Optimum shift point

[mickr32gtr]

Probably a stupid question. Ive got an r32 GTR and plan to take it down the 1/4 mile soon. To get the best time and assuming all other things being equal, should i be shifting at the point of max torque (4400 rpm) or max power (8000 rpm)? Got a PFC and AVCR installed and A/F ratios perfect through the entire rev range.

Cheers

[Guest two.06l]

Probably a stupid question. Ive got an r32 GTR and plan to take it down the 1/4 mile soon. To get the best time and assuming all other things being equal, should i be shifting at the point of max torque (4400 rpm) or max power (8000 rpm)? Got a PFC and AVCR installed and A/F ratios perfect through the entire rev range.  

Cheers

Hi Mick32gtr

Advice from drag racing guru's (croydons) and our experience has shown that changing at the point where torque starts to drop away, high in the rev range is the optimum time. Can you look at your dyno print out and see where the torque starts to drop away?

[mickr32gtr]

Stacey

looking at the dyno chart, the horizontal is speed. The left vertical is kw and the right vertical axis is in "N". If u read the chart the top curve "power", it climbs from 50kw at 80kph to 160kw at 130kph, the gets a little less steeper but keeps climbing to a peak of 208awkw at 180 kph. I have no idea what rpm this was and i think the readings were taken in 4th gear which would make it about 4500 - 5000 rpm from experience (ive had it at 211 kph at 6500 rpm before). If the std r32 gtr has peak torque at 4400 rpm mine (with the PFC) has peak torque about 5500 then. Does that sound right to you?

[ferni]

Not a stupid question, i'm intested too.. if i went now i would be changing at around 7500-8000rpm? so is that wrong?

[blk180]

I would think there is Two things to think about when changings as is already said around when torque drops off and you would aslo want to keep the car on boost the hole time ie; changing at 5500rpm would drop your car off boost in the next gear and u would lose some time while it spoles again.

my 2c

[cameron]

I'm sure SK will help you out

somthing to do with average power ?

[martydaman]

on a stock vechicle optimum "should" be just before redline... often its not though

[Laurence]

This is where some logging G-sensors are a nice little thing to have...

[Duncan]

somthing to do with average power ?

that's it....its time to change up a gear if you would make more power in the higher gear....so check the dyno graph

[Bass Junky]

You need the "Quarter Junior" software.

You put all the details of gear ratios and power figures into it and out comes your optimum shift points

[TIMMMAYYY]

why not just go out there and find out what works for yourself. Its not like you're going to do one pass and call it a day.

[WazR32GTSt]

why not just go out there and find out what works for yourself. Its not like you're going to do one pass and call it a day.

too true. best way to learn is from exerience.

we can sit here all day speculating, but at the end of the day if you take the car to the strip and do a change @ 4400rpm and the car drops off boost, then i guarantee you will never do it again.

try different shift points in different gears and you will learn alot.

my 2c...

oh, and when you find a good shift point combo, post it up for others in future with the same question

[JH32]

there was an article in zoom or high performance imports once about it

but i can't remember what it said