Solutions for too much compression
Your statement was:
If you drive down the road @45 -50mph and it surges, its lean on the primary side jetting.
Look at the chart mains flow doesn't completely take over until 4500 RPM. So unless you Cruise around doing 45-50 MPH @ 4500 rpm then you're still on the T-slot.
Here ya go something that might help you understand this a little better and what RPM you should be doing with tyre size and gear ratio.
What is cruising rpm? Why is it important?
What is cruising rpm? Why is it important?
Engine RPM @ 60 MPH Chart
Your cruising rpm will affect fuel mileage and engine durability. It is important to get it right so you can enjoy your vehicle for years to come.
You want the cruising rpm to be in the
Sweet Spot of your camshaft. This will give you good power and throttle response.
If the rpm is too high, it will:
- Burn more fuel,
- Generate more heat, and
- Wear engine parts faster.
If the rpm is too low, it will:
- Provide poor performance, and
- Cause the torque converter to slip, causing excessive heat.
You should consider your cruising rpm if you want to change tire size or
Ring and Pinion Gears. You should also take it into consideration when buying a
Torque Converter. For the best performance, your cruising rpm should be at or above your converter stall speed .
This chart shows the rpm @ 60 mph, based on gear ratio and tire height.
Rear Axle Gear Ratio Tire Diameter
24" 26" 28" 30" 32" 34" 36" 38" 40" 42" 44"
2.18 1,831 1,690 1,570 1,465 1,373 1,293 1,221 1,157 1,099 1,046 999
2.50 2,100 1,938 1,800 1,680 1,575 1,482 1,400 1,326 1,290 1,200 1,145
2.74 2,301 2,124 1,973 1,841 1,726 1,625 1,534 1,545 1,381 1,315 1,255
3.08 2,587 2,388 2,218 2,070 1,940 1,826 1,725 1,634 1,552 1,478 1,411
3.23 2,713 2,504 2,326 2,170 2,035 1,915 1,809 1,714 1,628 1,550 1,480
3.50 2,940 2,714 2,520 2,352 2,205 2,075 1,960 1,857 1,764 1,680 1,604
3.73 3,133 2,892 2,686 2,507 2,349 2,212 2,089 1,979 1,880 1,790 1,709
3.90 3,276 3,024 2,808 2,621 2,457 2,312 2,184 2,069 1,966 1,872 1,787
4.10 3,444 3,179 2,952 2,755 2,583 2,431 2,296 2,175 2,066 1,968 1,879
4.56 3,830 3,536 3,283 3,064 2,873 2,704 2,554 2,419 2,298 2,189 2,089
4.88 4,099 3,784 3,513 3,274 3,074 2,894 2,733 2,589 2,460 2,236 2,139
Now tell me who's doing 4500 RPM at 45-50 AGAIN!!!???
Even with a 4.88 gear and 24 inch tyre they just break 4000 RPM.
Oh and you were talking 45-50 MPH and this chart is for 60 MPH so the RPM's will be lower still.