Calling all experienced tuners! Trouble with L86/8L90 combo

[15SSS]

Hello,

I am looking for some guys that have experience with tuning trucks with 8L90?s, any knowledgeable advice would be greatly appreciated.

Short story- is it possible to tune a 6.2L 8L90 to have throttle response and quick shifts without destroying the transmission. Possibly similar to a tuned 6.0 4L65 combo? (That has to be aiming low right??)



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?

[Alvin]

You should be able to get an uncomfortably hard shift out of it. (if you wanted)

Most people carry over what they learned from 4L transmissions when taking on 6-10 speeds. The newer stuff is all shift time based. It needs to be a reasonable number but you can get pretty damn firm without touching TM or shift pressure. So set a time that you want the shifts to complete within (0.15-0.25 seconds upshift for example)

[GHuggins]

Sounds like a lot of stuff isn't tuned right, especially if it's taking that much throttle to shift. These require engine and trans adjustments to get right. Just as much on the engine side as the trans.

The main problem is your year model. It was one of the one's that hpt decided not to map everything out on the trans side. Requires some serious work arounds on the engine side if you want it to shift at higher rpms. Your better off to have it shift in the less than 6000 rpm range then you won't have problems with having to work around it.

[15SSS]

Thank you very much for the reply, I am not looking for uncomfortably hard, just firm and quick. Im glad to know that it is possible to do that... will the transmission survive shifting quickly under load? my tuner is telling me it is impossible to have it shift quickly without blowing up the trans. I find this hard to believe being that the truck has a stock engine, and there are guys running boosted motors that seem to get around just fine...

[15SSS]

Greg, I am with you there, I am losing faith in my Tuner, gaslighting me into thinking that the truck needs granny shifts to survive the whopping stock hp of an L86... I am still learning this L86 engine, what is the maximum safe rpm for it bone stock?

Assuming I just keep the shifting under 6000, do you see any problems with tuning the engine/trans to be very responsive, have very little torque/abuse management, and Also shift often in the 1/3-3/4 throttle range to make use of the 8 gears available?

Thanks again!

[GHuggins]

Haven't had one fail setup that way yet - at least to my knowledge. The converters are the biggest issues on these things. Super thin metal. Whole reason GM has so many issues with them. Even in my time talking with tranny builders the ones shifting quicker and firmer always lasted longer than the ones granny shifting. There are some internal metal parts that aren't the strongest, but usually clutches or valve bodies go first shifting soft.

I don't have any cut and dry way of getting them right. Got one right now - that's built - giving me a lot of trouble that I haven't had out of a non built one. BUT it's a year model like yours and I can't change the desired final settings in it...

[Camaro6]

You can have great throttle response, quick firm shifts, tq mgt still on, and the truck work fine. GHuggins is correct on crappy converters from GM. They slip them so much in the stock tune and create heat which leads to tq conv shudder. These trucks will chirp 2nd and 3rd gear with just a cam or on E85 tune. Stock power is just a little low for the chirp effect.

[15SSS]

Greg, it makes perfect sense that the quicker shifts would make for better transmission longevity.
Also you mention the 2015 having less access to trans tuning than newer years, I heard on another forum that you could send the actual tcm to hp tuners to have it modified to correct this. Have you heard of this or is it a rumor?

Can the issues with the crappy converter be corrected or masked with proper tuning for stock HP or is it something that is necessary to change out?

Camaro6
You are describing exactly what I want the truck to do. Some day I would love to learn tuning, but right now I have too many other big jobs on the go to give it the time it would need, that being said I need a reliable tuner that can make this thing go without causing it to grenade. I have access to HP tuners and EFI live. Also I am willing to drive anywhere in bc/Alberta Canada, as well as Idaho/Montana/Washington if a dyno tune or in person tune was necessary, do you guys have any recommendations for a tuner that has experience with that specific truck?

Other tune questions:
Is it possible to disable stabilitrack or at least make it stay off when it is shut off?

Can the tow haul be used to make the truck shift and drive differently? In my older SS it was tuned as a really aggressive auto cross like setup that was a fun novelty for city driving

Thanks again