I give all, no point having a suit if you only wear the pants!!

 

I don't think there's any need to go past the point where an upshift takes you much beyond 2k rpm in the next gear - this is where the maximum torque is.

 

... but you won't get the max BHP at 2k rpm !

I had the rev limiter kicking in in my ealry days of ownership while overtaking on a B road and it's frightening .... must say that I was used to reaching 7.5k rpm with my old 156 1.8TS.

The GT was remapped and since then the rev limiter never ever kicked in again but I pay a bit more attention to the rpm counter because the engine is willing to go well above 4.5k rpm....

 

A couple of years back i went on an Alfa Experience day and a chap there was test driving the GT 1.9 JTD, he set off and floored it in 1st gear,the rev limiter kicked in and made a right racket, made everyone look around and "admire" his driving skills When he got back, the Alfa guys picked him up on it and actually said they hadn't known anyone rev limit a GT. He reckoned it cut in at just under 6K or thereabouts which he thought was rubbish, until they pointed out it was diesel - he looked a bit embarrassed and walked away. Might answer this question though - i've taken mine to 4.5 then bottled it - no RL at that point as you say.

 

You want max power not torque for acceleration, which will be much further up the revs. Power is pretty much just how many bangs of a given torque you can pull in a set time. Normally about 4k for diesel as suggested by this (randomly grabbed) torque+power curve

New Cummins V6 And V8 V8 Power Curves Photo

But no point revving beyond here beacuase the torque drops off to such an extent that the power decreases even though the revs are rising. So you change up at max power which drops you down the power curve but only by <1krpm where you still have good torque and can build up to the max power for the next shift.

 

You want max power not torque for acceleration, which will be much further up the revs. Power is pretty much just how many bangs of a given torque you can pull in a set time. Normally about 4k for diesel as suggested by this (randomly grabbed) torque+power curve

New Cummins V6 And V8 V8 Power Curves Photo

But no point revving beyond here beacuase the torque drops off to such an extent that the power decreases even though the revs are rising. So you change up at max power which drops you down the power curve but only by <1krpm where you still have good torque and can build up to the max power for the next shift.

Totally Agree. The kneebone is connected to the thighbone, therefore, when the distribition of torque is at the maximum, engage the flux capacitor and select 1st.

 

Got it! :thumbs:

 

The graph in the brochure suggests that the power starts dropping off after around 3700rpm.

 

Graph?? Brochure??

 

Ricer

"my JTD costs 27.3p/mile in parts and labour alone"

I love the sig...

 

Ricer

"my JTD costs 27.3p/mile in parts and labour alone"

I love the sig...

I should amend it, it's come down slightly - about 24p/mile at the moment.

 

What's the conclusion then chaps?

Do remapped cars have no rev limiter then?

Mine is factory, but does have the "sport" button which gives me more boost I believe, would this explain why I've not found the RL yet?

Any unmodded owners out their regulartly bouncing into it and embarssing themselves in a drag races?

Thanks

Kendal

 

I never hit the limiter, petrol or diesel . The power has dropped off by that point so no point.

 

In a road car the rev limiter is only there to stop your pistons taking a sight-seeing tour through the bonnet

 

Quite right. The rev limit is to protect the engine from spinning itself to pieces in a fast revving petrol car. In a diesel combustion is limited by mixture preparation. When you rev higher than around 4k there is insufficient time for the injected fuel to thoroughly mix with the available air before temperatures and pressures are too low to sustain combustion - therefore you burn less fuel in a less efficient manner and your power drops significantly before you would ever endanger the con-rod/bearings etc.

 

Now I'm talking from experience in the 2.4 10v, but the fuel pump stops at 5,400rpm and injectors stop firing at 5,700rpm.

This means you can only be between 5,400 and 5,700 rpm for a short time.

I think.. :lol: