I have recently done some very consistant power runs with a friend's G-Tech timer, and it's raising some questions as I review some of the power/torque curves in comparison to the g-force/speed graph.

Being that the F23 is slightly modded, and is naturally more stout in low-end torque compared to most smaller engines, my g-force acceleration curve tends to suggest that the majority of my accel power is from 2500- 4500 rpms, and tapers off above and below that range.

My torque curve starting at 2000 rpms remains fairly level at 150-160ft/lbs until it starts to taper off around 4000, and continues linearly to 128ft/lbs at 6800rpms. Whereas the power curve starts around 70hp at 2000, and climbs evenly until 4200, where it levels out at 155hp and carries until 6800rpms.

Now with the majority of the acceleration between 2500, and 4500 rpms, should I be shifting early?? or should I draw it out to redline in order to avoid time lost to shifting?? I can run the 1/8th without leaving 2nd gear, so obviously that would be preferred, but if my goal was to run a 1/4 mile or a much shorter distance than the 1/8th, would I benefit from a different shifting profile?



Modified by AFAccord at 2:39 PM 8/5/2005

 

i understand what you are saying w/o pictures

to me i think shifting early would lower your times

from my experience(just driving w/o a computer or anything) if im WOT and i shift sooner as the obvious, the RPM's drop lower than if you shifted later

if your tryign to get a faster time, and shift too soon, the RPM's could drop below your torque band and cause lack of performance, but on the contrary, if your power falls off, then there is no real point to rev that high, conserve the motor a little bit and keep the exhaust tone down

back on track, i would say keep shifting where you are unless you feel that you can keep the RPM's within the torque/power band

 

Hey, thanks for the comment! I was mainly asking this because if I'm at full throttle, and I shift at 4500rpms, then my rpms still fall into the strongest part of my accel curve (2500 - 4500rpms). I'll get some pics up to further clarify when i get home from work.

 

G-Tech is crap, slap that baby on a dyno

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vt4cPwn35 &raquo;</TD></TR><TR><TD CLASS="quote">G-Tech is crap, slap that baby on a dyno </TD></TR></TABLE>

Completely irrelevant comment...

I'm not relying on the G-tech for a dyno. It can only measure net power, which is affected by whatever vehicle weight you enter. ie. completely useless... What I DO see as relevant, is the rpm vs g-force reading it provides. Please focus your comments on this...

 

 

okay

well that picture just confused me more but i get the jist of it

 

The graph is the acceleration g-forces in run. This was done by launching in 2nd gear and flooring it all the way to red-line. this gives an overall idea of how hard the car accelerates through the entire rpm range.

Left to right = rpm's go up

Bottom to top = g-forces go up

 

gotcha

 

With peak power at 6800 and peak tq from 2000-4800 I would probably see where your rpms fall if you shift at 6700 and 6800. I would think if you shift from 1-2 at 6700 it should go right around 5500-5800.

Tq will be basically your 0-60 and hp will be your top end...you could experiment mainly with your 1-2 shift but from 3rd on I would shift at 6800.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .ken &raquo;</TD></TR><TR><TD CLASS="quote">With peak power at 6800 and peak tq from 2000-4800 I would probably see where your rpms fall if you shift at 6700 and 6800. I would think if you shift from 1-2 at 6700 it should go right around 5500-5800.

Tq will be basically your 0-60 and hp will be your top end...you could experiment mainly with your 1-2 shift but from 3rd on I would shift at 6800.</TD></TR></TABLE>

That's what i'm talkin about! I especially agree with the torque being the 0-60 and hp for top end. Sounds like a good plan. Anyone second that?

 

to get accurate shifting points you need to know where your car makes the most power in teh RPM range, you then, by trial and error, find points in your gearing that drops your next gear right in that RPM area within a few hundred RPM

I am also sorry to inform you that GTech will not accurately give you this info, you need to dyno the car, corner weight it, etc. then use that info with teh GTech to get its best results

 

i do second that

and i also second what urbanlegend said

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Vt4cPwn35 &raquo;</TD></TR><TR><TD CLASS="quote">G-Tech is crap, slap that baby on a dyno </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by urbanlegend21 &raquo;</TD></TR><TR><TD CLASS="quote">I am also sorry to inform you that GTech will not accurately give you this info, you need to dyno the car, corner weight it, etc. then use that info with teh GTech to get its best results</TD></TR></TABLE>

What he said just in less words