Horsepower versus torque

[Frank]

Yes, if you put the computer on instantaneous mileage, and you accelerate from 0-60 in 6 seconds, you see your mileage drop into the single digits.

Its kinda hard to do a full tank of gas that way, though.

Well, I was talking about filling the tank, go driving, fill it up agan when done and calculate it yourself.

But I agree, that most people tend to take things easy when the initial thrill is gone.

 

[Moloch]

That and very good aerodynamics, a 6th gear, and an engine that shuts off half the cylinders when not needed.

Where did you read about cylinder deactivation?
It doesn't have it...
http://www.superchevy-web.com/technical/engines_drivetrain/accessories_electronics/0405sc_gmdod/

 

[RussSchultz]

Maybe it was just a prototype or something. ...

 

[Moloch]

well that article I posted suggested a prootypo ls2 with it got 35 mpg on the highway compared to 30.

The bottom line is, DOD on more cars could mean more--and better--choices for enthusiasts. As an example, an early prototype C6 Corvette with an LS2 running DOD provided equal power and acceleration to an LS2 without DOD, but produced 35 mpg instead of 30 mpg

 

[_xxx_]

Where did you read about cylinder deactivation?
It doesn't have it...
http://www.superchevy-web.com/technical/engines_drivetrain/accessories_electronics/0405sc_gmdod/

Mercedes V8 in the S500 has it.

 

[scooby_dooby]

Displacement-on-demand, commonly known as cylinder deactivation, is about to phase in on GM's big-truck V-8s. It was considered for the Corvette but discarded for three reasons. One, the natural frequency of the Corvette's rigid chassis was uncomfortably excited by the four-cylinder operating mode. Two, the lifters that collapse to deactivate the valves in the cylinders that shut down are heavy enough that they can't tolerate 6500-rpm operation. And three, the fuel economy of the Corvette is deemed high enough without it--Chevy claims this is the only 400-horsepower engine that doesn't pay the gas-guzzler tax.

http://www.motortrend.com/features/performance/112_0408_2005_chevrolet_corvette_c6/tech_photos.html

 

[stevem]

Power vs torque, displacement vs forced induction, manual vs slusher vs CVT, where does one start...? You guys do realise that an engine is just an air pump, right?

DOD is an interesting package & although I haven't tried the GM L76/L98 6.0l V8s, the MDS system in the Hemi 5.7l works as advertised. Unfortunately, even GM LS1 V8s (without DOD) get better mileage. Both of these OHV engines employ dedicated hydraulic DOD lifters, & both suffer from lifter rattle if DOD is disabled. There were even experiments in the 60s with mechanical cylinder de-activation.

The LS7 based Corvette is a monster (500fwhp/630Nm).

 

[Moloch]

Mercedes V8 in the S500 has it.

Relevance?

 

[nthd]

Relevance?

Cadillac also produced engines with cylinder deactivation some years ago... about the time that Corvettes were outfitted with engines designed by Lotus (because American designed V8's didn't cut the mustard any more).

 

[Powderkeg]

Where did you read about cylinder deactivation?
It doesn't have it...
http://www.superchevy-web.com/technical/engines_drivetrain/accessories_electronics/0405sc_gmdod/

You didn't read your own link very well.

What GM Powertrain came up with--the 5.3L LH6--is almost identical to the outgoing LM7 on the surface, but technologically advanced on the inside. That technology enables cylinder deactivation (called displacement-on-demand or "DOD" by GM insiders) during periods of low load demand and is the source of the increased efficiency mentioned earlier.

Yep yep, right there in your own link. 4th paragraph to be precise.

 

[Basic]

Did you think anyone missed that the whole article were about cylinder deactivation?

What he referred to was that the article says:

DOD technology did not make it into the C6 Corvette

 

[RobertR1]

Cadillac also produced engines with cylinder deactivation some years ago... about the time that Corvettes were outfitted with engines designed by Lotus (because American designed V8's didn't cut the mustard any more).

The only Lotus engine I can think of is the ZR-1.

 

[Mize]

My Chrysler 300 C has cylinder deactivation and I'm not convinced it does a whole lot. I think the four deactivated sensors put enough drag on the engine that the impact is minimized.

 

[nthd]

The only Lotus engine I can think of is the ZR-1.

Standard Forum Reference.

 

[RobertR1]

Standard Forum Reference.

Like I said, only the ZR-1 which was a limited production model. GM had also aquired Lotus at that point and were using corporate assets that belonged to them.

Would Fiat be wrong to goto Ferrari (which they own) if they wanted to get a performance engine?

 

[Moloch]

Did you think anyone missed that the whole article were about cylinder deactivation?

What he referred to was that the article says:

Ya
It's amazing how people will not only miss important pieces of an article, but will then go on to claim that I did not read my own link

Cadillac also produced engines with cylinder deactivation some years ago... about the time that Corvettes were outfitted with engines designed by Lotus (because American designed V8's didn't cut the mustard any more).

And it didn't work very well at all for them, horrible horrible results. (caddy DoD)
Btw the lsX is a superior engine to the LT5.
Just goes to show that pushrods still have it
More weight and costs more.- a lose lose situation.
btw

(still works since the ls2 and ls7 are based off it)/

 

[darkblu]

to those fellows who were wondering earlier what high torque is good for in a performance car (i.e. not discusing towing, apparently) - rally tunings tend to maximise torque. i.e. in driving where you get too numerous slow-down/near-stand-still situations, or what some call 'technical driving', and you have high dynamics of the RPM which close- or super-close gears alone cannot handle, you want high torque. and then sometimes you cannot afford very close gears (when you still want that vmax) but you are still in a high-dynamics RPM situation.

so next time before dissing torque get your ass on a rally course : )

 

[nthd]

Like I said, only the ZR-1 which was a limited production model. GM had also aquired Lotus at that point and were using corporate assets that belonged to them.

Would Fiat be wrong to goto Ferrari (which they own) if they wanted to get a performance engine?

Yes, that's right. Only the ZR-1, selling less than 7,000 cars in 6 years (according to Wiki). The engine was revised in that time, for what that is worth. It didn't sell well because it cost nearly twice as much as standard-engined cars.

Why should an Italian corporation using Italian expertise from an Italian subsidiary company be in any way wrong?

Are you aware of the connection between the Jaguar V12 and the ZR-1?

 

[Moloch]

to those fellows who were wondering earlier what high torque is good for in a performance car (i.e. not discusing towing, apparently) - rally tunings tend to maximise torque. i.e. in driving where you get too numerous slow-down/near-stand-still situations, or what some call 'technical driving', and you have high dynamics of the RPM which close- or super-close gears alone cannot handle, you want high torque. and then sometimes you cannot afford very close gears (when you still want that vmax) but you are still in a high-dynamics RPM situation.

so next time before dissing torque get your ass on a rally course : )

WRC cars also breath though a tiny restrictor
Moreso they're turbocharged so of course they have great torque.
And btw wrc cars don't go very fast on rallies so "vmax" isn't really a concern.
I'd say they prolly get up to about 130mph on long straights?

 

[ShootMyMonkey]

And btw wrc cars don't go very fast on rallies so "vmax" isn't really a concern.
I'd say they prolly get up to about 130mph on long straights?

vmax is a concern on the road? High torque is hardly all that different from having higher horsepower sooner, and TDI engines make a far flatter power curve than all the power whores seem to believe. Many of the complaints people have, I'd totally agree with if this were 1997 or so.

If you want high-end power, then get yourself a gas turbine. Their power still grows all the way up past a few tens of thousands in the rpm range. They're also most efficient up there, too (recuperators and all assumed as a given).