Efficient car for higher speed cruising

[Fat Charlie]

LAPD reported Rodney King's Hyundai going so fast, Hyundai had to point out that his car wasn't capable of those speeds.

I'd rather be drafting in traffic. Being the slowest looking car in the line makes them overlook you in the first place, rather than make you explain that your car is slower than the cop says it was going.

[Xist]

[ennored]

Lots of smaller engined cars will need to enrich the fuel mixture to keep the engine components cool at high speed. Something like the Prius may not, if it can get enough power from the electric side of things.

A car with a larger engine may be a better choice. Maybe even really big. A C6 Corvette has a CdA of .55 m^2. They can easily get 30 MPG on the highway. It'd probably do pretty good at 100 MPH too.

[freebeard]

Find yourself one of these :



I've got a stroker 1776 on the bench (the famous Mileage Motor) that would push this to 50mpg at some speed >60mph. It would do 90 mph with 25hp.

Since I haven't scored one of the two in existence () I've settled on this:



The Audi/Passat/Dasher body in the three-door bodystyle, with a longitudinal diesel and a five-speed. If the money were to show up unexpectedly, I'd make it a mild hybrid with a Buick altermotor. Then add the turbo.

[19bonestock88]

I wonder how well a person would fare by swapping a Duramax diesel into a base model C7 Corvette... it has the gearing to get 29 highway(rated) with the LT1... would have torque comparable to the new ZR1, with expected highway mileage of at least 32-35mpg, maybe more if the engine were “emissions deleted” and the car itself aeromodded...

EDIT: I just seen the latest version of the Duramax V8 is rated at 445hp and 910lb/ft (2800 and 1600 RPM respectively)... imagine mashing the throttle at highway speed, in 7th gear, and be met with that much torque!

The funny thing is, the people that swap these into other cars seem to claim that the Duramax doesn’t seem to weigh much more than the LSx engines native to the Camaro and Corvette... I don’t think handling would be negatively affected much

[Ecky]

Depends on the generation of LT1, but more recent ones with cylinder deactivation probably get very close to diesel fuel economy, with the major difference being the energy difference in the fuel (and price per gallon).

EDIT: I'm willing to bet running the engine on the lean side under low-load cruise conditions would be a better use of time and energy. Let the gasser act like a diesel under some conditions by varying AFR.

[19bonestock88]

I was referring to the 6.2L variant in the C7... I’m not at all against lean burn at low load... just was figuring that the diesel would be better at high speed due to all the extra torque

[niky]

Diesel VWs have awfully long gearing, and should be doing just 3k rpm at 100 mph.

[joemac]

Find the best CdA that you can. If you can modify the vehicle, pay close attention to the road-load at 100 mph and optimize the final drive in top gear to coincide with a high efficiency region of the BSFC map. You could do this on a BSFC map (assuming you can find a published map for your engine) by estimating road-load power and fitting lines of constant power across a BSFC map. Look for minimum BSFC at the 100 mph road-load power and select your gearing.

[joemac]

Originally Posted by Ecky

Depends on the generation of LT1, but more recent ones with cylinder deactivation probably get very close to diesel fuel economy, with the major difference being the energy difference in the fuel (and price per gallon).

EDIT: I'm willing to bet running the engine on the lean side under low-load cruise conditions would be a better use of time and energy. Let the gasser act like a diesel under some conditions by varying AFR.

Of course, that would cause the NOx emissions to go through the roof since the 3-way catalyst cannot reduce NOx when lean of stoichiometry.