Old 09-15-2007, 11:14 PM   #1
Phusion
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Default How-To: Make Ratios

PLEASE DO NOT EMAIL ME IN-GAME ABOUT THIS THREAD

Here it goes guys. I'm going to try to explain this the best way I can. First of all, this is not how you make your super fast H2H ratios. This is used as a start off point to base the ratios off of. Once you complete this, you should be able to adjust the ratios little by little until they are perfect for your car.

The Formula:
RPM After Shift = (Ratio Shift Into / Ratio Shift From) x RPM Before Shift

What does this mean?
RPM After Shift [equals] Ratio Shift Into [divided by] Ratio Shift From [multiplied by] RPM Before Shift

Let me try to explain this a bit.
RPM After Shift - The RPM at which you want your needle to drop to after you shift. This is usually the RPM at which you have the MAX torque.
Ratio Shift Into - This is the ratio at which you will get to after you shift. This is the unknown variable in the equation. We will be find out how to get this later.
Ratio Shift From - This is the ratio at which you shift from. All you have to do here is input the ratio you used on the previous gear.
RPM Before Shift - This is the RPM at which you should be shifting every gear.

Step #1:
-Get your MAX horsepower and @ what RPM
-Get your MAX torque and @ what RPM
-Get the RPM at which you want to shift at
-Decide on your 1st gear

Step #2:
-Input your information

In this example we will be using my semi-stock Mustang.
-MAX 265.72 HP @ 5600RPM
-MAX 295.06 FT-LBS (Torque) @ 4100RPM <- "RPM After Shift"
-Redline is 6200RPM. That is the shift point I want <- "RPM Before Shift"
-1st Gear = 3.750 <- "Ratio Shift From"

So this is what we have so far:

4100 = ( ? / 3.750 ) x 6100

So what we have to do now is find out the "?" so we can get each ratio.

Step #3:
For those younger kids who don't know how to compute this equation I will help you out.

Equation:
4100 = ( ? / 3.750 ) x 6100

You want to get rid of the 6100 so you divide 6100 by 6100 and get 1. So meaning if you multiply what's in the parenthesis by 1 you will just get the same number so you don't even have to put the 1.

Now you have to divide 4100 by 6100. Your answer is a long decimal. Just round it to the 4th number and you should get .6721

So now we have:
.6721 = ? / 3.750

After you divide the "RPM Before Shift" by itself and divide the "RPM After Shift" by the "RPM Before Shift" then the outcome will be the only formula you will need from now on.

Step #4:
-Finally we are on our way of finding our 2nd gear ratio.

Now what we have to do is multiply our "Ratios Shift From" by our "RPM After Shift". That would be .6721 x 3.750.

Our answer is 2.520. That is now our 2nd gear ratios.

Step #5:
-Now we can figure out the rest of our ratios like this:

Remember how we got 2nd gear? Now all you have to do is change 3.750 to 2.520. After you've done 2nd gear then continue with the rest. Just input the previous gear in the spot of "RPM Shift From"

1st gear: 3.750
2nd gear: .6721 x 3.750 = 2.520
3rd gear: .6721 x 2.520 = 1.694
4th gear: .6721 x 1.694 = 1.139
5th gear: .6721 x 1.139 = .766
6th gear: .6721 x .766 = .515

Now as for the Final Drive gear. You are going to have to play with that yourself. Usually you want your last gear finishing at redline. If your gears are too slow and your last gear finishes way before redline then raise up your Final Drive ratio. If they are to fast and your last gear is redlining too soon then simply lower it.

Remember this is just how to get a base for ratios. Not ratios for an actual setup. I tried to explain the best I could. If there is anyone who can explain this better than please do.

-Phusion

PLEASE DO NOT EMAIL ME IN-GAME ABOUT THIS THREAD

Last edited by Phusion : 03-04-2011 at 11:47 PM.
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Old 09-15-2007, 11:41 PM   #2
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.. i think i got lost some where at the top i cant remember tho lol
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Old 09-16-2007, 12:17 AM   #3
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Let me know what part you need help with. It's a confusing but not impossible to understand. If you read it thoroughly you should be able to get.

Again, just tell me which part confused ya.

-Phusion
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Old 09-16-2007, 01:04 AM   #4
7rhymes
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Doesn't even need to be all that lol. Making ratios is based on the max hp of your car and on how you wanna leave. If you wanna rev launch then your first and final need to be alittle lower so you don't spin. To take your Stang if you wanna make it a h2h kinda car. Then you will need to leave on a roll start so you can make the first and final higher in order to leave with nos without spinning. Take practice to make ratios everyone runs and races differently so therefore your ratios will be different.
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Old 09-16-2007, 06:31 AM   #5
Jordan
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lol

i did everything you said & i was running faster with my stock ratios.
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Old 09-16-2007, 12:45 PM   #6
smirz
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Quote:
Originally Posted by Jordan View Post
lol

i did everything you said & i was running faster with my stock ratios.
hahahahahaha really?
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Old 09-16-2007, 03:51 PM   #7
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Trust me it works. You might not have put the right numbers in the right spots. If you give me your MAX TORQUE @ RPM, the RPM that you want to shift at, and your first gear ratio then I will be glad to make you a set with this formula. I promise you it works.

Then all you have to do is tweak them a bit. But they should be way better than stock ratios.

-Phusion
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Old 09-16-2007, 05:19 PM   #8
initialspark
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Question get me started please

i tried what you said but i got a little lost. so here is my stuff and if you can help me wit the first set of ratios than i can do the rest thanks.
i have a evo

max 373.47 HP @5600
max 295.06 Ft-Lbs @4100
redline is 7000
1st gear 2.928
2nd 1.950
3rd 1.407
4th 1.031
5th 0.720
6th 0.000
final 4.529

if you can help THANKS
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Old 09-16-2007, 05:48 PM   #9
Phusion
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Quote:
Originally Posted by initialspark View Post
i tried what you said but i got a little lost. so here is my stuff and if you can help me wit the first set of ratios than i can do the rest thanks.
i have a evo

max 373.47 HP @5600
max 295.06 Ft-Lbs @4100
redline is 7000
1st gear 2.928
2nd 1.950
3rd 1.407
4th 1.031
5th 0.720
6th 0.000
final 4.529

if you can help THANKS
So im guessing you want to shift at 7000RPM? Also, your first gear doesn't have to be what it has already. Pick your first gear depending how you like it. Higher if you want it faster or lower if you want it slower. You sure that's what you want?

When you reply I will work on your set.

-Phusion
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Old 09-17-2007, 05:56 PM   #10
Sk8rboy1
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Good tuning guide
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