'97 C1500 4L60E to 4L80E Swap

[df2x4]

Yeah, I've had this truck tuned for 91 octane before, but only because I was experimenting with ethanol free fuel and that was the only grade available in my area. Spoiler alert, ethanol is not the devil. I got way worse mileage on 91 ethanol free than I ever did on top tier 87 with up to 10%. Justin at Black Bear has told me in the past that I'll definitely pick up some power on 89, but anything more than that is a waste.

I like the TCC lockup and shift points where they're at, so I won't be messing with those, and my speedo is within 5MPH at all times when checked against GPS. Probably just have Black Bear bump the timing a little and set my (now useless) factory PCM up for 89. That way I can always swap between the 87 and 89 tunes as needed/wanted.

 

[L31MaxExpress]

Yeah, I've had this truck tuned for 91 octane before, but only because I was experimenting with ethanol free fuel and that was the only grade available in my area. Spoiler alert, ethanol is not the devil. I got way worse mileage on 91 ethanol free than I ever did on top tier 87 with up to 10%. Justin at Black Bear has told me in the past that I'll definitely pick up some power on 89, but anything more than that is a waste.

I like the TCC lockup and shift points where they're at, so I won't be messing with those, and my speedo is within 5MPH at all times when checked against GPS. Probably just have Black Bear bump the timing a little and set my (now useless) factory PCM up for 89. That way I can always swap between the 87 and 89 tunes as needed/wanted.

My 5.7 Vortec in the Express van would detonate on 89 enough to retard the timing with the stock timing map in hot weather. 91+ I never saw any timing retard. Straight 93 improves my MPG about 1-2 mpg.

 

[df2x4]

My 5.7 Vortec in the Express van would detonate on 89 enough to retard the timing with the stock timing map in hot weather. 91+ I never saw any timing retard. Straight 93 improves my MPG about 1-2 mpg.

I don't doubt it. My issue with the mileage reduction was that the ethanol free 91 I was using wasn't from a larger gas station. It was more of a general store type location. I get great mileage on top tier 91 or 93. My discovery was that buying fresh gas from a top tier distributor is a lot more important than running ethanol free.

 

[98chevy2500SS]

Great thread! Glad you liked the 4l80e conversion, makes me want to ditch my 60 and get an 80.

But yeah I have been told that the 4l80e is not as fast at take off as a 60 would, slower, but lasts so much longer and stronger! I really don't care about launching performance or speed, I just want the durability, longevity, and strength.

I think you should totally get a 14 bolt 5 lug rear end with 4.10s, that build would be killer.

 

[df2x4]

But yeah I have been told that the 4l80e is not as fast at take off as a 60 would, slower, but lasts so much longer and stronger! I really don't care about launching performance or speed, I just want the durability, longevity, and strength.

Honestly the difference in performance isn't that extreme, I'm sure in a V8 truck you'd hardly notice it. I actually just swapped in my other PCM from Black Bear with the 91 octane tune a few minutes ago, about to go test drive it.

I think you should totally get a 14 bolt 5 lug rear end with 4.10s, that build would be killer.

It's already in the works. Hopefully grabbing a 454SS axle here soon!

 

[df2x4]

Just got back from a test drive with the 91 octane tuned PCM. Not sure exactly what they did at Black Bear but it definitely pulls harder now. Not a huge difference and it still won't break the tires loose on pavement, but it was absolutely worth the $15 in shipping costs. Very happy with the results!

The more I drive it the more I think different rear end gears are the key to regaining some momentum off the line. With my 3.42s a wide open throttle run holds first gear to roughly 50 MPH.

 

[Z71Hobbs]

Just got back from a test drive with the 91 octane tuned PCM. Not sure exactly what they did at Black Bear but it definitely pulls harder now. Not a huge difference and it still won't break the tires loose on pavement, but it was absolutely worth the $15 in shipping costs. Very happy with the results!

The more I drive it the more I think different rear end gears are the key to regaining some momentum off the line. With my 3.42s a wide open throttle run holds first gear to roughly 50 MPH.

I’m wanting to say @Cokeman95 just swapped rears from 3:42 to 3:73. He seems happy with the results.

 

[Cokeman95]

I’m wanting to say @Cokeman95 just swapped rears from 3:42 to 3:73. He seems happy with the results.

Correct on both statements. Not a huge difference but gets rolling easier for sure.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[L31MaxExpress]

I went from 3.42 in the 8.5" to 3.73 in the 9.5" to 5.13s in the 10.5. Had 29" tall tires with the 3.42s. Had 31.5" tall tires with the 3.73s. With the 5.13s I am running 32" tall tires. Biggest difference I notice is with the travel trailer in tow. I can easily pull down the highway in OD with the converter locked and can go uphill without racing the engine in 2nd gear. The 1-ton rear end, suspension and brakes added somewhere close to 500 lbs overall. Rolling along at 6,500 lbs it gets up and goes like it never has before. Part of that is the 215/224 custom grind Comp cam and 205cc aluminum heads though.

 

[df2x4]

So I took the truck on its first long-ish voyage since the swap today. Nothing major, but I put about 170 highway miles on it. I noticed something awesome that I was not expecting. It holds fourth gear on the highway way better now! It doesn't downshift on every incline as it liked to do when it had the 4L60E. Must be the overdrive ratio difference, .75 for the 80E and .70 for the 60E. It runs about 200RPM higher than it used to at 75MPH. Cruising down the highway is much more pleasant now.