best gears for 800hp
- Thread starter jcveron
- Start date
I am going 3.27 so I can stay in boost longer. With my 3.73 in 1st and 2nd gear is so short I would always have to shift right away when I use up the rpm.
exactly, and with 800-850 whp he should be trapping in the 140 area.
RPM Speed
6000 133
6100 135
6200 137
6250 139
6300 140
6400 142
6500 144
6600 146
:thumbsup:
There are more variables that need to be answered when discussing which gear for a 1/4 mile run. Just like above stated is all true.
You have to know where your car makes peak power at and that will put you in the ball park of what RPM to cross the line which is usually a couple hundred over peak depending on how fast the power drops off.
What size is the height of tires you plan on using. This affects your overal ratio. A taller tire has some advantages such as larger contact patch at the same width size and a more side wall when used with same rim size. This can help soften initial hit, allowing to hit the rim a little harder to get wheel speed up as fast as possible. It can also cause driving the car at speed to sway a little more on the big end when doing steering corrections.
Weight; 800 rwhp will trap 140mph----in a ~4200#. However a 800rwhp will trap 145 in a 3800# car. There is a formula to calculate out potential MPH in the 1/4
(FWHP/Weight)^.333 x 234=mph
I would agree that 3.73 would probably be the right gear for you assuming some of the typical owners modifications/weight.
You have to know where your car makes peak power at and that will put you in the ball park of what RPM to cross the line which is usually a couple hundred over peak depending on how fast the power drops off.
What size is the height of tires you plan on using. This affects your overal ratio. A taller tire has some advantages such as larger contact patch at the same width size and a more side wall when used with same rim size. This can help soften initial hit, allowing to hit the rim a little harder to get wheel speed up as fast as possible. It can also cause driving the car at speed to sway a little more on the big end when doing steering corrections.
Weight; 800 rwhp will trap 140mph----in a ~4200#. However a 800rwhp will trap 145 in a 3800# car. There is a formula to calculate out potential MPH in the 1/4
(FWHP/Weight)^.333 x 234=mph
I would agree that 3.73 would probably be the right gear for you assuming some of the typical owners modifications/weight.
for road racing you don't want a 28" tire
you'd want a closer to stock 27" or shorter tire, less sidewall flex is needed for road course
3.73's with 28" will top out in 4th in the mid/upper 120's
Sorry dude that math is way off or its a typo.
I hit 137.7 with 410's and 28 slicks at 6600-6700
Robert thats pretty close to what the math says it should be. The math isn't exact but gets a person in the ballpark fairly close. Calculated out its ~6775. 3 things are going on also that can dirty up the math.
1: Is tire growth which is hard to calculate as each tire grows and there is a lot of factors in that so I usually leave them out. But every 1/10 of an inch is ~25rpm
2: Trap speed is calculated from the amount of time it takes to break the 2 beams of the last 66ft so the MPH is based on the computer calculations on that.
3: Factory Tachometer is usually off by a little bit. Although in the 99-later cars it's much much closer then the older ones. Due to the way they get their signal. My 99 cobra was extremely close although it was hard to break it done to the 25/50 rpm increments as the factory tac is just not that detailed. LOL I had a fox that was off by 50rpm at idle and almost 500rpm at redline! One of my friends had one that was close to 1,000 rpm off. Man has technology brought quality a long way.
I hope some of this information helps you guys seeing how we are all here to learn from each others experience.
1: Is tire growth which is hard to calculate as each tire grows and there is a lot of factors in that so I usually leave them out. But every 1/10 of an inch is ~25rpm
2: Trap speed is calculated from the amount of time it takes to break the 2 beams of the last 66ft so the MPH is based on the computer calculations on that.
3: Factory Tachometer is usually off by a little bit. Although in the 99-later cars it's much much closer then the older ones. Due to the way they get their signal. My 99 cobra was extremely close although it was hard to break it done to the 25/50 rpm increments as the factory tac is just not that detailed. LOL I had a fox that was off by 50rpm at idle and almost 500rpm at redline! One of my friends had one that was close to 1,000 rpm off. Man has technology brought quality a long way.
I hope some of this information helps you guys seeing how we are all here to learn from each others experience.
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