Alternator Turbo Hayabusa question

**fns** · 10-20-2019 10:10 PM

I have now been running 2 years on my Turbo hayabusa. I have always ran 2 pc950 batteries to help with the amp hour ratings. I am ready to put on an alternator to help with power issues. I was at "Atv motorsports" a few weeks ago talking to Neil. Back in the day when he was building "taz" cars he did a few alternators on cars that bolted directly on the input shaft of the rpm gear box. (yes I realize it will only be charging while I am driving) Due to room I am looking to do the same thing. He does not have any of his old notes of what alternator he used. I can make the bracket and the coupler between the gear box and the alternator. I was looking for some technical questions. To try and find the best setup.

Does anyone actually make this type of setup currently?
How do I calculate the speed of the transmission out put shaft? (If normally driving in the dunes 2nd and 3rd gear around 5000 rpm)
If I run a single wire alternator will it back feed to much and burn up the stator?

Thank you for any help or suggestionsimage0.jpg image1.jpg

**K-fab** · 10-21-2019 01:14 AM

Go look on yellowdogracing on the original Taz and you’ll see many attempts to get this done.
I just ran the basic GM S-10 alternator. Anything small works.

My RPM had a through shaft with a splined end. I machined down a brake rotor slug (from RPM) that fit the shaft and made an adapter that threaded onto the alternator.

The adaptor on the alternator "plugged" onto the end of the splined RPM input shaft.

Now here’s the tricky part...
This makes the alternator rotate in reverse direction (alternator doesn't care one bit what direction it spins) and that wants to unscrew the adapter from the alternator. When it unscrews, it pushes the alternator shaft out the back side of the alternator and stuff goes poof-ka-boom. Lots of bad squeaky sounds as it happens too - I think it's the cooling fans getting pushed into the coils.

You have to make an adapter that locks down onto the end of the alternator and will NOT come unscrewed. Red Loc-tite, set screws, jamb nut, swearing and a lot of threats seemed to finally do the trick.

It works very well once you get it locked down.

Alternator's fine with the input speeds - as I recall, they're capable of 11-12K rpm w/o issue. Mini-Raptor's will spin in the 10K range.

Never had any issues with feedback and burning up any stators or any engine outputs - have done it with three different setups now and expect to have the same results on the Mini-Raptor too. No worries.

Where'd those pix come from? Looks like the old Deztaz.

**plkracer** · 10-21-2019 01:28 PM

I'm not sure it will work with a motorcycle box, as the RPM at the input is quite a bit less than a box with a 8:1 or 9:1 ratio.

I'm running a power master mini denso 55 amp alternator. I have a 2.5:1 pulley setup (stock alternator pulley, and a SBC power steering pulley from a dress up kit, which I added a custon 1" clamp lock hub to). In 6th, at the 10,500 red line (reduced for 6th gear) the output shaft is around 6500 rpm, so I pushed the alternator to its 18k redline.

I'm using a 5.4:1 box, 29 inch sand squirt paddles. Gearing on the motor is 17t front and 18t rear.

I dont start making positive current until 12mph. At 10 mph, the alternator actually draws 3-4 Amps for the field coil, so it is working against you.

I did some rough testing on my drill press before installing it, but it took roughly 1500 rpm at the alternator to start producing positive current. Around 1000 or 1200 rpm it is drawing current to energize the field coils before making it's own power. It seemed like a linear ramp up from 0 to 1000 rpm for the negative current.

Positive current ramps up fast, and I see full voltage even under heavy loads at 20 mph or so.

**fns** · 10-21-2019 05:13 PM

Thank you both for the input. The last 2 years with just the stator and 2 batteries the car worked ok 90% of the time. However on hot days and the radiator fan kicked on more or at night and I am running all my lights. I when I would get on it hard the car would cut out for a second. I put a camera pointing at my fuel pressure gauge and would I see the pressure drop to 37psi when it cuts out. So I think an alternator would help keep the amp load more even at high speeds. I was more worried about back feeding the stator. Looks like "k-Fab" has not had that issue. On the newer rpm boxes the shaft does go through the other side but now it is a 1" Keyed shaft. I will pin the alternator so it does not back out.

(The pictures were off a car that Neil was working on at his shop.) His shop is only 15 minutes from my shop.

**fns** · 11-03-2019 02:19 PM

I found a guy at Tucson Alternator that is set me up with a 100 amp single wire small alternator. It starts charging at 600 rpm. If I did my math correct it should start charging at 15 mph and at 40mph I should be getting the full 100amp's. I have to do some fabrication to mount it to the rpmgearbox. I will post pictures when I am done. Planning on going to the dunes next weekend.