Safe RPM's to be at?
Safe RPM's to be at?
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If its a 4.0l SOHC engine then it makes its best torque/power at 3,000rpm so you should be shifting at about 3,100-3,200
But it makes best horse power at 5,200rpms
So running at higher RPMs is fine
Torque is what gets you up to speed, 0 to 60MPH
Horse power holds you at that speed, 60+MPH and top speed, this is a curve so you don't need max HP when cruising to hold speed, but you do need to stay near max torque range
In 5th gear, and cruising, you would want to be at around 2,500-2,600rpm, lower and engine would be lugging a bit to hold speed, higher would be using more gasoline, wasted power
If its a 4.0l SOHC engine then it makes its best torque/power at 3,000rpm so you should be shifting at about 3,100-3,200
But it makes best horse power at 5,200rpms
So running at higher RPMs is fine
Torque is what gets you up to speed, 0 to 60MPH
Horse power holds you at that speed, 60+MPH and top speed, this is a curve so you don't need max HP when cruising to hold speed, but you do need to stay near max torque range
In 5th gear, and cruising, you would want to be at around 2,500-2,600rpm, lower and engine would be lugging a bit to hold speed, higher would be using more gasoline, wasted power
Last edited by RonD; Oct 3, 2020 at 01:07 PM.
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From: Jahbraltar
it's okay to go higher.
the fear of rpm happened with conventional pushrod engines that operate the valve rockers through a long pushrod that is in constant contact with the cam lobes on the bottom (against a lifter) and rocker on the top.
if you spun too fast the risk was that the pushrod lifter would skip or lose contact and it would cause problems with actual timing.
this was largely alleviated by roller lifters, but valve float was an issue with springs up top then.
over head valves cut out the middle man (or rod) and you have much less issues spinning at higher rpm.
in pushrods from factory 5000rpm was an upper limit. the windsor small blocks were like 5800.
i havent checked my ranger but i am sure redline is wll above that and still conservative for the power band and not limitation of engine rpm capability.
your ideal shift point will depend on lots of things.
if you opened up the exhaust to make lots of noise you likely ruined the back pressure and traded away all your torque so will have to shift way higher to take advantage of a slight increase in horsepower.
your launches, hauling and track times **** the bed though unless you open up the intake equaly and tune your performance improvements appropriately.
the fear of rpm happened with conventional pushrod engines that operate the valve rockers through a long pushrod that is in constant contact with the cam lobes on the bottom (against a lifter) and rocker on the top.
if you spun too fast the risk was that the pushrod lifter would skip or lose contact and it would cause problems with actual timing.
this was largely alleviated by roller lifters, but valve float was an issue with springs up top then.
over head valves cut out the middle man (or rod) and you have much less issues spinning at higher rpm.
in pushrods from factory 5000rpm was an upper limit. the windsor small blocks were like 5800.
i havent checked my ranger but i am sure redline is wll above that and still conservative for the power band and not limitation of engine rpm capability.
your ideal shift point will depend on lots of things.
if you opened up the exhaust to make lots of noise you likely ruined the back pressure and traded away all your torque so will have to shift way higher to take advantage of a slight increase in horsepower.
your launches, hauling and track times **** the bed though unless you open up the intake equaly and tune your performance improvements appropriately.
Last edited by smak; Oct 22, 2020 at 10:32 PM. Reason: errand terminology
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