Another gear post, but with a slight twist

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Wild one

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This is where I'm coming from. My truck currently has 3.21s. I'm going to get a custom Jay Greene tune. I'm contemplating getting 3.92s as well, but I'm wondering how a custom tuned truck with 3.21s would fare against a stock truck with 3.92s both 0-60 mph and in the 1/4 mile.

I know I can't eat my cake and have it, too. I'm not going to lie - the MPG is pretty nice with the 3.21s, but at the end of the day, a quicker truck is the higher priority over a MPG princess. I know some may say get the 3.55s. That's not under consideration. I'm probably going to go with 3.92 gears, unless anyone has a compelling reason why a custom tuned 3.21 geared truck would be sufficient over a custom tuned 3.92 geared truck.

Jay usually reconmends 3.55's,that's the gears he likes to see in his tuned trucks,as it puts you at the top-end of 5th going through the lights.
 
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lnferno

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Jay usually reconmends 3.55's,that's the gears he likes to see in his tuned trucks,as it puts you at the top-end of 5th going through the lights.

Hmmm interesting. I’ve ordered the i3 and a PCM. Just waiting for them to arrive before I get the tune from Jay. I’ll ask him more about that. Thanks.
 

RLJ10X

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When you guys argue gears, you must state tire size also, because tire size also effects your final drive.

I can see how 3.92s with little tires would be slower than 3.55s with little tires. I don't know where optimal gearing is with 8s, but it seems that with little tires, 3.92s is a bit too far. Plus with 3.92s and little tires, the truck probably has to shift another time or 2.

But on the other hand, with 33s, 3.55s may be a bit tall gearing. You 8 guys have a complicated life. Those of us with the old 6 speed, just did 4.10a, and called it a day. Lol.
 

69GWC

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The tire height np doubt has a huge effect on the gearing one should run.. lol

With my light stock tires I was very please with my 3:21s, for a big heavy truck it flat out would scoot.
Now with the 35s and extra weight it just runs good lol, those big tires took the zip right away. 3:92s are on my to do list now.
 
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lnferno

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Another thing to mention is that I live at 7000' altitude. My 395 HP Hemi is really only at 300HP after the altitude sucks all the power away. Another reason why I'm itching for 3.92s.
 

RLJ10X

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28s with 3.92s aren't the same as 35s with 3.92s. Rear end gears are just PART of the equation.

Inferno, does the thin air help with fuel economy?

A few years ago, I was on vacation in Colorado, Wyoming, and Uath. My fuel economy went up 10%+.
 
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lnferno

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Inferno, does the thin air help with fuel economy?

A few years ago, I was on vacation in Colorado, Wyoming, and Uath. My fuel economy went up 10%+.

A little bit, but I'd rather have the power that you guys have a sea-level! lol
 

huntergreen

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Another thing to mention is that I live at 7000' altitude. My 395 HP Hemi is really only at 300HP after the altitude sucks all the power away. Another reason why I'm itching for 3.92s.

Skip the regear and do forced induction.
 

Wild one

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A little bit, but I'd rather have the power that you guys have a sea-level! lol

You got that right,a good day at my local track is if the DA's at 3500ft,it's not uncommon for our DA to be 4400+ft. About an hour away from me is Canada's highest elevation highway at 7200ft,and the power loss from 3300 ft to 7200 ft is very noticable
 
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lnferno

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You got that right,a good day at my local track is if the DA's at 3500ft,it's not uncommon for our DA to be 4400+ft. About an hour away from me is Canada's highest elevation highway at 7200ft,and the power loss from 3300 ft to 7200 ft is very noticable

I know what you're talking about. The track near me (Bandimere Speedway) is at 5800' and this time of year, the DA is consistently between 7500-8500. It's pitiful what that does to a vehicle’s performance.
 
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wester425

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There's a couple nitrous trucks that went from 3.21's to 3.92's and are actually slower at the track.My truck didn't gain squat when I went from 3.21's to 3.55's,and i'm still kicking my ass for going to the 3.55's

Do you have a lift, bigger tires, 4x4?? I have a 2012 4x4 with a level and 35x12.50x20's with 3.55's and am considering going to 4.10's or 4.56's......
 

Wild one

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Do you have a lift, bigger tires, 4x4?? I have a 2012 4x4 with a level and 35x12.50x20's with 3.55's and am considering going to 4.10's or 4.56's......

In your case with the old 5 speed,4.10's are probably the tallest gears you'd want,and the 4.56's might be even better.Depends on how you use the truck,if the majority of your driving is slower the 4.56's are the way to go,but if the majority of your driving is higher speed freeway style driving then you might want the 4.10's just to keep some milege and to keep your oil temps with-in reason.Going from 3.21's to 3.55's with no other changes increased my oil temps by over 5 degrees
 

SYKRAMMAN

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Another thing to mention is that I live at 7000' altitude. My 395 HP Hemi is really only at 300HP after the altitude sucks all the power away. Another reason why I'm itching for 3.92s.

Dam, you lost 100 hp from just the altitude? Can you tune your trucks air/fuel mixture to get those hp’s back?
 
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lnferno

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Dam, you lost 100 hp from just the altitude? Can you tune your trucks air/fuel mixture to get those hp’s back?

Yah, the altitude really hurts performance up here. Turbo'd vehicles lose ~12%, supercharged lose ~18% and naturally aspirated vehicles lose up to ~25%. I've been in the modding world for a long time here in Colorado and those are pretty good averages.

That's why I'll be getting a Jay Greene custom tune - I'm already -100HP in the hole just by being at 7000' altitude. A custom tune should give me back ~20 maybe 30HP, but even after getting tuned, I'd still be down by 70-80 HP lol
 
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wester425

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In your case with the old 5 speed,4.10's are probably the tallest gears you'd want,and the 4.56's might be even better.Depends on how you use the truck,if the majority of your driving is slower the 4.56's are the way to go,but if the majority of your driving is higher speed freeway style driving then you might want the 4.10's just to keep some milege and to keep your oil temps with-in reason.Going from 3.21's to 3.55's with no other changes increased my oil temps by over 5 degrees

Thanks for responding:
I actually have the 6 speed. I drive a mixture of city and highway and pull a Polaris Ranger Crew 800 with lift and tires on it....its heavy. lol
 

Pull Ya

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I know what you're talking about. The track near me (Bandimere Speedway) is at 5800' and this time of year, the DA is consistently between 7500-8500. It's pitiful what that does to a vehicle’s performance.

This is why, in the "old" days people went to Julesburg and Pueblo to race because of the altitude. The other reason is that Johnny Bandimere is a ****head---IMHO!
Jay
 

NCRaineman

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You got that right,a good day at my local track is if the DA's at 3500ft,it's not uncommon for our DA to be 4400+ft. About an hour away from me is Canada's highest elevation highway at 7200ft,and the power loss from 3300 ft to 7200 ft is very noticable

Less than 3500ft isn't really enough to be considered high altitude, but you reside at 5000ft or higher consider forced induction. Superchargers and turbos were originally invented for use on aircraft, to bring the air pressure in the engine back to sea level (14.7PSI). At 5000ft standard pressure is 12.2PSI, which means you could run 2.5PSI of boost and bring the engine back to sea level pressure. If you live at 10,000ft standard pressure is 10.1PSI so you could run basically 5PSI of boost without needing much in the way of supporting mods, you'd basically be operating the engine as if you lived at sea level.
 

Pull Ya

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^^^^ Great explanation--Thanks
Jay
 
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