Anyone out there with a custom tune 6.2L 8 speed??

2015silveradoSS · April 21, 2023

Hello,

I am looking for some guys that have experience with tuning trucks with 8L90’s

Short story- is it possible to tune a 6.2L 8L90 to have throttle response and quick shifts. Possibly similar to a tuned 6.0 4L65 combo?

Also, does anyone know of any transmission mods? Shift kit? Different accumulators? Internal settings?

Long story -

I have a 2015 Silverado 1500 Max HD with a 6.2L and 8L90 combo stock other than afe intake. My goal is to build a 2015 Silverado SS as a throwback to my 2003 SSS. My issue is drivability.

As all Chevy pickups from the last couple decades, the truck stock was very “mushy” lethargic, And not very responsive, making it very boring And frustrating to drive.

I have had it custom tuned, and was very disappointed in the lack of change.

Contacted the tuner they said it was a conservative tune and that they would wrote a more aggressive tune but that I would have to be very careful with any type of load on the truck as it could damage the trans.... it’s a little bit more peppy maybe 5% change, comparable to a stock 6L80 shift characteristic until you hit WOT. I told the tuner and they basically said the transmission won’t take any more? It holds whatever gear it’s in at 2500rpm until well over 3/4 throttle?!

To the experts out there, is it possible to get this thing to be enjoyable to drive?

new tune from someone like blackbear?

Get hp tuners and tune it myself?

Sell the truck and buy a ford??

6 speed manual swap?

jrmcswain · April 21, 2023

Yes it is possible to tune an 8L90. You have to send the Transmission Control Module to HP Tuners to be physically modified. Then you need extra credits to tune the TCM.

I have found several places that will build an 8L90 to take 1,000 Horse power.

My stock 2017 6.2/8l90 was not sluggish. But maybe you should get a ZO6?

That being said, I sent my 2017 to Hennessey Performance. It's way more fun. After 2 years I have not hurt the 8L90 yet with 650HP and 658 ft/lbs torque.

SeekAndDestroy · April 21, 2023

6 hours ago, 2015silveradoSS said:

new tune from someone like blackbear?

Get hp tuners and tune it myself?

Sell the truck and buy a ford??

6 speed manual swap?

I have a 6.2, 8 speed, cammed and tuned. Judging by your concerns, a higher stall torque converter will wake it up and get rid of most of the complaints. Sounds like your tuner doesn't know Gen 5 stuff. I'm just going to follow your list of concerns.

-Yes. You can tune them to have great throttle response. 8 speeds shift quick from factory but you can make them shift faster.

-Sonnax makes aftermarket internal parts for the 6/8 speeds. Check them out

-Torque management keeps the trans safe by cutting timing during shifts. A good tuner will know how much to safely remove. These 8L90's are very robust, they will take a lot of torque.

-Don't know what you mean by this: It holds whatever gear it’s in at 2500rpm until well over 3/4 throttle?!

-Yes, it's possible to tune it and make it enjoyable to drive. I love my 8 speed now.

-Blackbear can't tune 8 speeds. Learning HP Tuners and doing it yourself will take a while, and you have to know what you are doing. Don't buy a Ford, just turbo the 6.2, lol. Manual swap would be very cool, but it would be super expensive.

Call Davenport Motorsports here in Calgary, AB. Not to far from you. Very easy going and will steer you in the right direction. Their tuner knows Gen 5's. It's not cheap but they know what they are doing.

2015silveradoSS · April 24, 2023

On 4/21/2023 at 5:14 PM, jrmcswain said:

Yes it is possible to tune an 8L90. You have to send the Transmission Control Module to HP Tuners to be physically modified. Then you need extra credits to tune the TCM.

I have found several places that will build an 8L90 to take 1,000 Horse power.

My stock 2017 6.2/8l90 was not sluggish. But maybe you should get a ZO6?

That being said, I sent my 2017 to Hennessey Performance. It's way more fun. After 2 years I have not hurt the 8L90 yet with 650HP and 658 ft/lbs torque.

This is exactly what I thought... guys running around with built trucks with the 8 speed surviving. Does your 2017 Hennessy truck have a built trans or stock?

sluggish is possibly a bad way to word it, at 100% pedal position at 60mph+ after the 2 second delay... it is very clear that the truck has plenty of power! Probably more more than my slightly modified 03 LQ9... I just want to get rid of the delay between throttle input and vehicle reaction, as well as have it spend less time in the shift. I can’t see a fella with a 650hp built truck waiting 2 seconds for the truck to wake up when the pedal is pressed

My previous tuner did not physically modify the TCM so I wonder if that is what the issue is, we did pay double for credits though due to the tcm and ecm being separate.

2015silveradoSS · April 24, 2023

On 4/21/2023 at 5:34 PM, SeekAndDestroy said:

I have a 6.2, 8 speed, cammed and tuned. Judging by your concerns, a higher stall torque converter will wake it up and get rid of most of the complaints. Sounds like your tuner doesn't know Gen 5 stuff. I'm just going to follow your list of concerns.

-Yes. You can tune them to have great throttle response. 8 speeds shift quick from factory but you can make them shift faster.

-Sonnax makes aftermarket internal parts for the 6/8 speeds. Check them out

-Torque management keeps the trans safe by cutting timing during shifts. A good tuner will know how much to safely remove. These 8L90's are very robust, they will take a lot of torque.

-Don't know what you mean by this: It holds whatever gear it’s in at 2500rpm until well over 3/4 throttle?!

-Yes, it's possible to tune it and make it enjoyable to drive. I love my 8 speed now.

-Blackbear can't tune 8 speeds. Learning HP Tuners and doing it yourself will take a while, and you have to know what you are doing. Don't buy a Ford, just turbo the 6.2, lol. Manual swap would be very cool, but it would be super expensive.

Call Davenport Motorsports here in Calgary, AB. Not to far from you. Very easy going and will steer you in the right direction. Their tuner knows Gen 5's. It's not cheap but they know what they are doing.

Thank you for the reply, good to hear from another guy that has completed a similar build and is optimistic about it!

I have heard so many pessimistic things about these trucks, but it simply sounds like they Need a tuner who is very experienced with these gen 5 trucks....

im not opposed to a higher stall, what do you run? And do you have any other transmission mods?

Great throttle response, thank god, because right now my 97 Jeep TJ auto has Better response. The fast shifts are also optimistic, I had a built 4L65 in my last truck, it shifted extremely fast and was pretty aggressive, I know I’m not going to get that.. but I would settle for just “fast”

ive has good and bad tuners in the past, broke 3 output shafts on the built 4L65 due to bad tuning of torque management etc, switched tuners, truck drove great and I managed to put 150,000miles on that transmission build no issues before selling the truck.

I am glad to hear another guy mentioning that the 8L90 is a tough transmission, when I did the research before buying I kept reading and hearing 600+hp

the comment about “holding the gear” is tough to describe but here goes:

I am cruising at 40mph 1/8-1/4 throttle holding speed perfectly in say 4th gear at 2000 rpm.... the speed limit changes to 80mph... so I push the pedal to accelerate 1/2 throttle, the truck starts to speed up (slowly) climbing to 2300rpm. Not wanting to take all day to get to 80mph I push the pedal to 3/4 pos, accelerates a little faster, but still pretty pokey and still in 4th gear at what has now climbed to 2500rpm..... so I would get irratated and push the pedal to WOT the truck drops 2 gears and hits 5700 rpm.... is this common for tuned trucks to hold a gear like that?

“I love my 8 speed now” this is what I am shooting for, whatever it costs, those other options were more of a joke, not a ford man, and not someone who gives up easily. Black bear is on my list due to their history, I contacted them and they said they could absolutely tune the 8 speed trucks... but then again so did the last company I had do my tune

You recommend Davenport? Did they do your tuning? That’s easy for me to make the drive from here.

thanks again for the insight

SeekAndDestroy · April 24, 2023

17 hours ago, 2015silveradoSS said:

You recommend Davenport? Did they do your tuning? That’s easy for me to make the drive from here.

I don't have a stall yet. That's next on the mod list. Going to do a 3000 or whatever Davenport recommends. My cam wakes up at 2500 and pulls like stink until shifting at 6100. Trans is stock except the thermal bypass valve. I was running the pill flip until yesterday, then I bought the updated GM part that opens at a lower temp. Lots of info on this site about that mod.

8L90's will take more than 600. There isn't much good info about our trucks online, but I go on the Camaro/Corvette forums to look for mods and info. Any Camaro/Corvette with an "A8" is the exact transmission the trucks get, the 8L90. Their engine is called LT1 but it is 95% the same as the L86. Most mods for them work for us.

I know what you mean about the "holding the gear" thing. My truck did the same thing stock. It's a dumb fuel saving algorithm in the tranny's programming. It's trying not to downshift to save gas, until you floor it then the trans goes "OK! you want it, you got it". There is also flex in the gas pedal. Earlier trucks, like yours, are made of flimsy plastic that actually move when you push the pedal. So when you are pushing the pedal down the throttle position doesn't change as much as it should. There are fixes on here like the "paint stick mod" or you can get the newer pedal. When you get a proper tune most of that lag will go away when they adjust the throttle response and fine tune the tranny for performance.

My mistake about Blackbear. Last time I checked EFI Live didn't support the 8L90. They must have added that. I know of a couple guys with Player3 tunes in their Gen 5 trucks. They are from Edmonton and I have heard good things.

I will highly recommend Davenport. They did my cam and tuning, and I will be going back for a converter this year. They are one of the best in Canada, if not the best, at modifying and tuning late model GM products. They specialize in Camaros and Corvettes, but, our trucks are almost exactly the same.