[major]

Originally Posted by McRat

I'm trying to figure out what would be required to generate 500rwhp through a transmission by using electric motor(s) for 45 seconds duration.

A Tesla Model S would come close.

Hi there McRat,

Welcome. Yep, electric motors are different critters than those ICE jobs. The power ratings don't compare. But power is power. Just difference in the "rating" meaning duration and conditions. It'll take a while for it to sink in.

45 seconds, he? I wonder why I'll likely take some crap for saying this, but you'll need AC drives. DC works for the drag strip. And John did the mile with it. But barely if I interpret his reports correctly.

Regards,

major

[McRat]

Originally Posted by major

A Tesla Model S would come close.

Hi there McRat,

Welcome. Yep, electric motors are different critters than those ICE jobs. The power ratings don't compare. But power is power. Just difference in the "rating" meaning duration and conditions. It'll take a while for it to sink in.

45 seconds, he? I wonder why I'll likely take some crap for saying this, but you'll need AC drives. DC works for the drag strip. And John did the mile with it. But barely if I interpret his reports correctly.

Regards,

major

Thanks! One good thing is electrics don't hate high altitude ... Since the second run is done the next morning, there is plenty of charging time, unlike the dragstrip.

Is there a rule against using a 3 mile long extension cord?

[DavidDymaxion]

Is that your truck on the Salt Flats? Gotta love a sport where you run wide open for minutes at a time!

Electric motors are hp rated for 1 hour or continuous use. As the NEDRA drag racers show, they can be overloaded way beyond the rating briefly.

Google on "Buckeye Bullet" to see how they went 300+ mph electrically. Major's race team went 215 on an electric motorcycle on the Salt Flats.

Originally Posted by McRat

Newbie Dumb Arse Q's (no insult intended):

What is the raceweight of the Fiero?

What is "Electric HP" rating?

I've run bikes, cars, and trucks, and perhaps the closest ET data I have would be:

754rwhp (Westech Dyno's Superflow)
Raceweight 6420LB (HRP scale)
ET 10.59 @ 130 mph (HRP)
60' = 1.64

IIRC, another (LVMS) would be about 2800lb, 600HP, 9.3@145? Not sure, as it wasn't my car, just the driver.

Another even more stupid question is:

I see Warp 9 motor tech sheets. They say 34HP and 72v ? Are these the same motors?

I'm not trying to be a jerk, I just don't understand how electric motors are rated for racing. I want to start dinking with electrics, but I'm confused as to what I'm looking at.

I'm trying to figure out what would be required to generate 500rwhp through a transmission by using electric motor(s) for 45 seconds duration.

[McRat]

Originally Posted by DavidDymaxion

Is that your truck on the Salt Flats? Gotta love a sport where you run wide open for minutes at a time!

Electric motors are hp rated for 1 hour or continuous use. As the NEDRA drag racers show, they can be overloaded way beyond the rating briefly.

Google on "Buckeye Bullet" to see how they went 300+ mph electrically. Major's race team went 215 on an electric motorcycle on the Salt Flats.

Yes, that truck is "Casper". We ran it Bonneville 2 years with a best mph of 197+ mph but could not back it up, a piston failed.

IIRC, somebody went 175+ in the dirt at El Mirage on an electric bike. Same guy?

[John Metric]

Originally Posted by McRat

Newbie Dumb Arse Q's (no insult intended):
What is the raceweight of the Fiero?

What is the raceweight of the Fiero?
Started at 2950 and is now 2725#

What is "Electric HP" rating?
The peak battery HP peak I have hit is about 900. That is about the battery limit. That is the battery output, you need to take off about 15-20% for the motor efficiency and 10% for driveline efficiency to get rear wheel horsepower. And then on a drag race, that is the peak HP that is only reached once per gear change. You can go to http://www.wallaceracing.com/Calculators.htm and put in 2725 and 9.898 seconds and get various horsepower ratings. Those would be the average horsepower ratings equivalent.

I see Warp 9 motor tech sheets. They say 34HP and 72v ? Are these the same motors?
YES!!!, I run stock Warp9 motors. I just never let them get up to the speed where the motor emf cuts them back to 34HP. We also over amp and overvolt them, up to 2000A and 170V.
Take a look at some of the run charts from this build thread and look at batteryhorsepower. better yet, join NEDRA YAHOO GROUP forum and look up DC Plasma in Photos section and see a bunch of run data for drag racing.


I'm not trying to be a jerk, I just don't understand how electric motors are rated for racing. I want to start dinking with electrics, but I'm confused as to what I'm looking at.
I'm trying to figure out what would be required to generate 500rwhp through a transmission by using electric motor(s) for 45 seconds duration.

We made about 350RWHP for about 35 seconds on the Texas Mile. Finished at 155mph. That was at half power.
Well, one thing is we make a bunch of torque off the line putting out nearly zero horsepower, so that is in your favor.
Is this a truck application (tractor pulling by any chance?), what is the application? 1.5mile at Loring? LSR?
I would have to agree with Jeff, you may run into some cooling issues here doing it with DC motors.
Can I ask you, perhaps what you want to make is, 500 ftlbs of torque for 45 seconds that would be a lot easier? My little car puts out 1500ftlbs through a two speed transmission(not for 45 seconds). or do you need horsepower? meaning speed....

[John Metric]

Originally Posted by McRat

Yes, that truck is "Casper". We ran it Bonneville 2 years with a best mph of 197+ mph but could not back it up, a piston failed.
IIRC, somebody went 175+ in the dirt at El Mirage on an electric bike. Same guy?

So you are trying to build a new land speed racer?
A good contact here might be Bill Dube, Eva Hakkansen, Jeff Major of course, Dave Cover, Frank John.

Is 500RHWP what is need to get over the air drag and wheel drag? or is that the HP you think you need to get up to speed?
Take a look at my Texas Mile run chart up above. That is about the closest thing I have seen to data on high speed runs.
We were at 155mph at one mile and then cut it off but we were still accelerating really nicely. The rear motor brushes and coils had to be retired after that. But next time we will have some forced air cooling for both motors.
Given a long enough track and enough cooling and battery...My calcs had us at a top speed nearly 199mph. 2.73 diff, 27" tires, 0.78 overdrive.

Never got over 170V and 1000 amps per motor.
Check out he videos on my youtube site to check the acceleration.

[McRat]

First... What you have done with your Fiero is amazing. I'm a hotrodder by nature, I love making things go faster, and a stock Fiero is a slug. To think you could get into rollcage territory on batteries is truly impressive.

I'm still reading and exploring electric technology. I have lots of ideas what could be done with it, but I really need to start small and work up.

Will I run an electric LSR vehicle? Dunno yet. If someone told me 10 years ago I'd be racing 3/4 ton pickups I'd have asked them for a hit of whatever they are smoking. I was racing cars and bikes, and decided I wanted my tow vehicle to go a little faster, and got carried away.

My kids and I are building a small solar car to get our feet wet. Then I will play with hybrid technology, then perhaps a full electric racer if things go well.

[McRat]

Doh! 500rwhp is just a number off the top of my head. It's probably where I will start out with a hybrid setup.

[McRat]

Thanks!

I'm starting to understand the graphs better. It looks like you have better "HP area under the curve" with the Impulse motors but the track data doesn't appear to have any shifting? And the HP falls on the big end, whereas we gain HP the faster we go. Normal 9's for diesels are 140+ mph. We make more power the longer we run. We never hit full output in a 1/4mi.

So a Warp9 with a Zilla and 200v would hit over 400 battery HP with enough high discharge rate cells? I would sneak up on it, not go max effort.

You used high C rating R/C airplane packs? Before I found this board (or was aware that electric racing is getting big), I was looking at a lot of R/C parts. In theory, many of the RC motors are rated at over 10HP in a small package.

Anyhow, thanks for the graphs and info. It's very refreshing to hear a racer giving out data. While I do that a lot for diesels and cars, it's not the norm. Most are "Secret Squirrels" about what they are doing.

Sidebar - Could temperature be the cause of the HP drop? Would supercooling with a nitrogen tank be of any help? Problem is, it would create moisture where you spray it. You'd have to seal off the cooling areas.

[major]

Originally Posted by McRat

Sidebar - Could temperature be the cause of the HP drop?

Hi McRat,

What you see is characteristic of electric motor behavior. The motor has an internal voltage generated which is proportional to speed (RPM). It is called Back EMF and has a polarity opposing the applied voltage (from the battery via the controller). The current (which is responsible for torque) is the difference between the applied voltage and BEMF divided by the resistance.

So once the motor reaches a certain RPM (called base speed), the difference between battery voltage and BEMF diminishes and current drops therefore power tails off. There are limitations on the how much voltage can be applied to the motors so it is not as simple as increasing battery voltage.

I'm not saying motor parts don't heat up and wouldn't benefit from cooling, but that is not the reason you see peak power at less than peak speed.

Regards,

major