Box Stock

Predator gearing help

J

Joneskarting

New member
I'm new to this forum. We're running a adult box stock predator we are new to running predator. I'm trying to understand why you run lower RPMs instead of higher. We're turning about 5,800 RPMs with a 13 front and a 65 rear. I have read a lot of people saying try to aim for 4,800 RPMs and I was wondering why and what is the benefits? Thanks.
 
Let me ask; are you going faster on the top enq, or are they? 4800 to 5800, that's about 10 teeth on the axle. If you're going the same speed on the top, that should give you a distinct advantage on the low end.

Do you understand the term "power under the curve"? Have you ever had your engine on a dyno? What does your tachometer read coming out of the pits? Full throttle?
 
Maybe this will help. I have 2 Predator engines, a hemi and a non-hemi. We're allowed to add a header/muffler combo, an air filter/adapter assembly, change the jet in the carb, and remove the governor.

The hemi engine peak hp is at 5000 rpm and peak torque is at 4900 rpm. The non-hemi peak hp is at 5600 rpm and the peak torque is at 5000 rpm. After those plateaus, the hp and torque numbers drop off significantly. In addition, the engine builder doesn't recommend turning the stock flywheels more that 5500 rpm.

The trick here (if which I am still attempting to achieve) is to gear the kart where I'm reaching these peak hp and torque numbers without exceeding them. Once the kart hits the track, the gear swapping will begin to determine where I need to be.

I would imagine a big part of this equation is determining on a dyno where your engines hp and torque "sweet spots" are.

Good luck !
 
No way to know with out testing . Off hand i would say yes .
A 13/60 will give you more speed per revolution .
You could go faster and still turn 5000 rpm .
 
If there's a kart track out there racing predators that a 13 front driver is correct for I've never seen it, unless your using mini gears of course.
Your 10 teeth off for sure, then consider your so gear bound now you may pick up rpm as you pull teeth.
 
Chuck D17 said:
Maybe this will help. I have 2 Predator engines, a hemi and a non-hemi. We're allowed to add a header/muffler combo, an air filter/adapter assembly, change the jet in the carb, and remove the governor.

The hemi engine peak hp is at 5000 rpm and peak torque is at 4900 rpm. The non-hemi peak hp is at 5600 rpm and the peak torque is at 5000 rpm. After those plateaus, the hp and torque numbers drop off significantly. In addition, the engine builder doesn't recommend turning the stock flywheels more that 5500 rpm.

The trick here (if which I am still attempting to achieve) is to gear the kart where I'm reaching these peak hp and torque numbers without exceeding them. Once the kart hits the track, the gear swapping will begin to determine where I need to be.

I would imagine a big part of this equation is determining on a dyno where your engines hp and torque "sweet spots" are.

Good luck !
Click to expand...
where are you getting these numbers? have you put the engine on a dyno? peak torque at 4900??????? that is a little crazy when a peak torque on a built clone is 3600. on a box stock peak hp is around 3750-4000 rpm range. did you change the cam?
 
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