syncro rev match
 

looking for input... when upshifting, i noticed RPMs would run up +200-400 rpms once i pressed the clutch (off the gas)... i've been hestitant to bring it up because i figured it was me gaffing the pedals and probably staying on the accelerator too deep between gears... but after watching a bunch of youtube videos etc it seems to be fairly widespread, so...

theory a: we're all a bunch of hacks (especially me!) and need to learn to let up the accelerator more / faster when up-shifting

theory b: conspiracy... syncro rev match "blips" the throttle even on an upshift

theory c: something else causing RPMs to run up in between gears, e.g., mass of trannie clutch et al released and so engine and flywheel free to spin faster... suppose this is typical, but is there anything about this car that would increase the effect?

anyone else had the same observation?

I think this may be related to the overheating issue on my other thread... rev limiter works - when the driver is stepping on the gas, it steps in- but i'm not convinced it will defeat the engine from accelerating over the rpm limit when the RPM overrun happens in between gears as described above

Theory b is correct. SynchroRev Match assists you even when you upshift. I was just as surprised back then as you are now. I was looking at the Quick Reference Guide and that's when I saw the feature. You can learn in detail in the following thread

http://www.the370z.com/nissan-370z-g...html#post16157

Thanks... :cool: but i'm not completely sold... just read the other thread (and let me know if i'm off base by posting here instead in old thread), and i don't think the issue is just that it matches the lower revs of the next gear up, but that it actually over-accelerates in between gears for whatever reason... ie, I accelerate to 7,000 rpm in second gear, press the clutch / lift the gas, while in neutral it continues to spin the engine faster (to 7,500 rpm), then I shift to 3rd where it matches revs down to 3500-4000ish, and I release the clutch

I've noticed it too and I dont like it. I dont like when im coasting a little and it holds the revs up too long..makes me want to turn it off when driving normally.

Nope, has nothing to do with synchro-rev thing. i have had that on every manual car i have driven including my G35, and current car, but i dont know about 400 rpm. maybe 200

I've driven like 20 different manual cars and none have ever done this. It is definitely part of the SRM system..

different people drive differently. please dont do the i've driven x cars or been driving for x years. my e-penis is 100"s too

ok, gang... before everyone starts whipping out their thangs, realistically we're going to need input directly from nissan to resolve... or 3rd party that can test and verify...

In the meantime, I'd be interested to hear from others if they think they are experiencing the issue or not, and if they think it is unique to this car and possibly related to SRM... don't let the strong opinions above deter you from sharing. THANKS!

You gotta be kidding me, do you even own a Z?

Im not doing "the" anything. Usually it simply adds credibility if I have driven other cars. Please keep your comments under control and the unnecessary idiocy to a minimum. Notice you are starting an argument for absolutely NO reason, we don't look well to people that do that here. There are no e-thugs here and much less of a reason to jump out and start making comments like that. I am not going to argue with you man, but just take it easy...

Sorry Travis,

Sometimes when i put the car in neutral it still holds the RPM's up as if it were waiting for me to chuck the same gear i was just in back in. When I'm upshifting slowly, it likes to hold the RPMs up for the next gear and sometimes that can be annoying. Also when I had the indicator light set at 4000 I would shift at 4k, carefully getting off the gas before releasing the clutch and the RPM's would go over 4k for no reason.

I would definitely like to hear others opinion, people?

lol people like me? ur the one who started the argument! In any case sorry if i came off as a e-thug. but that's exactly my point, i do not own a Z and i still have the same exact behavior on every car i have driven. for credibility here's my list of cars i have seen this behavior on when i drive the car hard:
1. 2006 G35
2. 2006 350Z
3. 2007 335i
4. 2008 BMW M3
5. 2008 BMW M5
6. 2007 BMW M6
7. 2008 Subaru STi
8. 2009 370Z
9. i dont know what year but the turbo mazda 6 (like last year's model or the year before)

as far as holding the RPM that makes sense for the new synchro-rev feature. A lot of cars that have rev-matching features like BMW's DCT, and BMW's SMG, do hold that RPM for u, or even blip the gas if the shift is too slow (the case of SMG since it requires input from the driver on the throttle). But revving up? idk why it would do that

lol did you really just list out cars you've driven after you told me off for saying I've driven 20 cars....

Well thats what I was talking about, its that holding of the RPM's that other cars don't do..
Other cars may feel like they blip because your foot is still partially on the gas when you put the clutch pedal in... if you are completely off the throttle when you put the clutch in, that CANNOT happen as you are not giving the engine more throttle.. This is where the 370 is different, the SRM system holds the RPM after you let the clutch out...

yes, you made a point that you said the number for credibility. lol

actually SMG does blip the gas even if ur foot is off the throttle. in fact in shifting up this is a perfect example of when it blips the gas. same for DCT.

but see now it's making sense. the 200 extra RPM u see is just because when driving hard there's probably still gas getting injected while you depress the clutch. that's how _I_ get my extra 200 RPM's.

now in the Z's case it sounds like it holds the RPM + whatever i do so u get even more rev?

Correct.

Also SMG and DCT dont qualify as classic manuals ;) Which is what I was talking about.

:tup:

Ok all pointless bantering aside,

Why would the car increase revs between upshifts. The next (higher) gear you select will cause your revs to drop, so revving the rpms higher will make the rpms difference even greater during the upshift.

Basically, it seems to be replicating the "no lift shift" or "powershifting" which isn't exactly easy on the tranny. :confused:
I don't have a Z, so comments/corrections are welcome.

it's the right question, namir... just haven't found the answer yet

The flywheel on the 370z is extremely heavy in order to reduce NVH. The same was the case with the 350z but I believe the 370z flywheel might be even heavier. The flywheel is heavy enough that it will hang on to a lot of revs and sometimes seems to carry its momentum when you press the clutch and jump off the gas a the same time, building a few revs. I'd put money on it that if you got a lightweight flywheel you wouldn't have this issue, although who knows how much, if at all, that would screw up the SRM software...

Yeah we need a guinea pig to try a lightweight flywheel. I too am curious to know how it'll affect SRM. Most people are of the opinion that it won't screw up SRM at all. But I want someone else to be the first one into the pool. :p

I have only had my Z for a couple of days and limited opportunity to drive, but I have difficulty with smooth upshifts. After reading this thread (and the other that was referenced), I'll pay more attention to what's going on, but my first impression is that holding the revs on upshifting is probably unnecessary for someone who knows how to shift properly.

I guess I will just need to practice shifting until i get the hang of what the Z really wants. Perhaps just a break-in and some hard driving.

yah i had a hard time shifting from 1st to 2nd without getting some jerkiness. one way to get this smoothed out is shifting at high revs. which i'd enjoy on those cars :D

I'm in the same boat in terms of not owning one ... but I'd venture a guess that with the synchro-rev turned on, you'll have to adapt to what it does. I'd think you can't really drive it the same way you do a traditional manual without the feature.

And I'd agree that the blip-on-upshift seems kinda pointless if the flywheel is as heavy as claimed in the previous post. Having owned a 240Z with an extremely lightweight flywheel, that's something I had to do with that car because the engine lost revs SO quickly.

The RPMs on my 05 WRX would raise slightly during upshifts too, but it doesn't happen on all gears. It seem to only occur in lower gears.

I too had a wrx sti and it did the same too, almost randomly but more noticable in lower gears..

I have noticed the increase in revs especially when shifting from 4th to 5th. When I shut off the srm it's normal. I wish there was a way to edit the parameters of the srm system to match the drivers style and skill level..... I've just been keeping it off.....

It was in the brochure for the 370Z that the SynchroRev feature does indeed assist on UPSHIFTING as well as downshifting ;) Granted, before I read about it, I just thought that the flywheel must have been super heavy in the new Z causing the RPMs to float between upshifting. Turning SynchroRev off is night and day in how upshifting feels.. I lovelovelove having SynchroRev and the option to turn it off.. It's a god send for people like me who aren't the best at heel toeing during the twisties!

Edit: I don't think the SR system is blipping on upshifts, it seems to just be holding the RPMs at an equal level you were just in until it sees if you're going to upshift or downshift. But i've never seen it go higher in rpms before I go to the next gear. And to add, it will stop holding RPMs in neutral for about 3 seconds then drop down to idle if you don't do anything (i.e. coming to a red light or stop). I've always had a bad habit of checking to make sure i'm in neutral when coming to stop. Moving left or right while in neutral also blip the throttle when you're over a certain speed.. It's been a hard habit to break, sigh. People think i'm "showing off" when the engine blips when i'm slowing down.

Jay

See my other post in the General Section, I notice the holding (or slight increase) of revs in downshifting and upshifting. The holding rpms in a gear can be dangerous - I have taken a few on ramp turns, at near race speed, and when I lifted off the gas a little, it feels like the car still has the gas on - it holds the rpm, and can be a little discomforting. Once you slightly touch the brake, it will not hold the rpm. I have only noticed this on high speed turns, but that is probably only because of the speed mode I am presenting to the street. After driving this car for 4 months, I am not sure I enjoy the Synchro Rev as much, too much computer, and I don't think they have perfected it. On a racetrack, feeling this 'holding of the rpms' will not be something I would enjoy, and I spend many weekends racing at speed in real race cars. On the other hand, trying to drive this car smooth without it (heel/toe), you almost have to be perfect. The more I think about it, it is definately the heavy flywheel maintaining the momentum.

speedworks, I think you're right on! With clutch in and SRM on, it holds RPM in anticipation... takes getting used to... I'm still a fan of SRM on the track though, esp helpful when getting used to a new setup, new track etc... an easy way to take out one degree of complexity, and can add it back when you want

All, I have the JWT flywheel and clutch on order from Mike at DDM ! I think I'll be the guinea pig... will report back here and in my car journal once it's done

Travis, it should be interesting to hear the results. Since you have taken this car on the track, I have to know..when you come into a sweeping turn, after a long straight, and the correct line is to just lift on the throttle vs brake, to let the car slow just a little (this is similar to turn 1-2 at NH Motor Speedway), does the car continue at the last speed (as I have been experienceing), or does it slightly slow down. If I was in the car, I think it would probably cause me to spin, as I am usually at the limits at that point - and I think it would be very uncomfortable. I tell you I don't think the fastest way around the track will be with the SRM because of this, it would cause you to enter the turn at a slightly lower speed to compensate for whatever (flywheel?) is causing this attribute.

Take a look at the track diagram for PIR (referenced here http://www.the370z.com/track-autocro...-all-good.html)... On the NASCAR straight, I'm going about 120... I'm in 5th for a brief couple seconds ---- short shifting at 6500 rpm right now due to concerns of overheating... Downshift to 4th at the end of the straight immediately prior to rolling left... there is a wall to the left on turn 1, I'm about 5 feet from the wall going about 100 in 4th gear and I'm back on the throttle... Then I'm on the brakes and downshifting to third in a mostly straight line heading to the outside of the track on right side... hugging the right side, downshift to 2nd where SRM lands me at nearly 7K rpm... I'm then set up perfectly to steer through a 90deg left hander and make my way through the next couple... it is all SMOOTH AS BUTTER !!! I don't feel any concern about stability b/c of the downshifting... my thoughts tend to be more about dialing in the correct amount of brake pressure so I don't lighten the rear and step it out... which I've done on this turn at 100 - not fun !

continuing with thought... my desire for the lighter flywheel is more about having a more control on upshifts, less overreving, etc

Yeah, I guess my question wasn't about stability but more about the inability to scrub speed through the engine vs using the brakes, just enough to keep from oversteering or reaching the max capabilities of the tires. With this function, if you enter a turn where you were on the gas, full time, and then let off, just to scrub a little speed off, as you enter the turn, and then gradually get back on the gas through the turn (very common for tracks that use banked Nascar turns), this 'surge' or lack of deceleration will cause understeer/oversteer since you/I would be entering the turn at the edge of grip. I know seems confusing, but is normal on most turns, and with this feeling that get driving around town, I wouldn't feel good going into these types of turns with this scenario and the SRM on.

YAY! I'm excited to hear the results on your new flywheel with SynchroRev.. I just hope that SynchroRev doesn't apply too much gas anticipating a heavier flywheel.. but my logic is probably very flawed.

Sounds like engine braking force may be less in this car than what you are used to... makes sense... one of my driving instructors when I went through Bondurant would tell me, think of the brake pedal as a fine instrument with infinitely variable positions... taking that to heart, means that instead of relying on engine braking we will have to find that very precise braking point where we get the right amount of deceleration for whatever conditions warrant, e.g., constant/decreasing radius turns, negative camber, etc...

with every car, have to adjust driving style, right ? I think this one has advantages too, like a little extra weight on the front so less trail braking needed to get good hookup on front tires

anyways, this will be a much richer discussion once we all have some more track time w/ this car under our belts, we can all agree on that !

we'll see... should be interesting... my theory is that SRM is seeking out the correct RPM and that it will find its way there regardless of what forces are at play in the drivetrain... after all, the drivetrain faces variable resistance coming from the tires, in addition to the different forces associated with changing the mass of the drivetrain itself... but, we'll see

So glad you're getting a flywheel - it's down my mod list a little bit, but not too far. Are you going to change the clutch too?

yes to clutch... don't really view this as necessary but what they hey... i'll keep the oem clutch as spare

I believe what you're describing here is independent of the Synchro Rev Match feature... even w/ it disabled, I (and I'm sure others) have experienced increases in revs that hold upon a spirited gear shift.

What's interesting is that it doesn't happen all the time... has that been your experience also?

three potential contributing factors... 1) SRM, 2) heavy flywheel, 3) slightly mis-timed pedal coordination...

as for 1, i have no data to confirm that SRM would hold the revs higher when up-shifting but it makes some sense. imagine you are accelerating and in the next second you will go from 55 to 60 in 2nd, as that's happening, you press the clutch and start moving the shift lever... SRM sense that you are 'passing the gate' for second gear and b/c you are now going 60 as you 'pass the gate' out of the gear it momentarily thinks you may be going into that gear and ups the revs... then you're on your way to 3rd and SRM targets a lower RPM but the damage was done... just a theory

thing 2, I think this is definitely an issue... i agree, even with SRM off it happens... pushing in the clutch allows the engine to rev without the rest of the drivetrain to slow it down and the momentum built up in the engine internals and flywheel is so great that it gathers RPMs as the clutch is pressed

thing 3, legit... I've been working my timing to adjust to this car... the clutch engagement points are high in the clutch pedal stroke... that means that you have to get off the accelerator VERY early as you go for the clutch

I have no reason to rule out any of these... my solution is to replace the flywheel, work on my timing... but not sure i can do anything about SRM if it really is contributing... I like using it on the track, so not sure I want to defeat it

will know more once the single mass JWT flywheel is in... DDM is shipping to me late next week

I hear you on thing 3. I've been driving a manual since I was 15, but this car is challenging me. The height is odd (I was worried the dealership had burned my clutch off) and the friction point is just strange. I'm hoping the short shift kit will allow me to feel what's going on from the engagement side a bit better.