Porsche 911 engine swap - ideas?

[beatr911]

Seeking the wisdom of fellow modders on this one.

So for the project Porsche I'm turning away from the idea of an old school 300 hp carbed, cammed, dual plug 3.6L and thinking of going for high MPG. When complete, the curb weight should be arount 2100 lbs, so about like a Metro. It is a rear engine configuration with the transaxle in front of the longitudinally mounted engine. Assume coolant plumbing will not be an issue.

I'd like to use a very efficient engine like a Honda d15z1 but I believe they rotate in the opposite direction as everything else in the world, hence 5 reverse gears.

So far the ideas I have are:
Metro 1.0 3cyl - been done, like the cheapness, not the power.
Subaru - Like the low c.g. of the engine. Not sure which ones to consider.
Porsche Boxter 2.5 - Not sure how complicated this will be, smaller more efficient 6cyl than stock but still kind of expensive with ECU/etc. Keeps the fun factor high.

Any ideas for the engine to use for this?

[thebrad]

I don't know the condition of your Porsche, but I am sure you would be breaking even spending wise with just buying a Metro or a Civic. The swap would most certainly devalue any remaining worth in your car and be fairly labor intensive.

I forget what I was searching for exactly but about a month ago I came across someone willing to convert sports/super cars to hybrids he had a few pictures of Lambos, Ferraris and Porsches, but the cost was quite inhibitive- somewhere around $30k.

[JJW]

What year Porsche? What is your final intent with it (ultimate MPG, or economy/sport mix?) What are your design paremeters (driving for fun, commuting to work, how far will a round trip need to be, how long between refueling, temperatures, weather conditions, number of passengers, city/highway driving, cargo capacity, etc.) Would you consider an electric or diesel powerplant? Hybrid?

[beatr911]

Originally Posted by JJW

What year Porsche? What is your final intent with it (ultimate MPG, or economy/sport mix?) What are your design paremeters (driving for fun, commuting to work, how far will a round trip need to be, how long between refueling, temperatures, weather conditions, number of passengers, city/highway driving, cargo capacity, etc.) Would you consider an electric or diesel powerplant? Hybrid?

1978. Mostly commuting really I'd like to get back to autocrossing if future life gets less hectic - not all that likely. 30 miles one way on the freeway, temp range from 20*F to 95*F. Electric won't cut it - yet. Just can't get enough range at speed.

Diesel might be a possibility, good thought, have to look into a TDI. Hmmm.

Yeah it would probably devalue the car, but it's really not worth all that much right now anyway - needs work (and an engine). Done right it would be "easily" reversible back to more Porsche correct.

[Ryland]

why not a bettl or vw bus engine? a 1.8 or 2.0 liter engine should be plenty and we had a bettle when I was little that would get over 40mpg and it should bolt right in without issue.

[JJW]

If it were me, I'd be looking for the engine from a late model vanagon which should bolt in there without too much fuss except for the water cooling. The added advantage of the vanagon is that there were fuel injected models and they had hydraulic lifters (I don't care what anyone says, solid lifters in a commuter car is a PITA). Being a decendant of the Type 2 engine, I think you could scavange many of the parts necessary from the Porsche 914 which had a 1,7, 1.8, or 2.0 liter type 4 flat four, and many were made with the 6 cyl engine so it should be reasonably doable (big "should" there) and there is at least information out there about going in the other direction (most people went 4 cyl - 6 cyl). I'd say go for the Type 4 engine directly but its intake system would be a bit outdated and has solid lifters and its not quite as advanced as the vanagon engine would be. With this setup, you also keep the low CG, boxer configuration, and german pedigree. I know I've seen a 3.6 bolted directly to the 914 transaxle so I'd bet the bolt pattern is a match.

[BBsGarage]

If I were to replace the Porsche power plant I would use one from a Sube.

I have heard that it is a pretty good fit being the same configuration.

[IndyIan]

I vote for a VW TDI, especially if you get back into autocross. A fellow this last weekend had a Jetta TDI that had been chipped. He says it has about 300ft.lbs of torque and it drove like it, he was hampered by wrong wheel drive but still put up good times. He shifted to 2nd gear about 30 feet from the startbox and still could spin the tires in second. I think its nearly the perfect drivetrain for autoX and an old 911 must be with the best for an autoX chassis. Would make for a fun project, 50mpg and takes FTD!.
Ian

[beatr911]

The Vanagon motors would be the easiest, most likely bolt in. The old tech though isn't really what I'm after. It would essentially be just a conversion from a 911 (6 cyl) to a 912 (4 cyl).

IndyIan, 300 ft lbs is tasty! Coincidentally the max the 911 trans can reliably handle. New TDI tech is really awesome stuff and not so far away from the Porsche genes to be shown both nostrils at local events. I'd love to whup a $50k fancy Porsche with my beatr911 while burning veggie oil - hah!

Since this is gravitating back towards the fun end of the scale I'll have to consider engine weight and weight distribution. This is really getting interesting. I'll have to visit the TDI club to get an idea on weight, preferred engine, cost, etc.

Thanks all for your input! Any other ideas out there?

[whokilledthejams]

I'd avoid Vanagon Wasserboxers like the plague. A Subaru would be your best bet. They're generally reliable, easy to work on, and you wouldn't be the first to put one in a Porsche (it's becoming a common swap into the 914-- you can even buy a kit!). You can get anything from a ~100hp 1.8L NA to a 300hp 2.5 turbo, as well as 2.7-3.3L 6's.

You could always be lazy, and get an aircooled VW engine, but a modern Subaru would be more efficient and pollute less.

My last car was a Subaru Impreza with the 165hp NA 2.5L. Even with the Cd of .35, and AWD, it managed 28-30mpg on the highway at 75mph. In a 911, you could do pretty well (not to mention, you'd only be a couple of hp down from the original Porsche engine).