Vilhuer

No problem. Just make valves smaller and there is space for plugs in between them. Something like 20mm diameter for intakes and 15mm for exhaust will do fine.

JEC_31

Yes, that's Step 1. Buy the existing, tested, working system.


A large part of the feasibility would be using the stock controls from the donor Cayenne. If that's not possible... than the battle gets a lot longer and up a much steeper hill.



Until we have dissected that system and evaluated what sort of head configuration and support systems it needs to work, we cannot discount the possibility of employing modified stock heads, which is a huge step forward in feasibility.


That's the fun part!

Jim bailey - 928 International

You can twin plug a 911 head relatively easily because ....it is air cooled so it is a solid lump of aluminum no pesky water chambers passages in the head AND they are two valve per cylinderso there is more space for plugs and each cylinder has a seperate head and the camshaft carrier is a seperate housing ! Now try drilling an extra "spark plug hole" into a 4 valve 928 head missing the camshafts, oil passages, water passages , valves and existing spark plug...... PLUS the big advantage of direct injection is fuel economy NOT POWER although it does support higher compression ratios for a slight gain.

Imo000

Simple, convert the 928 engine to a flat head and now you have all the room you need for the injector.

Jim bailey - 928 International

Or just go diesel and use the spark plug hole for the injector ....

hacker-pschorr

You would need to run something like Autronic like Todd is using.

Here are some images of the VW / Audi setup:







Generic image:

Mongo

Wow I didn't think a theory would spark a few insulting comments in this thread, but I guess not everyone has a creative imagination.

By the looks of the 32v head, it would be impossible to incorporate it on a 928. While I would probably say the same thing with even a 16v, anything is possible with money. On the other hand, Mercedes' first fuel injected car used direct injection. For those that are unfamiliar of it, it's the 300 SL Gullwing and the direct injector was located in the cylinder wall. I'm pretty sure the new DI Cayenne's may have that same setup since they too have 4-valve heads.

123quattro

You would be much better off tossing the stock engine and installing something that is DI already. To adapt DI to a non-DI engine is a complete waste of money. It's mainly useful for emissions. Power it gains maybe an extra 2% at most. There are much cheaper ways to get that power and our cars are 20+ years old so emissions are a non-issue.

Imo000

This is nothing more than "Blah, blah, blah......" Show something more concrete, instead of the "would be possibe". Show us how your theory would work. Those that are familliar with the 928 engines keep teling you that there is no room for an injectors so tell us how you would solve that problem and keep it financially resonable.

Mongo

I can't hence why I said it would be expensive aka financially reasonable. Just a thought, like I said.

Imo000

Perhaps the third comment in this tread that sparked all the subsequent comments. Are you suprised?

Mongo

Not really. There a lot of people in this world that are skeptics about ideas and don't believe it till they see it. Perfect is example is those Porsche guys who didn't have faith in the 928 until they see a community as big as ours prove every 911 guy wrong that turned their back on the liquid cooled brethren.

I myself was a skeptic about supercharging the 928. Someone proved me wrong as far as my thoughts on reliability and they have created something that propels a 928 into late-model Ferrari performance and horsepower.

On the other hand, people are entitled to their own opinion as I am entitled to ideas. Whether they critcize them or not is up to them, but anything offensive such as the term 'MORON' to an idea is disconcerting and disrespectful. This is a board where people come to learn new things about their cars and share ideas......not OFF TOPIC.

RyanPerrella

kill this thread

this guy has no idea what he is talking about

I STAND BY MY FIRST POST!

Mongo

Right, I have no idea what I'm talking about...

I've been around 928 engines since 1985 and start helping my father on his 928 in 1988. But seeing that you have nothing better to do I'll close this thread off so you can be bored again Mr Perrella.

I think Johann Wolfgang Von Goethe said it best -

"Daring ideas are like chessmen moved forward. They may be beaten, but they may start a winning game."

Cheers to all those who have any idea on how to improve upon perfection