syncro rev match

speedworks · 05-05-2009, 05:09 PM

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.

Diversion · 05-05-2009, 06:20 PM

Quote:

Originally Posted by travisjb

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

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.

travisjb · 05-05-2009, 08:14 PM

Quote:

Originally Posted by speedworks

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.

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 !

travisjb · 05-05-2009, 08:15 PM

Quote:

Originally Posted by Diversion

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.

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

imag · 05-06-2009, 12:03 PM

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?

travisjb · 05-06-2009, 12:28 PM

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

monthtrial · 05-06-2009, 09:23 PM

Quote:

Originally Posted by travisjb

Thanks...

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 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?

travisjb · 05-06-2009, 10:37 PM

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

imag · 05-08-2009, 05:55 PM

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.

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05-05-2009, 05:09 PM	#31 (permalink)
speedworks Track Member Join Date: Jan 2009 Location: Boston, MA Posts: 550 Drives: PW purchased 01/09 Rep Power: 17	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.

05-06-2009, 12:03 PM	#35 (permalink)
imag Enthusiast Member Join Date: Mar 2009 Location: Oakland, CA Posts: 446 Drives: up the wall Rep Power: 16	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?

05-06-2009, 12:28 PM	#36 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	yes to clutch... don't really view this as necessary but what they hey... i'll keep the oem clutch as spare

05-06-2009, 10:37 PM	#38 (permalink)
travisjb A True Z Fanatic Join Date: Jan 2009 Location: GSO Posts: 2,803 Drives: VIR Rep Power: 188	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

05-08-2009, 05:55 PM	#39 (permalink)
imag Enthusiast Member Join Date: Mar 2009 Location: Oakland, CA Posts: 446 Drives: up the wall Rep Power: 16	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.