ShopTalk Forums | Aircooled VW Tech & Restoration Help

I'm a bit of an alternative energies enthusiast and I want to restore an old Beetle. Some of you may be familiar with bio-diesel, a fuel made from used cooking grease that can be used in diesel engines without much modification (if the fuel is properly processed). For the car to use bio-diesel, it must have a diesel engine (I suppose that's rather obvious though).

I've been unable to find a lot of info on the subject with searches because they have been riddled with information about the New Beetle TDI engines. I haven't been able to find an old Beetle with a diesel engine, so I'm assuming that there are only gas engine Beetles in the US and I will need to swap it with a diesel engine.

1. Is this a difficult thing to do?
2. Which diesel engine would be the best choice?
3. What year range would be the best to look for (for the car)?

I have found a bit of information, and it seems that the engine mounts are compatible with nearly all VW engines, even up to present. Is this true? If so, could I perhaps get a diesel engine from a Rabbit and use it?

Sorry if my questions seem dumb, that is why I'm posting in the Newbies forum though.

It takes an adapter and a special flywheel to graft a Rabbit engine into a bug transmission (and some surgery to the body, and obviously some provision for a radiator).
The first Rabbit diesels were 76.5x80 (gas engines came in 76.5x80, 79.5x80, 79.5x73.4, 79.5x76.4, and 81x86.4); in `81 they went to 76.5x86.4 which gave the identical displacement as the 79.5x80, but don't confuse the two. It's possible to use the gas 76.5 bore block to build a diesel but it's a real bad idea, the cylinderwalls will be too thin and weak. Good diesel blocks are hard to find, they're prone to cracking between the headbolt holes & water jackets, in particular near where the oil passage to the head is - more often than not, when one appears to just need a head gasket it ends up being far worse once you get the head off.
I'd hold out for a 1600, the longer stroke works better on a diesel and the fuel economy can even be better than that of a 1500 since it can pull a taller gear. You should not use 1500 injectors or pump on a 1600.

With the surgery and other difficulties in mind, would it be easier to pick another 3 or 4 cylinder diesel engine that might make a better fit?

Marc wrote:It takes an adapter and a special flywheel to graft a Rabbit engine into a bug transmission (and some surgery to the body, and obviously some provision for a radiator).
The first Rabbit diesels were 76.5x80 (gas engines came in 76.5x80, 79.5x80, 79.5x73.4, 79.5x76.4, and 81x86.4); in `81 they went to 76.5x86.4 which gave the identical displacement as the 79.5x80, but don't confuse the two. It's possible to use the gas 76.5 bore block to build a diesel but it's a real bad idea, the cylinderwalls will be too thin and weak. Good diesel blocks are hard to find, they're prone to cracking between the headbolt holes & water jackets, in particular near where the oil passage to the head is - more often than not, when one appears to just need a head gasket it ends up being far worse once you get the head off.
I'd hold out for a 1600, the longer stroke works better on a diesel and the fuel economy can even be better than that of a 1500 since it can pull a taller gear. You should not use 1500 injectors or pump on a 1600.

Also IMO you would also need to beef up the frame horns as a diesel would be a lot heavier than a conventional type 1 motor. The added weight and the flexing of the frame horns may lead to some exciting moments someday Just a thought!


Aloha from Hawaii,
Wayne

shbazjinkens wrote:With the surgery and other difficulties in mind, would it be easier to pick another 3 or 4 cylinder diesel engine that might make a better fit?

The Rabbit is the only one I know of for which there's a ready-made adapter and clutch solution (and that still uses the Beetle starter, which'd have a hard time cranking a diesel - an AutoStick starter or aftermarket gear-reduction one would probably be needed). You may find another engine which fits inside the body better, but you'll be on your own for bolting it up.

I'm having trouble finding a vendor that sells such adaptors, do you recall the name of one?

http://www.kennedyeng.com/
There may be some other small diesel for which one of their "gas" adapters will work (Ford Fiesta/Escort, maybe?)...you probably won't be the first to ask.

Thanks a ton guys, I really appreciate the help and advice. This is going to be a fun summer.

Why not just get a rabbit? i also make Bio diesel and burn it in my Jetta TDI.

I thought of putting a rabbit motor in a beetle, but another problem is the gearing is all wrong for a diesel. plus you need to a radiator, etc.

I think the TDI engine will work with the KEP adapter also.

James2 wrote:Why not just get a rabbit? i also make Bio diesel and burn it in my Jetta TDI.

In that case, why not get any diesel car?

I like Beetles, always have, and I want to drive one but also want to burn a clean fuel. Alcohol is out of the question because while I do live in rural Oklahoma and distilling it is possible, I couldn't travel long distances that way (if that wasn't the case I'd convert the Beetle engine to burn alcohol). I'm planning to get most of my parts from junkyards, so I could end up with any engine really, as long as I can use it with a Beetle.

As tactfully as possible, I guess I just find the Rabbit a little.. uninspiring?



I dunno, maybe it would be a better choice to start with a diesel though.

EDIT:
Heh, I just had a thought.. wonder how compatible the frames would be in consideration that maybe you could fit a Beetle body around it..

real, the deal is get an old MB or rabbit and run straight Vegggy Oil. The old MB can run on just about anything.

I say i run on Bio diesel, but truth is I'm burning dino deisel now, cause it's a pain in the ass to convert WVO to BD. I've got about 200 gallons of WVO at the house and it's starting to smeel. I'm looking hard for a decent rabbit or MB that I can run SVO in.

The nozzles in the TDI injectors are to fine for SVO and will clog after some use.

I did a lot of reading at journeytoforever.org and it seemed like bio-diesel was a better choice than SVO because of a lot of problems that could arise. I know some resturaunt owners and the waste oil will be totally free.. they have several 50 gallon drums of it sitting out back right now.

Ah, and last I heard the people who were buying it from them to use in liquid feed started charging them to haul it away.

oh yea, start asking around and you'll have more WVO then you can handle, I'd to stop picking up from one place. I just pick up from places that have good oil. If the oil is dark brown or black, leave it be. Only get oil that is gold to amber.

Anyway, good luck and let us know how it works.

shbazjinkens wrote:... wonder how compatible the frames would be in consideration that maybe you could fit a Beetle body around it..

The wheelbase is the same but that's where all similarities end. Since the Rabbit is unibody/Mac strut it must retain all of the front bay structure, and that wouldn't fit inside the lines of a Beetle. Now, you could build a tubeframe that would carry the Rabbit powertrain transversely behind the front seat (think of a Pontiac Fiero or Fiat X-1/9), that's been done, and drop the bug shell over it...be kinda noisy in diesel guise though.

James2 wrote:Anyway, good luck and let us know how it works.

Will do. I'll probably check back periodically as I run into trouble.. only familiar with my 87 Accord, really. I just hope I don't get too annoying - the big problem when I'm a newb to a forum is I don't know enough to help other people when I start and I feel like I'm leeching.

But hey, if you need to know anything about Computer Generated Art or Vacuum Tube amplifiers I'm your man. Particularly CG these days.

When the WVO is darker, does that mean it's degrading, or is it just really dirty?