when running the quarter mile on a stock r with bolt ons what rpm are u guys shifting at? is it better to shift at 8400, 9000, 9200????

 

My rev limiter is at 8700...

 

The EUDM ITR (i don't know about other) have a 500rpm tach error at 9000rpm.
On mine with a Mugen ECU i shift at 9000/9100 on the tach.(8500/8600 on real).

 

Assuming you are using a stock ECU, fuel cutoff is at 8500, so shifting at redline (8400) is optimal. Power drops off on stock cams after 8000rpm anyway, so even dragging the redline to 9000 isnt neccesarily helping.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Champ R &raquo;</TD></TR><TR><TD CLASS="quote">Assuming you are using a stock ECU, fuel cutoff is at 8500, so shifting at redline (8400) is optimal. Power drops off on stock cams after 8000rpm anyway, so even dragging the redline to 9000 isnt neccesarily helping.</TD></TR></TABLE>

Some may opt to shift higher in first to drop back into vTackk's powerband higher then you would if shifting at 8000 when our motors do in hit their peak when making power.

 

shift near redline without hitting rev limiter.. btw.. you powerband drops after 8K rpm.. and you can't rev past8400 or 8500rpm with stock ecu.. if it shows higher, your tach is off.

 

when the car was running, 10K was my shift point.


but its not here anymore.

 

my only choice is to shift at 8400 or lower. cuz for my car it fule cuts at 8400

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C-Rsi &raquo;</TD></TR><TR><TD CLASS="quote">Some may opt to shift higher in first to drop back into vTackk's powerband higher then you would if shifting at 8000 when our motors do in hit their peak when making power.</TD></TR></TABLE>

That's not correct.

Some people think that VTEC makes the car accelerate faster (just because it gets louder above the VTEC crossover point), but it doesn't - not on the stock car, anyway.

Remember, acceleration is a function of torque, not horsepower. (And it's torque at the wheels - which equals torque at the crank, times gearing, minus drivetrain losses.) VTEC doesn't increase the torque as revs rise; it helps by keeping torque from decreasing as revs rise.

For the fastest acceleration in a stock ITR, shift at redline. The torque curve is flat enough that the gearing differences make you lose more torque at the wheels than the rev differences may gain, anywhere in the revband.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C-Rsi &raquo;</TD></TR><TR><TD CLASS="quote">

Some may opt to shift higher in first to drop back into vTackk's powerband higher then you would if shifting at 8000 when our motors do in hit their peak when making power.</TD></TR></TABLE>

You want to shift where it gives you the greatest area under the tq curve between shifts. This means going to the redline is the best place on a stock ITR - might be different depending on modifications - but you should not shift at peak TQ OR peak HP, that is bound to give you a smaller area under the curve (lower bound = where you 'land' after shifting, upper bound = where you shift).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxtasy &raquo;</TD></TR><TR><TD CLASS="quote">

That's not correct.

Some people think that VTEC makes the car accelerate faster (just because it gets louder above the VTEC crossover point), but it doesn't - not on the stock car, anyway.

Remember, acceleration is a function of torque, not horsepower. (And it's torque at the wheels - which equals torque at the crank, times gearing, minus drivetrain losses.) VTEC doesn't increase the torque as revs rise; it helps by keeping torque from decreasing as revs rise.

For the fastest acceleration in a stock ITR, shift at redline. The torque curve is flat enough that the gearing differences make you lose more torque at the wheels than the rev differences may gain, anywhere in the revband.
</TD></TR></TABLE>

There is a noticable gain in torque over the cam transition point...around 10 lb/ft...on a stock ITR.

Proven and noticable.

 

You must also consider gearing in the equation too. If you just look at your torque curve on a dyno and fail to recognize the multiplication effect of gearing you'll end up shifting too early.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris N &raquo;</TD></TR><TR><TD CLASS="quote">

You want to shift where it gives you the greatest area under the tq curve between shifts. This means going to the redline is the best place on a stock ITR - might be different depending on modifications - but you should not shift at peak TQ OR peak HP, that is bound to give you a smaller area under the curve (lower bound = where you 'land' after shifting, upper bound = where you shift).</TD></TR></TABLE>

 

With the stock tach, around 8800rpm. The tach is about 400 off up top. Just keep an eye on the tach, cutoff comes quick

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris N &raquo;</TD></TR><TR><TD CLASS="quote">You want to shift where it gives you the greatest area under the tq curve between shifts.</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by typer_801 &raquo;</TD></TR><TR><TD CLASS="quote">You must also consider gearing in the equation too. If you just look at your torque curve on a dyno and fail to recognize the multiplication effect of gearing you'll end up shifting too early.</TD></TR></TABLE>

There are two different methods for determining ideal shift points - (1) the point when the horsepower is equal in both gears, and (2) the point which maximizes the area under the curve. The latter method is referring to the area under the horsepower curve, not the torque curve. Either method takes gearing into account (because horsepower equals torque times revs).

On a stock ITR, though, there is no point below redline which satisfies these methods. Shift at redline, just before the rev limiter kicks in.

P.S. You'll find a shift point calculator here which you can play around with if you like...

 

Yes, my mistake. Maximize area under HP curve, not TQ.

 

stock itr with toda valve train, 9600rpm

 

10,000 rpm.

 

9800rpm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by esponet &raquo;</TD></TR><TR><TD CLASS="quote">stock itr with toda valve train, 9600rpm</TD></TR></TABLE>

Um?

 

i have a stock ecu and my fuel cut off is at 9600 rpms. do u think something is wrong with that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by danny98r &raquo;</TD></TR><TR><TD CLASS="quote">i have a stock ecu and my fuel cut off is at 9600 rpms. do u think something is wrong with that.</TD></TR></TABLE>

Nope nothing is wrong..you just dont have a stock ecu

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Champ R &raquo;</TD></TR><TR><TD CLASS="quote">

Um?</TD></TR></TABLE>

my old motor was a stock jdm itr with toda C,springs,jun retainers,toda gears. chiped p30 (toda program) i shift at 9600rpm,
on the dyno it peaked at around 8800, but if i drag it to 9600 hp drop after i shift is not as bad as hp dro if i shift at 8800,9000.
ex, at 8800 i have 200hp, at 9600 i have 180hp, at 7000 i have 160hp, at 7500 i have 175hp
on first gear, if i shift at 9600(180hp) my rpm drops to 7500(175 hp)
while at 8800 (200hp)my rpm would drop at 7000 (160hp)
does this make sense???