[quattrofrog]

Doesn't the Boxster use what is more or less an 012 gearbox... I believe that there are some limited slip differentials that are shared with the Audi 01A.

The big question is not so much the components inside the gearbox but the casing of the gearbox, specifically the bell housing casting.

For the V8 I'd want to score an 01E gearbox... maybe from scottmandu, he can probably import or build up a nice 2wd one with some gear ratios that will work with the V8.

 

[quattrofrog]

Don't the 986 engines have intermediate shaft failure issues?

 

[quattrofrog]

Ah the M96 sounds like a disaster of an engine, we don't see a whole lot of those sort of failures on the Audi side of things.

I'm not so sure the Porsche V8 and the Audi V8 are of common origin. While I have not studied the Porsche V8 engines closely I remember something about the early 928 engines being of some relation in bore/stroke possibly valvetrain design to the 944 2.5L I4. If that were true the Porsche V8 is not like the Audi V8, the bore spacings are probably different and as such they are not the same engine. The picture I just dug up of the Cayenne's turbo V8 shows a front mount chain drive... the 079 Audi V8 is chain drive but the chain drive is rear mounted. Audi also used roller rockers on a lot of the V8 engines and in some engines 5v/cyl design heads. Porsche looks to be using lifters in the Cayenne... again signs of different engineering.

The Audi V8 engines can withstand turbocharging, that much has been demonstrated on this forum. Marc Swanson is bonkers for boost and he has been tinkering with the V8 engines, I think he managed over 350awhp from a 3.6L V8... plenty of power for a Boxster.

If you don't have room for the V8 you may be able to fit the V6 or more specifically I'd consider maybe assembling a hybrid. The 2.8 and 2.7T are both 078 engines and you can supercharge the 2.8, and folks use the 2.8 heads on the 2.7T... so maybe if you don't have space for the turbochargers of a 2.7T an Eaton blower mounted in the valley of a hybrid V6 with upped boost pressures (limited by intake air temps and fuel type, E85 might work well here) could yield a potent engine in a smaller package than the V8.

 

[quattrofrog]

Goog point but exteriors, intakes, etc appear to look very similar. So I suspect that based on smaller bores the Audi motor is a little smaller than the Porsche which would be better. Does somone have all the exterior dimensions of the 4.2 liter Audi V8? Is there a cutaway view of this motor somwhere?

The users I'd ask are a4kquattro, Cbullen and Timmy. They may have that info or be able to provide it.

 

[quattrofrog]

04 A8 engine is the last of the 077 engines (front belt drive) These were first used in the Audi V8 which was a large car with an engine bay suitable for an inline five with a side mount radiator. Space galore. These engines range from 250 to 360hp.*edit* 450hp+ for RS6/RS6 plus with turbocharged engines*edit* Some 077 engines were 32v and later ones were 40v.

05 S4 engine is the first of the 079 engines (rear chain drive) These were meant to be smaller to fit in the B6 A4's engine bay and the C5 allroad's engine bay too. These range from I want to say just over 300hp ~2004 allroad to 340ish in the S4 and 420 in the RS4 and R8. Early 079 engines were 40v and later ones were 32v the 32v are FSI.

 

[quattrofrog]

Anytime... Just want to give him an idea of just how varied our V8 engines are, to date I've observed two main groups (077/079) each with two subgroups (valve count). I believe that all three of your engines are 40v.

I'd love to see an Audi powered Boxster... we have some really good engines yet we never got the fun mid engined sports car. Just seems like an all around good idea, till the sheet metal work starts. Maybe add in a turbocharger... they make good mufflers... sorta.

 

[quattrofrog]

Interesting... I've never seen that view of a Boxster.

 

[quattrofrog]

I'm starting to see why you think the V8 might fit.

 

[quattrofrog]

Eh....fire + plastic valve covers = $1000 list price fix. No thanks.

Find another engine that hasn't been in a fire.

 

[quattrofrog]

It wasn't a comment on cosmetics as much as it was on avoiding a potential pain in the ass. If the valve covers are warped they wont seal properly. I'm not kidding that they list for over $500 each. They're silver painted plastic which I've seen melt and warp from heat. I've seen a coil failure require a new valve cover. Unlike 1.8T engines (I've got four spare valve covers for those) 079 V8 engine valve covers are less common and could be harder to track down. If you're okay with all of that then by all means proceed.