LocostUSA.com

Greg, thanks for keeping a sharp eye out, much appreciated. Yes, its from the 2.5 I5 which is a CCW motor. The 3.2 V6 is a CW motor so wouldn't address the cooling question.

Here's a clip from the ND catalog, part number 210-0201: I plan to run it upside down from what the picture shows and, as mentioned, pulley-end pointed towards the LS motor. Not 100% sure on this model yet, still waiting on idle amp and size information.

Marcus, the water pump draws 7 amps (less than I thought it would,) the fuel pump 15 amps and the cooling fan a whopping 21 amps when the water's hot. So that's a total of 43 amps before I turn the engine and lights on.

Here's a table out of the Powermaster catalog for "sizing a race alternator." My numbers fall in the ballpark.

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Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."
Ultima Spyder, Northstar 4.0, Porsche G50/52

Idle amps depends entirely on how fast the alternator is spinning. Also, an alternator shouldn't be put on any old engine without first calculating its maximum speed, which should be around 15000 or so.

You may well have to change pulley sizes or risk needlessly low output at idle, or risk destroying it by over-speeding it.

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

My buddy went with a 1-wire ND alternator. My problem with doing that was, aside from the obvious issue of not inducing charging at idle, there's no provision for a charging system warning light.

Personally, I'd rather know it's time to get home, or to a shop, than not know ithere's a problem until the lights dim & I sputter to a stop on the side of a dark country road. I've had British cars - I know what that's like

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Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/

Good points, Kurt. Most specs seem to peg "idle amps" at 2500 alternator rpms (approx. 800 engine rpm with a 3:1 pulley ratio.) With that pulley ratio, a 6500 rpm engine redline would be pushing 20,000 alternator rpms. Must be why "race prepped" alternators focus on overdrive pulleys which result in low idle amps combined with improved bearings to keep them spinning.

Here's a generic graph from the ND website showing output current vs. alternator rpm. I imagine the curve goes flat beyond the max speed shown, at least until the bearings get fried.The output current scale shown isn't as interesting as the shape of the curve and the rapid current drop on the left side of the graph. It does pay to do a little planning.

Amen to that!

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Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."
Ultima Spyder, Northstar 4.0, Porsche G50/52

We had a very nice set of posts recently about how to design and build electric indicators including idiot lights. $5 of parts will set you up for warning on alternator current and also water temp, oil pressure and whatever else you want. Don't be afraid to solder a couple of wires after welding your frame!

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
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Either a voltage gauge or an ammeter will do that for you. Each has it's own purpose and advocates.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

It's probably a dumb thought, but are there any alternators with a "smart" pulley, say with an electric clutch or mechanical governor that will disengage when a safe RPM level is exceeded? You'd think someone else has solved this before. All those endurance racers must have the same problem: need big draw at night, but can't fry the alternator at high RPM.

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

I'm not sure what you are asking. I would think that the frying at high RPM is related mainly to bearing life. It has little to do with current draw, with the exception of the temperature derating of the bearings. You might be able to fry an alternator if operating at full output (watts) for extended periods of time. This would be due to internal temperatures and cause winding insulation failure. I would think modern internal regulators have some sort of temperature sensing and would fold back the output power if necessary. Easy enough to do by regulating the field current.

I just googled maximum RPM of alternators and it seems that somewhere between 12,000 and 18,000 RPM would be their rating, depending in which "expert" you believe. My rX-7 for instance has a red line of 8,000 RPM and about a 2:1 pulley ratio. Which would spin the alternator at 16,000 RPM.

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

Tom you may find what you are looking for in the marine world, many chevs etc running ccw so there may well be alternators available with fans to suit. Just thoughts.

Bob

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Build Log viewtopic.php?f=35&t=16640&p=187700#p187700

Mancave http://s1116.photobucket.com/user/mypic ... ow/mancave

Of course there's the little issue of when you add Marine to any part it becomes even more expensive than when you add Harley Davidson.

And also it's not as readily available should one fail you in Podunk, USA

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

LOL!!

In the "marine parts" world, we refer to money in terms of "marine units", where one "marine unit" = $1,000. Ask me how I know...or how many "marine units" I've spent in the last few years!

It matters not if the identical part is available as a terrestrial-use item...once a nautical reference is attached, its price increases by orders of magnitude...and its availability decreases in the same proportions.

_________________
Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.

http://zetec7.webs.com/

@rx7locost
It was a poor choice of wording on my part, Chuck. I was really referring to the RPMs of the alternator exceeding its design limits.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Based on all your inputs I found an alternator that should work. To get the fan rotation needed for a reverse-mount, I researched the Denso on-line catalog for CCW Honda units that were rated for at least 90 amps. Using the cross-referenced pictures in the catalog, mounting lug and output terminal positions and case size became the next priorities. After some mock-up exercises, I settled on this "95 amp" unit from a '97 - '01 CR-V:

Had it rebuilt (locally ) with USA quality bearings, an OEM Delco regulator and a 6-groove pulley. At speed it tested at 125 amps output and at 3400 alternator rpm, 65 amps. Output will drop off quickly at my idle target of 2500 alternator rpm, but that can be adjusted with my right foot if stuck in traffic for too long. It's set up as a three-wire: an ignition-on wire for the exciter, an alt. light ground wire and the + terminal (output.)

Thanks for all your help, gents. Now back to my build log to get this puppy mounted.

_________________
Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."
Ultima Spyder, Northstar 4.0, Porsche G50/52

My brother put an alternator on his LS3 without first calculating how fast it would spin. It worked fine - for about a week - then quit. He put on another, which did the same thing. Turned out that he was spinning it up to around 20,000. It's not the bearings that failed, it was the armature wires that pulled away from their "nesting" areas and got ground off by the stator.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Yo Tom! Are you "not planning a big battery" because of size limitations or just general adding lightness? I have a "full size" Optima dry cell in the Slotus, with no alternator at all. If fully charged, it will run the electric water pump, the fuel pump and all the engine electronics as well as crank the engine numerous times for a full autocross weekend, with two drivers. I realize that no alternator is not a practical thing for a street car, but I'm saying the battery is equally important to the alternator for the operation of the various electric/electronic stuff on the car.

My original point when I started typing was "If you use a good size battery, you don't need a 60 amp alternator" but now that I think on it a bit more, I guess the converse is true too. OK, I'll get me hat and coat on the way out...


JDK

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JD, father of Quinn, Son of a... Build Log
Quinn the Slotus:Ford 302 Powered, Mallock-Inspired, Tube Frame, Hillclimb Special
"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom