What if we already have the 5.0L block John? and why would you need to convert to a DIS? the stock system is good

 

PorKen, that is too cool when stuff works. Eureka. I didn't think the difference would be very noticeable. Yay.

 

The reason that you have to convert to DIS is not because the ignition system is poor, but because the distributor runs off of the camshaft, which means that the 10 degree retard sweep in cam timing is also a 10 degree retard sweep in ignition timing. I can't say whether this applies to the 32v models, but it definately applies to the North American 16v cars. The stock cams in North American 928s are quite small, and I think the gains will be minimal at best.

 

so that with a "wild" cam might make it worth it, correct

 

I suppose, but with the 928 you're still stuck with the problem of removing the gears to lubricate them every six months, which is easy and cheap in the 924 but considerably more difficult and expensive in the 928. A design that didn't need lubrication (or at least didn't need removal to perform the lubrication) would be great combined with larger-than-stock camshafts and a free-flowing intake and exhaust. Sounds like fun, but I've always wondered why the Franco gear never took off, even for 8V VW/5-cyl Audi owners. I suspect that they either don't work as advertised, don't last very long, or you need a very modified engine to extract enough gains from them to be worthwhile.

 

anyone else have any thoughts as to why they never took off, or have any proof that they didn't last

 

ok so how can i do this to my 84 928????

 

could it really be this simple
mmmmmmmmmmmm

 

would'nt having some new cam pulleys made do the same thing

 

Ken,

That is wickedly simple! good job. When I saw you had the extra pulley on the tight side, I understood the concept immediately, It seems like a really good way to get all the torque where we really need it. I don't make it to 140 too often... - Ruf

 

Jon F - thanks for the additional info on the Franco.

Lizard931 - Cross-post over on the 924 boards and see if someone bites.

Gregg K - "I love it when a plan comes together"

Rufus Sanders - thanks!

I'm going to go ahead and make a more robust prototype.

This may not have as great an effect on unmodified cars. Here's a sample of what I've done before this; changing the cam timing may have been what I needed to tie it all together.

'81 US 4.5 L-Jet with automatic.
>200 lbs lightened.
3" single exhaust, with Flowmaster Delta 50.
Open airbox.
No vacuum connections, except for the brake booster and heater controls.
Permatune ignition box.
Stock coil, plug wires, OEM Bosch Silver plugs.

See here for a more complete list over time: PorKen's Posts

If all goes well maybe I can sell them to y'all. Then maybe my girlfriend won't begrudge me for 'playing with Porsha'.

 

"Playing with Porsha"! I love it. Let's see, what would she look like...

I'd love to try your mod, but my t-belt already has popped once (PO, not on my watch), and I got a rebuilt top end because of it. Don't want to risk it just yet since I haven't done my own belt yet (Sharks 201, 8 credits, Pass/Fail) - Ruf

 

There is one bit of advice I should give. From what is shown, it looks like a bearing with a pressed on cylinder that is cantilevered. I caution that with a bit of time, it may decide to part ways with the bearing. Even if it did come off, it may not cause a problem. And it looks pretty solid. Remember, that thing's turning around at 20,000 rpm. I'm assuming it's a fourth of the crank pulley diameter, and the engine's running at 5000 rpm.
In fact, I'd opt for no cylinder and using one wide pulley. Hell, order an idler pulley and use IT instead of the prototype.

 

Gregg K - that is an idler pulley, 83+...

I'd rather use the larger tensioner pulley, if it could be fit.

You'd really have to cut a big chunk of the cover though. My planned 'cover' design requires only about a 2" 'window' cut in the side of the center cover.

 

Funny. I'm just going thru the PET, and suddenly I see that roller. Oops, I said. So I came back here, and you beat me to it. Yeah, like I spend my evenings going thru the PET. Borrrring!