## Tuning Formulas

If you're having a problem with your scoot, drop us a line!

Moderator: Tuna Cowboy

### Tuning Formulas

** borrowed from the tuner Wayne Miller over the pond **
if you feel the need you can add to this thread = PM the admin w/ your data

Calculating CC
=SUM((C5/2)*(C5/2)*3.14*C4/1000)
C5 = Bore
C4 = Stroke

Port Timing Calculator
=((180-DEGREES(ACOS((((C4/2)+C6+C8-C9)^2+(C4/2)^2-C6^2)/(2*(C4/2)*((C4/2)+C6+C8-C9)))))*2)
C4 = Stroke
C6 = Conrod
C8 = Deck Height*
C9 = Dist from top of cylinder to top of port
When measuring Deck height. If you piston is 1mm lower than the top of your cylinder at TDC then you have a negative deck height of 1mm. If you piston is 1mm higher than the top of your cylinder at TDC then you have a positive deck height of 1mm

Do not be confused and enter -1 if you have a negative deck height. You need to enter 1 as this is the measurement from the top of the piston to the top of the cylinder. You should enter -1 if you have a positive deck height

Blowdown calculator
=SUM(((360-G10)/2)-((360-G9)/2))
G10 = Transfer Port Timing
G9 = Exhaust Port Timing

Calculate torque from BHP and RPM
=SUM(J5/J4)*5252
J5 = BHP
J4 = RPM

Calculate BMEP from RPM, BHP and CC
=(600000*(J5*0.746))/(G4*J4)
J5 = BHP
J4 = RPM
G4 = CC

Calculate engine power in Kw from BHP
=SUM(J5*0.746)
J5 = BHP spiderwebb

Posts: 2661
Joined: Fri May 25, 2007 3:15 pm
Location: Eugene, OR

### Re: Tuning Formulas

New gearing calculator...!!

http://gearingcalc.free.fr spiderwebb

Posts: 2661
Joined: Fri May 25, 2007 3:15 pm
Location: Eugene, OR 