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Old 03-19-2016, 09:48 PM
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Jeep 4.0 vs. Ford 4.9 inline 6 engine

Recently I read that my 1999 TJ 4.0 L puts out 180 horsepower compared to the 150 horsepower Ford 4.9 L.

Does that sound right, and if so, how can a larger litre engine put out less horsepower?

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Old 03-19-2016, 10:12 PM   #2
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I don't know about the horsepower.
The Ford engine could have a lower compression ratio, that would make less power. But I'm not a engine expert.

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Old 03-19-2016, 10:20 PM   #3
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Old 03-19-2016, 10:22 PM   #4
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http://www.jeeptech.com/engine/amc242.html

Compare RPM of rated HP to understand difference
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Old 03-19-2016, 10:25 PM   #5
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3400rpm vs 4750 rpm

So jeep hp measured at 40% higher rpm so apples and oranges
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Old 03-19-2016, 10:34 PM   #6
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Carburetor vs injector.

With an older, carburetor fed engine, it was said that the maximum you could expect, (without going to a racing engine), was about one horsepower per cubic inch. Modern, fuel injected, computer controlled engines can do much better than that.
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Old 03-19-2016, 11:20 PM   #7
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Seems like you have a lot of extra time on your hands, I have plenty of chores you could help with.
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Old 03-19-2016, 11:46 PM
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Seems like you have a lot of extra time on your hands, I have plenty of chores you could help with.
After a long week...plenty of work...I was trying to distract myself! And I am accused of having too much time on my hands. Can't win.

A friend of mine brags up his 4.9. So I was looking for an edge.
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Old 03-19-2016, 11:51 PM
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Originally Posted by Digger84 View Post
Jeep Engine: 4.0L I6

Compare RPM of rated HP to understand difference
Thanks Digger for humoring me, and for the links. Apples to oranges. Now I see why I came across lower horsepower for the 4.9. They measured it at a lower RPM reading.

Wonder why they would measure them at different RPMs. Perhaps the Ford engine isn't capable of safely running at such high RPMs?
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Old 03-20-2016, 09:01 AM   #10
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Don't stop at reading "Horse Power"

Look up "Horse Power VS Torque" curves, I suspect the Ford has a wider range torque curve.

Who beats who at a stop light?
Who can pull a boat up a mountain?
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Old 03-20-2016, 09:21 AM   #11
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Rpm redline is much higher

Ford has longer stroke a good thing tot torque

Ford numbers reflect more realistic number at RPM you would use while driving or towing

Both these straight six are very smooth very reliable engines with a useful broad torque band and neither is a god rod dragster engine

HP is very RPM dependent but in our type vehicles usable broad torque and reliability is what it is about for me

Sadly the straight six as a workhorse has become extinct in new vehicles for the common man as it does not fit short hoods or transverse and has increased weight over similar displacement V engines

But straight six (or 2 in a V12) is still the only inherently balanced engine with no harmonic balancer or counter weight balance shafts it is just inherently balanced with no primary or secondary shaking force or primary or secondary rocking couple
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Old 03-20-2016, 01:17 PM
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Maybe there will come up with a big three cylinder that would provide inherent balance?
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Old 03-20-2016, 01:18 PM   #13
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I spent many miles behind 300 6 Fords with np435 4 speeds. They were bullet proof and usually outlasted the rest of the truck. Our forester used them as well as logging crews back before the F250's with Diesels took over.
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Old 03-20-2016, 02:22 PM   #14
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No three cylinder would ever be inherently balanced
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Old 03-20-2016, 04:03 PM   #15
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Who can pull a boat up a mountain?
Yes, i imagine that comes in handy...;-)
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Old 03-20-2016, 04:08 PM   #16
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Don't believe a word of it !
You put that 4.9 in yer TJ and go blow the doors off everything else !
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Old 03-20-2016, 04:11 PM   #17
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I spent many miles behind 300 6 Fords with np435 4 speeds. They were bullet proof and usually outlasted the rest of the truck. Our forester used them as well as logging crews back before the F250's with Diesels took over.
100% ^^^ I put over 400K miles on my '77F250 with the same combination.
Bullet Proof for sure. Spent 1 winter unplugged. Started every day at 60 below.

not sure if mine was a NewProcess435... maybe 205? but the transfer case was heavy.
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Old 03-20-2016, 04:15 PM   #18
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Don't stop at reading "Horse Power" Look up "Horse Power VS Torque" curves, I suspect the Ford has a wider range torque curve. Who beats who at a stop light? Who can pull a boat up a mountain?
Horsepower is a calculated variable. You measure torque then calculate horsepower from that so the engine with higher torque at a given RPM has higher hp. If an engine (like the 4.0) has higher hp at higher RPM it has a higher torque figure at that RPM also. A flat torque curve will give an increasing hp curve and if torque is completely flat the hp rise will be a straight ramp.

Things like piston mass, rod length, crankshaft radius (distance from crankshaft centerline to rod bearing centerline) and materials have an effect on ultimate piston speed which limits RPM while rod length and crank radius affect torque and when designing for pulling power these are taken into account when creating the induction system to tune it for efficiency in the expected RPM range so an engine designed for more low RPM torque probably won't have high RPM hp numbers to brag about.
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Old 03-20-2016, 06:10 PM   #19
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We're far from having too much horse power......My definition of too much horse power is when all 4 wheels are spinning in every gear.

Mark Donohue.






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Old 03-20-2016, 06:16 PM   #20
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torque and horsepower are influenced by design but they are independent of each other.
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Old 03-20-2016, 06:20 PM   #21
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speaking of Mark Donahue.... name the car... sort of off topic
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Old 03-20-2016, 06:48 PM   #22
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See link example 1 and 2 relate to RMP difference

http://www.epi-eng.com/piston_engine...and_torque.htm
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Old 03-20-2016, 07:06 PM   #23
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Originally Posted by rvator View Post
I spent many miles behind 300 6 Fords with np435 4 speeds. They were bullet proof and usually outlasted the rest of the truck. Our forester used them as well as logging crews back before the F250's with Diesels took over.

Add me to that list, I still own one although not with that kind of miles on it. IMO it was probably one of the best I6 engines ever made.

The Ford 4.9L makes a lot of torque in the lower rpm range. It is a stronger engine for towing and low speed grunt work than the 4.0L. No disrespect intended. It is a low rpm, high torque engine for lack of a better term. I'd love to build a Wrangler around one.
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Old 03-21-2016, 02:50 PM   #24
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speaking of Mark Donahue.... name the car... sort of off topic
Well if it had a spare tire hanging on the back and milk jugs on the bumper it would be easier.
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Old 03-21-2016, 03:24 PM   #25
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speaking of Mark Donahue.... name the car... sort of off topic
Porsche 917-30

Isn't it Donohue though?
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Old 03-21-2016, 09:52 PM   #26
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Porsche 917-30

Isn't it Donohue though?
WINNER !!! In Edmonton 1973? CanAm. The car that killed unlimited sports car racing. I think that car currently holds the world speed record on a closed course track.

It was very cool in 1973 to be that close to Mark Donahue, Roger Penske and the 917. Mark Donahue won that race. I doubt a high school kid can buy a Paddock Pass today and wander at will taking pictures of the team, cars, drivers, girls.
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Old 03-21-2016, 10:10 PM   #27
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WINNER !!! In Edmonton 1973? CanAm. The car that killed unlimited sports car racing. I think that car currently holds the world speed record on a closed course track. It was very cool in 1973 to be that close to Mark Donahue, Roger Penske and the 917. Mark Donahue won that race. I doubt a high school kid can buy a Paddock Pass today and wander at will taking pictures of the team, cars, drivers, girls.
I was 3 years old when that car hit 1500hp, and maybe 4 when he died from the result of the head injury sustained in his crash. My favorite hotwheels at that time was the Porsche 917, I had the orange one with the purple stripes. It started a love affair with machines in general, particularly fast machines piloted by skilled madmen. In 1983 when I was in the 8th grade Stefan Bellof turned 6:11:13 at the Nordschleife configuration in a 956 and cemented my obsession. Thanks for bringing back the memories!


Ok, back to the Jeeps.
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Old 03-22-2016, 09:37 PM   #28
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See link example 1 and 2 relate to RMP difference http://www.epi-eng.com/piston_engine...and_torque.htm
Exactly
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Old 03-22-2016, 10:15 PM   #29
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HP = Torque x RPM ÷ 5252

crock of shit there
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Old 03-23-2016, 07:26 AM   #30
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Not a crock but you can learn or wallow in ignorance

https://www.wisc-online.com/learn/ca...rpm-and-torque

Nothing wrong with not knowing but your comment does you a disservice

Work is force times distance

Power is work per unit time

Basic 10th grade physics you know the pre calculus version of physics taught by 10th grade in any decent school

Plus basic units conversions like

Seconds = minutes * 60 seconds/1 minute

Or

Miles = feet * 1mile/5280feet

Unit conversion should be about 4th or 6th grade
It is just multiplying by a select 1 and we all now multiplying by one does not change the value just the units



Finally radius vs circumference of a circle maybe 9th grade geometry

Those basics will get you there

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