I have a Ford 7.8 liter engine in a truck and am wondering if some one could look at the attached image page and communicate what the maximum engine rpm is driving the truck down the road. is it the 2300 rpm at rated engine speed and max HP of 225. or is it the high idle speed of 2680/2760 rpm or is it some other rpm? I have not been able to locate this information on the internet. Can not locate the engine power curve or torque curve information.
Should be a tag on the engine. On a Brazilian, iirc, it should be on the intake manifold of all places. You want to see what hp rating it has. That hp would be theoretically available at that RPM. You'll notice peak torque comes in a lot lower. That's what you should concern yourself with. Am I in my power band and am I lugging my engine?
Appears to be based against Torque curve to a particular injection pump(Bottom row). Could be associated to gearing or final drive ratios or type work being delivered(as difference from Mixer Chassis to highway Truck) or type load considerations(LTL Freight or Dump truck service), other variables as to Federal or California or Export emissions levels.
OK so I understand what you are communicating the 225 HP engine version would have a maximum RPM of 2300 on the highway. Not the 2700 RPM high idle speed.
It will have 225 HP at the rated speed. It will go to the high idle speed, or close to it, but it won't have any more HP at that faster speed, lower torque obviously.
And in top gear (whatever that is) there is a very good chance that the engine would not even reach the quoted 2300RPM. It should "rev out" (as it is known) to 2300 RPM in all the lower gears though, should the driver care to take the RPM that high. Usually it's common to keep the engine around the peak torque RPM for best performance. Horsepower is not what gets you from A to B, torque is.
High idle is static and WFO
With the truck out of gear and engine at wide open throttle, it should get up to the high setting. With the truck in top gear running on a level road with any kind of load it should get the 2,300 RPM on the tach. Where you will notice a loss of motive force is in the gears you are using to climb a hill. Horsepower is the ability to accelerate the vehicle. Torque is what gets you up the hill.