Saw a 928 engine for sale on Craigslist last night if anyone out there was thinking of doing a conversion. It was only $700 and looked complete. I'm very tempted but with a small garage and things yet to finish on my car, I'm going to pass on it

For $1500 to $2000 more I'd rather have the V8 from the Cayenne or Panamera.

You don't want a Cayenne V8. My 2004 Cayenne S has a scored cylinder with piston slap. Bought another wrecked with only 60K. Worse than mine. Took head off. I can show you pictures. Bought a rear ended 05 V6 and put the 2 together to finally get a good vehicle. Scored cylinders on those V8's seems to be a known flaw.

Scored cylinders are not THAT common and can easily be checked with a scope prior to purchase of a used motor.

The biggest issue is the water lines on the v8. But if you put some custom fittings on it then no worries.


I wouldnt do a 928 motor in a 914 if you paid me to take the motor....

For me the v8 choice is Cayenne or Audi 4.2 if you want to keep it in the family.

We await Richs reply as he has done it,I think the Audi 4.2 is a well proven motor and a good choose.

The 928 motor is fairly long. It usually requires modification of the firewall to get it to fit. Parts are pretty scarce at this point. You'd want that to be your favorite engine if you went for it.

I'd say a V6 from a Cayenne would be pretty sweet in a 914. And, it's still all Porsche.

Hey Andrew (or anyone) what's your take on the 4.2L timing chains thing? Sorry for the hijack but it might help someone.

928, Cayenne 4.5/4.8 and Chevy Vega all have similar aluminum bores with an impregnated coating...which eventually fails.
On our 5.0L Cayenne v8 project we are using steel sleeves and piston oil squirters for a longer life engine. We will see

The earlier 4.2 had a timing belt, much less of a hassle. I had one in my 2001 Audi S8. Smooth as butter and was running beautifully when I sold it around 220,000 miles. Shares a lot of parts with the Audi 1.8t and 2.6/2.7t, so pretty cheap to maintain. The S8 version had something like 360hp, so even a standard A8 or A6 version would ve plenty for most of us.

The standard US 4.5-4.7 version is around 218 HP. You can get that from a Subi. My suggestion for anyone wanting to try this is to get either a US 4.7S (310 hp) or a 5.0 32 valve engine. The other option is to combine the 4.7 euro spec S engine which is what I started with. This engine is factor rated at 300 hp. The blocks are made of solid Alusil. The lower half split at the crank line like a formula One engine. Very cool.
The only pistons you can run (unless you install liners) are factory pistons. They have a special iron coating to run in the Alusil bores without galling. I had a block bored and used 32 valve 5.0 pistons re-notched for 16 valve euro heads. This is known as a Hybrid. The 928 guys that have done this and dyno tested their cars (turning PS, AC, Alt, clutch fan, etc.) are over 350hp. I'm turning an alternator. Everything 928 is held close to the breast and expensive. a core set of rebuilding euro heads are 1k. The have larger ports and bigger valve and a better combustion chamber shape. A set of used euro cams are $ 500.00 if you can find them. The profile is about as steep as you can run with CIS without fighting the sensor plate action. The euro intake has a larger inside diameter and the throttle body is way bigger. I think I remember the last gasket set I purchased was $ 800.00 No one makes any conversion parts. I made all my own stuff including shortening the transaxle.

In short it's not for the faint of heart.

This, and you can swap parts from an S8 motor in an A6 or A8 motor to bring it up to spec. An RS4 motor has 420hp but thats an expensive motor. And the timing chain could go at any point.

An S8 motor tuned by a tuner will have 95% of the power of an rs4 motor at about 30% the price.

Whoa ...that timing belt info is really helpful! I ain't afraid of no belt.

This...I am afraid of a little.

Click to view attachment

So they used chains but went with cheap plastic guides, etc... GENIUS!!!!

The site I got the pic from explains it pretty well:

redilespeedworx

edit: link fixed

Even with the engine out the replacement of all that stuff looks like it could be screwed up if you weren't familiar with the engine. Interference engine, no mistakes allowed.

Wow! That's messed up!

Bingo. German engineering at its finest.

So for the Audi 4.2... post 2004 is the conversion point from belt to chain... . Sound right or are there other factors? 2004 isn't old to me so that's another check mark in the "YEAH" column (say "yeah" loud to get full effect like YEAH).

For anyone interested in the 928 engine, review Rick's build and any subsequent engine posts. He's done a LOT with his.

Audi 4.2 and either a boxster 6 speed or if your cheap a Audi FWD from a 2.8.

This would be a killer combo IMHO.

You can get the 4.2's at the local pick a parts as well. I see them every couple months and boy its tempting to grab some friends and pull it...

Yeah I think I'm in trouble now.

So if I wanted to ruin it...what auto trans's could you use? Bolts up to a Boxster tip? Which is also a Passat variant?

Well there are a lot of audi/passat FWD tiptronics that will work, but you have to have the tip computer and wire it in properly. The boxster/cayman will also work.


The tiptronic transmissions are pretty weak, primarily because the torque converters have such a low stall speed.

You should really get a parts car to rob everything from. The v8's never came in automatic fwd's though so thats going to be difficult, but they did have many automatic awd's. So you could pull the quattro trans in favor of the FWD trans. Or you might be able to weld up the quattro diff to send equal power front/rear and ignore the rear spinning out drive. That will however leave you with a very long transmission though.