Whipple 2.9L 2017 GMC Sierra 6.2L...boost and hp limits
 

Great site, 1st post.

Have a 2017 GMC Sierra w/ 6.2L. I just had the Whipple (Gen 2) 2.9L kit installed as Xmas present for wife. I coudn't get the headers delivered or the tcm unlocked in time for Xmas, so running the canned whipple tune and "stock" 4.0" pulley. I plan on adding (parts ordered)Texas Speed Headers & Y Pipe,, Loud valves cutout upstream from the muffler and alkycontrol.com alky system. I expect to lose a lb or 2 of boost with exhaust and I have thought about pulleying down to compensate, but concerned about reliability. I have searched high and low and I'm not finding a ton of info for upgrades beyond what I have planned (e.g. blower, exhaust, aky).

My question is around durability, engine, trans, driveline...for what I have planned. For guys that have gone beyond just the blower (e.g. smaller pulley, exhaust, et.c) on the 2015 and newer DI setups...what are your mods/boost? How has your experience been? What parts have you had to replace (engine/trans/driveline)? Thanks in advance for any hep that you can provide.

Note: its the wife's daily and occasional race car tow rig, so want to keep it reliable. Just want to see how far I can go before I get into the "danger" zone.

The motors themselves are very reliable and respond amazing to boost.

You probably wont lose as much boost as you would guess using the stock cam with changes to the exhaust system.

Sounds like a hell of a combo! The headers will certainly make it LOUD!

The one gray area I think it the 8 speed. They seem hit or miss unfortunately. I think they can handle a lot of power, but they were plagued with input shaft issues when they were first introduced to the trucks.

For the wife??@@

Yeah..its her daily when she doesn’t have company vehicle. I will be towing with it as well. Purchased it specifically to get the 11K tow rating (6.2L). It suddenly occurred to me shortly after I purchased it that I could actually make it a little fun for her. She recently got the bug after driving my TT V and my stock (for now) C7 Z.

I used to have a wife that wanted to race her '42 Willys Jeep with BB Chevy at the track most every weekend. God I miss that Jeep!

:dewey:
Gotta laugh at that...


And welcome to the site!

Sounds like you have a hell of a lot more experience in the performance world than I assumed!

You're on the right track! Mimic your C7z's fuel system in the truck and you'll be golden. Hell if you really wanted you could swap to the LT4 cam too. Seeing as its a tow vehicle and compression is higher in the NA motors I would keep the boost in check. 8 PSI should be enough for her to have fun while keeping things safe for parts while hauling.

I would change to a colder plug too. If you keep boost modest the same plugs that go into the vette would work for you and have the longevity you want out of a daily driver.

Yeah, I've been modifying cars for the past 20 years. Problem is, I go way too far...So far that any build that I do now with my fun cars, starts with a built long block. In the case of my wife's truck, I want to balance fun and reliability. I find that asking guys that pushed things a bit typically know where the "limits" are. My wife accepts when my fun cars are down. She wouldn't be quite so understanding with her daily...lol. Thanks to all that have offerred input. Right now I'm thinking blower, exhaust w/ cutout and Meth injection (safety) and calling it a day.

:dewey:

WELCOME!

Seems TSP could set you up,unless something has changed there headers they build/have built, are for 5.3 only


I cannot kill the 8sp ,I try everyday.

Thanks. It looks like, from your sig, that your build is pretty close to where I want to go for my wife's truck (e.g. LT/Whipple/Smaller Pulley), with only a few differences: Alky Kit and Cutout. Glad to hear that the 8L90 is robust enough to handle a little extra punishment. FYI, TSP does in fact offer Headers/Y-Pipe for 6.2L's. The truck is going in for upgrades next week...all set with remaining parts. However, while perusing the forum I did come accross the next weak link...driveshaft. So I will have to add that to the list of final upgrades. I think I have found a good source, just need measurements for 4wd Double Cab DS length. Unfortunately, finding this out late means that I won't have it in time for my install appointment. How are tuners getting around this for dyno tuning (e.g. 100mph speed limit/driveline safety limit)...doing runs in 3 or 4th gear? I don't really care about the numbers, just that fueling/spark is set appropriately throughout rpm range.