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Horsepower?

NickMcAFP

Newbie
Joined
Aug 8, 2021
Messages
70
Loc.
Sturbridge
This is less of a question and more of an invitation for discussion.

I have no gauge of what horsepower means. I understand what it IS but it isn't something I can imagine in my head.

I have never driven a Bronco. My Bronco was handed down to me non-drivable. 90% of my experience driving stick (the only time I've ever had to consider RPM, gearing, or horsepower) is in my 1982 Landrover Series 3. The 2.25L Diesel in my Rover puts out a whopping 62 Horse Power. First gear with the factory 3 speed in the Bronco sits right in-between 1st and 2nd on my rover (adjusting for the current oversized tires). Aside from trying to maintain 50mhp uphill I've never felt the Rover was detrimentally lacking in power. Obviously it isn't winning any races but it is a truck. I can comfortably pull away from a stop light in second gear.. Once, accidentally, in 3rd.

The other 10% of my stick experience is in an 09 Jeep Wrangler Rubicon 4 door. My father felt it was lacking power so he supercharged it. I always found this hilarious because, according to the numbers, he added more horsepower to his engine with the super charger than my Landrover even has stock. Granted, he often towed a boat with his Jeep.. But my Rover is a retired tow truck itself so there's that. I also did the final drive gear ratio out for the Jeep and have similar results. with the 35s on it 1st gear on the Bronco sits in-between 1st and 2nd on the Jeep.

Given the number of threads I've read about increasing horsepower and dissatisfaction with the factory gearing I just feel like I'm missing something.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
44,005
Weight can be a factor as well, but so is the torque of the engine and where it develops. Which equates to how happy is the engine with the gearing in the transmission.
Broncos are not lightweights, but they're probably on parr with the other vehicles you listed. A stock Bronco comes in at between 3600 and 3800 if I remember. A mildly modified and outfitted one easily tops 4,000 to 4,250. By the time they hit the 4,500 to 5,000 lb range however, they also usually have engines that have been updated and gearing to match.
Rolling resistance due to the tires and differentials is a thing as well.
But basically even with double the horsepower of your Rover, the Bronco gearing is kind of sucky from the factory for larger tires. Was not a bad thing with stock height tires (about 28" or so) but every notch larger is another nail in the coffin of performance. The 3-speed gears never seemed to be the right one no matter what speed you were going.

I can't say for other things. Other than the horsepower ratings of Broncos with V8's should use the '72 and later listings with "net" horsepower. Before that they were using "gross" power ratings to the tune of adding 40 to 60 additional horsepower to the numbers. So figure 140bhp for a stock V8 and you're in the ballpark.
All in all, Broncos just never seemed to roll as easily as many other vehicles did. For whatever reasons...

Paul
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
44,005
The above is one of the reasons I've always wanted someone with plenty of dyno time and extra time on their hands to run a single vehicle on a wheel dyno, but change the differential type for testing power losses with different common differentials. Dana 44's and 60's, GM 10-bolt and 12-bolt and 14-bolt diffs, Ford 8.8 and 9 inch diffs, etc.
And then take the winner (or just the 9" since it's so easy to change) and change gear ratios to see what effect that has on output at the wheels.

I think it would be a real eye-opener.

paul
 
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NickMcAFP

NickMcAFP

Newbie
Joined
Aug 8, 2021
Messages
70
Loc.
Sturbridge
Weight can be a factor as well, but so is the torque of the engine and where it develops. Which equates to how happy is the engine with the gearing in the transmission.
Broncos are not lightweights, but they're probably on parr with the other vehicles you listed. A stock Bronco comes in at between 3600 and 3800 if I remember. A mildly modified and outfitted one easily tops 4,000 to 4,250. By the time they hit the 4,500 to 5,000 lb range however, they also usually have engines that have been updated and gearing to match.
Rolling resistance due to the tires and differentials is a thing as well.
But basically even with double the horsepower of your Rover, the Bronco gearing is kind of sucky from the factory for larger tires. Was not a bad thing with stock height tires (about 28" or so) but every notch larger is another nail in the coffin of performance. The 3-speed gears never seemed to be the right one no matter what speed you were going.

I can't say for other things. Other than the horsepower ratings of Broncos with V8's should use the '72 and later listings with "net" horsepower. Before that they were using "gross" power ratings to the tune of adding 40 to 60 additional horsepower to the numbers. So figure 140bhp for a stock V8 and you're in the ballpark.
All in all, Broncos just never seemed to roll as easily as many other vehicles did. For whatever reasons...

Paul
I really expected there to be a noticable weight difference as the Rovers have aluminum bodies. Mine is a long wheel base and according to the numbers online they are in the same ballpark as the bronco. The Jeep is a behemoth. Factory curb weight is listed as 4315lbs and that's not factoring in the larger tires, off-road bumpers, and winch on my Dad's old jeep.

Maybe it's the way I drive but I don't FEEL a huge difference aside from holding speed uphill.

I do think it would be great to have that sort of information!
 

Broncobowsher

Contributor
Total hack
Joined
Jun 4, 2002
Messages
33,601
My old diesel tractor only made 25HP. But it had torque. HP is deceptive, it is a factor of torque and RPM. A lot of torque but not much RPM is low HP. Modern truck diesel engines are a good example, 400 HP but the torque is 1000 ft-lbs. A high strung motorcycle engine that turns 14,000 RPM is the other way around. It might make 100 hP, but only has 30 ft-lb of torque.

Your rover had little HP, but good torque, just no RPM. If it could keep the torque but double the RPM, that 62HP would be 124HP. It would still drive like you think the rover drove like. You just can keep a lower gear and the pulling power of that low gear up to a higher speed. Instead of running out of power at 10 MPH in first, you can keep that pull going until you are doing 20 MPH. Still keeping the same level of torque, but with double the RPM, double the HP.

Now it isn't perfect. Engines have torque curves, not flat lines. Aerodynamic drag starts to be a major player as speeds get above about 40 MPH.
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
80,080
Weight can be a factor as well, but so is the torque of the engine and where it develops. Which equates to how happy is the engine with the gearing in the transmission.
Broncos are not lightweights, but they're probably on parr with the other vehicles you listed. A stock Bronco comes in at between 3600 and 3800 if I remember. A mildly modified and outfitted one easily tops 4,000 to 4,250. By the time they hit the 4,500 to 5,000 lb range however, they also usually have engines that have been updated and gearing to match.

Definitely a key factor
 

sprdv1

Contributor
REBEL
Joined
Mar 8, 2007
Messages
80,080
My old diesel tractor only made 25HP. But it had torque. HP is deceptive, it is a factor of torque and RPM. A lot of torque but not much RPM is low HP. Modern truck diesel engines are a good example, 400 HP but the torque is 1000 ft-lbs. A high strung motorcycle engine that turns 14,000 RPM is the other way around. It might make 100 hP, but only has 30 ft-lb of torque.

Your rover had little HP, but good torque, just no RPM. If it could keep the torque but double the RPM, that 62HP would be 124HP. It would still drive like you think the rover drove like. You just can keep a lower gear and the pulling power of that low gear up to a higher speed. Instead of running out of power at 10 MPH in first, you can keep that pull going until you are doing 20 MPH. Still keeping the same level of torque, but with double the RPM, double the HP.

Now it isn't perfect. Engines have torque curves, not flat lines. Aerodynamic drag starts to be a major player as speeds get above about 40 MPH.

well stated sir.. and good to keep in mind
 
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NickMcAFP

NickMcAFP

Newbie
Joined
Aug 8, 2021
Messages
70
Loc.
Sturbridge
My old diesel tractor only made 25HP. But it had torque. HP is deceptive, it is a factor of torque and RPM. A lot of torque but not much RPM is low HP. Modern truck diesel engines are a good example, 400 HP but the torque is 1000 ft-lbs. A high strung motorcycle engine that turns 14,000 RPM is the other way around. It might make 100 hP, but only has 30 ft-lb of torque.

Your rover had little HP, but good torque, just no RPM. If it could keep the torque but double the RPM, that 62HP would be 124HP. It would still drive like you think the rover drove like. You just can keep a lower gear and the pulling power of that low gear up to a higher speed. Instead of running out of power at 10 MPH in first, you can keep that pull going until you are doing 20 MPH. Still keeping the same level of torque, but with double the RPM, double the HP.

Now it isn't perfect. Engines have torque curves, not flat lines. Aerodynamic drag starts to be a major player as speeds get above about 40 MPH.
That's funny because, for me, all of the numbers seem deceptive. According to the numbers the Bronco should be putting out twice the torque of the Rover as well.. but that's at 2,200 rpm where the Rover is quoted at 1,700. So it's never quite apples to apples.. and even if it was there seem to be so many other variables that aren't accounted for mathematically.

I guess I really won't know until I'm actually driving the thing.
 

1969

Contributor
Jr. Member
Joined
Feb 28, 2022
Messages
110
I’ve seen plenty of Toyotas over the years with 4 cylinder engines, and 37”+ tires running all over and wheeling just fine. Sure they’re not flying up a steep grade but they will get there. Granted they’re geared down low in the axles 5.38s and such. But they still scoot around. I am going to apply this same logic to my bronco. I have a 225hp 289, and I am going to gear it down low and get an AX15 trans and it should do just fine. It won’t win any races but that’s not what it’s for.
 
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NickMcAFP

NickMcAFP

Newbie
Joined
Aug 8, 2021
Messages
70
Loc.
Sturbridge
I started digging around again from back when I first got my Rover and had a million over-the-top plans for it. There's a site out there called Expedition Land Rover that is put together by a lady who drives around in a huge Series Rover camper. At some point she swapped a 302 into it. There's a big write up on the swap and I enjoyed rereading some of it with the new perspectives I've got on here. It's a pretty detailed look at her thought process with the engine and transmission options.
 
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