24 volt starter

[woz]

I have a large engine that requires 24 volts to start.  I am looking at two options starting with the CSR model with a 168 tooth flexplate...

http://www.csr-performance.com/Merchant2/merchant.mvc?Screen=SFNT&Store_Code=SC

or the GM military spec CUCV starter...

http://cgi.ebay.com/ebaymotors/Chevy-GMC-Truck-Starter-6.2-Blazer-Military-24-Vlt-CUCV_W0QQitemZ370212637422QQcmdZViewItemQQimsxq20090608?IMSfp=TL090608207002r28722

the above requires a 139 tooth flexplate which is no problem although I
already have a 168 tooth SFI plate so the cost would be similar either way.

Does anyone have any experience with the CUCV unit?  I have dug around but can't find any real specs to compare to the CSR unit.

I know the 139 tooth setup would be stronger but I am looking at all the options before pulling the trigger.

Thanks

Woz

[Ron Gibson]

How big is your engine? My 920 ci Caterpiller and 855 ci Cummins started fine on 12 volts. More than one battery for more amperage but still 12 volts.
Is it cranking power or cranking RPM you need? Maybe your cables are too small. A gear reduction starter gives more torque but less cranking RPM.
Most 12 volt starters will handle 24 volts, for more power, just fine as long as you don't stay on it long enough to melt it down. The solenoid switch post needs to be wired 12 volts so it pulls in normally then activates the 24 at the large post to the starter.

JMHO 
Ron

[Jonny Hotnuts]

I believe that 24 volts on a 12 volt starter will spin the starter with less torque but more RPM vs. the same 12 volt batteries in parallel.

Someone tell me if I am wrong....
I might be because the amps would stay the same no matter if the batteries were run 12 or 24.

~JH

[manta22]

JH;

24V on a 12V starter motor will generate more RPM & more torque because the current will be much higher. It is an invitation to disaster if you stay on the starter button too long.
I'd check the connections & wire size to see why a good 12V starter won't do the job.

Regards, Neil  Tucson, AZ

[woz]

The engine is a 773 cubic inch Ranger V12.  It has the 24 volt inertia starter which functions fine.  We are adapting a Chevy transmission and installing a secondary starting system as 70 year old inertia starters can be problematic and rather costly, although they sound incredible.   

Woz 

[woz]

I found someone who has used the CUCV with great results.  For those needing alot of voltage it may be a viable alternative to the CSR unit.


Woz

[DallasV]

JH;

24V on a 12V starter motor will generate more RPM & more torque because the current will be much higher. It is an invitation to disaster if you stay on the starter button too long.
I'd check the connections & wire size to see why a good 12V starter won't do the job.

Regards, Neil  Tucson, AZ

Not the case. If you put 2 12V batteries in series you will have 24 V but the same current. If you put them in parallel you will have 12 V and twice the current. Unless you are meaning the starter will draw more of the available current from the battery, but I don't think it would?

[woz]

I have always started with the 24 volt inertia starter but people I know who have run with an automotive starter indicate that 24 are required to turn over.

 
Woz 

[Ron Gibson]

Long, long ago in a far, far distant galaxy. Whooops, wrong story. LOL 
Any way do some checking before you spend big bucks on something that you may not need. When I was in the Army in "64", long, long ago, we had 2 1/2 ton trucks with 302 Jimmys in them with 24 volt systems. The 24's turned over no better than a 12, just longer, witch was needed because the crap wouldn't start on a good day. We also had 5 ton semi's with 205 Mack Diesels with 24 volt starters. They also wouldn't turn any better than 12 volt. Some over the road trucks used 24 volt starters with 4 six volt battery's and a device called a series-parallel switch. They weren't any better than 12 volts and a lot more complicated wiring. I don't think any are in use today, at least on new trucks.
The 168 tooth flex plate will give more reduction to turn the crank.
Just some more to confuse you in your quest.

Ron

[manta22]

Dallas;

The current in two series batteries will be the same in each but the current into the load (12V starter motor) and therefore in the batteries will be alot higher. I = E/R

Regards, Neil  Tucson, AZ

[Ron Gibson]

Cable size is important as is distance. The farther a battery is from the starter the larger the cable needs to be. Also needed is a separate ground cable to engine, not chassis ground. There are several charts on the web for cable size and distance.

Ron