Why is the rpm redline so low in a Jeep Cherokee ?

Question

its at like 5,000 i think that seems low

Answer 1

since I accidently closed the window while i was in the preview part I'm going to make this short.

The answer lies with the crankshaft. A little after 6000 rpms the strait 6 crankshaft will tear itself apart along with the rest of the engine.

Answer 2

Its not a 4 cylinder sports car.. It is a "truck"... Why do you need 5K rpm? Though the HP is 190hp @ 4,750 RPM.. the torque is 225 lb-ft @ 4K rpm.  I usually shift my 93 XJ at about 2k rpm and it is smooth with no bogging.. and I get about 20 mpg.  If I am really on it, it may get up to 3k rpm but that sounds like the inline 6 is screaming...  

Answer 3

You cannot compare a standard overhead valve, standard lifters, standard rock arm,  cam in block engine to a over head cam, or four valve engine of much smaller displacement.

This engine is designed for and gives 200,000 miles of service easily. There is no reason to make MUCH heavier valve springs just to increase rpm. Additionally, you would have to increase the strength of the connecting rods and probably, due to length of a straight 6, go to a steel crank.

More so, I have done flow testing on the heads and installed over size valves. The heads were never designed for extremely high flow and again, you would gain nothing by spinning it up.

Bare in mind, this engine has it's roots back to the 1960's at 199, 232, and 258 cu inch with AMC.

Hope this helps.

Answer 4

It's an old school straight six that's built for torque and off-road situations. They are wonderful engines and I know that engine has legions of fans around the world.

The only draw back that we have found is that the I-6 tends to run hot and it took us a bit of research to find out why. When the Cherokee was introduced they stuck a 4 cylinder and a GM V-6 in them and the designed airflow from that body around that engine when underway was for those engines. The long and big 4.0 I-6 changed all that and the engine doesn't get good airflow underneath the bonnet. Always ensure you've got a water pump in excellent condition, the radiator is always in excellent shape (Add some water wetter-it really helps heat transfer!) They even make hood kits that are a simple install that helps heat out from underneath...AND KEEP THE OIL CHANGED!!!! That motor will reward you with a long life if you do!

Cheers!!!

Answer 5

it takes a lot of gas to rev it up and speed

Answer 6

Its because the engine is designed to produce more power at lower rpms rather than power at a higher rpm, it's because the vehicle is designed to drive off road, not accelate quickly out of a tight turn.

Answer 7

Is it the diesel?

Diesel engines do not rev as hard as petrol engines, because their internal components are significantly heavier as a result of being much stronger than petrol engine componets.

This is because diesel engines use much higher combustion chamber pressures, therefore the load on the components is much greater.

The downside of this is that the heavier components require much larger forces to move them in the same way as the petrol engine components, which increases stresses exponentially.

The much higher stresses create balancing difficulties, and would lead to catastrophic failure of engine components if they were subject to sustained high loadings, despite the fact they are so much tougher than petrol engine components in the first place.

Answer 8

because its a truck?!!