D2 Generator to alt conversion

2bluejon - I'd be interested in seeing the design you produce. My best buddy is a machinist, and we are looking at fabricating an all-steel, alternator conversion for the D4400 engine. I have a D4400 generator and a U/S engine to work from.
I guess the secret is to keep it simple, and the machining to a minimum. I had thoughts of using a larger size, vehicle water pump shaft, about 3/4" diameter and around 8" long, for the main shaft.

The water pump shafts come complete with a sealed needle roller bearing .. but I could see that perhaps the drawback might be the cost, over the counter, at a bearing supplier.

I have another buddy who has a huge stock of surplus commercial products such as bulk bearings, couplers, and whatnot .. who may be a better (read cheaper) source of shaft and bearings.

I'd like to see how many people would be interested in a conversion adaptor, and whether they would be happy supplying their own pulley, or would want it complete, ready to run. I'd also like to get a $$ figure that people would be happy to pay. I'm thinking around about US$250. Any advice/thoughts/recommendations welcomed.

If it's another variation of these types I'd be interested.....if it's another piggy back generator type.....no thanks.

I would think the most useful conversion would be the double belt pulley version that would also replace that "mickey mouse" adjustable pulley arrangement as well as mount the alternator.

Well looking at the pic you posted i think that the one i am makeing will be the same yours looks good

Hi 2bluejon,
Didn't mean to imply that it was one of mine, or that I was the fabricator. Just another variation that is already out there. The pictures were provided by one of the BB posters....and the unit purchased in Canada....not sure where as I didn't get any more info on follow up questions. I'd be interested in seeing your version.

OM - Does the standard drive arrangement of the earlier generator setups, develop enough RPM to run an alternator directly, as in the setup you pictured? I see in the parts book where there are numerous size gearsets, with later ones appearing to have smaller and smaller gears, to obviously increase generator speed.

The RD-4 engine I have, has a 26 tooth gear on the generator .. but I haven't counted the gearset teeth yet, to determine the generator RPM.
At a quick glance it appears that the generator is only doing about 1500-1800RPM at rated engine RPM, and I was under the impression that alternators need more RPM than this to produce adequate output.
I do understand that alternators produce near maximum output at relatively low speed, but I have never seen the actual RPM figure.

Oz, at that rpm a one wire delco rated at 65amps should put out about twenty. More than enough to charge a starting battery. The alternator pictured looks just like the one I built for my d318 marine. I have never seen or heard of another one either. Some minds just think alike I guess.
On the one I built I used a lovejoy coupling to join up the shafts.

Hi Oz,
The low rpm cut in one wire regulators and also the 2/3 wire low cut in units will start producing amperage (reduced) as low as 1200 rpm with 1200 - 1500 as an operating range. You have to watch the gear ratios for the installation. For example the D318 & D315 drives used with 24V systems typically have a drive of 33T crank, 66T cam, 17T idler and 19Tooth generator drive gear. This gives an overall ratio of about 1.73 times engine rpm so at say 1400 engine rpm your at about 2422 rpm on the drive.

With the same crank and cam gears but with the 26T (single) generator drive gear your at a 1.27 times engine rpm or about 1778 rpm generator drive.

The D4 full load engine rpm is less so dropping back to a 1.27 times say 1200 operating gives a 1524 rpm on the generator which is still withing the low cut in range but is not going to be a high amp output but ample to keep batteries charged.

One Wire alternator. 12 Volt 63 amp.
Excitation speed 850-900 rpm rotor speed
14 volts reached at 1200 rpm
45 amps at 2100 rpm 14.5 volts
the way that i am figuring i think that this will do the job when i get the nose peice built i am going to put it in the cat and i have a RPM meater and i am going to see what the low idle and the high rpm is that is coming out of the old gen shaft thanks i will keep you posted

OM - Thanks for the assistance with those figures. I like the idea of the direct coupled alternator, it's whole lot more compact and the adaptor should be simpler to build, too.