Gearing and power adders?
04-22-2010, 06:11 AM
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Gearing and power adders? Why do various power adders such and nitrous, turbos, and superchargers effect your gear selection choice or do they?
I'm referring to drag racing.
I see why a turbo car may want to use numerically lower gears to some extent, but what about other power adders like centrifugals, direct displacement, and nitrous?
I'm referring to drag racing.
I see why a turbo car may want to use numerically lower gears to some extent, but what about other power adders like centrifugals, direct displacement, and nitrous?
04-22-2010, 10:49 AM
#2
Usually, Power adder cars would put up high traps speeds and would run out of gear. Myself i have 4.56 and you need a 28 inch tall tire so dont hit the limiter, N/A, but if i added nitrous i would hit limiter unless i ran a taller tire which is a challenge on a Fbody without cutting like crazy.
04-22-2010, 11:11 AM
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Usually, Power adder cars would put up high traps speeds and would run out of gear. Myself i have 4.56 and you need a 28 inch tall tire so dont hit the limiter, N/A, but if i added nitrous i would hit limiter unless i ran a taller tire which is a challenge on a Fbody without cutting like crazy.
Your response only explains why you chose the tire size that you have and not why you're running the gearing you are.
Are you saying we need to choose our gearing based on the tire size you want to run?
How do you select gearing based on HP, torque, and limiter?
04-22-2010, 11:53 AM
#4
This question really needs to be posted in the Forced Ind. Nitrous, and Dragracing section as well.
To give as MUCH clarification that I can.
There are MANY varibles in deciding what works best for what situation you put your vehicle in.
Gearing is in my OWN opinion that should be picked last, after you have determined.
ET expectations
Race Weight
Drivetrain
Engine combo
Required suspension and tire
Gearing will dictate two things.
1) Torque Multiplication- Effectivly how much TQ is applied based on RPM launch speed, TQ # (at the given RPM), 1st gear ratio in the trans, and rear gear ratio and also to a minor degree Tire height.
2) Where your power band comes in and how much RPM you can use. Again augmented by things like tire height and also if its a radial vs bias ply. As a Bias ply will grow at speed.
Your asking a VERY broad question and I can go days talking about every different engine combo, drivetrain, rear suspension, and in different scenerios.
In relation to Drag Racing, you need to cut a 60 foot that is at least in the 1.4's and to some thats still garbage. But for the average drag car, its good.
Depending on drive train and a host of other factors. For MOST cars that are truely competitive, its called....
Trial and Error.
Once mentioned to me by a few senior members and moderators. The most expensive part of racing is the dialing in of a combonation, spending the time and money to go to the track and try out 4 converters, and 5 different sets of tires and the hundreds of suspension adj. for each to see what works for THAT car the best.
Most good racers can definitly "Ball Park" you but in the end, how determine it is by going out there and trying it out and see what works, and what does not.
Like said. Not meant to be "The" answer but it should help you narrow down your broad question.
To give as MUCH clarification that I can.
There are MANY varibles in deciding what works best for what situation you put your vehicle in.
Gearing is in my OWN opinion that should be picked last, after you have determined.
ET expectations
Race Weight
Drivetrain
Engine combo
Required suspension and tire
Gearing will dictate two things.
1) Torque Multiplication- Effectivly how much TQ is applied based on RPM launch speed, TQ # (at the given RPM), 1st gear ratio in the trans, and rear gear ratio and also to a minor degree Tire height.
2) Where your power band comes in and how much RPM you can use. Again augmented by things like tire height and also if its a radial vs bias ply. As a Bias ply will grow at speed.
Your asking a VERY broad question and I can go days talking about every different engine combo, drivetrain, rear suspension, and in different scenerios.
In relation to Drag Racing, you need to cut a 60 foot that is at least in the 1.4's and to some thats still garbage. But for the average drag car, its good.
Depending on drive train and a host of other factors. For MOST cars that are truely competitive, its called....
Trial and Error.
Once mentioned to me by a few senior members and moderators. The most expensive part of racing is the dialing in of a combonation, spending the time and money to go to the track and try out 4 converters, and 5 different sets of tires and the hundreds of suspension adj. for each to see what works for THAT car the best.
Most good racers can definitly "Ball Park" you but in the end, how determine it is by going out there and trying it out and see what works, and what does not.
Like said. Not meant to be "The" answer but it should help you narrow down your broad question.
04-22-2010, 10:45 PM
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excellent respone black. This is information I knew but and just trying to make an intelligent and informed decision. The stock 3.42's with a 26.5 inch tire a definitely hurting my 60 and trap speed. My quickest ET was at 112. I'm racing in really high DA also and I'm nowhere near the limiter at the traps. The way I figure it some 4.11 gears if I can hit the limiter will net me 120 mph and be deep in the 11's
Car is near stock weight. I may be able to get another 100 lbs. Off of it but that's about as far as the weight reduction will go.
Car is near stock weight. I may be able to get another 100 lbs. Off of it but that's about as far as the weight reduction will go.
04-23-2010, 03:17 PM
#6
Great post by "black..." above!
In short, my gearing choice was one of the first decisions I made however the selection was made to reflect my future planned mods and goals. On the front side I didn't get much benefit from going from a 3.42 to a 3.90, however everything eventually fell into place. A 4.56 would've been a blast but I would've had to pull it out once I finished my mods.
I chose a 3.90 because I know I can get up to 132 mph in 4th gear before I run into the rev limiter (tire is a 315/35/18). My goal from an ET standpoint was to crack into the 10's and I wanted to have room to trap up to 130+.
The rest of my mods compliment the gear selection: middle of the road cam mates up nicely with a 3.90 (still have a decent band to pull through before I have to shift), higher compression setup with nitrous, traction with a 3.90 on a warm tire is still manageable, needed modest gas mileage and good street manners and I can still pull almost 20 mpg cruising on the highway, etc.
In short, my gearing choice was one of the first decisions I made however the selection was made to reflect my future planned mods and goals. On the front side I didn't get much benefit from going from a 3.42 to a 3.90, however everything eventually fell into place. A 4.56 would've been a blast but I would've had to pull it out once I finished my mods.
I chose a 3.90 because I know I can get up to 132 mph in 4th gear before I run into the rev limiter (tire is a 315/35/18). My goal from an ET standpoint was to crack into the 10's and I wanted to have room to trap up to 130+.
The rest of my mods compliment the gear selection: middle of the road cam mates up nicely with a 3.90 (still have a decent band to pull through before I have to shift), higher compression setup with nitrous, traction with a 3.90 on a warm tire is still manageable, needed modest gas mileage and good street manners and I can still pull almost 20 mpg cruising on the highway, etc.
