Humboldtgrin

I'm looking for help on this transaxle mounted alternator project/idea I have just decided to add to my life's list of $#!+to do before I die. And I need ideas/help finding pully's that will work and are the right size for the job. If anyone knows if there is a bracket that works the best on holding the alternator I would be interested in that information. Any wire manufacture and pro's and cons. Thank you in advance
All advice/info/ideas are welcome regarding this topic. Much appreciated.

V2Rocket

can't remember which version but one of the factory-prep racers did this but they had a tube frame to hang the thing from.

there's plenty of room on either side of the trans "tail" and you could come up with a suitably beefy bracket to attach it to the trans case (would be easy to attach using the bolts that hold the "side cover" over the diff).

i bet you could take a standard 944 "accessory pulley" and drill the CV flange bolt pattern into it...
or do like some V8-swappers have done (to get a 40-tooth VSS signal), modify a standard 944 cam gear to fit and you could have a tooth-belt alternator drive.

odonnell

^ just make SURE you change it every 30,000 miles.

PaulD_944S2

I wasn't going to post but here goes:

You realize that the stock alternator will have very low current (amperage) output because it will be turning at a much lower RPM than when it is attached to the engine and driven by the crankshaft?

s14kev

Why? Because racecar?

If this is for a street vehicle which I assume is the case looking at your avatar, keep in mind that you won't be generating anything from the alternator when idling and not moving. Even when moving, you won't be generating much until you are going at a fair rate.

The GTR's were generally mounted over the transaxle being belt driven from the CV flange.

V2Rocket

^^thats the one

yes you would need to way overdrive the alt to get any decent charging...alt likes a minimum of 2000rpm or so to really get to its rated output, 3000 is mo'betta

problem is even at 3000rpm in 5th gear the trans output shaft (axle) is only doing about 1000-1100 rpm.

if you are looking for space for whatever reason, you can agree to a small licensing fee for one of my old ideas...$1000000000
i never actually wired this alt up or ran it "in anger" with a belt on but i had the alternator hanging in that spot for probably 3 years...

https://rennlist.com/forums/944-turb...thout-p-s.html

Humboldtgrin

I'm thinking more like having the driveshaft hold the drive pully somehow. Maybe a gear or worm gear drive off the driveshaft would work better so it doesn't put side stress on the bearings inside the TT and transaxle and mount a pully off of the gear.

lart951

Someone definitely has too much time in his hands

Humboldtgrin

Well if it were driven off the driveshaft it would be like driving it off the front crankshaft (same speed). If the car is used for race/street then it will charge when the trans is out of gear with the clutch engaged (beniffit of our cars) and the pully size can stay the same stock size. That way in stop and go traffic it will still charge. It took a split second to think it up, emplementing it takes time. And sharing it with you all takes even more time. Luis there's three turbo's up here on craigslist you might want to critique on. Here's one,https://sfbay.craigslist.org/pen/cto/6081437877.html
And the other
https://sfbay.craigslist.org/pen/cto/6047355684.html
And
https://sfbay.craigslist.org/nby/ctd/6079617678.html

PaulD_944S2

Ok, let's say you have done it. You are driving the alternator off the driveshaft.
What advantage will it provide in a street driven car? Race car?

(Granted, you have moved about 25 lbs to the rear. Could have done the same relocating the battery.)

The load on the engine will be the same, except when you have the clutch in.
You also make it more of a maintenance problem since the alternator is setup in a non-standard way.
And how will you replace the belt since it would have to go around the driveshaft?

Thoughts?

Humboldtgrin

Move the alternator and battery/super capacitors to the rear. Belt can be changed by sliding the trans coupler out of the way. More room to fit the MAF pipe I got from Luis in its desired location because it's too big to fit over the alternator. Move alternator to a cooler environment. Something to do.

V2Rocket

Have you seen the Nissan Quest alternator mod? It was invented for the same reasons you mentioned.

odonnell

A worm drive would spin the rotor too slow to even make up for the power being used to run the car, unfortunately.