upgrade for 4l80e maybe?

[99xcss4]

I am most like going to pick the 4.56s I could not find the calculator I used but I did find a different one though it did not have what I am guessing is tire speed charted out it did give me an engine speed and I think in od at 75 mph 2329 rpms 4.88 were over 2400 and that is just too high even for a truck that will see little highway use. 2329 rpms is not super bad would like it to be in the 1800-2000 range but that is not going to happen and I could be wrong but I think most people with big lifted trucks do not care that much about mpgs or they know to expect poor mileage and I think we can all agree that it is more about the smiles per gallon

 

[yevgenievich]

I am most like going to pick the 4.56s I could not find the calculator I used but I did find a different one though it did not have what I am guessing is tire speed charted out it did give me an engine speed and I think in od at 75 mph 2329 rpms 4.88 were over 2400 and that is just too high even for a truck that will see little highway use. 2329 rpms is not super bad would like it to be in the 1800-2000 range but that is not going to happen and I could be wrong but I think most people with big lifted trucks do not care that much about mpgs or they know to expect poor mileage and I think we can all agree that it is more about the smiles per gallon

4.10 will get 2000rpm at 70mph. However for a heavy truck it will likely hunt between lock up/no lockup and 3rd/4th a lot.

Edit: depending on driving style it might be border line ok. My burban has 3.73 gears and 33" tires which puts it at 2000rpm when at 70mph. When towing, up until about 70-75 I keep it in 3rd. When 80 or greater can put it in od. Unless trailer is really light. When not towing and just standard load in od by 55mph

37" tire are still considerably more weight to get going

 

[L31MaxExpress]

I am most like going to pick the 4.56s I could not find the calculator I used but I did find a different one though it did not have what I am guessing is tire speed charted out it did give me an engine speed and I think in od at 75 mph 2329 rpms 4.88 were over 2400 and that is just too high even for a truck that will see little highway use. 2329 rpms is not super bad would like it to be in the 1800-2000 range but that is not going to happen and I could be wrong but I think most people with big lifted trucks do not care that much about mpgs or they know to expect poor mileage and I think we can all agree that it is more about the smiles per gallon

I go everywhere at ~2,350 @ 75 mph. The old 350 Vortec got 18-19 mpg running that RPM and the 383 does slightly better. ~2,200 @ 70 is a nice sweet spot on a SBC in a heavy truck or van.

 

[99xcss4]

I am going to have to find that calculator again other than hunting between 3rd and 4th I think do not know but tire rotations may have also been not to good I am going to search again and hopefuly I will be able to post the charts for 4.56 and 4.88

 

[RDF1]

I use this. or a spreadsheet i made.

Gearing Calculator | RPM and Tire Diameter to km/h - mph with Shift Tracer

Enter Gear Ratios, Tire Diameter and Diff Ratio to Calculate km/h mph and Shift Points with Tracer. Large Animated Gauges

www.blocklayer.com

my 2500hd runs 2350 at 70 and no complaints.
4.10s and 33s.

 

[99xcss4]

this is the cart for 4l80e 4.56 and 37s

Gear	Trans Ratio	Final Ratio	1000 RPM	1500 RPM	2000 RPM	2500 RPM	3000 RPM	3500 RPM	4000 RPM	4500 RPM	5000 RPM	5500 RPM	6000 RPM	6500 RPM
1st	2.48	11.16	9.9	14.8	19.7	24.7	29.6	34.5	39.5	44.4	49.3	54.2	59.2	64.1
2nd	1.48	6.66	16.5	24.8	33.1	41.3	49.6	57.8	66.1	74.4	82.6	90.9	99.2	107.4
3rd	1.00	4.50	24.5	36.7	48.9	61.2	73.4	85.6	97.8	110.1	122.3	134.5	146.8	159.0
4th	0.75	3.38	32.6	48.9	65.2	81.5	97.8	114.2	130.5	146.8	163.1	179.4	195.7	212.0

 

[99xcss4]

this is the cart for 4l80e 4.88s and 37s

Gear	Trans Ratio	Final Ratio	1000 RPM	1500 RPM	2000 RPM	2500 RPM	3000 RPM	3500 RPM	4000 RPM	4500 RPM	5000 RPM	5500 RPM	6000 RPM	6500 RPM
1st	2.48	11.90	9.2	13.9	18.5	23.1	27.7	32.4	37.0	41.6	46.2	50.9	55.5	60.1
2nd	1.48	7.10	15.5	23.2	31.0	38.7	46.5	54.2	62.0	69.7	77.5	85.2	93.0	100.7
3rd	1.00	4.80	22.9	34.4	45.9	57.3	68.8	80.3	91.7	103.2	114.7	126.1	137.6	149.1
4th	0.75	3.60	30.6	45.9	61.2	76.4	91.7	107.0	122.3	137.6	152.9	168.2	183.5	198.7

 

[99xcss4]

this is the calculator I used https://hgmelectronics.com/pages/gear-ratio-calculator it is very simple that might be a bad thing but at least my stupid slow idiot brain can use it reading parts of the chart is kind of confusing to me though

 

[RDF1]

If you think your rpms might be too high for your comfort just remember how much more power it takes to push those taller/wider/heavier tires down the road.



I get trucks in every week with 35s and 3.42s with 4l60s and they have put too big of a cam in and want it tuned. Then complain it doesn't make any more power.

I suggest 4.56s for 35s to get the final ratio back a little better than stock. Got buddys that went from 3.42/35s to 3.90 or 4.10 and 35s and regret it. Eventually they went to 4.56 or 4.88s and finally were happy.
Don't fear the gear.

 

[99xcss4]

I am having a hard time picking what to I know it is not right how it is now. after the replies I have gotten I am fine with the engine rpms but I am having a hard time understanding the tire rpms at given engine speed. I know it must matter at some point I just do not know how much. if it can be fun offroad be a back up topig to a 97 k3500 6.5 turbo diesel and just go for a drive form time to with out hunting for gears that is all I can ask.


sounds like my former buddy 350 vortec with a small cam and some of the usual things beginners tend to their engines on top of it being bored over .40 35s 4l60e and 3.73