Black R

I just saw a thread the other day with the 4.4 vs 4.7 vs 4.9 final drives in graph form from a dyno or maybe plotted in excel as well... but I can't find it in a search...

Anybody still got it in their internet history? Please post the link!!1


TIA!

RTW DC2R

I have a chart somewhere but I couldnt find it. You can take the info from this page (by Bense) and plug it into an Excel sheet, then just view it as a chart or graph.

http://thebense.livejournal.com/56502.html

ZygSpeed

Do you mean this one?
http://www.fatboyraceworks.com/gears/

neo_

This?

tartje

iTrader: (1)

wow, didn't realise the 4.785 had such a big effect

CXtypeR

JDM ITR, 98+
1st - 3.230
2nd - 2.105
3rd - 1.458
4th - 1.034
5th - 0.787
final - 4.785

this is a good way to explain why shifting high in the rpm is beneficial even if it doesnt make any power anymore.

lets take a stock block jdm itr with headwork. 8400 vs. 9500

8400rpm 1-2, 2-3, 3-4
5474, 5818, 5957

9500rpm 1-2, 2-3, 3-4
6191, 6580, 6737

we all know that the higher rpms make more power so when you change gear, you put more power to the ground

*cliff* revving past redline isnt ONLY for ricers*

ZygSpeed

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CXtypeR &raquo;</TD></TR><TR><TD CLASS="quote">... lets take a stock block jdm itr with headwork. 8400 vs. 9500

8400rpm 1-2, 2-3, 3-4
5474, 5818, 5957

9500rpm 1-2, 2-3, 3-4
6191, 6580, 6737

we all know that the higher rpms make more power so when you change gear, you put more torque to the ground</TD></TR></TABLE>

I'd want to see a dyno chart of each motor before jumping to this conclusion, because you're past your tq peak @ 9500.

And even then the road speeds at those engine speeds need to be compared.
On the plus side your acceleration will be better ...

nsxtasy

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CXtypeR &raquo;</TD></TR><TR><TD CLASS="quote">we all know that the higher rpms make more power so when you change gear, you put more power to the ground</TD></TR></TABLE>

That's a very misleading statement, in several ways. For one thing, you use the word "power" in two different ways - the first mention appears to be to "horsepower" whereas the second one appears to instead imply "acceleration".

You might want to read this article to learn the difference between torque, horsepower, and acceleration. Briefly, what matters, in terms of acceleration, is torque at the wheels. Torque at the wheels equals torque at the crank, minus drivetrain losses, times gearing. And that's what this graph shows - quite well, in fact. You can consider these to represent graphs of the rate of acceleration.

This graph can be used to show optimal shift points as well as gearing advantages/disadvantages. As you can see, when any of the torque curves ends, at the 8400 RPM redline, it is still above the torque curve plotted for the next higher gear. That means that you will achieve the best acceleration by going all the way up to redline before shifting. If you have a higher redline, as Ed (zygspeed) notes, you would need to plot the entire curve up to that higher redline to see whether you would still want to shift at redline, or at a lower point. If the curve for one gear crosses the curve for the next gear, then you would want to shift where they cross, rather than at redline.

On this graph, within these rev ranges, the shorter gearing consistently gives better acceleration within each gear. However, it also requires upshifting at a lower shift point (road speed). As long as the two gearing setups are within the same gear - for example, comparing the 4.9 with the 4.4, this is at 0-36 mph, 40-55 mph, 61-79 mph, etc - the shorter gears provide faster acceleration. At the other speeds - 36-40 mph, 55-61 mph, 79-88 mph, etc - the taller gears provide faster acceleration, because they permit you to remain in a lower gear at these speeds. (I posted the same thing, in greater detail, in another topic three years ago, here.)

These numbers are the calculated shift points using an 8400 RPM redline. They appear slightly different on the graph; I suspect the graph uses shift points at 8500 or 8600 RPM for its calculations. In either case, the effect remains the same.

Overall, from a standing stop - such as at a dragstrip - the shorter gears will give you faster overall acceleration. However, as you can see, there are specific speeds at which taller gears provide faster acceleration, so on a road course, it depends on what speeds you're driving.

The same phenomenon will remain true if your mods give you a higher redline, since that higher redline would apply regardless of your gearing setup.



Modified by nsxtasy at 12:12 PM 1/2/2007

Flux

Good write up Nsxtasy...

Black R

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

</TD></TR></TABLE>


DING DING DING

WINNAR!!!11

Now where did you find that in a thread?

neo_

^^^ I found it over at team-integra in the final drive article.

RTW DC2R

this is useful as well, awesome little calculator
http://autocrossing.com/cgi-bin/gearcalc.cgi

BlueTeg

iTrader: (2)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">
Now where did you find that in a thread?</TD></TR></TABLE>

You can find it on here by searching for posts by: SurferX

surferx = co-founder of team-integra.

neo_

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

You can find it on here by searching for posts by: SurferX

surferx = co-founder of team-integra.</TD></TR></TABLE>

Yeah, he wrote the article on T-I. Don't know if he created all the graphs, but its an great article.

MorningZ = Founder of team-integra and lives two blocks away from me, great guy.

get RIGHT

Good topic.
Ive been debating these same ideas lately.

88 rex

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITR 00-0477 &raquo;</TD></TR><TR><TD CLASS="quote">Good topic.
Ive been debating these same ideas lately. </TD></TR></TABLE>

^

DOOOOOO IIIITTTTTTTTTTT!


Your car will thank you

4.7/4.9 FTW!