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Absolute power does what?
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Discussion Starter #1
Gents,

Was just reviewing my video/data from a lapping day yesterday and realize I'm not heel-toe'ing smoothly sometimes. A few times I shifted rather late and didn't get the blip high enough so when I dumped the clutch I got a small rev-bump (say 1k revs off).

So the question is when I blip it should I really pound it and let the rev-limiter deal with it (which seems painful to me) or do I just need to improve my technique and time it better? Is it ok to hit the limiter with the clutch in (so no load on the motor) or is that a "not good" thing too.

Thoughts?
 

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If you hit the rev limiter while blipping that means you are downshifting to early and is kinda pointless because the limiter will do the same as incorrect rev matching -> lock up the wheels which you are trying to avoid by using this technique. I know you get excited when you're braking hard, and just want to dump gears fast, but this is how you blow oil pump gears and valves so cool down, and delay your downshifts a little and you should be fine.
 

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Absolute power does what?
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Discussion Starter #3
Totally get what you're saying - but it's actually the opposite. I'm shifting late in the turn so say I'm in 3rd at 4k and need to blip to 2nd. That means I need to be near, say 7k (for arguements sake). I'm only blipping to 6k (again all rough numbers) and so when I dump the clutch it's not totally smooth (mind you this is just on occasion). In those instances I've not blipped harder as I try to do the minimum to get it there (as I don't want to over-rev).

So my question is should I be slightly more aggressive and not really worry about it or should I be more vigilant to keep the revs as low as I can. If I only need 7k I should only blip to 7k - or can I blip to say 8k and not worry about over-blipping by that much?

Make better sense?
 

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blipping

As you know, you blip so the lower gear rotation matches the car's speed so engagement is smooth/easy on the tranny and balance of the car. Stab the throttle, the rev's go up, and as they start to fall back the lower gear is engaged. The rev increase only needs to be a little higher than what the gear speed/engine speed will be when under load after the lower gear is driving the car. Let the brakes slow the car, and the shifting,/ gear engaging is easier on the parts when the car is going slower; so delay the downshift as deep into the corner as you can. The design of a syncro brings the next gear up to speed so it can "slot in"with out chewing things up, so heel and toe is more important in a car with straight-cut gears, non syncro, like a Hewland, where if you don't rev match correctly, it won't go into gear. No need to hit redline on the blip.
 

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Absolute power does what?
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Discussion Starter #5
As you know, you blip so the lower gear rotation matches the car's speed so engagement is smooth/easy on the tranny and balance of the car. Stab the throttle, the rev's go up, and as they start to fall back the lower gear is engaged. The rev increase only needs to be a little higher than what the gear speed/engine speed will be when under load after the lower gear is driving the car. Let the brakes slow the car, and the shifting,/ gear engaging is easier on the parts when the car is going slower; so delay the downshift as deep into the corner as you can. The design of a syncro brings the next gear up to speed so it can "slot in"with out chewing things up, so heel and toe is more important in a car with straight-cut gears, non syncro, like a Hewland, where if you don't rev match correctly, it won't go into gear. No need to hit redline on the blip.
Thanks, but as you say I know every bit of that - what I'm asking is how safe is it to go above the point I need and how bad is that? Again if I need 7k should I shoot for 7k (which I can nail many times but not every time) or do I shoot for 7.75k and let them drop as the clutch engages (much better than making the motor spin up due to the clutch/wheel speed).
 

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If I stick to the number you just gave me I would say you're overdoing it. Downshifting from 4k you should be able to double up and not hit the rev limiter, so if you shift with reasonable speed, you wont be able to blip to redline no matter how hard you try.
Post some data if you can, that would make it a lot easier.

Oh, and don't be surprised if you thread gets moved :D
 

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Absolute power does what?
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Discussion Starter #7
Oh, and don't be surprised if you thread gets moved
Yeah, I thought that might happen - figured I'd get a better response in general ;-)

Post some data if you can, that would make it a lot easier.
Agreed, the only thing I haven't installed yet is the RPM sensor. I can see it in the video but it's pretty tough to read. The numbers I gave you were 100% made up - just trying to get to the point of is it better to over blip vs. under blip. I believe it's over blip - so my question then becomes how over is too over?

RPM sensor goes in this week so next weekend I'll have hard data.
 

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They are both bad, it upsets the car as you probably already felt before...
Lets call it rev matching, that's the goal, anything under or over will have a negative effect but even if you do it right you want to avoid doing it in turn because the best case scenario is it will have the same effect as if you lifted!
 

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Absolute power does what?
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Discussion Starter #9
Yeah, ok - I can buy that. So that answers my original question of - just get better and be more consistent :)

And agreed, never mid corner - that would be bad....
 

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Ross, hard to hear from your video, but it does sound like you are stabbing and yanking it a little fast
;)

Maybe hurrying it a little to fast.

I think your blips are a bit quick, i would think of it less as a blip and more of a roll of the foot with a smooth 1-2-3 motion. More smooth, less stabby.

Then you have more control to get a slight higher rev to catch the falling rate of the engine flywheel mass so you release the clutch at the smoothest place.

So if it takes you .5s to release the clutch lets say, then you just need to rev the engine high enough so that it takes the revs .5s to fall to the point where you have fully released the clutch. If you rev it to the limiter, and it takes 1s for the revs to fall to the point where your next gear matches your speed, then the engine will buck as it tries to slow down since it only took you .5s to release the clutch and the engine was still 500revs too high.
 

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Absolute power does what?
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Discussion Starter #11
Ross, hard to hear from your video, but it does sound like you are stabbing and yanking it a little fast
;)

Maybe hurrying it a little to fast.

I think your blips are a bit quick, i would think of it less as a blip and more of a roll of the foot with a smooth 1-2-3 motion. More smooth, less stabby.

Then you have more control to get a slight higher rev to catch the falling rate of the engine flywheel mass so you release the clutch at the smoothest place.

So if it takes you .5s to release the clutch lets say, then you just need to rev the engine high enough so that it takes the revs .5s to fall to the point where you have fully released the clutch. If you rev it to the limiter, and it takes 1s for the revs to fall to the point where your next gear matches your speed, then the engine will buck as it tries to slow down since it only took you .5s to release the clutch and the engine was still 500revs too high.
Ok, I get what you're saying - I think - let me clarify this. Is the perfect rev-match that you blip the motor to .5k above where you want it and as you release the clutch the time it takes for that to happen (say .5s as you say) then you lose the .5k in revs in that space - blamo, perfect match.

Which ultimately answers one of the things I was trying to understand - it's preferable to overshoot the rev you need vs. undershooting it. Revs fall easier/naturally but don't rise.
 

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Actually looking at it again on a real computer instead of my tablet, it sounds like you are pretty smooth, but there is that slight balloon of revs after you shift.

Does your Exige still have that feature on the clutch that keeps you from releasing the pedal too fast? It sounds like after you release, there is a fraction of a second where maybe the clucth cylinder is slow to return and it is holding the clutch open, slipping a bit.

I remember reading that the Elise and Exige had a "feature" that tried to prevent you from releasing the clutch too fast, I guess to prevent people from side-stepping the clutch for drag starts. Something like that could slow your release to the point where the revs drop below what you had planned, and then the engine needs to speed up to match revs.

Something similar happened in my acura before I replaced my master and slave last week. The clutch would be slow to fully release, after I took my foot off, due to the gunk that was in my system and probably bad seals in the pistons.

Oh, it's a clutch delay valve. http://www.lotustalk.com/forums/f157/lotus-exige-s-240-fast-gear-change-63327/ Sounds like the '06 Exige wouldn't have it...
 
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