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Discussion Starter · #1 ·
i was just curious to find out if it is best to shift at max torque or max horsepower. any input??
thanks,
mike
 

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Putt Putt...Vroom Vroom!
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shift at max rev; that way you're going to be putting out as much power as your car can possibly put out when you complete your shift.
 

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Yeah shift at max rpms which is like 8000 or so on our tach. Max torque I think is like somewhere areound 5600 rpms. Max hp is rated at 7600 rpms but you can squeeze a little more out of it by going to about 8.
 

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Discussion Starter · #4 ·
that doesnt make sense. i make my max torque (203.2 ft/lb) @ 4750 rpm and max hp (235.7 whp) @ 6750. what good is served by shifting past 6750 when my power is decreasing (i.e. 227.2 whp @ 7000 rpm)?? please let me know if i am mistaken.
thanks.
mike
 

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because if you shift right at your peak, the power you're making AFTER you finish shifting is less than if you shifted at the MAXIMUM rev. that your car can put out. The higher that you shift at, the closer you're going to end up to your peak, which is where we want to be.

I suggest you do a search since this topic has been covered extensively.
 

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^you guys are right for every other car except ones with variable valve timing. generally cars with small stock turbos you lose so much power on the top end you don't take it to redline.

for motors like the H22 you shift high enough so you stay in VTEC from, which is w/out a VAFC would be around 7600-7700 for the 1st to 2nd shift just before fuel cut. staying in vtec is the more important than losing power up top, cause falling out of vtec will hurt you even. for 2nd to 3rd, you can probably shift at 7400 since i think it'll stay in VTEC.

have you noticed why the 2002 celica GTS sucks so much. they lowered fuel cut from 8200 to like 7,800 or 7,900. so now they can't stay on the high cam during 1st to 2nd shifts which makes them much slower.
 

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theres a formula for when to optimally shift and his has everythign to do with dyno'd HP and Torque...you're looking for a point whcih contains both...but a weird factor is our VTEC

but when i shift, i notice taht there is a point when even tho the RPMs are climbing...im barely accelerating...this is because the hp/torque has dropped off in higher revs...

so you have to think like this...

1. DO i want to take it up as high as i can go so the next shift will be in VTEC; but at the same time i may end up losing time b/c im not really accelerating towards the upper RPMS

or

2. Should i shift earlier even tho i may run risk of falling a little short of VTEC but be able to make it up b/c i didnt spend useless RPMs up top?

The fine shift point becomes up to the driver and a good feel for the car.
 

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AndoOKC said:
theres a formula for when to optimally shift and his has everythign to do with dyno'd HP and Torque...you're looking for a point whcih contains both...but a weird factor is our VTEC

but when i shift, i notice taht there is a point when even tho the RPMs are climbing...im barely accelerating...this is because the hp/torque has dropped off in higher revs...

so you have to think like this...

1. DO i want to take it up as high as i can go so the next shift will be in VTEC; but at the same time i may end up losing time b/c im not really accelerating towards the upper RPMS

or

2. Should i shift earlier even tho i may run risk of falling a little short of VTEC but be able to make it up b/c i didnt spend useless RPMs up top?

The fine shift point becomes up to the driver and a good feel for the car.
this why a VAFC is so important:bigthumb:
when you lower the changover point, you don't have to rev as high to stay in VTEC so you not in that area where it doesn't make alot of power.

i do believe without a VAFC option #1 is the only way for best 1/4 times.
 

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Discussion Starter · #9 ·
i should mention that i do not care about VTEC. my car is turbo'ed and VTEC is almost insignificant. i also have a stand alone (AEM EMS) and have turned the VTEC down to 5200.
DUDEWITHALUDE made a good point that i should shift after my max hp, so that i dont fall to far between shifts, but clearly not as high as he had suggested. if i am taking it to the redline, i am just wasting time because of the drop in power. i suppose it would make sense to shift just past the max hp and land just below the max torque. does this sound right to anyone else??
 

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well it really depends on your car, but normally, you still shifts at redline if you're turbo'd.

basically what you want is, like the others said, upshift at the point where you can still be in your powerband before and after shifting. you need to look into your dyno graph to see how your power curves, and your gearing to see what your engine RPM will drop to, and find the best point to shift at every gear. and i think you probably need to shift at redline or even higher than that at 1st and 2nd, or you'll fall out of your powerband. 3rd and 4th, i don't know, it depends on your car.

EDIT: by the way, that's the advantage of shorter gearing, you don't fall out of powerband.
 

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here is what you can do.
get your car dynoed.
then get a sheet that has your cars gear ratio's.
pick a rpm you want to shift at say 7800.
get the hp from the dyno sheet.
multiply the hp by the gear ratio.
then take the rpm you will drop too and find the hp made at that point.
multiply that by the gear ratio for the gear that you are in after you shift
*you will probably have a higher hp number after you shift but it is less effective because of gearing*
so after you have the two effective power numbers compare them. if the power after the shift is higher pick a lower rpm to shift at and repeat the process.
 

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What gear are you guys in and at what RPMs as you reach the 1/4 mile mark?
 

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^^I'm pinned in 3rd gear, but next time I go out I am gonna try shifting at around 7500 and see if that does anything for me.
 

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brendon2k said:
here is what you can do.
get your car dynoed.
then get a sheet that has your cars gear ratio's.
pick a rpm you want to shift at say 7800.
get the hp from the dyno sheet.
multiply the hp by the gear ratio.
then take the rpm you will drop too and find the hp made at that point.
multiply that by the gear ratio for the gear that you are in after you shift
*you will probably have a higher hp number after you shift but it is less effective because of gearing*
so after you have the two effective power numbers compare them. if the power after the shift is higher pick a lower rpm to shift at and repeat the process.
:eek: damn that's a lot of math:confused: :laugh:
 

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brendon2k said:
here is what you can do.
get your car dynoed.
then get a sheet that has your cars gear ratio's.
pick a rpm you want to shift at say 7800.
get the hp from the dyno sheet.
Actually the number you want is the torque numbers not the HP numbers. HP is dependant upon torque and RPM. It's torque, not HP, that is multiplied by the gears.

However, in the case of MOST Honda N/A engines shift at redline. Why? Because we don't have the extreme torque fall off that many other engines do near redline and generally Honda's have a very flat torque curve.
 

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i think you want hp. hp is your engines ability to do work, you multiply that by the gearing. you want to maximize your hp not necessarily torque.
 

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Discussion Starter · #18 ·
there was a formula printed in SCC about two years ago that explained all of this. i tried the numbers and came out with some rediculous answers. i gave up on it after a few tries with the same results. i think i was probably having a hard time understanding something in the formula. i have a dyno chart for my car now, so that is what i am going off of (see above #s). finding exact numbers is almost a waste of time because of the difficulty in shifting at exactly that rpm, but a rough idea will work. what is the redline on our cars anyway?? isnt it like 7500? that is almost 1000 rpm higher than my peak. there would be almost no acceleration that high.
 

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i just rev mine to 8K on the tach in every gear 1-4....id probally do the same if i was turbo'd but if i noticed the car not accelerating after a certain RPM i would shift earlier
 

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jitsu666 said:
what is the redline on our cars anyway?? isnt it like 7500? that is almost 1000 rpm higher than my peak. there would be almost no acceleration that high.
the point of shifting at redline is not for acceleration after your peak power output, it's for keeping you in the powerband after upshifting. you really should redline it in 1st and probably 2nd.
 
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