[wludavid]

SMD: Found more info here: http://www.greencarcongress.com/2006...troduces_.html

I think you're right. It allows the battery to discharge, and then uses voltage created by engine overrun or regenerative braking to recharge.

Jazzbass, I stand corrected regarding battery charging.

[Charlie Stylianos]

A little input from the peanut gallery.........

Fans 'always on' position may be a good idea IF thermocouple/sensor fails.....unless this is spoken for elsewhere.

Nice job there Jazzy!

[smdubovsky]

Originally Posted by VaSteve

Why don't they use the same type as cars do?

Cost, weight, space? A PM machine is very small and light. It also doesn't have brushes which take space and can have reilability issues. I can't remember off the top of my head if the bike alternator is in the oil side of the case like the clutch is. Brushes wouldn't work in oil.

In a nutshell, the power demand of a bike is small enough that you can get away w/ a simpler PM + linear regulator approach. It means wasting a bit more energy as heat (in the regulator) if your @ 10krpm constantly w/ the headlights on. The load characteristics of bikes is far narrower than cars, so the design is a little more tailored to that. It may be very likely that a big goldwing or beemer has a field driver alternator. But, not sportbikes.

AHHH, it just came to me. W/ a field driven alt, you need a battery to get the charging started. In something w/ only a kickstarter that doesn't exist. A PM machine will generate power whenever its spinning. So, probably just a throwback from the older days.

SMD

[TD in DC]

Here is the datasheet for the Dash II display that I will be using.

[Trak Ratt]

So if it's so little HP loss why bother? Wouldn't it be better to have a reliable "hands off" system so you can concentrate on excuses for being slow. Instead of one that needs constant attention from the drone behind the wheel?

[Andy Clements]

Chris,

I haven't said much on this thread since the early photos....but there are a few thoughts on my mind. Let me preface by saying I'm no EE (just a hack with a voltmeter) so take this with a big grain of salt.

As for the amusing cooling debate....I've learned a few things by this discussion, but it still seems ridiculous to me. It has been shown that the amount of hp loss is very small.....but it is true that this could be significant in the most tightly contested podium battle. Personally, I hardly think it is worth melting a motor on the chance that TD could forget the fan switch and potentially not see the warning light in the "heat" of battle. Perhaps I'm wrong, but at race speeds the fans do more to impede air flow than to improve it, and as such the blades are largely driven by flow rather than the electric motor. If that is the case, the current draw should be considerably less at speed....thereby making the load on the alternator draw exceedingly small in insignificant.

In another topic I have been meaning to mention since your first post......you indicated that you plan to eliminate the stock fuse block and all relays except the DME relay. You probably already know that the DME is a very common failure mode for the 944, and a bad relay will disable and/or cause flaky problems very easily. A spare relay is a glove-box item for any 944 owner that has been previously burned by this little achilles heel. My question....if you are going to the trouble of all this extensive rewiring and circuit design.....why not eliminate the relay as a failure mode in a race car? It should be a fairly simple matter to establish these circuits as high current switches that are operated manually in sequence to start the car? You would also have the added benefit of physically hearing the fuel pump functioning before firing the ignition.

Last thought.....you haven't forgotten that this car is being built for a stock/spec class......right? 44Cup is not exactly known for extremely strict rules enforcement, but I hope all of these electrical "upgrades" don't catch the attention of an over zealous scruit. Doesn't seem like much of anything is going beyond repairs of faulty wiring, but I'm just playing devils advocate.

Ok. I'm done. Nice work on the project.....give us some completion pics when you finish.

[Jazzbass]

Good input Andy. I think at this point I'm ready to pitch the the fan relay circuit after the debate we've had here. Reduce complexity and all that.

As for the DME relay... hmmm.. interesting thought. I'm concerned simply because I don't know exactly the circuitry that's in the relay (and it is more than just a relay), so at this point I'm not 100% confident enough to pitch it. In particular, I'd like to know exactly the left hand side of the relay circuit (circled in red below) is doing.



The right hand side is pretty straight forward - switch battery power to the fuel pump when the ignition is on. The left side is switching power to the injectors (seemingly by having Pin 20 of the DME pull pin 9 of the relay to ground). I'm not sure what pins 18 and 35 of the DME are doing here.

BTW, I'd like to here ideas from anyone on this. Yes, I'm an EE, but I didn't take "Race Car Wiring 3220" back at Virginia Tech . Ideas regarding safety (kill switches, warning lights, etc from people who have BTDT (or have even just thought about it) are welcome.

[TD in DC]

Chris, as you know, I am completely fine with ditching the no fans option. I had already deleted that option after I bought the car.

With respect to the DME Relay, it would be great to delete if it is easy and does not delay the completion of the project. If it does, just forget it because I always carry a spare DME Relay in the Sequoia.

[Andy Clements]

Originally Posted by Jazzbass

As for the DME relay... hmmm.. interesting thought. I'm concerned simply because I don't know exactly the circuitry that's in the relay (and it is more than just a relay), so at this point I'm not 100% confident enough to pitch it. In particular, I'd like to know exactly the left hand side of the relay circuit (circled in red below) is doing.

Clarks has it pretty well laid out I think, although this does not necessarily explain the 18 and 35 DME pins. See if this pinout diag makes more sense than the factory shema.



http://www.clarks-garage.com/shop-manual/fuel-05.htm

Originally Posted by Jazzbass

Yes, I'm an EE, but I didn't take "Race Car Wiring 3220" back at Virginia Tech .

This stuff was only covered in "Rewiring TD's race car for fun and no profit" 3494

[Lucky]

Chris, fantastic project. Too bad all this quality EE work is going into a lowly '44...

As my sig states, I have one of those 'merican V8 powered cars. Sometimes I visit Mustang forums to see what mods all of those wholesome folks that like to race in a straight line are doing to improve performance. Turns out they have some nifty ideas to free up HP the engine is already making -- two of the biggest are underdrive pulleys (so the accessories like AC, alternator, and water pump spin a bit slower) and electric water pumps (which eliminate the friction lost to yet another belt and pulley). Seems like you could apply the same tricks to a '44 and free up 5+ HP.