4.77's
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From: No va
i did that time without gears.
Fuelrush if you have an ap1 i think u will beable to trap in 4th with the 4.10's because of the 9k redline i didn't because i have an ap2 and the shorter redline but with the 4.77's you will have to shift into 5th. you make up for so much down low with the 4.77's the extra shift won't make a huge dent on the time. i been practicing my 4-5th shift.
im shooting for a 12.999-13.0 with just gears aem v2 and berk tp and a custom 3" single exhaust vafcII tuned. If i don't break 12's all motor with just bolt on's then im going ITB's or 2.5L stroker kit.
Fuelrush if you have an ap1 i think u will beable to trap in 4th with the 4.10's because of the 9k redline i didn't because i have an ap2 and the shorter redline but with the 4.77's you will have to shift into 5th. you make up for so much down low with the 4.77's the extra shift won't make a huge dent on the time. i been practicing my 4-5th shift.
im shooting for a 12.999-13.0 with just gears aem v2 and berk tp and a custom 3" single exhaust vafcII tuned. If i don't break 12's all motor with just bolt on's then im going ITB's or 2.5L stroker kit.
wow lmao
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From: No va
its still cold here in n. va but i think the first track day is gonna be march 3rd but im going to get dynoed and hopefully tuned that day so i won't be going to the 1/4 until the next weekend. i think its gonna take quite a bit to break that 12 second mark with street tires we'll see. i heard with gears alone it takes something like .5 off your 1/4 if drivin properly. i never lower my tire pressure which i am definately doing this season.
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I see alot of misinformation here... lets see where to start...
Your acceleration is determined by the actual TQ produced by the wheels. This is the engine TQ x transmission ratio x rear end ratio minus friction. If you take that torque rating (which is not the same as RWTQ and is typically in the ballpark of 3k+ lbf-ft for 1st gear) and divide by the diameter of your tire (in feet), then you will get a force in pounds. If that force equals the weight of your car, then you will accelerate at 1g or 9.81 m/s^2... and it can of course go up and down from there as well.
By adding steeper rear end gears, you effectively increase that wheel torque by 16% in your first gear. The effects die off fast after that point.
One way to look at gearing is to think of a race from 0-100 (or whatever speed)... if you have your gears set up so that your top gear maxes out at 100 and your oponent has much lower gears, then you will get to shift more times and keep your RPMs up.
An extreme example of this is to say that you have a car with a 2 speed racing a car with a 6 speed (all else equal), then the 6 speed will win because it can utilize its powerband more effectively.
Now lets take the example of 2 cars, one with steep gears 5.xx+ and one with low gears 3.xx, and they are both cruising at the same RPM and the same speed. If the cars both made the same power, then they would both accelerate at EXACTLY the same speed, regardless of the fact that they have different gears.
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On the topic of HP gained or lost on a dyno with gears... in my experience, steeper gears tend to have a higher drivetrain loss than lower gears and are always weaker due to the nature of ring and pinions. In order to make a higher ratio, you have to sacrafice tooth contact. The question is really where the weak point is. I am not very familiar with the S2K rear ends enough to say if the weak points are in the ring gear, posi unit, output shafts, or simply the casing itself. But I can tell you that 2 equal quality ring gears, the higher the ratio, the weaker the ring gear.
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This whole "16% power gain" is not the propper way to look at it. Just think that it will accelerate 16% faster in 1st gear, but you also lose 16% speed in that gear. You need to understand the basics of horsepower...
Acceleration can be determined by TQ and gearing (but that requires you to know your individual gears) or by HP and Speed.
Acceleration is directly related to HP produced at a given time (in whatever gear, all that is important is the HP at that RPM) and the speed (the faster you go, the more horsepower it takes to accelerate).
If you double your speed, you need to double your horsepower to obtain the same rate of acceleration due to the fact that horsepower and speed are both rates of time, whereas TQ is not.
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Horsepower is often hard for most people to understand, but I hope that helps.
Your acceleration is determined by the actual TQ produced by the wheels. This is the engine TQ x transmission ratio x rear end ratio minus friction. If you take that torque rating (which is not the same as RWTQ and is typically in the ballpark of 3k+ lbf-ft for 1st gear) and divide by the diameter of your tire (in feet), then you will get a force in pounds. If that force equals the weight of your car, then you will accelerate at 1g or 9.81 m/s^2... and it can of course go up and down from there as well.
By adding steeper rear end gears, you effectively increase that wheel torque by 16% in your first gear. The effects die off fast after that point.
One way to look at gearing is to think of a race from 0-100 (or whatever speed)... if you have your gears set up so that your top gear maxes out at 100 and your oponent has much lower gears, then you will get to shift more times and keep your RPMs up.
An extreme example of this is to say that you have a car with a 2 speed racing a car with a 6 speed (all else equal), then the 6 speed will win because it can utilize its powerband more effectively.
Now lets take the example of 2 cars, one with steep gears 5.xx+ and one with low gears 3.xx, and they are both cruising at the same RPM and the same speed. If the cars both made the same power, then they would both accelerate at EXACTLY the same speed, regardless of the fact that they have different gears.
-------------
On the topic of HP gained or lost on a dyno with gears... in my experience, steeper gears tend to have a higher drivetrain loss than lower gears and are always weaker due to the nature of ring and pinions. In order to make a higher ratio, you have to sacrafice tooth contact. The question is really where the weak point is. I am not very familiar with the S2K rear ends enough to say if the weak points are in the ring gear, posi unit, output shafts, or simply the casing itself. But I can tell you that 2 equal quality ring gears, the higher the ratio, the weaker the ring gear.
--------------
This whole "16% power gain" is not the propper way to look at it. Just think that it will accelerate 16% faster in 1st gear, but you also lose 16% speed in that gear. You need to understand the basics of horsepower...
Acceleration can be determined by TQ and gearing (but that requires you to know your individual gears) or by HP and Speed.
Acceleration is directly related to HP produced at a given time (in whatever gear, all that is important is the HP at that RPM) and the speed (the faster you go, the more horsepower it takes to accelerate).
If you double your speed, you need to double your horsepower to obtain the same rate of acceleration due to the fact that horsepower and speed are both rates of time, whereas TQ is not.
----------
Horsepower is often hard for most people to understand, but I hope that helps.