Performance gains of '08 Yukon Denali

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Javi

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I recently bought a new 2008 (zero miles) Yukon Denali. Been the gear head that I am, started to do some research about the 6.2 engine, and the performance gains in terms of WHP I could achieve with different mods available for my truck. To my surprise, not many people have done before and after dyno sessions or nor have shared the information in public forums (only the alleged numbers of the vendors). I’ve tried many times the search option with no luck, emailed some vendors about actual numbers, dyno sheets, with no answers... therefore, I decided to do my own, and share it with the community. I’ll try tomorrow to do a base line dyno in a local AWD dyno jet for now. Later, hopefully this week, I will test the gains of the Vararam Tri Power Ram Air Intake and then (same day), custom EFILive tuning (don’t work for them, nor sell their products). Performance gains should be fairly accurate, ever since it’s not about how high the numbers are (which depends of the dyno), it’s about how much an intake and programming can give before and after in terms of whp.
I would like to make clear that when I drove for the first time my truck, I noticed that although GM claimed that peak HP was achieved at 5600 rpm’s the tranny shifted at 5500rpm’s, so the first thing I asked my tuner to change was the shift points in the tranny, to 5800rpm’s, set the rev limiter to 6200rpm’s, and delete the top speed limiter. No other modifications have been done. Keep in mind this when looking at the dyno sheet, because it will be revving higher than stock. I have to say though… by simply doing that, the truck came alive! WHAT A DIFFERENCE!!
I will be getting back to you guys (and gals) tomorrow hopefully with a baseline. Hope this is just the beginning of many more, from me and other members that wan't to do the same.
Thanks!
 

Tonygxp

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loking forward to seeing what you gain. My friend has an AWD Mustang Dyno at his shop, few and far between are these AWD Dynos out here. make sure you let us know what octane you're running and what brand. These high compression engines are very sensitive to octane numbers. if you scan your truck on a regular basis you should see the ridiculous knock/timing pulling going on and the "false knock" as well. you should gain a good 20+ to the wheels just tuning it. Good Luck.
 

Zed 71

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Javi, this will be good especially for all those that are new to performance mods. Too many are just throwing parts on... Thanks for your efforts and looking forward to the results/review.

Tony, 20+ whp with just a tune. How are you guys completing the tune and is this on 87 or higher?
 

Bowtye8

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Good stuff. I will be following as well.
I use HP tuners and read my 09 ECM. Did not make any changes. Dont know if I will just yet.

I have heard of some occurances with modifying the ecm and voiding the warranty.. Been happening in the corvette world..
 
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Javi

Javi

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Well, today I was able to get the Denali on the dyno to do a base line. The truck was hot (no cool down period 90+ deg. ambient) and it was running 93 octane gasoline (I always use 93oct), it has 3800 miles and haven’t done the first oil change (tomorrow I’ll be doing it). This truck is huge, it barely fit the dyno, but we managed to pull some runs. The truck gave me all sorts of failure messages, traction control, stability control, ABS, Brake, etc. and for the first couple of pulls, it wouldn’t gave accurate numbers, it wouldn’t rev past 4500rpm’s. The Torque management was going crazy but I kept trying, until it let go (a couple of pulls). At the end we were able to get 291whp and 324rwt in third gear. The air/fuel ratio was way too rich all the time, so there is ample room for improvement. After the pull, I called my tuner to get his impressions and he said that with all things good, stock it could pull 320whp but with all those safety features it is very difficult to achieve. In my opinion, 310 or 315whp is the real number. I have a friend who has a 2008 Tundra (380hp) and we raced side by side until 3rd gear, when I start pulling on him. I’m sure that it has to do with my shift points been higher than stock, but there is like 300lbs of weight difference in favor of the Toyota, so in my opinion this engine is very capable of putting down stock more than 300whp.
Anyway, I have already received the Intake, so I’ll be installing it tomorrow. I will use the truck a couple of days, and then dyno again to see any gains with intake alone, then start to program until final numbers are achieved. Here are the pics:

CIMG0574.jpg

DenaliStock.jpg
 

mikeb33

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SO AWESOME! Glad to have someone doing this! I'd like to see how that intake works for you.
 

Zed 71

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At the end we were able to get 291whp and 324rwt in third gear.
QUOTE]

Hey Javi, wow that thing barely fit!

Were you trying to get numbers in third gear or was it just the stability going crazy? I am not familiar with the 6sp auto, so I am not sure what the ratios are and if third gear was optimal (1:1). Did you try disabling the TCS? In the Tahoe, you press it for ~5 secs and I believe the TCS and stablity are turned off - need to verify.

Your numbers aren't too bad considering the issues and AWD. There is a lot of room for improvement with the A/F. Looking forward to see the results of the tune :).
 
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Javi

Javi

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Hey Javi, wow that thing barely fit!

Were you trying to get numbers in third gear or was it just the stability going crazy? I am not familiar with the 6sp auto, so I am not sure what the ratios are and if third gear was optimal (1:1). Did you try disabling the TCS? In the Tahoe, you press it for ~5 secs and I believe the TCS and stablity are turned off - need to verify.

Your numbers aren't too bad considering the issues and AWD. There is a lot of room for improvement with the A/F. Looking forward to see the results of the tune :).

It all went crazy, stability, traction control, etc. I disabled the traction, but it seems it wasn't enough, maybe next time I'll try your method. The pull was done in third gear, because 4th goes beyond 120mph and we figured it wasn't very safe to go beyond that.
Thanks!
 

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