Awd, Boosted, 5spd, Hybrid Gas/Electric 1990 Caravan?

[Vigo]

About 4 years ago i spotted an ad on Craigslist for a 5spd (tbi) Caravan. I dont think i was looking for a van, but the 5spd part made me call the number. I went to take a look at the van and it was VERY clean but did not run. I figured out immediately that the motor was completely locked up from having run with a blown headgasket for thousands of miles with oil contamination.

It was advertised for ~$350, but i arranged to put a motor mount on one of the seller's other vehicles and got the van for around $280.

It sat for a while as i didnt have piles of spare motors around back then , but eventually i decided it was so clean and nice that i wanted to take the perfectly functional 2.5 tbi out of my DD aries and put it in the van. I was able to get the motors in and out through the top with the trans in the van and get it fired up.

From that point i daily drove it for a solid 2 yrs, putting ~25k on it (total ~225k now?), averaging 27mpg , holding a crap load of stuff, being super practical and reliable. It ran 18.2@73 like clockwork It became my most-loved vehicle! I really didnt do ANYTHING to it in that time other than oil changes, a stereo, and some 15" wheels. Unfortunately, some previous rust repair began to fall apart (van was from wisconsin) so it lost that 'good condition' sheen along the way.


I always had thoughts of turbocharging it and gradually collected the few parts i needed like harness, and computer (thanks Fastasleep!). In 2009 when i was building my Aries for the GRM $2009 Challenge i had thoughts of towing it there with the van, but i didnt think it would tow it well as a tbi (shoulda tried) so i decided to take it apart and start the turbo install. All i did was slap stock turbo manifolds and a mitsu on the TBI motor, and modify a tbi EGR pipe to add to the oil pan as a turbo oil drainback. I had put on a stock turbo-van exhaust a bit earlier from a parts van i used to build the Aries.

Unfortunately i didnt have a spare turbo fuel pump at the time and it wouldnt fire on starter fluid, so it had SOME issues and i got busy with life and the Aries project and never went back to it. I ended up towing to GRM with my 93 Dynasty which worked AWESOME and led me to start towing everything else with that car as well.

Continued VVVVVVV

[Vigo]

Its been almost 2 years since then. In that time, i schemed over it and did a few things to it here and there. I put a proper fuel pump in it and figured out the reason it wouldnt fire was because i forgot to put a turbo distributor base in it (lol). I also took apart the interior to fix some weird wiring issues and do a badass 4channel amp install (no pics )and what ended up happening was that i never put it ALL the way back together and daily drove it again.

Because of my friendships with Ondonti and Big_P id always had 3.0L ambitions and decided at some point that this was the car to take them out on, even though i hadnt put 20 miles on it as a turbo. Its fun @14psi, dont get me wrong, but its only the same kind of fun as my other 8v's, and kinda redundant! Plus, i have never had a supercharged car and figured, like most of my other car 'firsts', i should BUILD my first one.

Big_P contributed a 543 and an m90 to the cause, along with his own 3.0/543 van experience.
Ondonti contributes a pile of 3.0 and general knowledge on a regular basis.

And along the way a QUINTET of parted/swapped/recycled vans contributed piles of miscellaneous parts, like a boatload of spares, factory tint windows, brake upgrade parts, AC system (mine was non-ac), 89 3.0 harness/comp, several 3.0 motors, rust-free body panels, and contributed to other causes as well.. one of them is Strax22's formerly-3.0 2.5/568 turbo van and the other ones contributed in various ways to my Aries, other cars, and probably that big dam in China Some of the parts off these vans now reside in Illinois and Ohio, too.






Continued VVVVVVV

[Vigo]

RANDOM PICS POST

AC SWAP






Front brake upgrade (now 11"ers)



Hitch Installed (from my parents' cash-for-clunker'd 97 Grand Caravan)

^That install was tedious but i custom-installed it REEL GUUUD, aint never coming loose

Continued VVVVVV

[Vigo]

So at some point after i started getting my 3.0 parts together something completely unrelated happened.. I found an electric car on CL and bought it
http://www.turbo-mopar.com/forums/sh...t=electric+car


And after i sat on that and did a bunch of research for a while, i decided "Hey, wouldnt this electric motor be much more interesting in an AWD HYBRID BOOSTED CARAVAN?!??!"

So i took all the electrical goodies out and traded the *1200 miles total* Colt shell to a friend of mine who's building a monster 4g63 car out of it. That car is going through an AWD swap as well! I got some neat hardware in trade like an AEM FIC ill be using on my 93 dynasty.

Here's the only pictures i ever took of the 52hp electric motor, and amazingly i NEVER took pictures of the rest of the hardware. Very dirty, nasty, homebrew install in the Colt.



And of course after i started getting hyped about trying some electric power i ended up selling the fiancee's clapped out Mazda3 to buy a Hybrid daily driver (my honda Insight).

So about that AWD HYBRID BOOSTED CARAVAN idea, i figured hey, ive got many thousands of dollars of hardware here (which i only have a few hundred bucks into), and a caravan with a very roomy underbelly, and there's a factory bolt-in driven rear axle setup from AWD vans.. how convenient! Thus began my search for an AWD donor van.

---------- Post added at 12:19 AM ---------- Previous post was at 12:17 AM ----------

Well, AWD caravans are a rare bird in dry, sunny Texas, so it took a while to find one. I didnt really want to buy an entire van just for the rear axle either, which nipped a few potential deals in the bud. I finally found one in a cheap junkyard last October and got everything from the the viscous coupling to the leaf springs, the whole shebang, for $220 total. Finally!

Well that was October, and now FINALLY i got around to putting the AWD rear axle in the van. Since my van is FWD the fuel tank sits where the rear differential would in an AWD van (they have different tanks), so i could not mount the diff and CV axles without moving the fuel tank. Since i didnt feel like doing it just yet i figured id put the rear axle in without the CV axles or diff by just running some axle stubs in the wheel bearings.

I had some spare, junky front axles (same splines) to salvage the outer ends from, but it turns out the 'body' area was too bulky to fit on the backside of the hubs. Luckily Mason (Strax22) cut them down to JUST RIGHT for me at his work.


Has anyone noticed just how HUGE the AWD rear brakes are?

That's next to the already-beefy stock van drums.

---------- Post added at 12:26 AM ---------- Previous post was at 12:19 AM ----------

Ok, HERES ANOTHER SWEET MOD BROUGHT TO YOU BY VIGO.

Since ive had the van, ive seen every attempt or idea at lowering the rear that has been posted to the net, from Dempsey's spring-under to Pachner's shackle-drop to removing springs and just riding on the bumpstops everywhere (Reeves? ).

Having this AWD axle sitting around made me realize something.. on a stock FWD Caravan rear axle, the centerline of the wheel (the axis) is pretty much level with where the leaf springs sit behind the drums. Well, on an AWD, you need a CV axle to go through there, so you cant have leaf springs in the way! What do you do? You make the leafs attach at a lower position and just run taller springs!

So what happens when you run an AWD rear axle on FWD leaf springs? You get a ~3" drop with NO loss of suspension travel, NO change in ride/load characteristics, AND a giant brake upgrade to boot!


Rock out now!
Its like a drop spindle for your rear axle!


AWD rear axle with taller AWD springs.

in progress

NEW HOTNESS!

Thats a 245/35 autox slick, ill be running 245/45/18 street tires (which will fill out the well better) when the time comes.

---------- Post added at 12:35 AM ---------- Previous post was at 12:26 AM ----------

And yes, it works.

To run the AWD rear axle in a FWD van you will need to keep/reuse the longer AWD u-bolts, make axle stubs from the stock AWD cv axles or make something on your own (its possible that a nut, bolt, and washers is all you need), and THATS IT. The leaf spring pads work, the shocks work (but are compressed 1-2" more), the e-brake cables work, and the brake hoses work.

Since most if not all (not sure) AWD vans are long wheelbase, the passenger side e-brake cable which loops back around to the drivers side, is noticeably longer than the short wheelbase van cable. I did not check if these cables are interchangeable, because i was able to stuff the extra cable length into the van and keep things routed well with a few well-placed zip ties.


THE ONE MAJOR CAVEAT is that AWD vans are 5x114.3, requiring you to swap to the 5x114.3 fronts (from the same donor?) to have matching wheels, unless you get some of the many dual bolt pattern 5x100/114.3 wheels..

---------- Post added at 12:38 AM ---------- Previous post was at 12:35 AM ----------

Here is a VERY UN-proportional, MSpaint rendition of BASICALLY what is going to happen:

[RoadWarrior222]

Vigo! Vigo! Vigo!

Yeah, that's cheering you on, very interesting....

I'm a little disappointed at the proposed arrangement so far, if I do similar I don't want to lose ground clearance and have it dragging it's nuts in the snow. I would be trying to flip the axle and use up the space where the spare sits (Used to sit on mine, the crane got unusable so I deleted it) Also I think I'd try and lose a battery, or some electronics in the side panel behind the driver's seat. Lots of room there that's kind of wasted (Though that's where my spare goes when the van is full ATM)

Also think there's a bit of room in the passenger side, behind the wheelarch... thinking that I might go for getting the controller and inverter behind there, and giving it vents for cooling. With your arrangement it looks like you're going to have some fun trying to keep the exhaust away from batteries, controllers etc. Bear in mind also that engine heat tends to flow back under the vehicle, so even with the exhaust out of the way, the electronics might get warm. If you wanted to be really clever though, you could do something like space a cover 2" off the firewall, all the way into the cowl and continue it to an underbody tray that exits at the rear in a diffuser.... (and have the exhaust outside of it) that way cooler air is pushed in at higher pressure above the cowl and sucked out the back. That would leave less clearance for the turbo though.... unless you hybridded your hybrid with a 2.4 head, then you could hybrid while you hybrid. You might achieve that effect just by having some 3" pipes either side of the engine bay to hood vents close to the back of the hood, feeding the front edge of the undertray.

Anyway, probably best to figure out the mechanics first, you can have forced air cooling temporarily if necessary until you figure out something fancy and efficient.

[Vigo]

I am going to try and maintain as 'normal' of a Caravan interior as possible. However, there is probably going to be some floor intrusion somewhere (the motor is ~1ft diameter) and i MAY end up moving making a false floor that moves the entire floor behind the front seats up by 2-3". That would depend on headroom for the back seats.

The charger and dc-dc converter i have are small enough to potentially put in other places, but the motor controller is about the size of a 5" thick car radiator, and realistically the ONLY place i can put it is flat up against the bottom of the car.

Ground clearance will definitely be an issue, although im hoping to keep at least 4" or so. Putting the taller tires on it will raise it a bit from where it sits in the last pic, and if i need more height i can use leaf blocks or custom shackles to bring it back up a bit more. I hope thats not necessary as i really like the look right now.

The front engine is being swapped to a 3.0 with stock exhaust manifolds so there wont be any firewall issues, but if you look closely at my nasty MSpaint work you can see im planning to Y off the exhaust over the k-frame and send it down the sides of the van, outside the main framerails. However, thats just a working theory, because unless two 40" glasspacks makes it acceptably quiet i will have to come up with more room for mufflers.

I am hoping to keep a space saver spare in the stock location, but if i need more room i may end up changing that plan.

[RoadWarrior222]

Doh, 3.0...

Right, though I don't know why you'd "Y" it, rather than just run it off each manifold seperate... blank the crosspipe entry on the rear one. Rig an injector cutout for the front bank and it will chug nicely on 3 cyl too. Though with boost you'll want an O2 in the front bank for monitoring purposes.

Motor controller sounds like it could go behind the driver... get an extra inch by pulling the trim panel.. then repanel it flush over the top and probably no-one will notice it's there.

[Vigo]

More info:

The motor and controller are a matched pair from UniQ Motors designed to run on 200 volts.
http://www.uqm.com/

The motor is a 52hp 3-phase brushless dc motor complete with rotary encoder.

Motor

Type: SR180/2.8P
Kw: 32
Voltage: 200
RPM: 7000
Amperage: 400 A Peak
Serial No.: 1519


The controller has full analog power AND REGEN ability. Oh yes, i plan to have regenerative braking.

Uniq model No.: CR20-300/3
Serial Number: 1486
Voltage: 200 VDC
Amperage: 300 A
Patent: 5,107,151



These parts were developed way back in 1993. Ive heard that UQM supplies motors for military vehicles, including some that are required to be able to move silently in urban settings.

Here is a PDF of a graduate student's work using this same system on a Neon in 1996.
http://etd.lib.ttu.edu/theses/availa...5009895870.pdf


The charger i have is a K&W Model BC-20. I believe the highest voltage output of this charger is 108 volts so in order to use it as a grid charger i will have to incorporate some components to break the 200v battery packs to 2 100v pack circuits for purposes of charging.

I have another PDF written for the Department of Energy about the UQM systems that i will figure out how to upload.




___________________________________


On the subject of the motor, i do not know how much torque it makes, but i do know its rpm range, 0-7000rpm.

Knowing that the rear differential ratio is roughly 3.45:1, 7000 rpm would not be reached until ~160mph if i dont use any more gear reduction. Obviously that's stupid.

If i add a 3:1 gear reduction between the motor and diff, then 7000rpm will get me to roughly 50mph. That is more in line with my goals.

My goals for the electric portion are PRIMARILY that it be able to strongly accelerate the van and hopefully be able to spin the 245/45r18 tires at a standstill. If i use a 3:1 gear reduction, the ~3.45:1 diff, and assume 200lb ft from the motor, i should have roughly ~2000lb ft at the wheels. I know that will be enough for decent acceleration, but im not sure it will be able to spin those tires. When i had my nearly stock tbi aries i calculated that it had about ~1600lb ft to the front wheels in 1st gear, and it blew off the 205/50r15s easily, but that is a much smaller tire and 2000lb ft does not seem like very much more than 1600. However, i only need it to spin the tire for AWD or RWD burnout/donut purposes, and i could always bolt on smaller tires for that one video i have to make to prove it can do it..

The secondary goal for the electric portion would be to be able to cruise at low speeds on electric power. If 7000 rpm on the motor seems unpleasant (maybe it wont) i think the 3:1+diff reduction would still be comfortable up to ~40mph, which fulfills that requirement.

One thing i havent figured out yet, is if the motor turns 7000 rpm to run 50mph, how do i de-couple it for purposes of going 100mph? I dont want neodymium iron boron magnet fragments flying off at 14000 rpm and cutting my van in half like a 100mph clutch explosion.

The awd rear diff DOES have an overrunning clutch built in, i believe, and by itself that would be enough to fix that problem..

BUT, by itself that means that the AWD system would be defeated in reverse gear, so the awd rear diff has a dog clutch that engages in reverse to defeat the overrunning clutch. I need to keep that clutch engaged for my regenerative braking to function.

Pic courtesy of Ondonti


So the problem becomes, can i de-couple that dog clutch at speed (I think yes)? It is moved by a vacuum actuator. Even if i do that, does it mean that i would have to come to a complete stop to re-couple it for purposes of regen braking?

The motor does have a rotary encoder, so THEORETICALLY one could design a rev-matching system to match (within a few rpm) the motor speed to the diff speed for purposes of re-engaging the dog clutch at speed. Take that 370Z! I dont think any brass shavings were ever ground off an electric synchro..

---------- Post added at 09:47 AM ---------- Previous post was at 09:40 AM ----------

Check out the factory-built electric Caravans that Chryco produced in the mid 90s.

http://www.allpar.com/corporate/electric-cars.html

[Vigo]

Right, though I don't know why you'd "Y" it, rather than just run it off each manifold seperate...

I dont think i would gain anything from that if i was still running a stock front manifold. It might sound different but for the added effort i dont see any other benefit.

Motor controller sounds like it could go behind the driver... get an extra inch by pulling the trim panel.. then repanel it flush over the top and probably no-one will notice it's there.

It's possible that it would fit there if i cut up and modified the interior panel there. On non-rear ac vans that trim panel is basically scalloped into that empty space so i dont think the depth is there without modifying that panel. The other issue is that if i put it there and someone bangs into the side of the van i just lost an irreplaceable component. According to the previous owner you couldnt buy replacement, equivalent stuff from UniQ for less than $80,000 and none or VERY FEW of the hobbyist electric-propulsion people can build a controller for 3-phase brushless dc.

One of the advantages of having everything on the bottom is that im hoping to design a component tray that will lower from the van chassis with everything bolted to it for access AND protection. I can count on no fingers the amount of times ive crushed something on the bottom of one of my cars by dragging it over something, so ill feel pretty safe with it down there.

Although technically i DID drag Strax22's old van with a chain over a giant rock and crush his muffler, but that wasnt MY car.

[RoadWarrior222]

Yeah, I'd want lots of protection for spendy components underneath, I've had 3 incidents of actual damage (and a few more of potential if something was lower hanging and more delicate) one was "surprise rock" on a dirt track, sitting in the grassy middle, dinged the tranny pan, another was a 2x4 on the highway, flipped up and dented the muffler, another was a rock I saw on a dirt road, but caught an awkward double bounce just as I got to it and the suspension ended up bottomed as I went over it, resulting in a down pipe mashed flat. Have encountered a few more 2x4s, logs, branches, hammers, etc on the highway that might have done damage.... on the other hand, have avoided all side impacts. I don't suppose therefore, it would squeeze under the passenger seat? One of the safest places I can think of.

I don't suppose you wanna consider a two speed shift on the fly transfer case? Might make a gearing choice a little easier.

I would want the electric motor to be in an efficient range at about 60mph, providing ~20-25HP for cruise.

Also I'd want to rig a "charge through the road" method, which would load the IC motor into an efficient BSFC range under light demand, though who knows where that will be with a supercharged motor.

[Vigo]

Im not really looking at being able to cruise on electric at higher speeds because 1. i picked a terrible vehicle to try that, and 2. Battery capacity. Im looking at making the batteries out of 2-3 older Prius packs, and I dont think i'm going to have enough battery capacity to cruise any meaningful distance at a higher speed.

It really all comes down to torque, too. My first and foremost goal for the rear drivetrain is to be able to push the van hard enough that it can 'launch' similarly to a conventional AWD vehicle (albeit 3500lbs). If that means i have to use gear reductions that make 60+mph electric power impossible, that's what im going to do.

The controller wont fit under the stock passenger seat bottom. Its possible i could build an entirely new passenger seat bottom that would make room for most of the controller (it is bigger widthXlength than the seat bottom), but i havent looked at it with that thought in mind, so all i can give to that is a vague 'plausible'.

[RoadWarrior222]

I'd be thinking in terms of 10 mins on 10 mins off cruising, which I think in theory could raise mpg by about 20-30% but it would be a PITA without some means of automating it. Though if there was no charge through the road, I might think of getting a high amp alternator and tryna get full output of it into the battery under favorable load conditions (Even if you have to stick it through a 115V inverter to use the onboard charger instead of having another unobtanium 12V to 100 or 200V charging solution)

Another couple of thoughts, there was someone with a manual rack in the classies recently. Also was the ABS system for these electric rather than vacuum assist, forgot, might be an idea to convert to that system, so i) you can have full braking power (more than a couple of times) with the IC motor off, and ii) you can possible more effectively integrate regen braking with the rest of the system. (Who knows, maybe that rotary encoder on the motor will somehow work with the ABS controller in a way that you fool it into doing aggressive regen braking, instead of modulating the rear brakes)

[Vigo]

I am not really interested in maximizing the MPG of this thing. I will be running huge tires and a terribly inefficient supercharged motor in a giant brick-shaped object. I DO have a minimum in mind, though. I have gotten it to avg 27mpg and max 33 with no effort whatsoever, and think WITH some effort i can match that even with a supercharged 3.0, bigger tires, and some extra weight.

As for braking, i probably WILL design in the possibility of driving around with the gas engine off at low speeds. I would probably do nothing about the steering other than push harder on it, but i DO have an electric vacuum pump from the electric Colt that i can use to keep the brake booster primed if the key is on and the pressure is above a certain point with a vacuum switch. That sounds easy enough to qualify for 'why not?'.

Im not going to have any automated controls on this thing whatsoever unless i feel like designing a light braking regen signal coming off my brake switch or something like that.

Im building around the idea of using the electric propulsion for it's utility factor in parking lots, drive throughs, city streets, etc.

I may do a super simple constant-charge scheme running the grid charger off an inverter (for maximum inefficiency/who cares?) IF the charger i had could charge all the way up to 200v. If i have to break high-voltage circuits to get two ~100v packs to charge with it, i dont think id want to be pulsing those things on and off all the time when i go from charging to brake regen to assist, on the fly. It would only need/use it if the dog clutch was not engaged and i wasnt regening normally.

I dont have GOOD pics of the electric hardware but for some perspective on the size of the controller, here's one. It's probably bigger than anyone thinks right now.

[StraX22]

It's about time you made this thread!

For my own selfish curiosity I'm really stoked to see that electric motor run.

[Spr-T-23]

why run with the motor off? just put the trans in neutral and let the elec. one push you. you will still have brakes, steering and a/c well no a/c on a race van

[RoadWarrior222]

Coz you probably only save 30% of the fuel you would from driving it on the IC motor. Idle, probably makes around 5HP to keep motor and accessories spinning at something like .7lb/bhp/hr so 3.5lb an hour whereas chugging along at city speed might take 10HP at .5lb/bhp/hr so 3.5lb vs 5lb...... or some motors are horrible at idle and suck 1.2lb/bhp/hr... dunno what the BSFC/load curve for chrysler app 3.0s is but I'd REALLY like to see it.

[Vigo]

Whether i am cruising with the gas engine on or off will be a decision i make based on random impulse, not mileage concerns. It might come down to whether i remember to turn it off, or how hot it is that day, or how lazy my arms are at that moment. Keep in mind that my motivations with this thing are not necessarily what anyone else's might be, and i HAVE typed them out. It is not a max-mpg effort. Its just doing something 'neat' and putting a notch in my belt.

I have a feeling this project is going to make me REALLY WISH i owned a 2post lift.

As for non-electric mods:
I have some car struts to lower the front. I am debating whether to try it with car springs or cut van springs first.
I have some poly bushings for the front control arms
I have a 1 1/4" front swaybar that im going to mod for endlinks
I have a big front swaybar off a Dakota that im going to use as a REAR swaybar
I have 6 27lb log t1 injectors (ultrasonically cleaned by Strax22, thanks!) for the 3.0
I have a tbird SC m90 to put on the 3.0
I have a Boers UDP for the 3.0 (which ill need to keep boost low.. for a start.)
I have a big spline 3.77 543 and a small spline 3.50 543 that i am thinking about combining to make a large spline 3.77 gearset 3.50 differential 543

The only thing i am really waiting on to put the 3.0 setup in the car is a pressure plate im getting from Cindy at FWD. Im not going to bother putting a stocker in if i'll be supercharging it, but i AM going to run a stock, full face organic clutch disc (already have that too).

[zin]

That 52HP has got to translate into some MEGA TORQUE!! Seriously, what is it's torque rating?

As to the over-riding clutch, seems like you should be able to, or even need to remove it for regenerative braking... the motor should free-wheel as long as the field wires are not energized.

If you don't mind a side exhaust, the motor might fit, though I'm sure some reinforcement of the floor would be needed to contain the torque and prevent ripping out the floor...

I gotta say it should be a pretty cool runner when it's done, and fast too!

Mike

[Vigo]

That 52HP has got to translate into some MEGA TORQUE!! Seriously, what is it's torque rating?

Unfortunately i dont know. Thats a major hang-up right now because i need to know that (ballpark at least) to make an informed decision of how much gear reduction i want between the motor and the rear diff.

As to the over-riding clutch, seems like you should be able to, or even need to remove it for regenerative braking... the motor should free-wheel as long as the field wires are not energized.

I can leave it engaged for the regenerative braking but the problem becomes when the road speed x gear multiplication in front of the electric motor ends up over-revving the motor, i need to disengage it. I CANT have the motor directly engaged to the diff 100% of the time unless i am willing to gear it so that it stays under the 7000 rpm red line at every conceivable road speed, which im thinking is up to 130 just to give myself some margin. If i gear it that tall, the motor might not have the guts to push the van very hard. It is a big unkown right now.

If you don't mind a side exhaust, the motor might fit, though I'm sure some reinforcement of the floor would be needed to contain the torque and prevent ripping out the floor...

The motor would probably be tied to the framerails (vans have biggish, box framerails as part of unibody).

I gotta say it should be a pretty cool runner when it's done, and fast too!

Thanks! If i go with a conservative estimate and say that the supercharged 3.0 will make ~250hp, id guess the AWD would help push it to a mid 13 1/4 mile. However, if things work out well i could conceivably push the supercharger setup well past that if i open up the ring gaps and run proper timing and meth injection. Even e85 is a possibility, although i want to keep my hwy mpg at 25+.

[zin]

Unfortunately i dont know. Thats a major hang-up right now because i need to know that (ballpark at least) to make an informed decision of how much gear reduction i want between the motor and the rear diff.

If you know the RPM that the rated HP is taken, you can back into the torque, just do the HP formula backwards... Good Ol Algebra, who would have guessed we'd use it so much (Trig too!)

I can leave it engaged for the regenerative braking but the problem becomes when the road speed x gear multiplication in front of the electric motor ends up over-revving the motor, i need to disengage it. I CANT have the motor directly engaged to the diff 100% of the time unless i am willing to gear it so that it stays under the 7000 rpm red line at every conceivable road speed, which im thinking is up to 130 just to give myself some margin. If i gear it that tall, the motor might not have the guts to push the van very hard. It is a big unknown right now.

Here's an idea I've had for a while, since electric motors produce their max torque close to their stalling speed, I've felt for some time now that using a CVT, or an element similar to they way they work, maybe something like a snowmobile clutch, would allow you to keep the motor speed down/constant, while allowing the wheel speed to vary. If you added something like this between the motor and the diff, you should be able to overcome this issue and maximize the use of torque from the electric motor... OR, you may just find that that motor has so much torque that it wont' mind the gearing... BTW, have you calculated the wheel RPMs for the ratio and tire size you'll be running? It might not be nearly as high as you think...

The motor would probably be tied to the framerails (vans have biggish, box framerails as part of unibody).

Thanks! If i go with a conservative estimate and say that the supercharged 3.0 will make ~250hp, id guess the AWD would help push it to a mid 13 1/4 mile. However, if things work out well i could conceivably push the supercharger setup well past that if i open up the ring gaps and run proper timing and meth injection. Even e85 is a possibility, although i want to keep my hwy mpg at 25+.

With the help of the electric motor and the regenerative braking, not to mention a tune optimized for power/mileage, I think you could be in for a pleasant surprise!

Mike