Max. RPMs for a 2H?

[Justcruzin]

I was wondering what 2H engine owners think would be a normal, sustainable RPM/speed
for a long highway drive, think across-the-country style...

My '83 HJ 47 has a four speed and revs are around 2750-2800 at 60MPH (100KPM).

Is it realistic to think my motor can run at those RPMs for hours without problems?

What would then be the max comfortable RPM for my 2H? 3000???

All thoughts welcomed here!

 

[Jan-78FJ40]

I was wondering what 2H engine owners think would be a normal, sustainable RPM/speed
for a long highway drive, think across-the-country style...

My '83 HJ 47 has a four speed and revs are around 2750-2800 at 60MPH (100KPM).

Is it realistic to think my motor can run at those RPMs for hours without problems?

What would then be the max comfortable RPM for my 2H? 3000???

All thoughts welcomed here!

On long runs I keep her at 2500, but that is with a 5 speed. It is not fast, but comfortable and with the turbo the boost is then around 9psi, and I do not have to slow down on hills.
and there is plenty of power left for overtaking and for speeding up.

I would not run her at 3000 for hours.

cheers,
J

 

[blis]

I'd say around 2600 or so for long runs , but it is sure to hog some diesel at those revs....

OT: my hj61 revs on highway (80kmh) are around 1850-1900

 

[amaurer]

Sheesh you guys have been spoiled by your 5 speeds and new fangled engines!

I run my 3B at 2800 all day long.. and then some. Psychologically, I do try to avoid 3000, but also because the EGTs are high if I'm going that fast, but I think the engine could take 3000 for extended periods.

 

[kim]

I was wondering what 2H engine owners think would be a normal, sustainable RPM/speed
for a long highway drive, think across-the-country style...

My '83 HJ 47 has a four speed and revs are around 2750-2800 at 60MPH (100KPM).

Is it realistic to think my motor can run at those RPMs for hours without problems?

What would then be the max comfortable RPM for my 2H? 3000???

All thoughts welcomed here!

I have run my 2H, under heavy load, for days on end at 2800 rpm. I consider 3000 my max which I surpass only when needed for the next gear power band, even then never beyond 3500.

Now, my preference is to drive at 2500.

 

[Gold Boy]

at what rpm's is the max torque?

 

[kim]

From what I understand, it is around 2200.

 

[CDN_Cruzer]

yup 2200 rpm is where max torque is then it drops off like Niagara falls

I cruise @ 2200RPM @ 95km/h @ 750 degrees

If you don't already have a Pyro install one and check out how high your EGT's are cruising @ 2800RPM I wouldn't be surprised it they are near 1000 degrees

 

[kim]

yup 2200 rpm is where max torque is then it drops off like Niagara falls

I cruise @ 2200RPM @ 95km/h @ 750 degrees

If you don't already have a Pyro install one and check out how high your EGT's are cruising @ 2800RPM I wouldn't be surprised it they are near 1000 degrees

Most of us don't want to know how hard we have been on our trucks.

 

[Henry James the 47th]

I've driven my Hj47 across the continent, with the H41 4-speed, and at 60 mph I was doing about 2600 rpm. That is running 32" tires - what size of tire are you using?

The 'sweet spot' for rpms in the 2H seems to be in the 2300~2500 range. My truck will run for hours at 2800 rpm, 70 miles per hour, but it doesn't sound quite so easy-going and I wouldn't want to do it day after day.

 

[kim]

I have been using a number of tire sizes, originally stock 28-29 inch, then 31's, 33's for a short while and currently 35's.

The 35's are a long tire with 3.73 gears. I have 4.11's but haven't installed them yet.

 

[canucksafari]

But it's good to run our indirect injection engines hard every once in a while - like across Canada and back towing a monster travel trailer. You got to work them to clean the crap out of them every once and a while. I am sure that's why Kim's 2H runs so nicely.

 

[Tapage]

I'm just not feeling comfortable ar 3K for much time .. maybe psicological . ?

Most of my cruising time it's around 2500rpm .. sometimes little more, sometimes little less .. it allowme keep 100 - 110 km/h nicely ..

There are few ( can cound with one hand ) that I rev my 2H over 3400 rpm ..

 

[CDN_Cruzer]

I am running 255/85/16 33.4" O.D. with 4.11 and the H55F it's a very nice setup.

I do notice the truck seems to run better after a hard wheeling trip that includes some full throttle action

 

[Justcruzin]

I've driven my Hj47 across the continent, with the H41 4-speed, and at 60 mph I was doing about 2600 rpm. That is running 32" tires - what size of tire are you using?

The 'sweet spot' for rpms in the 2H seems to be in the 2300~2500 range. My truck will run for hours at 2800 rpm, 70 miles per hour, but it doesn't sound quite so easy-going and I wouldn't want to do it day after day.

I run 7.50 R 16 (from Aussie) which are ridiculously skinny but about 30,5 in. tall... I guess that explains the difference in RPMs at 60... I will probably end up getting some 31s for it. At some point in the future, I want to take it across central and South-America and I don't want to tax the engine too much by using too big tires.

IYO, what would be the ideal tire size and brand to get a good compromise between drivability, lighter footprint, fuel economy, resistance to punctures, etc for an expedition across central ans south-America?

Back to RPMs, I guess I should think keeping them around 2500-2700 to get reasonnable speed/fuel economy and long term reliability.

 

[Justcruzin]

On long runs I keep her at 2500, but that is with a 5 speed. It is not fast, but comfortable and with the turbo the boost is then around 9psi, and I do not have to slow down on hills.
and there is plenty of power left for overtaking and for speeding up.

I would not run her at 3000 for hours.

cheers,
J

Yeah... Just does'nt feel good, does it?

I'd say around 2600 or so for long runs , but it is sure to hog some diesel at those revs....

Makes sense to me...

Sheesh you guys have been spoiled by your 5 speeds and new fangled engines!

I run my 3B at 2800 all day long.. and then some. Psychologically, I do try to avoid 3000, but also because the EGTs are high if I'm going that fast, but I think the engine could take 3000 for extended periods.

Yeah but the 3B is a 4cyl. right? Anyhow, I don't know why but 2800 did'nt seem all that terrible as far as vibrations, sound, etc were concerned...

I have run my 2H, under heavy load, for days on end at 2800 rpm. I consider 3000 my max which I surpass only when needed for the next gear power band, even then never beyond 3500.

Now, my preference is to drive at 2500.

Well 2500 is definitely my preference also but that means 85-90Kph (barely 55mph) so that OK for short runs or on smaller back roads but if i want to take it on the highway to the other side of the country... It just seems like it would take forever... The fact that you're saying you did run it ar 2800 for extended periods makes me think it would probably be comfortable at 2600-2700.

Anyway, thanks to all of you for your input. And let me know what type tires you all think I should get for that trip to South-Am???

 

[R2HKS]

Sheesh you guys have been spoiled by your 5 speeds and new fangled engines!

I run my 3B at 2800 all day long.. and then some. Psychologically, I do try to avoid 3000, but also because the EGTs are high if I'm going that fast, but I think the engine could take 3000 for extended periods.

Same here 3B and 4 speed. Tacho doesn't work and I rev my 3B hard, well over 3krpm. In fact after some advice I got from a diesel mechanic I know, "drive it like I stole it" and I do and my truck runs great, no smoke and that is with the fuel turned up.

Keep it under the redline and you'll be fine and "drive it like you stole it."

 

[canucksafari]

And let me know what type tires you all think I should get for that trip to South-Am???

You are going to want a turbo for the high altitudes of South America. Then you can put on bigger rubber - like 33-35s which will lower your revs. You can ask Josh what South America high altitude driving is like without a turbo.

Yes, I know some will say no to a 2H and turbo because of the lack of piston oil skirting. I am sure you'll be fine if you keep the boost reasonable.

Tapage, isn't your 2H turboed? If so, what boost do you recommend?

 

[kim]

You are going to want a turbo for the high altitudes of South America. Then you can put on bigger rubber - like 33-35s which will lower your revs. You can ask Josh what South America high altitude driving is like without a turbo.

Yes, I know some will say no to a 2H and turbo because of the lack of piston oil skirting. I am sure you'll be fine if you keep the boost reasonable.

Tapage, isn't your 2H turboed? If so, what boost do you recommend?

From what I have read, you don't want anything larger than a 31" tire when travelling because of tire availability in the more remote places. Everybody has standard truck tires but not many have 33's or 35's.

 

[CDN_Cruzer]

I Love my 255/85/16 (33.4x10.5) and I am fairly sure they are widely available around the world.

Lots of info on expeditionportal.com about tire sizes.

this is a great article about tire sizes for expeditions

Expeditions West: Tire Selection for Expedition Travel