Hi everyone,

I was wondering if someone could guide me through calculating the RPM landing points for 07 civic si. I can't seem to find the equation to do so. Here's what I've calculated so far using SEARCH.

Transmission code: PNN4

Ratio MPH
1st 3.266 38.85
2nd 2.13 59.57
3rd 1.517 83.65
4th 1.147 110.63
5th 0.921 137.78
6th 0.659 192.55
Reverse 3.583
Final Drive 4.764
LSD Yes


Modified by Tam N at 12:56 AM 1/31/2007

 

Damn you people with a 6th gear
sorry I can't help, math is not my strong suit

 

maybe this should be in another forum?

 

there is a tech discussion in that forum. bense is the guy to ask although most of us here could give you a good idea. what I would do is calculate the rate of change from gear 1 to gear 2 and then take that and apply it toward rpm. if you know the current gear lands at 5500 from 2 to 3rd and there is 8% rate of change you can do the math. ultimately, you will know exactly whats there once you drive on it

when I went to the B16 3rd,4,5th gears in my gsr tranny I wanted to play with the numbers since the second gear is longer than ITR/B16. it definately stays up there
pretty nice from what I was used to

 

see below:

http://www.autocrossing.com/cgi-bin/gearcalc.cgi

 

*intercom*

"Paging doctor Bense! Doctor Bense to the All Motor forum."

*/intercom*

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MikeSarr_GSR &raquo;</TD></TR><TR><TD CLASS="quote">there is a tech discussion in that forum. bense is the guy to ask although most of us here could give you a good idea. what I would do is calculate the rate of change from gear 1 to gear 2 and then take that and apply it toward rpm. if you know the current gear lands at 5500 from 2 to 3rd and there is 8% rate of change you can do the math. ultimately, you will know exactly whats there once you drive on it

when I went to the B16 3rd,4,5th gears in my gsr tranny I wanted to play with the numbers since the second gear is longer than ITR/B16. it definately stays up there
pretty nice from what I was used to </TD></TR></TABLE>

Only 200 miles on the car =P Still breaking her in. Either way no real fuel tunning options right now. Just sitting back and calculating the math for now =]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">see below:

http://www.autocrossing.com/cgi-bin/gearcalc.cgi</TD></TR></TABLE>

Thanks, I'll give that a try. If someone has the actual formula/calculations that would be awesome.

The results for an 07 si:

Gear Shift landing RPM@8000
1st N/A
2nd 5217
3rd 5698
4th 6049
5th 6424
6th 5724

Now on to find stock dyno graphs and look see where the powerband is located

 

Here you go.

Tire_Width=205.0;
Aspect_Ratio=55.0;
Tire_Diameter=15.0;
TireSideWall_Hieght=2*(Tire_Width/25.4)*Aspect_Ratio/100;
d=Tire_Diameter+TireSideWall_Hieght;
d_m=d*0.0254;
pi = 3.14159;
d_m is in the unit of meters


J1 gear ratios
gk(1)=3.230;
gk(2)=2.105;
gk(3)=1.458;
gk(4)=1.107;
gk(5)=0.848;
Final_Drive=4.400;

v0 : enter in mph
v0=v0_mph*0.44704
rpm=(v0*60)*Final_Drive*gk(i)/(pi*d_m)

you can use the final equation to solve for rpm

 

Thanks!

ps. I looked at the stock powerband location and ewwwwwwww. Okay one more noob question. With mods and tunning I can extend and increase my powerband location right? My First car with 3 cam lobes! I've spent years reading HT but no car to mod. (well i had a stock rs integra)