# Some Questions



## flexer (Sep 7, 2012)

*Re: Factory Five Project 818 4wd EV*

Sorry let me add more to this. An old R32 1989-1993 skyline could send its power 70 rear and 30 front if it was spinning. In stock form......so 280 whp and around 300 wtq I have seen the cars launch hard and the front wheels are spinning all the way in first and almost all of second gear. Assumming only 30% of the torque is going to the front wheels than I would be looking for an electric motor that only has 90 torque. Something like the AC-20 hooked to a diff would work?

http://www.electricmotordepot.com/ac-20-induction-motor/

And to the OP i would suggest to not use the electric motor for MORE POWER per say......use it to provide the thing the 818 and lotus never have.....traction.

JR


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## flexer (Sep 7, 2012)

*Re: Factory Five Project 818 4wd EV*

Would it be better if I just started my own thread asking these questions?


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## Woodsmith (Jun 5, 2008)

*Re: Factory Five Project 818 4wd EV*



flexer said:


> Would it be better if I just started my own thread asking these questions?


I have moved your posts out to a thread of its own. Let me know if you want a more specific title to suit your project.


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## flexer (Sep 7, 2012)

*Re: Factory Five Project 818 4wd EV*



Woodsmith said:


> I have moved your posts out to a thread of its own. Let me know if you want a more specific title to suit your project.


Hey thanks Woodsmith. Hopefully it will get some action now. I have tried EVERYTHING to come up with a way of getting more traction on a car, and to set-up a 4wd set-up from a mid mounted engine is not going to happen without BIG $$$$$$. I think this might be a sweet way to get a TON of performance. If I can do it and keep the weight under 325 lbs than I will be all over this.

Plus I like doing different things.

JR


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## Ziggythewiz (May 16, 2010)

*Re: Factory Five Project 818 4wd EV*

You could try adding a ton of lead. That'll keep the tires on the pavement.


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## major (Apr 4, 2008)

flexer said:


> Can I make a car 4WD light enough and strong enough to add traction to a car that can never find it?


Hi flex,

What you describe is a road coupled parallel hybrid for launch assist and charge sustaining energy recovery from regenerative braking and power take off. It is possible to do although none here have. I think the high end hybrid SUVs use a similar system on the rear axle for added traction.

I'd recommend only considering AC drives as you can direct drive through a single ratio and spin the unenergized motor to high RPM after you exceed its useful torque range and it will provide regeneration, which might do little w/r/t actually slowing the car at the required race rates, but would get you some of the recharge for the next acceleration event.

Such a system could use a relatively low energy EESS (Electric Energy Storage System) capable of high power (for its size). Ultracapacitors come to mind, however high power density Lithium batteries would likely be easier to implement.

The system is pretty much like the KERS except attached to the front wheels instead of the crankshaft.

Good luck,

major


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## flexer (Sep 7, 2012)

major said:


> Hi flex,
> 
> What you describe is a road coupled parallel hybrid for launch assist and charge sustaining energy recovery from regenerative braking and power take off. It is possible to do although none here have. I think the high end hybrid SUVs use a similar system on the rear axle for added traction.
> 
> ...


Excellent info. I wonder if there is a way that I could disconnect the motor from the drive above 60 mph and only have it engaged when traveling under 60 mph?

I guess we should say anything is possible if you have money? Does anyone know any diffs on the market that can be electronically engaged and disengaged? How do they work on 4wd trucks that are electronically controlled? I need to do some google searching.

JR


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## flexer (Sep 7, 2012)

OK,

Here is what I thinking now. Can I hook an electric A/C motor directly to a front diff and drive the wheels up to 60 mph, and then dis-connect the winding around the motor somehow and just let it free spin after that?

QUESTIONS:

1. Can you some-how unhook the windings so the motor will just free-spin?

2. Will this damage the motor you think? I have read it can damage brushless motors, but should be ok for brushed motors to just freespin them with no charge?

3. If it was in freespin would I be able to spin it faster or would I still only be able to spin it as fast as its max "powered" RPM?

THANKS!

JR


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## major (Apr 4, 2008)

flexer said:


> OK,
> 
> Here is what I thinking now. Can I hook an electric A/C motor directly to a front diff and drive the wheels up to 60 mph, and then dis-connect the winding around the motor somehow and just let it free spin after that?
> 
> ...


Hi flex,

The AC Induction motor (ACIM) will spin freely when the windings are de-energized. They do not have to be physically disconnected. The ACIM would necessarily be connected to an inverter where the phase leads from the motor are connected to the outputs from the switching transistors. So once those transistors are turned off by the control logic, the motor itself is free to spin. The speed at which the motor can be driven to spin is solely a function of the mechanical integrity of the rotor and bearings. There will be some loss due to friction and some energy required to alter the rotor momentum, but these might be tolerable and preferable over using a disengaging clutch mechanism.

For example, you could power it up to 10,000 RPM but allow it to spin as high as 20,000.

Regards,

major


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## flexer (Sep 7, 2012)

Major,

EXCELLENT RESPONSE! Thanks. I will avoid the clutch idea and now discount the power through a relay or whatever logic I use. 

NOW THIS QUESTION: If I just hook it directly to a differential, and that differential had a final drive gearing of like 4.1:1, and the motor would spin to lets say 8,200 RPM. Than that would get me to about 148 mph. If I hooked a motor like the A-20 with 107 lb feet of torque and a max rpm of 8,000 rpm. With that 4.1:1 gearing....would it even be giving me much acceleration? Like could that give me a zero to 60 of lets say 8-9 seconds?

JR


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## major (Apr 4, 2008)

flexer said:


> NOW THIS QUESTION: If I just hook it directly to a differential, and that differential had a final drive gearing of like 4.1:1, and the motor would spin to lets say 8,200 RPM. Than that would get me to about 148 mph. If I hooked a motor like the A-20 with 107 lb feet of torque and a max rpm of 8,000 rpm. With that 4.1:1 gearing....would it even be giving me much acceleration? Like could that give me a zero to 60 of lets say 8-9 seconds?





major said:


> For example, you could power it up to 10,000 RPM but allow it to spin as high as 20,000.


I wasn't kidding. I'd gear it higher and leave way to alter the ratio over a pretty wide range. You'll have to do your own calculations but regardless, testing will dictate the best configuration


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## flexer (Sep 7, 2012)

major said:


> I wasn't kidding. I'd gear it higher and leave way to alter the ratio over a pretty wide range. You'll have to do your own calculations but regardless, testing will dictate the best configuration



Your probably right. But having a way to alternate it will cause two things:
1. It will be heaver if I install a transmision
2. Will complicate things

3. I looked up a tesla and it has a 8:1 ratio and runs 0-60 in 4 seconds supposedly. Now they do that with a motor with 300 ft/lb of torque I think.....

If I use my 100 ft/lb motor with a 4:1 ratio will it be that bad? Remember I only want the car to go 0-60 in 8-9 seconds.

Is there another motor you could suggest major that either has more power, or one that could rev higher? 

Really since I am only looking to use the motor 0-60 it would be great if I could gear the electric motor with more of like a 5:1, which I might be able to do if I use a front diff from a truck or something that is used for rock crawling where I will be able to get the front diff cheap. 5:1 or even higher would be great, but then with my direct hook-up even with it FREE SPINNING after the car hits 60 mph I would need a motor that could spin safely to around 10k RPM. Does one exist that wouldn't break the bank?

JR


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## major (Apr 4, 2008)

major said:


> ....leave way to alter the ratio over a pretty wide range.


Not a multi ratio transmission, just a way to change ratios back in the shop.


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## toddshotrods (Feb 10, 2009)

I missed this thread. AC would be awesome for regen, but if you're just looking for the 0-60 boost, with a single ratio drive system, brushed-DC is kind of hard to ignore. You'd be able to dump a lot of current into the motor. The downside is less RPM capability, but the fact that DC can be pushed to the ragged edge and come back theoretically makes up for it because you can gear it to not exceed its max RPM, but still have low end torque (theoretically, and depending on the vehicle, batteries, controller, etc).

I think I mentioned in the thread this was plucked from that we are running a rear ICE/front electric drive on Schism. It's DC, with a big 11" motor going in front, and final weight in the neighborhood of where your car is (our goal is 1500lbs). The whole point is just what I said, unload a lot of current into the motor, with a single ratio geared for the top speed, and use the large motor's torque to add as much "boost" as the front wheels can convert to forward motion - my guess is we'll have too much torque, even with the taller gearing.

In the latest project (Pistachio), I am running a motorcycle engine in back, coupled with a small AC motor (that needs to be rewound). The number one purpose of the AC motor is to provide reverse, but while it's at it a little boost, some regen, and hopefully even a bit of all-electric range are there for the taking. Currently the plan on that one is to just add the AC motor to the rear-drive system, to keep the car simple - plus, there's not exactly a lot of real estate under the body. It's going to have massive rear tires, so traction _shouldn't_ be an issue.

For the RPM concerns on Pistachio, I have two choices: Build the motor to match the ICE's 11-12K red line, or add a clutch. I've been planning on the clutch, but would prefer to just let it spin if it'll take it.


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