Corvette V8 diesel conversion - 40 mpg (US) avg.

[Big Dave]

Actually this guy has been around for some time.

One thing he had working for him is that everything GM ever built will bolt up into everything GM ever built, so the engine conversion had some minor challenges but since that model corvette could have had a 454, the 6.5 was an easy conversion. Going with the mechanically-injected NA 6.5 saved him a bunch of heartache doing electronic brain surgery or the plumbing involved with turbo engines.

The 700R4 is probably the reason he doesn’t drive it more. I had a 6.2 with a 700R4 and went through transmissions like a teenager through potato chips. Not just noise but spectacular failures with parts and tranny fluid scattered down the road.

I do agree that much better performance could be possible with a stick and a very low gear ratio, but getting much below 3.08 is problematic. A T56 has a 0.5:1 overdrive that would drop RPM a lot.

This is a very do-able conversion. There are lots of C4s and some older C5 ‘Vettes available for under ten grand. Find one with a stick – stick ‘Vettes are moderately common – hoist out the gas engine and bolt on the 6.5 (or 6.2 if you really want good MPG.) You will have to monkey with the accessory drives a bit.

Get a set of front springs for a 454. The 6.5 is 200 lb heavier than a mouse motor.

‘Vette have good aerodynamics to start with as long as you stay away from the “Sting Ray” mid-60s versions, but these are all held by collectors anyway. ‘Vettes take a little getting used to. To many people they seem “loose.” They are. Fiberglass has a higher coefficient of thermal expansion than sheet steel has, so the car has to be built loose so it won’t buckle in mid-summer.

[H4MM3R]

Why not install a 4L80 from GM. That would handle the diesel with no problem.

[Big Dave]

Here's a thought:
Get a late-model C4 or early model C5 'Vette with a stick and instead of the 6.2 or 6.5, find a Benz engine out of a Sprinter van. 150 HP. 280 ft-lb @ 1200-2400 RPM. Much lighter and the RPM is OK for running chevy accessories.

I bet 60 MPG would be achievable. Would that ever give the TDI guys heartburn.

[H4MM3R]

Originally Posted by Big Dave

Here's a thought:
Get a late-model C4 or early model C5 'Vette with a stick and instead of the 6.2 or 6.5, find a Benz engine out of a Sprinter van. 150 HP. 280 ft-lb @ 1200-2400 RPM. Much lighter and the RPM is OK for running chevy accessories.

I bet 60 MPG would be achievable. Would that ever give the TDI guys heartburn.

That would awesome. I do not think it would be that hard to find a vette with a bad or no motor for cheap.

[igo]

This is really good mpg for a vette. That engine is really jammed in there (not room for much anything else).

[Ryland]

With a fiberglass body, you can use it as your winter car!
Just make sure other corvett owners don't flogg you.

[Big Dave]

Other 'Vette owners would be up in arms. You'd have to be like this guys - doing a "Corvette Rescue."

A C5 with 3.45 gears and a T56 manual cruises in top gear at 1300 RPM - just perfect for the Benz sprinter engine.

Sprinter engines should be available in junkyards of from rebuilders like Jasper in a year or two.

You think that 'Vette engine compartment is tight, you should see my Super Duty. I'm pretty sure they had to grease the engine to get the cab down on it.

[Big Dave]

I found a source for the Sprinter engine. About $4500 for a rebuilt I-5 2.7 liter diesel. Not a bad price for a rebuilt diesel.

No dimensions, but just looking at it I see a problem. Like all inline engines it is tall and would have to go into an engine bay desgned for a 90 degree Vee engine.

[dremd]

There are v6 diesels available. I know VW has at least 1, but I'll bet Mercedes does as well.
This is awesome, and another higher MPG one would be even cooler. (just incase you thought the TDI guys would be mad lol)

My thought on ultimate tdi fuel economy is a Polo 1.6 tdi (or equiv. from another manufacture) in an insight (or Aero Civic).

[Big Dave]

2008 Sprinters come with a 3.0 V-6 that looks a lot like their Blue-Tec engine. There is no chance of getting one on the used market right now. a crate motor might go over $15,000. That will change with time.

The corvette is a very seductive start. It is light, sturdy, and aerodynamically excellent.