28-12-2012, 12:27 PM
What you really need to do is cruise at 50mph and, if you can, log the throttle input vs rpm.
Then cruise along with the orange plug unplugged, thus running on 3 pistons vs 2 pistons.
Then log again.
You'd need to run over say 5 miles, three times. Get a baseline/average for unplugged then plugged in.
Who knows if there is much in it.
Cully, as per my post two posts back, 3rd piston de-activation makes a difference when the parasitic losses are a high percentage of the total engine output required for the current cruising speed.
If by my figures at 45mph you are needing 25bhp from the engine, and you can save 2% in those cases by de-activation, then great.
But at 85mph you are needing about 60bhp from the engine and if the 3rd piston deactivation now saves you 0.5bhp, or even 1bhp at these speeds, then you are gonna struggle to see 1.5% down to 0.75% improvement.
It's at these levels that no test gear will show the difference alongside statistical noise, bar an engine dyno which is what the manufacturers will have used to determine the duty cycle for the 3rd piston de-activator.
It will work, it'll be slight but valid.
But I really don't think there will be any benefit at 85mph cruise speed. The engine speed itself is so high at that speed, the pump speed so high, that parasitic savings from de-activation will be tiny vs the power needed to cruise at that speed (60bhp+)
You honestly will find more saving by cruising at 84mph than at 85mph hehe, than you ever would tinkering with a control map for the 3rd piston deactivation!
Or just 1psi more in your tyres. Or better eco tyres.
Or a better engine/gearbox oil with lower frictional losses.
Not wishing to put you off, tweak the control map by all means. I've done stuff like that for years out of interest but it all comes down to usually being below the sensitivity of very well orchestrated on-road testing. Ie, results just mix in with statistical noise, thus in my view they are pointless to worry about as they might cost you a slight bit of power more than gain it.
Only when you see a clear benefit should you pursue it to get net gains in power/economy.
As said, the test at 50mph doing a run plugged/unplugged would be interesting. If you can see a benefit in those cases above statistical noise then it might be worth pursuing, but I think you'll just see noise even at 50mph... if it's not clear at 50mph it certainly won't be clear at 85mph
Dave
Then cruise along with the orange plug unplugged, thus running on 3 pistons vs 2 pistons.
Then log again.
You'd need to run over say 5 miles, three times. Get a baseline/average for unplugged then plugged in.
Who knows if there is much in it.
Cully, as per my post two posts back, 3rd piston de-activation makes a difference when the parasitic losses are a high percentage of the total engine output required for the current cruising speed.
If by my figures at 45mph you are needing 25bhp from the engine, and you can save 2% in those cases by de-activation, then great.
But at 85mph you are needing about 60bhp from the engine and if the 3rd piston deactivation now saves you 0.5bhp, or even 1bhp at these speeds, then you are gonna struggle to see 1.5% down to 0.75% improvement.
It's at these levels that no test gear will show the difference alongside statistical noise, bar an engine dyno which is what the manufacturers will have used to determine the duty cycle for the 3rd piston de-activator.
It will work, it'll be slight but valid.
But I really don't think there will be any benefit at 85mph cruise speed. The engine speed itself is so high at that speed, the pump speed so high, that parasitic savings from de-activation will be tiny vs the power needed to cruise at that speed (60bhp+)
You honestly will find more saving by cruising at 84mph than at 85mph hehe, than you ever would tinkering with a control map for the 3rd piston deactivation!
Or just 1psi more in your tyres. Or better eco tyres.
Or a better engine/gearbox oil with lower frictional losses.
Not wishing to put you off, tweak the control map by all means. I've done stuff like that for years out of interest but it all comes down to usually being below the sensitivity of very well orchestrated on-road testing. Ie, results just mix in with statistical noise, thus in my view they are pointless to worry about as they might cost you a slight bit of power more than gain it.
Only when you see a clear benefit should you pursue it to get net gains in power/economy.
As said, the test at 50mph doing a run plugged/unplugged would be interesting. If you can see a benefit in those cases above statistical noise then it might be worth pursuing, but I think you'll just see noise even at 50mph... if it's not clear at 50mph it certainly won't be clear at 85mph
Dave