Diesel + CVT = great performance & fuel economy?

[Caleo]

From what I understand, diesels get great gas mileage and produce a high amount of torque. The problem though, lies in the narrow powerband where the high torque is only achieved at a certain (small) RPM range - true, right?

 

Assuming yes, then wouldn't a Diesel coupled with a CVT (tuned to keep the engine in its sweet spot) provide very competitive 0-60 times and performance in general? If not, why not?

 

I'm aware that the problem of CVTs in diesels is that they're generally not ready to handle that kind of torque.

 

So, beyond that, is there anything stopping a diesel+CVT from getting better 0-60 times than (gasoline) vehicles with similar torque?

 

One last thing - this may seem to be a bit of an idiotic question, but I've always been under the impression that torque is far more important than 'horsepower' when it comes to acceleration. The problem with diesels (high torque, low hp) in this aspect is that with traditional transmissions (be it auto/manual), they can't be kept in their narrow powerband. Is that the only thing holding a diesel back from getting performance similar to a gasoline engine with similar torque? (Example: 140hp diesel/230lb-ft torque vs 220hp v6 gasoline with 230 lb-ft torque)

[burnout8488]

It sucks this combination doesn't exist as a 2.0d trim here, it'd sell like hotcakes.

 

Your thoughts about the diesel shredding a CVT with torque are probably correct though. I don't recall any diesel CVTs existing yet. If it could keep the engine around 3500RPM, turbo fully spooled, it could really consistently throw you back in your seat for a good long time, while the gear ratio constantly changes.

[GEE-OTTO]

Well if you go to the EDM you can buy yourself this very combo

 

I commented mainly to say that welcome to the Roanoke Valley I lived right off 220 in Cave Spring near Tangle Wood Mall I grew up there and miss that area

[BAC5.2]

1) You can gear a diesel taller than a gas engine. This eliminates the "narrow powerband problem" for the most part. That is NOT why diesels are currently slower than gasoline cars.

 

2) Torque doesn't win races alone. Torque is an indicator of work (torque = force x distance. Work = torque x angle). Horsepower is a rate of doing work ((torque x rpm)/constant). If you make 1000 foot-pounds, but only 100hp, you can do a lot of work, but not quickly.

 

THAT is why diesels don't accelerate as quickly as similar torque gasoline engines. They can do just as much work, but not as quickly.

 

The inverse is true as well. High revving engines are typically smaller. They make lots of power (because horsepower is a function of RPM), but very little torque. They can do work quickly, but are incapable of doing a lot of work.

 

Would a CVT in a diesel be a match made in heaven? Yes. A CVT is a match made in heaven to any engine. They are simply plagued with unreliability at high power, and high power losses. They are also limited by shift rates and undeniably poor transmission logic.

 

They need refinement, but they are going good places. One of the best ones I've driven is actually the Subaru CVT.

[rakapur]

CVT will be destroyed when the car starts!! just put more gears, the 5th gen 3.6 has 5 speed auto, put a 7 or 8 speed in it, 24 city 31 hwy!!!!

[GEE-OTTO]

hence why our new Holland 5000 has a straight 6 that makes 90 HP but probably 700 ft/lbs it is gear fairly well on the high side of the gearbox in "8th" gear it can do 28 mph ish great for those long trip btwn pastures around the Blue Ridge in the roanoke valley area