912 motor swap for dummies

[911&12]

I have searched all of the forums for swapping a newly acquired hotrodded 914 motor into my '68 912. While there are lots of posts on this topic, much of it centers around the following comments~

"It's easy, I've done it"
"Don't do it"
"I did it and love it"

Etc.

Disclaimer ~ I know nothing about Porches or VWs. I am into musclecars, hotrods, and I race at Bonneville. I am a skilled fabricator, welder, and machinist.

The 912 motor is broken... bad. I bought the car for $4000. I bought the 914 motor for $1500. I am cheap and in a hurry.

What I am looking for is SPECIFICS, geared towards an air cooled Porsche/VW newbie.

For example ~

Use a flywheel off a XXXX
Use the clutch out of a YYYY
Modify the recirculating wobbleshaft by inserting a sphincter valve
Use the rear motor mount from a ZZZZ

My goal is to get this done quickly and with as little down time as possible. I don't want this to drag out for a month. I want all of the necessary parts in-hand to expeditie the process; so models, years, part numbers, etc. would be greatly appreciated.

Any input from knowledgable, experienced swappers would be greatly appreciated.

Thanks in advance!!

PS - the blownup 912 motor will be safely tucked into the corner of the shop for a future purist.

[Matt Monson]

The biggest thing is you need the engine tin and engine mount from a 1976 912E. Or you need to make that stuff.

From there it is pretty much plug and play. You'll reuse your clutch, flywheel, etc. Assuming your 914 engine is carbed that will be pretty straight forward, though I believe the throttle bell crank rod needs to be modified, though again, if you fabricate you can do it on the fly.

The challenge is getting it hung and getting it cooled properly. Jake Raby at FAT sells a tin template if you want to make your own tin. Don't know that anyone has ever done a write up or made an aftermarket engine mount. Could be done pretty easily with some pipe and a welder. But a lot easier if you can just find a stock 912E mount.

[Jaems]

The 912 BBS has a section on engine swaps under the Renegade Section. They deal with the VW type 4 engines.

Apart from additional relatively expensive 912E exhaust system including heat exchangers - if you need a heater - I have some doubts regarding the performance of the 914 engine in combination with the standard 901 transmission. The 5 gear will probably perform better than the 4 gear transmission.

As a skilled fabricator fabricating the engine tin and support will be no problem for you.

Otto

[911&12]

Originally Posted by Matt Monson

You'll reuse your clutch, flywheel, etc.

The 912 clutch and flywheel, or the type IV clutch and flywheel? Same starter? I read somewhere that the depth of starter tooth engagement on the ring gear can be an issue with certain combinations. I'd like to have the clutch in-hand when I get ready to do the swap.

Thanks for the info!

[Jrboulder]

I am going to be that person who says go find another 616. They aren't hard to find.

Once you sell your warmed over type IV you will be WAY ahead in terms of cost, effort and time, not to mention the drastic improvement in the value of the vehicle.

As mentioned, The gearing on a 902 is way off for a Type IV.

[911&12]

Originally Posted by Jrboulder

I am going to be that person who says go find another 616. They aren't hard to find.

Once you sell your warmed over type IV you will be WAY ahead in terms of cost, effort and time, not to mention the drastic improvement in the value of the vehicle.

As mentioned, The gearing on a 902 is way off for a Type IV.

I already own the car and the motor. It's a well built, fresh, 140 HP 914 motor. I have $5,500 into this whole package (car and engine).

I've looked, and finding, or building another 912 engine for that kind of money is impossible. Although I don't plan on selling it any time soon, I find it hard to believe that a running/driving car with the wrong motor (and the right one in a crate) would bring less money than a non-operating one with the right motor. I'll do just fine either way. The thing I like about these swaps is that they are completely undoable, and don't require any butchering of the car.

In addition, I'm a hotrodder. I've been putting the wrong motors into cars since I put a 12 HP motor into my 3 HP gokart 36 years ago. I own about a dozen vintage cars, about half which have motor swaps, and/or interesting forced induction systems. My 1928 Dodge 4 banger makes over 200 RWHP Montana Dodge Boys Fast Four Special - The Story Simply put, that's the stuff that turns my crank (pun intended). I was told by purists that it was a crime to put a 500 HP stroker small block Mopar and a 4speed into my '70 AAR 'Cuda, but if you drove it, you'd change your mind... again, it's all undoable.

Please do explain the gearing issue for me though.

Thanks!

[Jrboulder]

Well it sounds like you are at least the right man for the job

The 616 is what I guess you could call "high strung". The Type IV is built for much lower revs. Even a hotrodded motor just can't do the revs like a Porsche motor.

Your 5-speed is most likely a 902/02. It is specifically geared for the 616.

The 912E has a 923/02. They use the same final drive (7:31) but your 5th gear is .85 (28:24 "X") rather than the .72 ( 29.21 "TL") in the 923/02. At 75 mph the 923/02 is turning 3400 rpm. The 902/02 is turning over 4000.

In your first post you are talking about a "hotrodded 914 motor". For the 914 three engine types where available: 1.7, 1.8 and 2.0 litre, all with fuel injection. The 2.0 version is comparable to the one used in the 912E, with the difference that the 912E had an improved FI system. The 914 2.0 had just a bit more than 90 hp, comparable with the early 912.

Regarding the gearing, the 2.0 version might give the best results. Is the FI system replced by carbs and the the engine tuned and able to rev higher, chances for a nice performing 912 are growing.

Otto

[Matt Monson]

Actually, the reason for the gearing difference is mostly tire size and lower highway cruising speeds on the older cars. A '66 911 & a '66 912 got the same gearing if they had a 5spd and even the 4 spd gearbox topped out with an X gear.

I don't understand how someone could have a ring gear distance issue. 901 gearbox, 901 flywheel and clutch, and 901 starter. Only way I see an issue is if someone tried to use the 914 parts on the 901 gearbox. There is a push versus pull clutch difference between the models. Use the parts that match you gearbox. I'm pretty sure there is no issue bolting the 912 flywheel to the 914 engine. That is the only problem I could imagine.

I overlooked 911&912's third post explaining the engine is a 140 hp freshly built 914 type. Bolting it on a 901/2 gear box is no problem. The only uncertain aspect is how the combination of transmission, engine and 912 body wil perform. Obviously that is part of the experiment and the fun.

Otto