(PROJECT) Yukon GT

[Fast Eddie]

Hi all. A little intro-I just bought a 2016 Yukon Denali AWD. This is my third Yukon. My others were stock but this one I bought specifically to do some work on. My plan is to build a Yukon GT if GMC built one today. I’ve already installed a Texas Speed LT1 cam with AFM delete and phase limiter, beehive springs and new lifters/pushrods, TS stainless long tubes, Magnaflow 3.5” street exhaust, Corsa CAI, new Magride shocks and a MaxTrac 2/3 drop. I’ve also done some dechroming, scored some cheap OEM 22s and trimmed up the front lower balance.

I looked forever for a truck with retractable boards but I couldn’t find one in my budget. I would like to remove these Dumbo-ear fixed running boards and replace them with just side skirts but they don’t exist. So I looked into trying to convert to factory retractable boards. I work at a GM dealership so there’s a chance I can get the parts and have access to the expertise to installed them. Then one day I was walking through the shop and I saw a set of rocker trim panels for a 2022 GMC Acadia. They looked close so I took some measurements. Looks like they will be almost a perfect fit! I grabbed a set that were being thrown away so my next step is to remove a running board and see how they actually mock up.

I have an appointment for the truck to go on the dyno next week at Mike Copeland‘s shop in Brighton MI-Diversified Creations. I’ve been waiting months to get in! I’m geeked to see how much HP this combo will turn out. I’m also hoping they can sort out some drivability issues. The truck now drives best in tow/haul mode. The increased shift points and pump pressure agree with the Cam a lot better than econo mode. Also, they can remove the pedal delay and some other items to make the truck more fun.

I’ll keep you posted with pics (and hopefully a dyno video!)

 

[swathdiver]

Go down to Milan and make some quarter mile passes. That will be the most accurate way to determine actual Rear Wheel Horsepower. Don't forget to weigh the truck.

 

[Fast Eddie]

Just picked her up from the dyno shop. 421hp/435tq at the wheels. Trans shift points and converter lockup much improved! 0-60 in 3.9 seconds! However I think the next step is a little stall converter…

Shop estimated 530hp at the crank. Sound right? About 20% drivetrain loss?

 

[mb1500]

Nice!

 

[OR VietVet]

Just picked her up from the dyno shop. 421hp/435tq at the wheels. Trans shift points and converter lockup much improved! 0-60 in 3.9 seconds! However I think the next step is a little stall converter…

Shop estimated 530hp at the crank. Sound right? About 20% drivetrain loss?

View attachment 380277

I am no performance guru by any means, I pretty much prefer stock that ALWAYS works when I need it. Years ago I was involved with a couple friends with their drag race cars and I remember a time when both cars were put on a dyno and just from listening to what was going on I did hear the guy that was running the dyno say it is normal to lose some horsepower thru the drivetrain and it depended on the particular drivetrain as to how much was lost. That was never explained as to what he meant by "the particular drivetrain" but I would assume he meant automatic or manual trans and gearing, but hell, I am guessing with that statement. He did say, the loss could be from 15% to 25%. That little bit of info had never tumbled out of my memory till you just said, "About 20% drivetrain loss?".

 

[gooffeyguy]

Does that shop have a 4 wheel dyno or did they disconnect the front driveshaft for testing?

 

[mb1500]

2015+ are not AWD they are regular 4wd like the rest of the lineup.

 

[gooffeyguy]

2015+ are not AWD they are regular 4wd like the rest of the lineup.

I did not know that, and apparently neither did the OP, as he stated AWD in the first sentence of the first post

 

[Fast Eddie]

I did not know that, and apparently neither did the OP, as he stated AWD in the first sentence of the first post

15+ Denalis have a transfer case that’s 4WD and AWD selectable. I can select either. When I said “AWD” in my 1st post, it was to clarify mine is not 2WD.

 

[Fast Eddie]

I am no performance guru by any means, I pretty much prefer stock that ALWAYS works when I need it. Years ago I was involved with a couple friends with their drag race cars and I remember a time when both cars were put on a dyno and just from listening to what was going on I did hear the guy that was running the dyno say it is normal to lose some horsepower thru the drivetrain and it depended on the particular drivetrain as to how much was lost. That was never explained as to what he meant by "the particular drivetrain" but I would assume he meant automatic or manual trans and gearing, but hell, I am guessing with that statement. He did say, the loss could be from 15% to 25%. That little bit of info had never tumbled out of my memory till you just said, "About 20% drivetrain loss?".

On a chassis dyno, power is measured at the rear wheels. The drivetrain sees parasitic losses that reduce actual power numbers at the crank. Most people use a standard percentage of parasitic loss. I did some research on four-wheel-drive trucks and 20% seems to be an average number.