Variable displacement V8 - thoughts?

[Frank Lee]

Originally Posted by bestclimb

how about 4 clutched v twins. The clutches could be designed to slip just a little bit with electronic pins that engage when the rotational difference is reduced enough not to shear them or they could be electronically controlled and the computer could closely match RPM then let the pins slip in negating the need for a clutch. The pins and holes could be located so as to reduce harmonic vibration...or what ever. Just begs for straight pipes out the hood, with flappers on them so you know how many pairs are running or nice mufflers under the rig with a set of lights on the dash if noise ordinances get you down.

Yup, exactly the strategy I've contemplated... well, you really, REALLY lost me when you added the straight pipe part.

[bestclimb]

I was mostly kidding with the straight pipes, tough to stream line and would be obnoxiously loud, not to mention you could make wild gains over straight pipes with an appropriately tuned exhaust. Trouble I see with it is that the timing of the power stroke on a 4 cyl would be different from a 6 cyl would be different from an 8 cyl That could be overcome by having more than one set of holes for the pins to drop into.

[Frank Lee]

I'd take a cue from the marvelous (kidding) Cadillac V8-6-4 and not even fool around with more than 2 modes. IIRC, many of the complaints with the 8-6-4 were with roughness in the 6 cyl mode.

[bestclimb]

well that would be more simple wouldn't it.

[Frank Lee]

Yup. I'm interested in doing a 2-2.

[t vago]

Originally Posted by mechman600

LOL...you will make millions!

Seriously, yank the 4.7 boat anchor and install a small turbocharged four banger.

Okay, give me the money and I'll do it.

Originally Posted by mechman600

Plus, thanks to the magic of variable geometry turbochargers, turbo lag is eliminated and torque curves are flat as a pancake all the way down to 'just above idle' RPMs. Hmm...seems like a magical recipe for ecommodding to me!

IIRC, VNTs don't do well with gasoline engines. It had something to do with their higher exhaust temperatures frying the exhaust vanes and/or mechanisms of VNTs... The only successful gasoline VNT I know of was the Dodge Shelby CSX, and that turbo was poorly matched to its engine.

Originally Posted by mechman600

Oh, and don't forget to attempt to freeze your slushbox. Torque converters ruin most economy attempts.

Again: Give me the money and I'll do it.

Otherwise, I'll pursue this on my own time, with my own dime. One of the goals of this project is to recoup, within 30 fillups, the money spent on a particular truck modification. For instance, the aerocap I spent $75 to make would pay for itself within 14 fill-ups, or 7 weeks of driving. Another goal is to not reduce the existing functionality of the truck. Again, the aerocap I made comes off in all of 30 seconds, and I can then haul heavy and/or large things.

So don't mention engine/tranny swaps or any other obviously costly measures. The goal is to save money, not piss it down the drain in an attempt to increase my gas mileage.

[mechman600]

Originally Posted by t vago

Okay, give me the money and I'll do it.

It's as easy a buying a total loss car from an insurance yard for $1000.

Originally Posted by t vago

IIRC, VNTs don't do well with gasoline engines.

Are not most new turboed cars VNT/VGTs? VW/Audi 2.0T, Ford Ecoboost, The coming Volt 1.4T? I assumed they would be, because I'm a diesel guy and that's mostly what I see. I know Porsche 911 turbos use them for sure.

[t vago]

Originally Posted by mechman600

It's as easy a buying a total loss car from an insurance yard for $1000.

And your point is what, exactly? Do I drive a totalled car to and from work for fuel economy gains, or do I spend many more thousands of dollars retrofitting the engine from this totalled car into my Dakota?

I seem to remember saying that I was going to spend as much money as I could recoup within 30 fillups in my truck. Somehow, that just doesn't seem possible with either option presented above.

Originally Posted by mechman600

Are not most new turboed cars VNT/VGTs? VW/Audi 2.0T, Ford Ecoboost, The coming Volt 1.4T? I assumed they would be, because I'm a diesel guy and that's mostly what I see. I know Porsche 911 turbos use them for sure.

Diesel exhaust tends to be cooler than a comparable gasoline engine exhaust, coming right out of the head. This is why there has only been one production gasoline car with a VNT. The production Volt is going to use a naturally aspirated E85 1.4L 4-banger, not a turbo of any sort.

[autoteach]

Are the parts that you pull out not marketable? I think you could sell them, for doll hairs, or what ever the currency of the day is, and use that for what you want to get.

Just checked, ebay tranny both manual and auto are equal in cost. Its like pure profit
engine you have $1400
engine you might want (pt turbo?) $1095

or, different truck that gets better mpg.

[mechman600]

With an entire donor car, all you need is a welder, cutting torch, soldering gun, heat shrink, and lots of imagination. Oh, and time. Not much extra money required.
Or sell the truck and get a smaller vehicle, unless of course you need a truck. Making a V8 Dakota get good fuel economy will be like squeezing cool-aid out of a watermelon. My V6 Escape is exactly the same way. Brutal on fuel even when I'm on my best driving behavior.