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Discussion Starter #1
Hello All,
New member/longtime lurker, seeking input on converting my 1987 Syncro T3/Vanagon TDI into a 'through the road' parallel hybrid. For those unfamiliar, this is a rear-engined vehicle with a transaxle (w/ diff lock) driving the rear wheels, and a prop shaft drive the front differential. (I've attached a photo of the stock Syncro drivetrain).

The idea is to retain rear wheel drive by the current (reasonably efficient) turbodiesel motor, remove/cut down the current prop shaft and adapt it to a mid-mounted AC motor which will drive the front wheels.

The goal is to have some electric assist for around-town driving or slow off-road driving, and ideally be able to utilize some extra 'boost' for steep moutain driving where the ~110hp diesel struggles sometimes with a nearly 5000 lb (when fully loaded) vehicle. Would like to have plug-in charging. Regenerative braking would be nice (though in reading other accounts, I shouldn't expect to get much back from it).

Your skill level with auto mechanics and fabrication

Reasonably skilled DIYer mechanic, with rudimentary fabrication skills. My T3 was originally 2WD with the stock 2.1L gas boxer 4-cyl, and I swapped in a 1.9L VW TDI 'drive by wire' motor, and at the same time converted it to a Syncro drivetrain and suspension. Also recently adapted an electrohydraulic power steering system from a Toyota MR2.

The range you are hoping to get (how many miles/charge)

The primary goal of 'Stage 1' is to create a through the road parallel hybrid. So the diesel motor will always be running (powering the accessories), but that the electric motor could carry a heavy part of the load during stop-go city driving, and contribute on-demand during highway driving.

What level of performance you are hoping to get

I'd hope to get 20-30% improved city fuel economy and increased performance on highway driving.

How much money you are willing to put into your project

US$5-7K for the first stage?

What parts you've already considered, if any.

Primarily started just looking at motors. The HPEVS AC-23 seems to pack a respectable amount of power/torque into a small package, which would be key given the limited amount of mounting space under the vehicle.

There is an undercarriage space that is approximately 50" long x 11" wide x 7" deep that could house the batteries.

I know there are numerous other recent and past VW T3 EV conversions (including at least 1 current project on this forum), which have served as an inspiration to investigate the feasibility of this project!

Other current thoughts...
-'throttle' control: the current VW go-pedal utilizes a fairly standard 0-5V signal. My understanding is that this type of signal could be integrated patched into a Curtis controller to run in parallel? Ideally there would be some kind of set lag for the diesel motor so that the electric motor carries the heaviest load on initial start, giving the turbo some time to spin up...

-The final drive ratio is 4.86:1, so with ~28" tires, calculated RPM for a direct drive motor would be ~4600 rpm @ 80 mph (which is about as fast as I ever push this brick!). My understanding is that this is within the safe-range for most popular AC motor options?

Any ideas/thoughts/criticisms/resources are welcomed! Thanks in advance.

 

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It's an interesting idea, but I doubt that you'll see a fuel economy improvement with a through-the-road hybrid. The losses in the tires (both the ones driven by the engine and the ones driving the generator) make the recharging stage inefficient... which is one reason that there are no through-the-road hybrids in production.

Since you have already added the Syncro system, why not keep the shaft to the front, add the electric powertrain, and make it a normal parallel hybrid?
 

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Discussion Starter #3
Thanks for the input brian_

Your point about the regen inefficiencies are well taken.

Forgive my naïveté, but when you say 'normal parallel hybrid', I presume you mean a double-ended shaft electric motor inline with the drive shaft?
 

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Hi
I like the idea -

But you will need batteries and to plug it in to get any improvement in fuel economy

Effectively a "Plug In Hybrid"

The advantages come from the part of the journey that is made under electric - from the mains - power

There is a good reason that there are few or no "Hybrid Diesels" - one of the advantages of a petrol hybrid is that the part load running is reduced

With a diesel the part load running "penalty" is much less than with a petrol - so the gains are much less
 

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Discussion Starter #5 (Edited)
Yeah--a plug in hybrid setup is what I had in mind.

And it is a good point that the gains from adding a hybrid system to a diesel platform is likely to have less gains that a petrol car. Curiously, I recently found one example--the Peugeot/Citroën Hybrid4 system. Evidently it hasn't turned out to be game changer that they might have hoped for...

 
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