924Board.org

924RACR · Posted: Sat Oct 09, 2021 10:10 pm Post subject:

I am using a stacked plate style oil cooler like this:
https://www.summitracing.com/parts/der-13613

Mine was IIRC a B+M brand with dimensions about 8x11", so that one or similar size should work well. The stacked plate style is incredibly robust, we've stuffed it in a few tire walls and gravel traps without damage. Actually, this may be the exact one I have:
https://www.summitracing.com/parts/bmm-70266

Always, it's the cost of the fittings for all the plumbing that drives the cost up...

CV bolts; I'm not certain of the length, you'd best check, but I think they were 50mm:
https://www.summitracing.com/parts/stg-8324
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikeJinCO · Posted: Sun Oct 10, 2021 12:22 am Post subject:

I have the same B&M as Vaughan but will be going larger next year, pushing motor output higher and loss of efficiency due to altitude push it that way. I'll go to either Sabelt or Earl's(Holley), almost double the price.

For the CV joint bolts I bought 50mm 12.9 bolts from McMaster Carr, cheaper by the box and then use Thackery washers which are used on airplane propellers etc. they won't loosen by themselves, are inexpensive and reusable(McMaster Carr or Pegasus Racing). They torque to the washer requirements for tension rather than the bolt strength. The bolts are reusable also. I bought a set of the Grade 8 stuff, but with my old fumble fingers getting those tiny snap rings on and off would have been impossible.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

Fantastic info guys, thanks!

OK, I'm now setting up our analog gauges and telemetry systems.

Some further questions:

1. Keeping in mind this is an endurance car (12 and 24hr races), what should we set our redline to? We have an MSD box with a limiter function. I'd rather keep it pretty conservative.
2. What should be our water temp redline?
3. What should be our optimum water temp?
4. What should be our oil temp redline?
5. What should be our optimum oil temp?
6. What is the danger zone for oil pressure?
7. What sort of numbers should I be looking for on our AFR? (we have carbs now)
8. What should be our trans temp redline?
9. What should be our optimum trans temp?

924RACR · Posted: Tue Oct 19, 2021 4:35 am Post subject:

I'd definitely be comfortable (and we do) capping the revs at 6000rpm. It's a torque motor. Maybe even drop to 5500 if you wish.

We've seen water temps normally around 190F, but as long as you have a decent coolant cap pressure, 210F should flag a warning without really damaging.

Oil temp between 220-240F, and if you break around 270F I'd be concerned.

Oil pressure... as long as you've got more than 2 or 3 bar except at idle, no biggie.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikeJinCO · Posted: Tue Oct 19, 2021 5:18 am Post subject:

I have 45 DCOE Webers and the local Weber guru set them up a chassis dyno and got 13.0 and said that was perfect. I'm running 130main jets with a 190 air corrector but that is at 5000'. The Formula Ford racers tell folks coming up from low elevations to go down one size on mains so a 135 or 140 would probably be a good starting point. Air corrector typically +60 to main but not as critical. This is richer then internet"guru" recommendations. If you have Webers do not increase the venturi size, 32 for the 40's, 34 for 45's. Need to keep the air velocity as high as possible. The old Dprod guys ran 36's but then also had a better breathing head and ran at 7k+ rpm.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

Cedric · Joined: 27 Aug 2004 Posts: 2721 Location: Sweden

A standard engine normally stabilises around 120degC oil temp, but with more or less any kind of oil cooler you should get significantly lower temps even in hot weather. Revving to the max noticeably increases oil temps is my experience, shifting at 6 should be good. Normally most n/a engines produce max power at afr 12.7 or close to that

As I think I wrote before, the cars aren't so picky, at least not in standard form, if everything is in good condition it should work out just fine.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

OK, Here is what I got:

RPM: 6k max (lower if needed)
Water Temp: 210F max (normal 190)
Oil Temp: 270F max (normal 220-240)
Oil Pressure: above 2-3 Bar at idle
AFR: 13.0 or 12.7

Still need:

Trans Temp. Anybody know this one?

Here are some more pics of the finished, painted interior:

https://www.dropbox.com/s/zwp6nk861hj1bu6/IMG_0829.jpg?dl=0
https://www.dropbox.com/s/hcyq281wozb1xcs/IMG_0830.jpg?dl=0
https://www.dropbox.com/s/ngjokoubqmtii6v/IMG_0831.jpg?dl=0
https://www.dropbox.com/s/cunngq77xv0c59k/IMG_0832.jpg?dl=0

924RACR · Posted: Thu Oct 21, 2021 9:35 pm Post subject:

Oil pressure: no, that's not at idle. At idle it'll be below 1 bar hot. Those are on-track numbers.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

MikeJinCO · Posted: Thu Oct 21, 2021 11:24 pm Post subject:

I'll be out this weekend, I'll get an infrared temp of the tranny(not oil) for you. I doubt for our low power cars a cooler is necessary. I'd like to know myself what the tranny temp is. Use a good synthetic tranny oil, I like Redline MT-90. I'm going to change the tranny oil this winter after 3 weekends as it t probably sat with old junk oil for 15 years before I put it in the car.

I'd suggest you look at the harness bar on your roll cage, they generally recommend that the harness mounting points not be more than 4" below the shoulders to avoid compressing the spine.
_________________
Mike

'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild)

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

Cedric · Joined: 27 Aug 2004 Posts: 2721 Location: Sweden

Its about the angle, not a fixed distance, i tend to follow schrots advice, they are probably the most trustworthy in the belt business.

Harness guidelines

https://www.schroth.com/en/racing/service/installation-instructions/?file=files/default/pdf/racing/installation-instructions/racing-belts/ea-8-2-qg-2019-10.pdf&cid=308
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

Oh yeah, we know. It's pretty clearly laid out in the various series we plan to race the car in.

Generally, they require 0 to 5 degrees. That we easily accomplish.

Cedric · Joined: 27 Aug 2004 Posts: 2721 Location: Sweden

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

OK, I'm rewiring the car from scratch.

I have a few questions:

I've been going over the wiring diagrams from the Haynes manual, but I'm struggling.

Alternator:

Where do these 2 wires go?

https://photos.app.goo.gl/VGmLD3CT2dwQ1jN87

Starter:

Where do these 3 wires go?

https://photos.app.goo.gl/XrQW59AxHhVFS6MZ6

I'm assuming one of them goes to the cutoff switch we are using:

Thanks again for all the help guys!

ChrisCXC · Joined: 18 Oct 2019 Posts: 19 Location: Los Angeles, CA

I think I've figured out the Alternator and Starter now.

Now I'm moving onto ignition.

Does anybody run an MSD 6AL with their 924?

How do you connect it to your distributor?

It seems that my distributor has 2 contacts leaving it: 1 wire within another one.

The book is a bit fuzzy as 2 what these 2 do.

Any help would be apreciated!