4l80e?? use 4th or not for racing
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single digit dreamer
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From: omaha ne
4l80e?? use 4th or not for racing trying to pick a gear ratio
my next project will be a 4wd 2500 with a 4L80E, my first mods will be built tranny, stall, gears, posi and locker(front), 150shot. down the road i plan on seeing some serious HP, should i gear it to stay in 3rd or go ahead and plan on using 4th in the 1/4?
here are some numbers, figuring max 130mph and you have to add a couple hundred rpm for converter not being locked
130mph, 29" tire, 3.73 gear > 5618rpm
130mph, 29" tire, 4.10 gear > 6175rpm
130mph, 29" tire, 4.56 gear > 6868rpm
130mph, 29" tire, 4.56 gear in 4th > 4808
130mph. 29" tire, 5.13 gear in 4th > 5409
looking at a stroker set up so i wont be spining it much over 6k, by the time i add in converter slipage just going to 4.10's might be too steep to stay in 3rd gear so i was thinking about having it shift into 4th. this should be a seriously strong drivline with a true AWD so i think i can take advantage of the steeper gears if 4th can handle it.
any thoughts?????
my next project will be a 4wd 2500 with a 4L80E, my first mods will be built tranny, stall, gears, posi and locker(front), 150shot. down the road i plan on seeing some serious HP, should i gear it to stay in 3rd or go ahead and plan on using 4th in the 1/4?
here are some numbers, figuring max 130mph and you have to add a couple hundred rpm for converter not being locked
130mph, 29" tire, 3.73 gear > 5618rpm
130mph, 29" tire, 4.10 gear > 6175rpm
130mph, 29" tire, 4.56 gear > 6868rpm
130mph, 29" tire, 4.56 gear in 4th > 4808
130mph. 29" tire, 5.13 gear in 4th > 5409
looking at a stroker set up so i wont be spining it much over 6k, by the time i add in converter slipage just going to 4.10's might be too steep to stay in 3rd gear so i was thinking about having it shift into 4th. this should be a seriously strong drivline with a true AWD so i think i can take advantage of the steeper gears if 4th can handle it.
any thoughts?????
Adkoonerstrator
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From: Deep in the seedy underworld of Koonerville
Re: 4l80e?? use 4th or not for racing Hey Jim
Check out this website. It figures in converter slip also. You may want to figure out whose converter you'll be using and give them a call to ask what type of slip you might see.
<a href="http://www.smokemup.com/auto_math/mph_range.php" target="_blank"><font color="red">http://www.smokemup.com/auto_math/mph_range.php<!--color--></font></a>
It kinda looks like a 3.73 would be a decent gear and you wouldn't have to shift into 4th. I don't think most overdrives were designed to hold ALOT of power. There main purpose is for better gas mileage while cruising so I would try to stay in third gear. The 3.73 gear will be stronger than a 4.56 also. That might not be a concern with the big 10.5 inch gears though.
Don't forget to figure in some tire height growth at the top end. It might only be a .5" but, that can drop the rpms a little bit.
Check out this website. It figures in converter slip also. You may want to figure out whose converter you'll be using and give them a call to ask what type of slip you might see.
<a href="http://www.smokemup.com/auto_math/mph_range.php" target="_blank"><font color="red">http://www.smokemup.com/auto_math/mph_range.php<!--color--></font></a>
It kinda looks like a 3.73 would be a decent gear and you wouldn't have to shift into 4th. I don't think most overdrives were designed to hold ALOT of power. There main purpose is for better gas mileage while cruising so I would try to stay in third gear. The 3.73 gear will be stronger than a 4.56 also. That might not be a concern with the big 10.5 inch gears though.
Don't forget to figure in some tire height growth at the top end. It might only be a .5" but, that can drop the rpms a little bit.
Thread Starter
single digit dreamer
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From: omaha ne
Re: 4l80e?? use 4th or not for racing i have found some tranny sites that are saying 900+hp with full throttle shifts into 4th, looks like that answered part of my question.
now for my dream aplication, 5700lb's, GREAT traction, 30" tall tires, ~1000hp, no miliage concern, 408-422 iron stroker.... would 4.56 or even steeper be signifacantly quicker than 3.73's
Transmission Ratios:
1st: 2.48 2nd: 1.48 3rd: 1 4th: 0.75
Tire Diameter 1: 30 inches
Rear Gear Ratio 1: 4.88:1
MPH
RPM 1st 2nd 3rd 4th
1000 7 12 18 23
1500 11 18 26 35
2000 14 24 35 47
2500 18 30 44 59
3000 21 36 53 70
3500 25 42 61 82
4000 28 47 70 94
4500 32 53 79 105
5000 35 59 88 117
5500 39 65 97 129
6000 42 71 105 140
6500 46 77 114 152
now for my dream aplication, 5700lb's, GREAT traction, 30" tall tires, ~1000hp, no miliage concern, 408-422 iron stroker.... would 4.56 or even steeper be signifacantly quicker than 3.73's
Transmission Ratios:
1st: 2.48 2nd: 1.48 3rd: 1 4th: 0.75
Tire Diameter 1: 30 inches
Rear Gear Ratio 1: 4.88:1
MPH
RPM 1st 2nd 3rd 4th
1000 7 12 18 23
1500 11 18 26 35
2000 14 24 35 47
2500 18 30 44 59
3000 21 36 53 70
3500 25 42 61 82
4000 28 47 70 94
4500 32 53 79 105
5000 35 59 88 117
5500 39 65 97 129
6000 42 71 105 140
6500 46 77 114 152
TECH Junkie
Joined: Mar 2002
Posts: 3,019
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From: memphis tn
Re: 4l80e?? use 4th or not for racing I'm planning on using a 4L80E in my Tahoe.From the research I've done a built 4L80E is actually stronger than a built Turbo 400 and can live with 900hp.I'm planning to use a TCI computer setup to control the transmission run 4.56 gears and 26"tires so I will need to shift into 4th to finish the 1/4mile.
