[TD in DC]

Race Technologies is supposed to be sending me pdf versions of the manuals for Dash II and the DL-1, so the final stage of planning can be completed . . .

[Jazzbass]

Originally Posted by CrewChief

I think track cars need a balance between simplicity and function. For the cooling fans I favor eliminating the relays entirely. The reuse of the AC switching relays and cooling fan is very clever (wish I was that sharp); but needlessly complex. After much consideration I have opted to split the 2 stock fans both for redundency and reliablity.

The 'main' fan I wire directly as oem except without the bigass ceramic resistor (which lowers fan speed with key off) and without the fan relay which normally bypassed said resistor with key to 'run'. This leaves a single fan operating as per oem but without 2 failure points (relay and resistor). The fact that it runs on high speed when stopped has not been an issue.

The 'secondary' fan I wire through a simle toggle switch. My drivers are directed to turn the secondary fan 'ON' when entering pit lane and 'OFF' when leaving pit lane. I find even drivers can be trusted to follow such simple instructions. Best of all, even if they don't the cars are not really in need of the secondary fan and/or the temp guage serves as a reminder.

Yeah, after our initial discussions, and seeing how little difference it really makes, I ditched the whole "fan kill" idea. Too much shit going on. My thought was to go with two fans, run on relays, the relays switched by the thermo-switch. I was running relays because I felt the load of running both fans through the switch was a bit much, and because TD wanted to fans off with the ignition off.

That said, I like your idea better. Run the main motor fan like so: [battery] [fuse] - [fan] - [therm switch] - [ground] and the AC fan [battery] - [fuse] - [toggle switch] - [ground]. There is still the chance of running the fans with the car stopped, but I think reduced complexity in the system outweighs the chance that he'll leave the fans on and kill the battery.

Originally Posted by CrewChief

Early 44s use the same fuse board as 24s and I have the same revulsion to them as you. I installed ATP holders on the inside right side and so have short runs from the stock battery location to the fuse panels. The power distribution is then moved from the engine side of the firewall the behind the dash. More protected and it doesn't have to go in and out and in and out ...

Sounds like exactly the same thing I'm doing. My plan is to place the new fuse box under the dash on a custom fabbed plate bolted to the center tube. Access via the passenger side. One benefit is that the fire suppression is right there, so if there is an electrical fire the halon will hit it directly.

That said, I'd like to know exactly how/where you're mounting the fuse/relay panel. One idea I had was to remove the glove box and mount it there, making access to fuses/relays easy. There doesn't seem to be a good piece of metal to bolt the panel to, though.

Originally Posted by CrewChief

I'm curious what you think of my approach. And also, would love to find the site with the DME circuits. I've dabbled with sorting out the schematic of the relay on the 924Turbo (especially as it appears to have a rpm limit built in) but gave up did without -exactly as I shouldn't do.

Good ideas, and its great to bounce stuff around with guys actually in the process of doing the same thing. My guess is I'll be doing this same job again later this year with a 924S.

BTW, the internal DME schematics are available here on this site - I linked to them in an earlier post either on this thread or the DME relay thread.

[Jazzbass]

BTW, the in-out-in-out this he's talking about is not a Clockwork Orange reference. Its something that, when I realized WTF was going on, had me scratching my head. The was Porsche wired the 944 is they ran all of the main power lines through the engine bay to an access hole on the far right of the car, where the power lines went into the cabin to the main fuse box. This is the best part - the DME sits literally 3 inches from the main fuse box, right under the steering column. So - the power lines from the fuse box to the DME are how long? That's right, 4-5 feet. Why? Because instead of going from the fuse box to the DME, they actually go back out of the cabin through the engine bay, and back into the cabin via a hole in the middle of the car, then to the DME.

I'm sure there's a reason for this - giving one point in the engine bay for testing is my current theory - but its a curious design to say the least.

[TD in DC]

Originally Posted by Jazzbass

That said, I like your idea better. Run the main motor fan like so: [battery] [fuse] - [fan] - [therm switch] - [ground] and the AC fan [battery] - [fuse] - [toggle switch] - [ground]. There is still the chance of running the fans with the car stopped, but I think reduced complexity in the system outweighs the chance that he'll leave the fans on and kill the battery.

That's fine with me. And let's not do anything that could possibly eliminate the rev limiter. I seem to bounce off that too frequently as it is.

For those of you who have yet to experience the start of a race, I can't imagine how guys without rev limiters do not blow their motors every other time, if not each time. The noise (you can't hear your own car) the traffic, and the adrenaline can lead you to wonder WTF is wrong with my car until you realize you are bouncing off the rev limiter . . .

[Jazzbass]

Originally Posted by TD in DC

That's fine with me. And let's not do anything that could possibly eliminate the rev limiter. I seem to bounce off that too frequently as it is.

The rev limiter in your car is in the DME. Try as I might, I think we're going to have to leave that part of the system in the car .

[CrewChief]

Originally Posted by Jazzbass

Yeah, after our initial discussions, and seeing how little difference it really makes, I ditched the whole "fan kill" idea. Too much shit going on. My thought was to go with two fans, run on relays, the relays switched by the thermo-switch. I was running relays because I felt the load of running both fans through the switch was a bit much, and because TD wanted to fans off with the ignition off.

That said, I like your idea better. Run the main motor fan like so: [battery] [fuse] - [fan] - [therm switch] - [ground] and the AC fan [battery] - [fuse] - [toggle switch] - [ground]. There is still the chance of running the fans with the car stopped, but I think reduced complexity in the system outweighs the chance that he'll leave the fans on and kill the battery.

One upside to deleting the voltage dropping bigass ceramic resistor is that the fan on full speed is loud enough to not be un-noticed. I also always turn on the number 2 fan to blow down the heat after a run with the hood up. Did you explain to TD that the fan is never actualy turned off with the factory setup? I know how hard it can be dealing with high maintenance technically unsophisticated drivers. (Actually, I want to say that I'm very lucky that my current in-house driver is an excellent mechanic able to accurately debrief and diagnose with precision).

Sounds like exactly the same thing I'm doing. My plan is to place the new fuse box under the dash on a custom fabbed plate bolted to the center tube. Access via the passenger side. One benefit is that the fire suppression is right there, so if there is an electrical fire the halon will hit it directly.

That said, I'd like to know exactly how/where you're mounting the fuse/relay panel. One idea I had was to remove the glove box and mount it there, making access to fuses/relays easy. There doesn't seem to be a good piece of metal to bolt the panel to, though.

My steeds are not so cosmeticaly maintained as you fellas like. As in, I just cut off the right 2 feet of the dash. But you can get to the same spot with the glove box out. Mounted on the sheet metal 'inside' of the batter tray area. I use a couple of 'feedthrough' from Summit or Jegs to bring the power through the same general area.

[Jazzbass]

Hmmm... I don't have a lot of quams about using the sawzall for an emergency dashboard-ectomy. In fact, I quite like cutting up 944s with large power tools.

Where do you cut the dash and do you use anything to brace up the remaining part? If its easy, I'm up for it since it'll make putting in and maintaining the new wiring that much easier.

[CrewChief]

Originally Posted by Jazzbass

Hmmm... I don't have a lot of quams about using the sawzall for an emergency dashboard-ectomy. In fact, I quite like cutting up 944s with large power tools.

Where do you cut the dash and do you use anything to brace up the remaining part? If its easy, I'm up for it since it'll make putting in and maintaining the new wiring that much easier.

You will no longer, I think, be PCA Clubrace legal, with the lone exception of SP2. H and I (all 'stock' ) cars need a dash. Other than that:

It's soft stuff. Carboard and foam and plastic. And a metal bracket at the very bottom. Light enough the center fastener behind the old speaker grill is enough to support the remainder. Enjoy.

[TD in DC]

Originally Posted by CrewChief

Did you explain to TD that the fan is never actualy turned off with the factory setup? I know how hard it can be dealing with high maintenance technically unsophisticated drivers.

Hey, why the shot????

[Trak Ratt]

Originally Posted by Jazzbass

The rev limiter in your car is in the DME. Try as I might, I think we're going to have to leave that part of the system in the car .

Can we talk?