Yep, there is a taper point, where it feels like it’s not building power as quick as before. It’s where the torque curve goes flat or starts decreasing.
In a VHPD torque peak value is lower than 7000 rpm for sure, normally between 5500-7000, the moment to shift would be when after shifting you are close to the peak torque value.
Result: less frantic noise but faster acceleration (shhh, don’t tell anyone )
Max area under the graph is what you are looking for if you want max acceleration.
Nope, that’s power produced, as in total executed power (BHP graph)
If you mean the torque curve, I don’t know what it would mean… total produceable force?
You want to be engaged in the zone with the highest torque = max acceleration.
Thinking about it it’s max torque at the wheels you are looking for. The area under that graph.
It’s difficult to work out the shift point on most cars because the power drops off at the top end.
I think the correct way of calculating it goes something like this:
You make a cascade graph of torque at the wheels for each gear. Torque at the wheels is engine torque multiplied by the gear ratio. When you have such a graph, you can see where the torque in each gear drops below the level of torque for the next gear. This is your shift point.
What most people don’t realize is that the ideal shift point will vary from one gear to the next, so shift lights ideally need to know what gear you’re in as well as engine speed.
That’s one thing I like about the Exige: because the power peak pretty much coincides with max revs, you know the optimum shift point is always at the limiter.
Oooh. Lots of replies whilst I was writing that!
Peak torque has bugger all to do with maximum performance. Your torque might peak at 4000rpm, but if you’ve got 95% of that torque at 6000rpm, you will be better off using a lower gear to make use of those revs.
Spot on Brendan!
And since there is no shift light as clever as you mention, the best way is just to FEEL the acceleration, when it’s time for the next one to give the best pull, it’s time.
PS - Randy, you’re bent in this area thing, it’s not any area in this case, but torque value
…the best way is just to FEEL the acceleration…
You gonna tell every F1 driver (along with most other major formulas) that? It’s gonna stop me hitting the limiter, and that’s a good thing.
Right, off to find a VHPD torque graph…
Ian
The one I was looking for seems to have gooone - http://www.exiges.com/ubbthreads/showflat.php?Cat=&Number=15778&page=0&view=collapsed&sb=5&o=&fpart=1
Mr Admin, is it archived?
Ian
When your engine revs as quick as an F1 or top fuel dragset engine, you will need a light.
Compared to that, our engines are sooo slow, that it doesn’t make sense.
Moto GP for ex, doesn’t use lights (and they do 10-62 in about 2.2 secs)
Ok, but I still want to find a torque graph and I still love my shift lights! Anyway, how’d you know they don’t have secret shift lights in their helmets (surely where you’d have to put them on a bike)?!
Makes me feel like I’m in a race car and I have always shifted quite high on revs and hit the limiter. I like the rush the prolonged revs gives me, not a lot of cars do that (I know, I know, the Honda does it even better).
Ian
Having said that, I have recently bought a light myself.
Figured that if I have an Emerald, I might as well use that extra wire.
Besides, it’s not as if it was so heavy
Not that I would need it though…
Ha! See, you think it’s cool too!
PS - Randy, you’re bent in this area thing, it’s not any area in this case, but torque value
I’ll get my coat…
Can i add my thoughts to this discussion ?
Peak torque has bugger all to do with maximum performance. Your torque might peak at 4000rpm, but if you’ve got 95% of that torque at 6000rpm, you will be better off using a lower gear to make use of those revs.
Brendan, i’m not sure i agree this… it will depend on what you are wanting (speed or acceleration). As Uldis said above, maximum acceleration will be achieved at Peak Torque… but this is true IN ANY GEAR. Also torque is a function of revs and horsepower, so the way i see it gearing won’t actually make any difference to the shape of an engines torque/power curves.
So, i think i’d be right in saying most NA cars have got relatively flat torque curves as compared to their power curves and therefore if you want to keep accelerating as hard as possibile then you need to change gear somewhere that will keep the engine at (or close to) its peak torque AFTER the change. So, ignoring ‘load’ on the engine, IDG’s ‘shift light’ should be correct if its set at this point ?
On the other hand if its maximum speed you want then this happens at peak POWER in every gear so maximum progress would be made by changeing gear at max power - however, if this is too ‘peaky’ and depending on your gearing then you may drop down the power curve too far and have to climb back up which may slow your progress up too much IYSWIM.
The other point to consider is if your engine makes more revs quicker than the torque curv drops off the peak, in which case you will continue to increase power even tho’ the torque isn’t at max anymore - however, you won’t be accelerating at max m/s/s anymore.
anyhow, you know me… usually always ready to comment but that’s how i understand this.
But does anybody have a torque graph for a VHPD?
I do, from my initial mapping, just after I installed the Emerald, but with a CAT.
I’ll send it stright to you.
OK, my 2p, why not eh?
toke (please bear in mind this will probably not make much sense )
Surely the best time to shift, and we’re talking track work here, is when it gets you round the circuit quickest!
So sometimes you’d need to short shift to stay in a gear and not max out exiting a corner, sometimes you’d want to hold onto those last few revs to keep you in a gear so you don’t have to shift (like N. Weald, to me it seemed best to keep it in 2nd gear even though I was hitting the limiter than shift to 3rd and then stright back to 2nd at the first chicane)…
But then as Rox says you get decent leverage in 1st and 2nd so it’d be worth holding onto them a bit longer then you need to in 3rd.
Persoanlly I find about 7.5k rpm is good to shift at but then having an extra 500rpm to “play” with is really useful rather than running out of revs IYSWIM…
Ah sod it, just change when you need to get you round quicker
IDG
Ahhh… the simple things ehh… I often over complicate things…
What about this ?
a bit rough but its the best i could google
RL
ISWYM…