[Rehaan]

Originally Posted by [b

Quote[/b] (Tom @ May 26 2004,16:39)]they must have been reading this thread....LOL

Quite possible

[Wraith]

If they were reading this thread then it says a lot about how good this site is!!!
Great going guys!!
Besides in the Autocar India article i think they say just the valves dont open but the gases trapped in the cylinder help the pistons move so that will avoid uneven wear.and the transition from 3 cylinders to 6 is done is 40 miliseconds!! Now that is awesome!

[bicyclerider]

Is whole thing of cutting of cylinders as per requirement efficient?I mean when ur running a say a v8 or 4 cylinders u loose a lot of power in running the idle cylinders(frictional) or is the loss neglible compared to the gain in fuel economy ?
Heard the Delhi police used to run the Yamaha RD350(once upon a time) on single cylinders to conserve fuel.
What about the balancing of the engine when run on such a setup?
Anyone who knows this please clear my doubt.

[Jaggu]

this gives a lot of explanation displacement-on-demand (DOD) technology

[Rtech]

Originally Posted by [b

Quote[/b] (Wraith @ May 13 2004,18:17)]One query i have is...is there any system on sports cars which can be used to drive them in economy mode when u r not in the mood to be a boy racer? and is it cheap?
I mean like in a v10 engine can we use only one bank of cylinders if required and get more efficiency?
Or are there any presets for power and torque curves to get more mileage or more power?

There is a cheap way, something that has been in use on Corvettes for a long time now. They have some kinda system whereby you shift directly from 1st to 4th when you are just cruising around (i guess you could do that yourself too on a manual!). They also have a "Valet" mode which allows the car to be revved to a lower rpm. Useful when you give the car for servicing!

Cadilac's Northstar V8's have used this cyclinder cut of since the advent of the STS. No problems seemed to arise out of it, and this is now more than a decade old.

Originally Posted by [b

Quote[/b] ]Heard the Delhi police used to run the Yamaha RD350(once upon a time) on single cylinders to conserve fuel.

Now thats just asking for trouble as the the fuel would jsut accumulate in the cylinder causing hydraulic lock at some point. Thats if the engine doesn't sieze first due to lack of lubrication!! If they wanted economy, why didn't they just get a Hero honda CD100!!!

[Jaggu]

actually rds can be run on single cylinder make sure u remove the plug.. its called limp home mode

[Rehaan]

Originally Posted by [b

Quote[/b] (rtech @ May 31 2004,18:13)]something that has been in use on Corvettes for a long time now. They have some kinda system whereby you shift directly from 1st to 4th when you are just cruising around (i guess you could do that yourself too on a manual!).

Hey Rtech,

The Viper had something similar, if you went too high up the revvs in 1st gear it forced you to shift into 4th on the MT. This device naturally lived a very short production life!

On the viper though i beleive a reason was that 2nd gear was just too violent to manage to control!

cya
R

[Rtech]

The reason they had and still use this on corvettes is to get a decent EPA figure - i.e. their fuel consumption figure, thereby avoiding the gas guzzler tax that is levied.

I never heard about this on the Viper though, thats news to me.

[GTO]

Originally Posted by [b

Quote[/b] ]if you went too high up the revvs in 1st gear it forced you to shift into 4th on the MT. This device naturally lived a very short production life!

Its called the skipshift. And is indicated by a blinking white arrow on the dash, when you revv hard in the first gear. The EPA had something to do with this.

GTO

[Rtech]

I was talking about the corvette GTO. The sole reason they installed that system was coz of the EPA.

Like I said, I don't know about the Viper.

[Rtech]

Originally Posted by [b

Quote[/b] ]Its called the skipshift. And is indicated by a blinking white arrow on the dash, when you revv hard in the first gear. The EPA had something to do with this.

Was just reading up on the skip-shift. The ONLY reason it exists on both the Viper as well as the Corvette is to satisfy EPA regs and bring fuel consumption and emmissions down, and hence avoid the guzzler tax.

Infact, contrary to what Rehaan and GTO have said, the 1st-4th shift ONLYtakes place under very light throttle inputs. If you revv it up, it will allow you to shift into 2nd like normal.

It really doesn't make sense on a sports car like the 'vete or Viper to force you to miss 2 gears when you are driving it in anger!

Rtech

[Rehaan]

Hey Rtech,

my bad, i had read about this on the viper about 4years ago...i guess i messed up the reasons!

cya
R

[GTO]

OOPPPSSSS!! Corrected.

GTO