Landracing Forum
Tech Information => Technical Discussion => Topic started by: John Burk on June 27, 2013, 02:47:06 PM
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What experience has anybody had running starters on 24 volts . In my case it's a Quarter Master (Hitachi) rear entry starter (9" ring gear , low ground clearance) . Doubt anybody has this combination so I'm asking the 24 volt starter question in general . My Electromotive direct ignition gets confused by the irregular cranking speed of a high compression big block on 12 volts . A 16 volt battery may not be enough to fix the ignition problem .
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I have not tried it. But i sure have run enough 6 volt starters on 12 to know that doesn't hurt them. They love it.
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I've been doing 12V starters on 24V equipment for a long time & not had a problem. It actually cuts down the cranking time on a cold diesel so it might even lengthen the life.
You might want to carry a spare when it comes to those pigmy Hitachi's on 24.
Sid.
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My car runs 2 parallel Quartermaster starters running 24v with solenoids at 12v for 5 years with good Enderle / mag starting and no problems (oops, I should not have said that-early apologies to the folks in line behind us). I would suggest keeping a spare drive and solenoid on hand.
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I know that 12 Volts will really wake up a 6 volt Ford starter provided you don't grind it to long. 24Volts on a 12 Volt starter should do the same.
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I run 24v to my stock 12v Hayabusa starter!!
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The only thing i suggest is don't plan on cranking for to long time. Cranking for more then a few(3) seconds could cause the armature to explode. Don't use the starter to build oil pressure before turning the ignition switch on.
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Ran 24v start/12v run and a standard Bosch starter in a daily drive road car 383 (308 holden based) for about 5 years with no starter troubles.
Used to chew out the same starters in about a month before swapping over.
High recommend as long as you keep both batteries fully charged.
I used a series parallel switch out of a Volvo truck to keep both batteries happy.
jon
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I have run 24 volts through --
a Chrysler starter adapted to spin the crank on a v-twin ( drag style, remote ) .
a stock style v-twin starter .
a stock zx12r starter .
no problems. like any starter, don't spin the pizz out of it .
I always carry spares.
franey
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My Electromotive direct ignition gets confused by the irregular cranking speed of a high compression big block on 12 volts .
Really? I'm surprised to hear this considering the high resolution of the 60-2 crank trigger wheel. Is the timing jumping during cranking? Worst case it advances a whole bunch and the motor kicks back? I've seen this happen before on other things but usually only with trigger wheels that have low resolution like one tooth per cylinder. Spinning the motor over faster is one fix but it's a bummer to hear that the Electromotive doesn't handle this condition very well.
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Electromotives are designed so the crank trigger re-establish the zero reference point on the first revolution every time the engine is started . My 13.1:1 CR and 4 9/16" bore causes enough difference in the time the crank trigger teeth pass the sensor that the logic continuously trys to refind its zero point and the timing light shows an odd series of flashes every second revolution . Electromotive used to advise using a 16v battery but now they say 24v . I considered going to MSD direct ignition till I learned they only work as an upgrade for production direct ignition and don't work even with MSD crank triggers .
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My brain + morning + no caffeine = totally backwards thinking. I do apologize.
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I don't think the current would be halved when doubling the voltage. Remembering Ohm's Law (which hasn't been repealed by Congress - at least yet) - Current equals voltage over resistance. Doubling the voltage and holding resistance steady would therefore double the current (ampere draw). That's how you get more cranking power when doubling the original 12 volt starting voltage -- you're getting twice (approximately) the original current, and therefor twice (or so) the original cranking power.
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One problem with 24v on 12v starter is with 24v to the 12v solenoid the solenoid engages so hard and quick that the spring on the bendix collapses and the starter spins before the teeth are engaged or fully engaged. The cure is to run 12v to the solenoid switch post and 24v to the cable. this way the starter engages normally as a 12v then gets 24v after it is engaged fully and the contacts close.
Some large diesels run two starters on one solenoids contacts. The second solenoid is used to pull and engage the bendix only. That way one won't start to crank the engine before the other is engaged.
Just my $.02
Ron
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... therefor twice (or so) the original cranking power...
Slim- good of you to correct the earlier misstatement. But a minor correction of your post- power is voltage times current, so 24v applied to a 12v starter would result in four times (or so) the original cranking power. Typically the "(or so)" is less, since a power increase will heat the motor windings more, which increases their resistance. [A complete calculation would also need to look at the RMS values of voltage and current- but ignoring the AC components as above is okay for ball-park numbers]
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24v spin my 16-1 Busa like the plugs are out. :cheers:
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we carry 2, 12 volt batteries onboard, we have 24 volts to the starter and 12 volts run water pumps and a msd pro mag the engine has to spin at a higher rpm to start our mag, in our case the driver will retard the ignition 10 deg while the engine is cranking when the engine is fired it will run were we have it set, our starter is from a dodge dakota we run a early injected chrysler on fuel and we havent had any problems yet but we do take an xtra starter. good luck anthony young #54 c/frmr :cheers:
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You'll be surprised at how well the 16v battery will spin that motor. If your using the Hitachi starter make sure your using the diesel model. They are more heavy duty than the standard one. I had that setup on my 632 BBC at 15.3 cr and it spins it about like the plugs are out on a 12v setup. I also used a start retard on the ignition which helps a bunch at higher cr.
Also with the 16v it will work with all your 12v stuff.
Blessings........Ron C