteries cost lots.
I think the best thing to do is to get a light battery, there are some special ones.

Guest · Posted: Fri Jul 20, 2001 4:42 pm Post subject:

From: Dave2
Email: david.c.russell@lmco.com
Date: 20 Jul 2001
Time: 16:42:14

I like to keep my 931 as stock as possible. However, one of the first things I did was switch out the Bosch alternator for a Delco. It does away with the rubber mounting, is cheap, has a lifetime warrenty, and has been in my Porsche for 15 years without a problem.