I went over to MTI today and got dyno tuned. All I have done to the truck is a 160 deg. t'stat, Airaid intake tube and K&N filter in stock airbox. Here are the results:

Baseline dyno: 267 HP and 293 ft/lbs torque

After tuning: 278 HP and 302 ft/lbs torque

I was expecting substantially higher baseline numbers based on what others have posted on the VHOs. But what really bothers me is that we only got 12 HP & 9 ft/lbs torque from the tune. I was hoping for about twice that. Were my expectations just too high?

Their dyno is a Dynojet Model 248C. I understand it is top notch. The temperature was close to 90 deg and humidity was probably 90% as well. Can the lesser baseline numbers be somewhat explained by weather, different dynos and perhaps unknown fuel issues? I use 93 octane Diamond Shamrock, but who knows what it actually is.

It does seem to drive a little better. I will post more on that later. Don't get me wrong here, the MTI guys treated me well. I'm just searching for answers.

 

Those numbers sound about right. Good results

 

You have to give the pcm time to relearm. After a few houndred miles it will wake up.

 

Yeah, the baseline numbers sound a little low. You have the LQ9 in that truck, correct? I've got a 2003 LM7 (285 FWHP) that dyno'd stock at 238 RWHP on a Dynojet 248c. This equates to a 17% or so driveline loss. Using that same 17% as a guideline, your 345 FWHP truck should have dyno'd at around 285. So you're not that far off, really. How many miles on the truck?

 

I have about 5000 miles. My expectations were based on about a 20% drivetrain loss, so I was thinking in the 280 hp and 300 ft/lb range.

 

Just keep in mind that the temp and humidity play a big roll in this being a low number. Also I got double that number because i'm supercharged. So don't be down about this, you got a good gain and when you add stuff you can get it retuned for those mods and you will pick up more then.

 

After driving it a day or so I notice some nice gains. When you punch it from various speeds the truck takes off like a bullet and it shifts much better. When launching from a dead stop, the first 60' or so it feels about the same as it did, but I was always happy with this trucks ability to launch. The truck pulls hard through the gears. The shift points appear to still be set at 5600. I'll have to follow up on this.

 

Did they dyno tune it or was it a live tune?

 

Dyno tune only. We never drove it.

 

I am surprised they didn't want to drive around too.