Peak Crusing RPM?

[JDS123]

Because, reducing emissions, increasing fuel economy, ie reducing carbon load, is what is driving regulations which govern what gets built, and what gets licensed. And computer controlled efi and transmissions have the biggest effect. By arguing against the proven science, you guarantee the demise of clutches.

So what we do with 20 year old Jeeps is driving regulations for new cars today?

My '87 YJ, 3.07s and 33s did 25mpg at 70 in 4th. 2200rpm.

According to a quick google search, Jeep rates the 1987 4.2 5 speed at 20 mpg highway. You are claiming you increased gas mileage by 25% by increasing the tire size and driving around in 4th? That is absurd.

 

[jjvw]

My 16 year old heavily modified Jeep that can still get 15-16mpg highway with some effort won't be the reason the world moves past the stick shift. That ship sailed long before my regear ever happened.

 

[Rob5589]

Everyone has to build their Jeep as they see fit. In the end, these discussions always come down to two different thought processes; those that bang away on their keyboards at the various online calculators trying to figure out what works best; and those that have actual in the seat/garage/shop experience and knowledge. Everyone should gear their Jeep how they want, no need to convince anyone of your reasons.

 

[billiebob]

You are claiming you increased gas mileage by 25%

google hyper miling.... altho I was not an addict, I practiced many of their tricks, including driving in socks, not shoes. For 10 years with the YJ home was 950 miles away..... with only 2 stop signs. You drive fast, and you stretch the gas stops. Next 10 years was a commute to my Uncle in Denver from Canada, 1200 miles, 20 hours. I drove the YJ 5 times, then the TJR. You learn where to stop foe gas on a 20 hour drive. I was sweating to find gas with the TJR. I went from 25mpg to 15mpg. Made me an even more dedicated hyper miler.

Hyper milers with the VW TDI regularly get over 100mpg.... but they are crazy.

 

[JDS123]

google hyper miling.... altho I was not an addict, I practiced many of their tricks, including driving in socks, not shoes. For 10 years with the YJ home was 950 miles away..... with only 2 stop signs. You drive fast, and you stretch the gas stops. Next 10 years was a commute to my Uncle in Denver from Canada, 1200 miles, 20 hours. I drove the YJ 5 times, then the TJR. You learn where to stop foe gas on a 20 hour drive. I was sweating to find gas with the TJR. I went from 25mpg to 15mpg. Made me an even more dedicated hyper miler.

Hyper milers with the VW TDI regularly get over 100mpg.... but they are crazy.

It is easy to see that you weren't a hyper-miling addict. If you were, you would have put the correct gear ratio in your YJ so that you could use all 5 gears.

 

[BuildBreakRepeat]

That is the transmission of compromise. That huuge jump from 3rd to 4th really narrows the choice to get the best from 3rd and 4th. So yes, 2500 at 70mph a good spot with a 0.69OD ratio.

I'd love to know why Jeep came up with a 0.69OD ratio. I've never seen anything to explain the design process.

I agree completely, and 5.38s and 35”s that’s the only way to get there with .69 OD

 

[billiebob]

Everyone should gear their Jeep how they want, no need to convince anyone of your reasons

Well if that were the case, these forums would not exist.

I come here to have my mind changed,
or to understand why you do it different,
or to confirm I'm doing it right to achieve my goals.

Most of us are open to learn about different ideas, goals, uses. And yeah, we are passionate about our goals, looking for others doing the same thing. Only a few of us have blinders on thinking a different opinion is a personal attack.

 

[billiebob]

It is easy to see that you weren't a hyper-miling addict. If you were, you would have put the correct gear ratio in your YJ so that you could use all 5 gears.

But you don't see the advantage of 3.07s and 33s. You have never driven a forestry road or a canyon two track in 4LO with 3.07s and 33s. You can hit 60mph in 4LO !! The Wrangler out performs a Mustang. No you are right, definitely not a hyper miler. But open to find the plus of any motor, transmission, rear end ratio.

You find a canyon, 33s, 3.07s, 4L and run it like you stole it. You'll love it too.

Heck, I had Pontiac with a 283 and a 2 speed automatic. 33s, 3.07s, 4L was a dream.

 

[strumble8]

Here in Colorado if I drove on the interstate at under 60 mph I would die from being ran off the road. Sure at 55 mph which with my 4.88 gears would put me right about 2k rpm I would get better mileage, but at what cost? My life? Someone else's life?

 

[jjvw]

AX15/28.5"/2.70=2200rpm @ 69mph/4th gear
AX15/28.5"/2.70=1886rpm @ 75mph
AX15/32.5"/3.07=2200rpm @ 69mph/4th gear
AX15/32.5"/3.07=1881rpm @ 75mph

AX15/32.5"/3.55=2175rpm @ 75mph
AX15/32.5"/3.73=2285rpm @ 75mph
AX15/32.5"/4.88=2989rpm @ 75mph

 

[billiebob]

Here in Colorado if I drove on the interstate at under 60 mph I would die from being ran off the road. Sure at 55 mph which with my 4.88 gears would put me right about 2k rpm I would get better mileage, but at what cost? My life? Someone else's life?

Thats just a stupid comment. I drove BC, Salem OR, Vancouver, almost all Interstate, under 60mph and I was not the slow guy. I did that specifically to try for good mpg, I hit 20mpg a few times. Same thing, Canada to Denver CO, at least 10 times, I usually ran 75mph but 60mph was not a problem. And I passed several cars doing 60 or less.

 

[jjvw]

But you don't see the advantage of 3.07s and 33s. You have never driven a forestry road or a canyon two track in 4LO with 3.07s and 33s. You can hit 60mph in 4LO !!

....

But I can do that in 4H !!?

 

[billiebob]

AX15/32.5"/3.07=2200rpm @ 69mph/4th gear

Yep, that was the number, altho in '87 it was not the AX15.

 

[jjvw]

Yep, that was the number, altho in '87 it was not the AX15.

BA-10 has the same ratios except for 1st gear.

 

[billiebob]

But I can do that in 4H !!?

I guess it depends on yer priorities,
I liked 2200rpm in 4th, direct, at 70mph on the highway.
And I'm more of an overlander than a crawler so 3.07, 4LO was perfect.

On the Interstate it was nice to be able to run 80-85 without throwing a rod.

 

[jjvw]

I guess it depends on yer priorities,
I liked 2200rpm in 4th, direct, at 70mph on the highway.

I guess I prefer to use 4Lo for not going highway speeds.

I will say that I do appreciate 2200rpm in 4th, direct, at 44mph on a nice two lane country road.

Tim, have you come to any conclusions?

 

[billiebob]

I guess I prefer to use 4Lo for not going highway speeds.

I will say that I do appreciate 2200rpm in 4th, direct, at 44mph on a nice two lane country road.

Tim, have you come to any conclusions?

Absolutely, we have different goals.

I used to live for this. I gave it up 40 years ago because it was freaking expensive. Since then I learned the greatest racing was street legal. Driving SuoerBees in the mountains of BC. Everyone had 500HP, 18gears, 32wheels. You only won if you got every shift perfect. And nothing ever broke, you never had to break the law. I loved driving truck. Today, with a TJR, I can be almost legal and have a blast driving fast. No need to exceed 60mph on a gravel road.

Different goals.

 

[jjvw]

Yes. We have different goals. Your goals may be more interesting than most are.

 

[Rob5589]

Same old, same old...

 

[jjvw]

Same old, same old...

Did you know that with proper gearing a Jeep with big tires can go 60mph in 4L?