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[Paul M]

Right! The penny's dropping. But surely people aren't really serious about most driving being in the 6/7k+ zone. My engine is in good nick, and it did tear away earlier today, and I think I will push it harder from time to time, but I don't envisage too much 7k stuff. I'm nervous about flying. (The real stuff anyway!)

It's designed for it, that's why there's a rev limiter at 7000 RPM -- that is a safe speed for the engine to be turning at without damaging it.

If you need to accelerate quickly, you should be using the full power of the engine, which means revving it up over 4500 RPM where it really comes on song. If, for example, you pull out from a side road onto a B-road (60 MPH speed limit), and there is a blind bend 70 metres up the road, once you decide it's safe to pull out you should be accelerating as quickly as possible up to the speed limit. That means revving to 6000+ RPM in 1st gear, quick change to 2nd and do the same. By this time you'll be at (or near) 60 MPH, so you can easily slot it into 5th and cruise happily at 2500 RPM assuming the road is straight.

There is a junction similar to that above near where my sister used to stay, and I wouldn't feel safe pulling out of that and shifting up at 3000 RPM -- it would take so much longer to get up to speed that you're in the danger zone much longer should a car come around the corner rather quickly.

Appropriate gear for the conditions -- if you need to accelerate, use the lower gears and the engine's power as it was designed. Not doing so is akin to only ever using half the travel on the brake pedal, to prevent wearing out the discs & pads too quickly

[Andy B]

...... revving to 6000+ RPM in 1st gear, quick change to 2nd ......

So ....... when do I change from 'D'?        

[platty]

I have had some second hand experience of engine testing, and I understand that with many modern engines, they run them flat out 24/7 for up to a couple of weeks - which is equivalent to 100k miles or something.  

My figures might be wrong but the point is that if it can take that, then I'm sure it will handle the occasional visit to the red line (as long as engine is at good temp).

[TheBoy]

I think you need to get Mark to take you out for a drive at some point.....

If you are a rear seat passenger, just ensure there actually is a rear seat, else it gets quite uncomfy as the back end goes from side to side  

[Paul M]

...... revving to 6000+ RPM in 1st gear, quick change to 2nd ......

So ....... when do I change from 'D'?        

Once someone teaches you the art of driving, and lends you a car that is designed to be driven

[Marks DTM Calib]

Paul......it has good low down torque, better than pretty much any other engine in this size and this can be easilt demonstrated by popping it in fifth at 30mph and noting how it still accelerates......dont confuse it with Bhp.....!

http://www.omegaowners.com/forum/YaBB.pl?num=1166809964

That's a pretty good torque curve (not really that curved at all) for a heavy car in my book. Low down torque could only be improved on that by tuning it as a 2v engine and forgetting about the region above 5K. And then you'd say it was gutless at the top end!  

Kevin

But still, with a multivalve engine it makes sense to match the gearing to the revvy nature of the engine IMO, and a 6sp allows that without compromising the lazy cruising ability.

Look at the torque curves and Bhp curves posted again....you will see that peek Bhp is over about a 2000rpm rev range.............a 6 speed close ratio box is not going to do a dam thing for you other than add an extra uneccassary gear change.

6 speed boxes only add a benefit to:

1) Engines with a narrow power delivery i.e. bike engines and modern high bhp diesels

2) Very high output engines needing an extra over drive gear.

Its horses for courses adn if you had a 6 speed on a V6 it would most likely be slower due to the extra cog shift that would be offering bugger all benefit.

[Paul M]

Why does the 2.5 have lower gearing than the 3.0 then? If anything, the torque peak is lower on the 2.5 -- certainly this is supported by the fact that the 2.5 produces less BHP per litre than the 3.0. Official figures for the x25xe are 227Nm at 3200 RPM, and x30xe are 270Nm at 3400 RPM.

So all else being equal (and considering only torque -- they both peak power at 6000 RPM), the 3.0 should have lower gearing than the 2.5 to get it to its higher RPM torque peak quickly, yet the 3.0 has higher gearing. I suspect it's at least partly to do with economy, but I believe the 3.0 would accelerate more quickly with the 2.5's gearing. Hence the benefit of a 6sp -- have the 2.5's existing lower gearing for 1-5, plus an additional 6th for overdrive cruising (say about 2600 RPM at 70 MPH).

[Paul M]

I should add that, as far as the 0-60 run goes, the current gearing is pretty much ideal as you can reach 60 in 2nd. So lowering the gearing will likely require an extra shift, giving a slower time. But that's not real world, what if you want to accelerate to 70 MPH? Either way you'd need to shift to 3rd. I think overall I'd prefer the arrangement described in my previous post.

[Jay w]

This is fascinating stuff from people who have knowledge of the performance capabilities of different set-ups. I wholly acknowledge that my impressions of the V6 take no account of its real capabilities through lack of in depth knowledge, but I still can't understand how one can achieve 6/7k rpm regularly during conventional driving.
I succumbed to the invitation to 'give it a go' today, and at 90mph (the road wasn't suitable for anything faster), in 5th gear, the counter was reading 3.6k rpm. Just dawdling, did I hear you say? So, without ragging it in a low gear, how the hell do I achieve top end rpm. without driving dangerously, (if only to see what it feels like)?
Surely I'd need to join the aircraft on a runway.  

We dont do high rpm in top gear......second and third gear yes.....

[/highlight]

Right! The penny's dropping. But surely people aren't really serious about most driving being in the 6/7k+ zone. My engine is in good nick, and it did tear away earlier today, and I think I will push it harder from time to time, but I don't envisage too much 7k stuff. I'm nervous about flying. (The real stuff anyway!)

Mine sees the redline a few times a week, i don't live there, just visit it frequently  

if i want to pull away quick then i slot it in D select sport mode, bury the fast pedal in the carpet and keep it there for 10/15 seconds or until traffic/speed limits dictate otherwise

[TheBoy]

I should add that, as far as the 0-60 run goes, the current gearing is pretty much ideal as you can reach 60 in 2nd. So lowering the gearing will likely require an extra shift, giving a slower time. But that's not real world, what if you want to accelerate to 70 MPH? Either way you'd need to shift to 3rd. I think overall I'd prefer the arrangement described in my previous post.

No, you get a proper gearbox, that will do 85 in 2nd

As I have said to you before, in real world, in many cases, the proper gearbox is quicker...

[Entwood]

If you want to

a) have fun

b) give your auto a burst of self cleaning

then, with a nicely warmed up engine, select 2nd / sports mode and don't move either !!

Watch out for slippery surfaces/speed cameras/men in blue/battenburg decorated cars/other folks travelling much slower than you !!!

Seriously, if you do this on a straight open road and just floor the right boot you will be VERY surprised at what 2 Tonne of luxury car can actualy do when she picks up her skirts and runs ...  

DON'T look at the instant fuel consumption and when you've frightened had enough just drop her into D and turn off sports mode ..... normal service will be resumed

[Marks DTM Calib]

Why does the 2.5 have lower gearing than the 3.0 then? If anything, the torque peak is lower on the 2.5 -- certainly this is supported by the fact that the 2.5 produces less BHP per litre than the 3.0. Official figures for the x25xe are 227Nm at 3200 RPM, and x30xe are 270Nm at 3400 RPM.

So all else being equal (and considering only torque -- they both peak power at 6000 RPM), the 3.0 should have lower gearing than the 2.5 to get it to its higher RPM torque peak quickly, yet the 3.0 has higher gearing. I suspect it's at least partly to do with economy, but I believe the 3.0 would accelerate more quickly with the 2.5's gearing. Hence the benefit of a 6sp -- have the 2.5's existing lower gearing for 1-5, plus an additional 6th for overdrive cruising (say about 2600 RPM at 70 MPH).

Its totaly to do with economy on production cars......you seem to have some belief that 6 speed gearboxes are better on all configs.....you are wrong and particularly in the case of the V6.

You seem to be missing the fact that you will get to the torque peek in first gear almost instantly (whilst loosing traction!), if you then rev it just past the peek and change gear, in the next gear you will be just below it again......and so on.

And of course the 3.0 would in theory accelerate quicker with the 2.5 diff (gearbox ratios are actualy fairly similar)...hence why the 3.0 manuals are no quicker than the 2.5 manuals in real terms.

Remember that the number of gears required has nothing to do with the position of the torque in the rev range......its all to do with the width of the torque peek (or bhp) and on high output engines, as already mentioned, you might throw in an extra overdrive gear.

Also, forget bhp.....torque is the useable power.....if I had an engine with 1Nm torque at 100000 rpm I would have a 190Bhp engine (this is part of the principal used with small electric motors to get output up).

[Paul M]

I should add that, as far as the 0-60 run goes, the current gearing is pretty much ideal as you can reach 60 in 2nd. So lowering the gearing will likely require an extra shift, giving a slower time. But that's not real world, what if you want to accelerate to 70 MPH? Either way you'd need to shift to 3rd. I think overall I'd prefer the arrangement described in my previous post.

No, you get a proper gearbox, that will do 85 in 2nd

As I have said to you before, in real world, in many cases, the proper gearbox is quicker...

In almost all "real world" cases the proper gearbox is quicker... not only because it has more sensible ratios (85 MPH in 2nd!?!) but also because it's not spewing half the engine's power as heat into the transmission fluid And that's before we even get into the difference over a twisty B-road, never mind the acceleration difference, the difference in control is where it really counts.

I'm waiting for the argument that the Omega V6 is actually better off with four gears now  

[TheBoy]

I'm waiting for the argument that the Omega V6 is actually better off with four gears now  

No, just better with a proper gearbox.  Why do you think the dear Lord gave you 2 feet?

[Entwood]

I'm waiting for the argument that the Omega V6 is actually better off with four gears now  

No, just better with a proper gearbox.  Why do you think the dear Lord gave you 2 feet?

Left foot - brake
Right foot - accelerator


What else who needs a 3rd pedal to confuse the issue  ??