Are My Rpm To High?

[Impellor]

At 110 kph my ba xr6 turbo is sitting on 2800rmp, 5 gear on cruise control, This is to high isnt it?

Just as a matter of interest what is your instant fuel consumption reading at 110kph, I'm thinking that it would be horrendous, Cheers

Edited 16/01/12 12:26 AM by Impellor

[Paulie2256]

Dillz it would be off boost as boost is generated by engine load not rpm.

Brian, what about TR6060?

[Dillz]

Thought it was rpm, more revs more gas. Either way you can here/feel it.

[MiKa]

My boost guage needle is in vacuum when cruising over 2000 rpm.. but when I put the foot down/load it swings into action..

[Paulie2256]

Thought it was rpm, more revs more gas. Either way you can here/feel it.

This is sort of true. Increasing revs are (kind of) a by product of combustion energy. The energy generated makes the engine spin faster because it has nothing else to do.

The friction between the tyres and the ground is the "load". The more friction there is the more fuel and air is dumped and more exhaust is generated creating more boost (this is why we have a wastegate). Does not necessarily mean revs will increase.

But not sure if this is the right thread to be getting into detail. I'm just nit picking.

Edited 16/01/12 01:53 AM by Paulie2256

[bcl]

In a 4 litre turbo you'd have a major problem if you were using boost on cruise at 110kph.

On a 1.3 litre OK, but not a big torquey motor like the Ford has.

Higher revs will use more fuel at a given speed than lower revs, dependent on load.

e.g if you were revving at 2500rpm under minimal load, at a given speed, then changed to a different diff, and had 2800rpm, again under minimal load, I'd expect to use more fuel at 2800.

Since the BA the overall drive ratio in tallest gear has got progressively lower (taller).

Not sure about FG manual ratios; I think the 6th gear has a very tall 0.55, but not sure about the diff ratio.

I've had the T5 & 3 different T56 boxes with 3 different ratio diffs. The taller overall drive ratios make a huge difference to cruise fuel economy.

Brian

[arronm]

Unfortunately the trade off for better acceleration is higher cruising RPM and higher fuel consumption. I bet with those diff gears it accelerates hard. It could be worse, in the old days we had 4 speed with 1 to 1 so at 110 with 4.11 the car was revving its head off.

[ratter]

has tyre height been changed?

[freeze_dk]

My 5sp was just over 2000 @ 100kph so close to 2500 would be right.. This is with 19" if that makes a difference

[riptide]

Must be fairly hard on the fuel consumption. At 110 I'm doing ~1700rpm with my ZF. It still pulls fine.