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High Elevation Gear Ratio - 33's - 6-Speed (NSG370)

rasband

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All I know is my Jeep on 33's and running 456's with the 6 speed has zero issues with power when wheeling in all the southern Colorado mountian passes. So what is different between mine and the OP's that mine can breath just fine up in the thin air.
Either you have a different tolerance for "zero issues" or your 33s are on the smaller size putting it where you want it to be. If the OP goes toward 33s/34s they'd be on the other side of the happy-path.
 
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JMT

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My point is pick your ratio and be done.it will put your motor in the powerband as steels long post tries to demonstrate.when you run out of power you need to put your motor at or near peak to get the most work from it.But if you want more power you need to address the motor.

If you are talking about the nsg being worlds different then yes,you aren't going to convince me.
We don’t want to downshift to keep it in the powerband
 
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Rickyd

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We don’t want to downshift to keep it in the powerband
So? I'm not arguing gear choice. As you already said that has been discussed. You don't understand what I'm saying. So either try to keep up or quit being insulting
 
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Zorba

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In my ten years of driving on 30.5s/4.10s I never took off in 2nd other than a couple of times just as a test. Also the 6 speed has a .84 overdrive as opposed to the .79/.78 overdrives of the 5 speeds. While not dramatically different it does make a difference on the highway when running 5.13s.
None of the Jeep transmissions are geared low enough to start in 2nd, although you can do it. How I miss the SM420 - Hell, even an SM465 would be great!
 
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Rickyd

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Your argument is that your range of acceptability is wider than ours is.
No, I'm saying that gearing is only part of the equation. Engine power is also part of it. Not once have i argued for a given ratio. Steel did that pretty well.with pros and cons

The o.p. said 9000ft and a lack of power. the thinnest mls headgasket that will work with timing events is a good start in addressing the motor itself.
 
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pc1p

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Carb vs injector has nothing to do with the effects of altitude. (on the same engine, a properly tuned carb makes the same power as fuel injection, maybe even a little more depending on fuel, but we're way past the weeds with that discussion) It's all about atmospheric pressure, i.e. available air, and yes modern computers will adjust for this on the fly, applying more or less fuel to match the available air. (MAP sensor)

The OPs location states he is at 9100 ft in elevation. That has an atmospheric pressure of approximately 10.5 psi. Sea level is 14.7 psi. That nearly a 30% reduction in available air from sea level to the OPs location, which translates directly to engine power output.
Let's not forget the almost 6% reduction in O2 levels (~20.8% to ~14.9%).
 

jjvw

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No, I'm saying that gearing is only part of the equation. Engine power is also part of it. Not once have i argued for a given ratio. Steel did that pretty well.with pros and cons

The o.p. said 9000ft and a lack of power. the thinnest mls headgasket that will work with timing events is a good start in addressing the motor itself.
There are at least three of us here who have driven past his house many many times on the way into the mountains. We know what works well on his roads.
 

pc1p

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The NSG370s first is not a granny gear. 5.xx first ... possibly. 6.xx first ... definitely. 4.46 first ... nope.
^ very much this!!

Hell back in the Golden Days of Granny Gear transmissions, the L gear was ~5.xx to 6.xx in some cases (the old Muncie 465 was 6.55:1). More importantly, 1st (actual first, not L) was a very streetable 3.58:1. The NGS's 2.62:1 2nd gear is not appropriate for starting from a stop in about 99.5% of driving situations.
 
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pc1p

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06 LJ, 35" MT/Rs, 5.13's, 6-speed here...

If I were to regear specifically for the NSG, I'd go 4.88's for 35"s for many of the exact reasons that @Steel City 06 pointed out (my axles came out of my 5-speed/35" tire TJ). The 5.13's and 35"s put common speed limits and shift points at very odd times (cruising at 50 MPH is annoying here in PA, where many local country routes are actually 50 MPH speed limit).

Now that said, as much as I like the ratios of the NSG overall, it still feels like I'm rowing a rusty spoon through a coffee can full of marbles at 72,000 miles (though I don't know the history well). I will eventually replace with a brand new AX15, where I will once again love the 5.13's.
 
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pc1p

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No, I'm saying that gearing is only part of the equation. Engine power is also part of it. Not once have i argued for a given ratio. Steel did that pretty well.with pros and cons

The o.p. said 9000ft and a lack of power. the thinnest mls headgasket that will work with timing events is a good start in addressing the motor itself.
Gearing may not be the "only part" but it's arguably the most important.

One could spend a lot of time, energy, money and effort to improve the power at the engine. Many have tried and few, short of forced induction, have made any appreciable gains to the 4.0L. Believe me, I was one of those idiots people that tried many decades ago.

In the case of the OP, going from 4.56 to 4.88 is an easy 7% increase in torque output at the wheels without any reliability or driveability issues.
 

Rickyd

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There are at least three of us here who have driven past his house many many times on the way into the mountains. We know what works well on his roads.
And i deferred to you guys on your gearing advise. Which seems to be 4.88?
I'm not sure what you're arguing? That engine power doesn't affect driveability? Or maybe that you can't build an altitude specific motor?
If you agree with those points then we don't have an arguement
 
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Artsifrtsi

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None of the Jeep transmissions are geared low enough to start in 2nd, although you can do it. How I miss the SM420 - Hell, even an SM465 would be great!
BW T89 in the '65 Wagoneer I had... 230 tornado, 4.10 axle ratios... I drove that jeep around town in 3rd gear without shifting
 
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Rickyd

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Gearing may not be the "only part" but it's arguably the most important.

One could spend a lot of time, energy, money and effort to improve the power at the engine. Many have tried and few, short of forced induction, have made any appreciable gains to the 4.0L. Believe me, I was one of those idiots people that tried many decades ago.

In the case of the OP, going from 4.56 to 4.88 is an easy 7% increase in torque output at the wheels without any reliability or driveability issues.
His 3.73 to 4.88 even more pronounced.
I bring up engine mods well, because i can't leave anything alone! I love the cammed high compression stroker in my tj.4.0l just can't compare.All the research i did before chosing to build it showed the failures people claim from them aren't from the rotating assembly so apply to rebuilding a 4.0l as well. Using quality parts and advise from good builders is key
 

JMT

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So? I'm not arguing gear choice. As you already said that has been discussed. You don't understand what I'm saying. So either try to keep up or quit being insulting
Ok dude. No interest in having further discussion.
 
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L J

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^ very much this!!

Hell back in the Golden Days of Granny Gear transmissions, the L gear was ~5.xx to 6.xx in some cases (the old Muncie 465 was 6.55:1). More importantly, 1st (actual first, not L) was a very streetable 3.58:1. The NGS's 2.62:1 2nd gear is not appropriate for starting from a stop in about 99.5% of driving situations.
If I recall correctly, the Bronco has an available seven speed manual with a 6.5ish "crawler" gear.
 
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pc1p

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His 3.73 to 4.88 even more pronounced.
I bring up engine mods well, because i can't leave anything alone! I love the cammed high compression stroker in my tj.4.0l just can't compare.All the research i did before chosing to build it showed the failures people claim from them aren't from the rotating assembly so apply to rebuilding a 4.0l as well. Using quality parts and advise from good builders is key
Dig around here long enough and you'll see that I too rarely leave anything alone, particularly engines - though the stroker engines I play with have a few more cylinders...


Strokers are fun, though a stroker 4.0L still leaves much to be desired IMO. When 4.2 cranks were cheap and easy to find, every town had a good machinist, and local tuners who worked on the JTEC were common, it made more sense. For me nowadays, it's a lot of time, money and work for a whopping 230hp and 315 ft lbs.
 
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