i need a power graph of when the rpms top out 1,2,3,4, and 5 so i know exactually when to shift
my car is an s-4 n/a 88 slight mods, exhaust, intake, high flow resonator, emmisions bs tookin off, ac removal and interior gutted.
sorry if i did not catch in the faq but i searched untill my eyes went numb and my shoulders caluapsed so if you have a nice plotted out graph showing hp in each gear i would much appreshiate it thanx

 

Take it to a dyno.

 

^^^

All cars are different. You need a dyno, and the appropriate program to calculate your optimum shift points.

 

As a general guideline, shift around redline

 

Once you start modding, the redline becomes somewhat superflouous. It is still a good rule of thumb, but take my car for instance, my optimum 1st gear shift is 7800. Well past the redline.

 

if i knew where ther was a dyno in my area i would take it but i just want to know ruffly, because i shifted at 8 grand and went to send gear and roasted the tires and my car hit zer0 to 80 in no time i was supprised i think my motor has been mildly ported because it handle high revs with out power loss. just wondering. it would make my day to dyno it but no clue where one is

i also bought the 7 of a kid that had the motor redone by maztech so it has ruffly 45000 miles on it runs strong too i dont know if it is a faster 7 or something because its the fastest n/a in my hood

 

Drive up through your rpm range until you feel the power drop off. Shift just before that (depends on your reaction time). Are you talking for street driving, or on the track?

 

mostly street,
the only thing close to a track that i been on was the downtown st. petersburg florida grand prix, it was 2 days untill they raced and it was open for traffic so i did a few laps cool as hell let me tell ya!!!

 

The butt dyno is pretty subjective, dont you think?

 

yea can anyone point out were there is a dyno in st. pete florida thanx

 

True, but he has only slight modifications. I still agree though, the only way to really know is take it to a dyno.

 

god damit

 

you guys are kickin my *** no offence

 

Kickin your ***?

 

None taken?

 

so no graphs?

 

I don't know about other cars, but in mine, it's pretty easy to tell where the usable power drops off. In my case, it's not so much about numbers, as about usable power.

 

LOL! So I guess I am just a numbers guy, eh?

 

So... you ever think that the "usable power" drops off at a certain number? Just a thought.

 

Yeah, it does, I just can't be looking at the tach, thats all. So, knowing that point with my butt is alot more helpful than knowing that it drops off at ~8300rpm. But there's nothing wrong with knowing numbers, or with being a numbers guy.

 

Go some place safe and keep doing runs while shifting at 8300, or whatever your optimum shift rpm is. You'll learn what it feels like with your "butt dyno", except now it will be accurate .

 

My butt dyno is accurate. I'm well past the "where do I shift at" stage of things.

 

Your butt dyno is inaccurate, and I will tell you why.

Once you start feeling a marked decrease in horsepower, you have LONG SINCE past the peak torque range. The BEST and ONLY way to calculate optimum shift points is to go to a DYNO, pay the $50 or so bucks, and then plug that information into a program such as the one my tuner uses.

Effective shifting, is a matter of AVERAGE horsepower over a useable range, not just shifting LONG after power decreases, or as soon as you percieve power to be lost. Its the same concept with turbos. Big turbos give big numbers, but over how much of your useable RPM band?

Anyways, have fun with the butt dyno, but it is wholly inaccurate.

 

Power and torque peak at the same places in the rev range regardless of what rear you're in, so that won't help you.

A dyno is totally unsuitable for determining shift points. The only way to accurately determine the perfect shift points is to measure and graph the acceleration vs. speed in each gear. The perfect shift point is where the acceleration curve of one gear crosses the curve of the next gear up. But this is assuming that this occurs before redline, which is not always the case.

To measure acceleration cheaply you can use an accelerometer like this one:

http://us1.webpublications.com.au/st...1/2133_8mg.jpg

Or you can use an inclinometer like this one (using simple trig to convert angle to g's):

http://us1.webpublications.com.au/st...1/2133_6mg.jpg

Here's the reslts of acceleration testing on an Australian Mitsubishi Verada (218hp 3.5L V6 FWD):

http://us1.webpublications.com.au/st.../2133_11mg.jpg

You can see that on this car the optimum shift point for all gears is at redline.

If you want to spend more money, the Gtech Pro is a pretty cool performance measurement tool.

http://www.gtechpro.com/

 

Not sure what the basis is for this statetement.

Dyno graphs are the only way to accurately plot your power curve.

Example dyno graph with the shift points superimposed: