#113528, "Max output SHIFT POINTS: tuning for 1/4mile"
I have looked over the search sooooo much that my eyes are now crossed and I think im losing sight in the left one, anyway here goes.
Has anyone here pinpointed a set of shift points which consistantly yeild acceptable 1/4th mile times?
I am interested in the power drop off points. I understand that with each mod you changed each peak power point. Assume we are working with this platform.
Stock RS 95 CAI,header back all aftermarket.
if I need to give you more information then by all means ask, I am just looking to gain that last 1/10sec to break out.
#113529, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 0
It would be easiest to do this with a dyno graph. The power curve depends heavily on header design, intake design, etc... What is still in the power or torque band with one header might be dropping off with another header. -=B-=
Dude, Boeing called. They want their wing back.
Dark0ne95: There is a butthole on that girl that his going to feel the wrath of 23 yeras of worldwide hate. Me: Can I put that in my sig? Dark0ne95: GO right fucking ahead.
#113530, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 1
Yeah you will have to review your dyno charts, even stock cars run a bit differently from the factory. If you really want to shave time off your quarter your going to need a recent dyno chart of the car your running. Thats the only way I can think to find the proper shift points for your car. I think i had seen some baseline shift points for a stock 2gnt a long time ago on the 2gnt home page, but i cant find it.
____________________________________________________ four nails four corners four riders and four horses
· What is the best way to launch my 5speed NT? These are the 4 techniques reported. - Dump the clutch at 4000 - 4500 rpms. - Rev to 5500 - 6000 and slip the clutch; once rolling, dump the clutch. - Slip clutch at 3000 - 4000 - From a complete stop, idle, floor the accelerator then dump the clutch once rpms get to 4000. The driver reported the last method worked the best.
These are the shift points used: 1st gear: 5800 2nd gear: 7200 3rd gear: 6500 - 7200 4th gear: 7000 (when shifiting, don't let off the gas, and release the clutch FAST).
#113532, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 3 Sep-11-03 05:27 AM by Michael_97RS
I don't agree that power shifting is the wy to go. The way the stock rev limit is you can loose too much power as it catches up.
If you have a CD box and a staged rev limit set to just before stock cut off, it might be better... but if you are putting down some serious power I could see this creating too much wheel spin when you shift.
I don't know how well those shift point work on a stock car... been a while, for many of us. First gear from what I remember always pulled strong I wouldn't cut it short. I think most of us run her out to redline, but my power band from the dyno really didn't drop off. Depending on what times you are running the decision to shift into fourth or not could be of interest. Running in the 15's I know it's close to run out third or grap fourth... *edit* high 15's
15.9 @ 86.7mph
Smooth idle? We don't need no stinking smooth idle.
#113533, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 0
I have a spreadsheet that you can use to figure out your shift points, but you need to know what torque your car is making over the whole RPM range. So, it is not useful unless you've dynoed your car.
Still, if you want it, E-MAIL ME DIRECTLY and I'll send it to you.
#113535, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 6
Here is a dyno graph of one of my older runs at 17 psi. It wasn't tuned the best, but you can see where peak hp and torque are. Hopefully this helps you out some.
Matt 1995 Eclipse GS 2.0L, S16g Turbo, 8 Injectors, 26psi
1998 Eclipse GSX 2.3L Stroker, AEM EMS Converted to Speed Density, FP3065 Turbo, 35psi , and so on...
#113536, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 7
Obviously I'm wrong, but an explanation would be appreciated:
why don't you just run the car to redline every gear? I mean, say you have a power curve so that you are making max HP at 5200 rpms. that means from 5200-7000 (redline) you are making max hp. If you shift at 5200, that means you "lose hp" that you have to build back up again, whereas if you shift from 7000, you will most likely stay above 5200 rpms and continue making max HP throughout the whole run.
#113537, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 8
To try and answer your question, if you would be making more power TO THE WHEELS in the next higer gear at a paticuar vehicle speed/engine rpm, then you would want to shift at that point.
If you had an engine with lots of top end power that did not drop off as you approached redline, then you'd shift at redline.
If you had an engine that did NOT make much top end power, but for some reason could spin to a high rpm, then you'd shift before redline. Also, this would depend on gear ratios.
If you have a large difference between your gear ratios, then you'd probably want to run your car to a higher rpm. If you have a small difference between gear ratios, you'd probably want to shift sooner.
You can't tell any of this unlessyou know your HP curve, your torque curve, and your gear ratios, thus why spreadsheets and calculations are done to figure out, for your car, what the appropriate shift point should be.
#113538, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 9
VX100 is right..
you have to calculate first the rpm drop in each gear.. and then find out how much power your making in the gear your leaving, and the gear your entering.
As your shifting you want to maximize the hp curve to the gear that your entering next.
Stock you'll want to shift at redline in EVERY GEAR..
shifting to torque peak or before torque peak isn't necessairly the fastest way down the track, HP is the application of torque over time,, you want to shift at where you maximize HP..
#113539, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 10
From my experiences and observations, test your car. Take note of where ever you shift what the RPM's are in the next gear. For example, if you make peak torque @ 3900, you'll want to shift so that the next gear grabs right around 3750-3800. You want to be on the rising edge of the curve in the next gear. I'm going to the track Friday so I'll shift @ a few different points and post the slips for each (if I can get enough runs...)
96 Indy Red Dodge Avenger I4 5spd 225.7whp/227.2wtq @ 10psi, currently running 12-14psi. HRC Stage III turbo setup JE 8.8:1 pistons Eagle rods block bored .020" over GReddy FMIC w/ custom piping 1G crushed BOV SPEC Stage 3 clutch 2.5" DP, 2.5" high flow cat, 3" ERT catback w/ Magnaflow muffler and 3" tip. much much more...
#113540, "RE: Max output SHIFT POINTS: tuning for 1/4mile" In response to Reply # 11
well my take on HP vs TQ is that in order to make high HP you need lots of torque or lots of RPM. HP= (TQ*RPM)/5252. considering the size of our motor gobs of torque isn't exactly possible so we should focus on making whatever torque we can in high rpms.
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