Factory Five Racing Forum banner

21 - 40 of 83 Posts

·
Registered
Joined
·
1,221 Posts
I sometimes wonder about moving the engine back a little and adding a couple of 200 amp alternators. Combine this with some small electric motors on/in the front wheels and maybe you have something without all the physical drivetrain changes. AWD has most of its usefulness at start-off/low speed acceleration and this might handle that case. Maybe add a couple of deep cycle batteries (just a couple to store a little charge). I haven't done any actual numbers into how much power you get for how long, but I know that there are people on the forum that would know how to do this.
 

·
North Florida
Joined
·
682 Posts
I sometimes wonder about moving the engine back a little and adding a couple of 200 amp alternators. Combine this with some small electric motors on/in the front wheels and maybe you have something without all the physical drivetrain changes. AWD has most of its usefulness at start-off/low speed acceleration and this might handle that case. Maybe add a couple of deep cycle batteries (just a couple to store a little charge). I haven't done any actual numbers into how much power you get for how long, but I know that there are people on the forum that would know how to do this.
I like the way you think !! 4wd is awsome dumping the clutch on a hard launch... but Im wondering if it could have benefit cornering also... the way you are thinking to set it up. What if (hypothetically) you could control the power to the outer front wheel on a turn ? would that benefit ... so that the wheel isnt sliding to make the turn, it is actually pulling ? What if you could divert 140 FTlbs dedicated torque to the outer front wheel on any given turn at any given speed under 7100 rpm on that axis ? and turn off power to the inside front wheel ? Does anyone think that would help or hurt handling overall ?? and what if the front wheels combined could only pull 280 FTlbs no matter the given power of the rear wheels ? and the same system only adding a total of 150 lbs at most the the car overall ?? and the system only have the draq equivalent of 20 lbs rotational inertia while cruising ? and total cost being 3200 $ plus some machining that I havent figured in yet....

That way this system doesnt care about tire size or gear ratios ... you can run whatever and there is no uneven wear or drag due to it... and still be "active" .

Heres where my idea differs from yours though, mine wont work for any rpm lower than 2800 in first gear with a 3.5 1st gear ratio... it would have to hit 800 rpm after the total gear ratio in order to "turn on" and start pulling. For turning it could be as low as 500, but would lose efficiency.
 

·
Registered
Joined
·
1,553 Posts
I like the way you think !! 4wd is awsome dumping the clutch on a hard launch... but Im wondering if it could have benefit cornering also... the way you are thinking to set it up. What if (hypothetically) you could control the power to the outer front wheel on a turn ? would that benefit ... so that the wheel isnt sliding to make the turn, it is actually pulling ? What if you could divert 140 FTlbs dedicated torque to the outer front wheel on any given turn at any given speed ? and turn off power to the inside front wheel ? Does anyone think that would help or hurt handling overall ?? and what if the front wheels combined could only pull 280 FTlbs no matter the given power of the rear wheels ? and the same system only adding a total of 150 lbs at most the the car overall ?? and the system only have the draq equivalent of 20 lbs rotational inertia while cruising ? and total cost being 2400 $ plus some machining that I havent figured in yet....
Sounds like you already have this figured out. Do tell!
 

·
Too much is just enough.
Joined
·
5,872 Posts
I like the way you think !! 4wd is awsome dumping the clutch on a hard launch... but Im wondering if it could have benefit cornering also... the way you are thinking to set it up. What if (hypothetically) you could control the power to the outer front wheel on a turn ? would that benefit ... so that the wheel isnt sliding to make the turn, it is actually pulling ? What if you could divert 140 FTlbs dedicated torque to the outer front wheel on any given turn at any given speed under 7100 rpm on that axis ? and turn off power to the inside front wheel ? Does anyone think that would help or hurt handling overall ?? and what if the front wheels combined could only pull 280 FTlbs no matter the given power of the rear wheels ? and the same system only adding a total of 150 lbs at most the the car overall ?? and the system only have the draq equivalent of 20 lbs rotational inertia while cruising ? and total cost being 3200 $ plus some machining that I havent figured in yet....

That way this system doesnt care about tire size or gear ratios ... you can run whatever and there is no uneven wear or drag due to it... and still be "active" .

Heres where my idea differs from yours though, mine wont work for any rpm lower than 2800 in first gear with a 3.5 1st gear ratio... it would have to hit 800 rpm after the total gear ratio in order to "turn on" and start pulling. For turning it could be as low as 500, but would lose efficiency.
You do realize how complex that is, right? You're looking at a lot of inputs in order for that to work. You'd need a steering wheel position sensor, a computer to control the system, and piggy back the RPM sensor and brake switch in order to even have a shot at making that happen. Then the code, not too difficult with simple on / off commands from the various sensors. But in order to make all that happen, it would just be easier to redesign the frame to use Subaru, Audi or Porsche parts. Electric FWD might seem simple, but it isn't. It would need to operate at the same speed as the engine, that's where things could become difficult. You're talking about using Hybrid technology on a GTM. :lol:
 

·
North Florida
Joined
·
682 Posts
You do realize how complex that is, right? You're looking at a lot of inputs in order for that to work. You'd need a steering wheel position sensor, a computer to control the system, and piggy back the RPM sensor and brake switch in order to even have a shot at making that happen. Then the code, not too difficult with simple on / off commands from the various sensors. But in order to make all that happen, it would just be easier to redesign the frame to use Subaru, Audi or Porsche parts. Electric FWD might seem simple, but it isn't. It would need to operate at the same speed as the engine, that's where things could become difficult. You're talking about using Hybrid technology on a GTM. :lol:
Who said anything about electronics ? My system doesnt involve a single electronic part ! hahaha. Thats why Im not saying anymore ! Cause someone out there always thinks they know more. I know it will work cause I have a prototype setup on a 4 wheeler and its disgusting !!! But dirt gives alot, this is asphault. Theres more to consider and more expense involved... so Im really just trying to work it through.
 

·
Junior Charter Member
Joined
·
2,632 Posts
I really don't think it is all that bad. It will take some planning and some thought, but there are FH teams doing it already, using CAN architecture for component connectivity and all sorts of cool things. There are also ways to couple the motors to achieve an action a lot like an LSD. There is A LOT of information on these subjects online if you really want to get into it.

Doing things mechanically is a good approach if you can keep it to 150lbs. The motors would weigh at least 40, then all the large gauge wire and controller, driveshafts, blah blah blah...would put it somewhere around the 150. It is infinitely more adjustable, though.
 

·
Registered
Joined
·
62 Posts
Who said anything about electronics ? My system doesnt involve a single electronic part ! hahaha. Thats why Im not saying anymore ! Cause someone out there always thinks they know more. I know it will work cause I have a prototype setup on a 4 wheeler and its disgusting !!! But dirt gives alot, this is asphault. Theres more to consider and more expense involved... so Im really just trying to work it through.
Hydraulics, baby! :w00t:
 

·
Too much is just enough.
Joined
·
5,872 Posts
Who said anything about electronics ? My system doesnt involve a single electronic part ! hahaha. Thats why Im not saying anymore ! Cause someone out there always thinks they know more. I know it will work cause I have a prototype setup on a 4 wheeler and its disgusting !!! But dirt gives alot, this is asphault. Theres more to consider and more expense involved... so Im really just trying to work it through.
You commented on another member using electric motors, so I figured that was your basis for making it work. Do you have videos of your prototype? I'm interested. As for the AWD kicking in at certain times (on its own), wouldn't there have to be some sort of electronic involvement? Mechanically, it's on all the time unless you mechanically disable it, via lock out hubs or a crank case shifter.
 

·
Registered
Joined
·
16,313 Posts
You guys DO remember the college team that built the front wheel drive, IIRC, hybrid, GTM in almost record time, right? They posted on here quite a bit while building. ;)

And BTW, it is my opinion that one would HAVE to have either independently controlled motors or a diff in order to allow the car to turn with front powered wheels.

A buddy of mine put a "Lincoln Locker" in his Jeep and told me he felt no difference in the turning abilities of the vehicle, so the other day, while driving down a paved road, I engaged my front axle ARB air locker on my Jeep...BIG MISTAKE! Turns out my buddy must be a crack fiend. I almost crashed into oncoming traffic at the next gentle bend in the road!

You simply CAN NOT have both front wheels being driven the same while trying to turn! PERIOD!
 

·
Registered
Joined
·
6 Posts
Discussion Starter #32
I am getting the impression that most everyone is trying to talk me out of getting a GTM. For me there is no point of building another car without a rear-mid engine AWD setup. The reason, I want a different driving experience compared to my other cars. I agree that I may achieve better lap times in a RDW GTM. However, my GTM would only see the track for testing. Besides, AWD is faster and safer while aggressively driving a powerful vehicle on the road where obstacles are unpredictable and the surface is unknown.

I am making a final plea. All I need are answers to my original two questions to determine if I can successfully build a rear-mid engine GTM.

Thanks

Reposted for your convenience.

Hopefully someone here can tell me if either of the following two concepts can be achieved.

1. Does a transaxle with an integrated transfer case similar to this one exist?



2. Can a typical front engine AWD system be turned around?
(a) Is it possible to change the power split. The factory setup is sending (for example) 70% of the power from the tail shaft to the rear diff. and 30% through the transfer case to the front. In my case, I need the transfer case to provide 70% to the rear and the tail shaft (now facing forward) to provide 30% to the front.
(b) Also how does reversing the entire drive train effect the direction the wheels will turn in forward gears?

 

·
Registered
Joined
·
16,313 Posts
In both cases of what you have pictured there, you will have to have a custom or, at the least, modified transaxle.

Mendeola CAN do it, but you better be prepared with $$$ to get it done.

On a side note, I have been building this exact setup in my head for quite some time now. I thought that Mendeola's new LQ box would cover this ground, but allas, no.

If times were different than they are, I think there would be more interest in putting something like what you propose together, but without a ton of capital, it just ain't gonna happen.
 

·
Too much is just enough.
Joined
·
5,872 Posts
Look at my previous posts. The Panamera setup should do what you want. You'll have to make sure the engine is as low as possible, but that system can be customized. You can shorten or lengthen the axles to your needs. If you really want to do this, I'd go with the AWD system from the Panamera. I haven't tried to talk you out of a GTM, just making it clear that what you want, isn't easy. Is there a budget? How much fab experience do you have? Can you weld? Just trying to guage your situation, as all of the questions I just asked play a part of making this happen. You want to know how to make this happen, and that's what many are trying to help you with. I don't think you can use any of the regular transmissions seen in a GTM.

Oh, and about your budget, to make this happen, you're looking at roughly $100K, easy. I believe the average cost to build a GTM is around $70K. I don't know what your budget is, but it's time that aspect of the build is talked about.
 

·
FFR Coupe - RF GT40 owner
Joined
·
106 Posts
I sometimes wonder about moving the engine back a little and adding a couple of 200 amp alternators. Combine this with some small electric motors on/in the front wheels and maybe you have something without all the physical drivetrain changes. AWD has most of its usefulness at start-off/low speed acceleration and this might handle that case. Maybe add a couple of deep cycle batteries (just a couple to store a little charge). I haven't done any actual numbers into how much power you get for how long, but I know that there are people on the forum that would know how to do this.
Mike,

200 amp at 12v = 2400 watts.... now at 746 watts/HP at 100% (motors are at most 95% efficient) so 746/.95 = 785 watts/HP ... this gives you 3 HP to drive each wheel (not worth doing) for the cost and weight.

So let's say you want 30 HP to drive each of the front wheels (60 HP total). 60* 785watts/HP = 47.1 KW

Now a average deep cycle battery has about 70 amp hours of charge and can produce 550 CCA. So at max the battery can produce 550*12 watts or 6.6 KW which is 8.4 HP at 95% efficient. So to drive both the front wheels would require about 8 batteries (400 plus pounds).

Note: This power level would last 7 min. before the batteries were dead.

If the two 200 amp were used to charge the batteries you could run the front wheels at 60 HP only 1/10 of the time as 47.1/4.8 = 9.8125. Now I don't think you can drive the alternators at 100% all the time either.

So on a 2:30 second track you could use the front drive for only 15 seconds.

Now a current 30 HP motor weighs about 125 pounds. So the total of the package....

250 ... motors
400 ... batteries
50 ... Alternators
50... Controller
750... total plus wires (large gauge), and drive shafts and....

Richard
 

·
Registered
Joined
·
16,313 Posts
You are correct. Weismann builds some cool stuff too. I have personally driven one of their race boxes and it was nothing like the Mendeola, but yes, they are an alternative.
 

·
Too much is just enough.
Joined
·
5,872 Posts
Hey Crash, how is the GTM-R? I remember a few months ago a Miata decided to play bumper cars and ran over it.
 

·
Registered
Joined
·
16,313 Posts
The GTM-R or what is now being termed the PDG GTM after a request from FFR, is doing fine. I just spoke with Richard yesterday and he and the guys are finishing up putting the Gen II body on. It is all repaired and ready to rock for the first race of the year which will be a 4 hour race in Seattle April 10th. We are all excited about this race, as last year we ran out of gear at about 130 MPH only 1/3 of the way down the drag strip front straight. Thanks to Mendeola, we now have some taller gears and hope to get to the 150ish MPH range. If we can do this, it will be the fastest this car has ever run. Thunderhill is a faast track, but not nearly as fast as Seattle. I broke 138 MPH at TH in practice, but, AFAIK, that's as fast as the car has gotten to.

Richard has done some modifications to the Gen II body to make the car easier to work on, and I can't wait to see how they turned out. They should be much like what I am doing with a Gen I body that I am working with for the GTM-R. Figure I'll take over that moniker since it is for the race model of a GTM, or at least it is as we use it, and since there no longer is the original Gen I PDG GTM(R), why not use it for my project? :)

Anyway, all is well with the PDG GTM Gen II racer and we are all excited to run it this year in selected events and, of course, the 25 Hours Of Thunderhill! Can't wait!!
 

·
Too much is just enough.
Joined
·
5,872 Posts
Sorry for going off topic, but the PDG GTM is pretty cool to watch videos of in action. Crash, will there be any changes to the body of the Gen II for aero? It might just be me, but I think the original GTM had better aero in the nose / hood, letting air out after it went to the radiator.
 
21 - 40 of 83 Posts
Top