How bad is it on the engine to hold the RPMs at redline?

Let's say that you are on a track where there are some relatively short straightaways and by the time you get ready to shift from 3 to 4 (at around 90-92 mph) you are getting close to running out of real estate because you need to brake for the next turn. Rather than do the 3-4 upshift and then heel toe back to third while braking for the turn, it is sometimes easier (and quicker) to maintain throttle at 9000 rpm in third and just hold there for a 2-3 seconds.

Is this OK on the engine to maintain revs at 9K RPMS for a few seconds?

 

No problems. Actually it would help to get any carbon deposits out of the housing, plus redline technically is 9500 or so. I've personally been up to 10k

 

Does the rev limiter work with the clutch depressed? Is it possible to over rev while doing a single clutch heel and toe downshift from 4-3?

I've also heard that the renesis doesn't really have a true redline, just a point of deminishing power return from the engine.

 

When I autocross mine, on a particularly fast set up, I was bouncing off the rev limiter for the last 100-200 yards or so of the straightaway. No worries. Also the rev limiter does work in neutral and clutch in.

 

Computer cuts fuel at 9500 or so. You can't overrev with the gas pedal. But of course you can overrev by downshifting.

 

Not to change the subject, but, speaking of 'heel and toe', did anyone watch the NASCAR race yesterday?
FOX had an in-car camera pointing at Boris Said's feet. Numerous times during the race they showed his heel-toe technique.......truly amazing in my opinion as I've 'attempted' this and failed miserably. They also showed multiple screens showing a view out the windshield along with him footwork so you could see the corners coming and anticipate the heel-toe.

 

if you're not expecting additional time shaved off by upshifting before the braking zone, then holding it at 9k before entering a turn would seem logical in the grand scheme of things, the time you saved from the extra downshift will probably cover the extra tenths of seconds you gain if you upshifted. Wouldn't know for sure unless you set up timing devices for lapping sessions of course, timing equipments do not lie

the 8's pedals are perfectly spaced for heel-toe, FYI :D

so learn how to do it!

 

When we drive up in the mountains around north georgia, we routinely hold at 8500 or close to 9000, rather than shifting. It is good to know that I am not killing the car. I have been told that the engine can handle a little more, it is the rest of the moving parts that have difficutly with the high rpm's, such as drive belts, a/c compressors and the like. I wish I could learn heel-n-toe, but my size 13's don't cooperate.

 

yes i seen the race he was really good at it.

 

with my size 12's I can heel-n-toe fine........just give it some practice:D

 

I don't think in the instance you describe that there would be any damage done to the engine. I've been practicing the heel-and-toe a bit ever since I realized how much it would help on the track. Man, it is pretty hard!

This may be a stupid question, but when you are in neutral and the clutch is fully depressed or even halfway depressed, is it bad on the clutch to hit the gas pedal (ie. rev it up)? I wasn't sure if you were supposed to let off the clutch completely when you rev-match or double-clutch.

 

Heel and Toe is easy with the RX-8. I single clutch heel and toe rather than double clutch. I just became proficient recently and this was the first time I used it on a race track.

The corner in question where I was deciding to upshift was the most dangerous corner on the track (the other 10 corners were quite open). Turn 11 is surrounded by concrete and guard rails so as David Hobbs would say I "decided that discretion was the better part of valour."

Most of the time I had cars in front of me that I could not pass in the corner (since this was a school not a race) so I could basically hold in 3rd gear at about 92mph or so for a few seconds and then brake later than the other cars and end up right on their six anyway. Then I watched them pull away on the straights because they had more hp and torque .

 

So when you say single clutch, do you mean:
1. Hit the brakes
2. Clutch in, shift to neutral
3. Hit the throttle (still on the brakes)
4. Shift to lower gear
5. Clutch out, back on the gas

Is that how you do it? I haven't tried it in a track setting, but I tend to let up on the clutch a little when I hit the throttle. I guess without practice it all seems to happen so quickly. I also find my foot is not wide enough to hit both pedals by rolling my foot, so I end up having to put my foot up high on the brake pedal and come down hard with my foot (heel) in order to get sufficient revs.

If I'm totally doing this wrong, somebody please let me know...

 

I'll start by saying that I am no expert but I understand it to by like this:

Normally with the double clutch it's

1. brake in and held whole time
2. press clutch pedal down
3. shift to neutral
4. clutch pedal up
5. blip throttle
6. clutch pedal in
7. down shift
8. clutch up
9. release pedal clutch

The key with the double clutch method is that the blip of the throttle is done in neutral with the clutch up. This speeds up both engine and part of the gearbox and is necessary for vehicles without synchros like racecars and old dump trucks. In the long run it will save wear and tear on the clutch.


In newer cars, you really don't need to doubleclutch because you can rev the engine and the synchros will still allow the shift.

Single clutch method is
1. brake in and held whole time
2. clutch pedal in
3. blip throttle
4. downshift
5. clutch pedal out

 

Right. That's exactly what I figured. The only thing is that I was wondering if it was bad for the clutch to be on the gas while the clutch is fully in, or even halfway in for that matter (while in neutral, of course).

 

You guys are making my brain hurt.

 

LOL

 

You mean "You were granny shifting when you should be double-clutching" in Vin Diesel's RX-7 was phony? :D :D :D :D :D

I do double-clutching just for the fun of it. But to really get going quick, single clutch does the job. I've been so used to it that I don't even have to look at the tach anymore

 

I think you are missing one step, I added in red. That is what I was told don't quote me on it, I am not an expert on it . In double clutching you have to be quick and accurate to pull it off smoothly. It sure fun when you pull it off, just don't practice on a crowded street. Safety first :D

:D

 

interesting that no one has mentioned excessive seal wear at 9000 rpm and beyond.....

 

do you have some kind of fuel cut-off mod that non of the rest of us have? (in a sarcastic tone)... if you do let us know where you got it and how much. otherwise..don't post b.s. when we all know what the rev cutoff is.


sorry..in a bad mood tonight. lol

 

I used to have an '85 Rx7 with a bad 2-3 syncro. You couldn't downshift into 2nd without rev matching, so I got in the habit of not even using the clutch. I'd just come hot into corners, left foot brake, downshift without clutching and jump on it. That same car in an autocross, being driven by a firend, was accidently shift 2->1 instead of the intended 2->3. Buzzed it up to around 12K RPM, but didn't do it any harm.

I pick up my brand new 8 this afternoon (silver GT), can't wait !

 

If you haven't tried double-clutching, give it a go. It makes down-shifting much smoother than a single-clutch rev-match technique, and its more forgiving of being a bit off on the revs. With the double-clutch method, you can rev slighly higher than you will be in the lower gear and still be very smooth, whereas with the single-clutch technique, you must be slower with the clutch release if you are off on the revs a little bit.

Try both (without doing heel-toe) and see which one feels smoother to you. Then, try doing it while heel-toe'ing. I used to use the single-clutch method for all my downshifts (including heel-toe) but I've found the double-clutch method to be so much smoother that I use that now for almost all my downshifts (including heel-toe). The only time I don't double-clutch is if the braking zone is short and there is not enough time to press the clutch twice.

Remember, the whole point of rev matching is to be smooth, and the whole point of heel-toe is to accomplish rev-matching while braking. Therefore, if you can feel any change or distruption in the chassis while you heel-toe, you aren't being smooth.

Some people will say that double-clutching is stupid on a modern trans with syncros. However, the syncros are responsible for spinning the layshaft of the transmission up to the same speed as the driveshaft. If you're rev's are off (too high or too low), when you connect the engine back to the layshaft by releasing the clutch, the car will lurch.

If you use the double-clutch technique, both the engine and layshaft spin at the same speed when you rev the engine (because the shifter is in neutral and the clutch released). Then, when you move the shifter into the lower gear, you can feel it slip in when the layshaft and driveshaft speeds match. This is why you can rev slighly higher than necessary and still be smooth. By waiting for the shifter to slip nicely into gear, you are letting the layshaft spin down to the same speed as the driveshaft. And since you spun up the layshaft with the engine, the speed of the engine is still about the same as the layshaft, so when you let out the clutch, everything is smooth. I should mention that this whole process takes only about as long as it takes to pump the clutch twice once you master it.

 

i think you just lost them with that dissertation :D

 

are people actually using their heel and toe? I find it much much easier to hit the brake with my big toe and roll on the gas with my small toe... the traditional way doesn't work at all for me - my long legs don't bend like that while still clearing the steering wheel.

oh and I do the single clutch method - i'm smooth with it and i find it much easier and quicker to pull off.