Useless Information

[Marky Dissod]

... back in 2018 I looked at the fuel economy of our actual trucks (Fuelly.com and window stickers) and saw that there was virtually no difference between the 2007-2008s with their 4-speeds and the 2009 with the 6-speed.

Check more closely. 6L80 trucks typically came with 3.08 axle gear. 4L60 trucks typically came with 3.73.
If more 6L80 trucks came with 3.42 (tow pack) or 3.73 (better tow pack), that'd've improved metro / urban MpG.

I've nothing against VVT - GM should've implemented that sooner.

 

[swathdiver]

Check more closely. 6L80 trucks typically came with 3.08 axle gear. 4L60 trucks typically came with 3.73.
If more 6L80 trucks came with 3.42 (tow pack) or 3.73 (better tow pack), that'd've improved metro / urban MpG.

I've nothing against VVT - GM should've implemented that sooner.

You may have a point there my friend. The 2008 and 2009 RWD Yukons have the same mileage rating from the EPA. The 4x4 2008 with 3.73 gears is rated for 19 mpg highway, 1 less than the RWD trucks. The 2009 Yukon XL 4x4s received no rating from the government. My window sticker is blank. In 2009 all 4x4s were 3.42 gears with the 2-speed transfer case. In 2009 all Yukon XL RWD were 3.42 gear only.

 

[swathdiver]

Supposed to go in the morning but my wife filled the tank with Rec 90 this afternoon. Argghh! Not sure what I'm going to do now.

Headed out onto the highway early this morning for the track. Put the truck in M4 and spun up 3,330 rpms @ 70 mph. Timing was 40 degrees. Engine load was 40% and in an hour she burned over 6 gallons. I floored it once and immediately pulled 6.5 degrees timing from knock. Pulled into RaceTrac and took on almost seven gallons of E85. Alcohol content settled at 20% later on. Truck weighed 6380 with me in it at the CAT Scale 24 miles from the track.

Apparently, I wasn't the only one who wanted to go racing this morning. At 9 am I was 1/4 mile from the entrance parked in the median on the highway. 45 minutes later I was through tech inspection and parked in the lanes ready to race.

Track was sticky. First launch felt great, no motor lag like before. Idle Launched in 4WD and back into RWD by the end of the 60-foot. To make a long story short, the truck ran about the same times as she did in January, same weight, but was faster through the traps, making over 325 rear wheel horsepower. She accomplished the coveted 1 horsepower per cubic inch! Love my @BlackBearPerf tune!

After the second run the pits were really filling up with cars now and I decided to call it day. I was tired from little sleep due to the dogs barking all night and didn't want to wait 2 hours for the next run. Both runs recorded 6 degrees of KR. Not enough E85 to offset that crap Rec90.

On the way home I made some observations. At 65 mph she was getting 19 mpg. At 70 mph she was getting 18.7 mpg with a 50% load. At 77 mph she was getting 18.2 mpg and running about a 55% load. These are not 2-way averages, just heading home.

What do you think Tom? @gooffeyguy

I've another 4 hour run to make in an hour or so to pick up a wayward relative from a distant airport and may make some more observations.



I'm on the right lane both times. Time is off by an hour.





At 6380 pounds with me in it, the cab is empty. All of my towing and recovery gear was out, the consoles had the bare minimum of stuff in them compared to normal. She was probably 100-125 pounds lighter than normal. Guess I'm not sure how much that new axle added to the weight of the truck.

Could the additional weight have negated the performance advantage of the 3.73 gear off the line? Have to make some more runs next year.

Sorry Lord, I know I should've been in church this morning!

 

[Marky Dissod]

Could the additional weight have negated the performance advantage of 3.73 off the line?

Always. Only time weight can help is if it improves either static weight balance, weight transfer, or both.
Keep in mind that addressing your suspension's ability to 'hook' and transfer power,
is worth more than power.

 

[swathdiver]

Merry Christmas!

While idling in the driveway this morning checking for codes and whatnot, I checked on the health of the fuel pump and thought I'd share the data for anyone who comes along.

Truck has almost 208K on the original drivetrain and fuel pump.

The pump was commanded to run at 41% and it's Long Term Fuel Pump Trim was 1.69. I've seen it a little higher before, maybe a year or two before.

Unlike the later model years, the engine's Long Term Fuel Trims creep up at idle, both sides were -8% with an alcohol content of 20%. They zero out for the most part on the highway.

That's it for now, think we're going to switch her over to E85 for the winter. The Sierra is already on it as it's $2.29 a gallon versus $4.10 for Chevron 93.

 

[swathdiver]

James,
Haven’t seen you in a while. Are you ok?

Maybe so. I just noted he was last on 11/1 and was concerned.

I wanted to check in with him cuz he was supposed to hit up the USS Kidd at some point on the trip and I wanted to try to meet up if the stars aligned. Life got hectic and I lost track of time. I shot him a text. Normally, I'd wait til the morning but he's often posting later than this.

Did you get a response? He usually checks in here even when he's on the road. Starting to worry...

I haven’t seen James for a long time now.

I hope he's ok.

I did. He had some troubles on the journey and, AFAIK, is home. I thought he'd have checked in and updated by now. Maybe I should bug him again.

Good to hear. Hoping he's doing well.

Fellas, my apologies! I didn't see these posts for some reason or did and forgot to thank you for checking up on me. That was very kind of you.

Which reminds me, I need to check up on Chris.

 

[mountie]

Fellas, my apologies! I didn't see these posts for some reason or did and forgot to thank you for checking up on me. That was very kind of you.

Which reminds me, I need to check up on Chris.

I went to the 1st event last year, in Bradenton, Fl.... It was great..... I'm planning to go to it this year..( Feb 6-7-8th ).. Are you going?
A friend, drives a Funny Car ( Dave Richards ) is driving there as part of the **** teams
( Why the heck, is the "S**G" Equipment word bad?? )

 

[swathdiver]

I went to the 1st event last year, in Bradenton, Fl.... It was great..... I'm planning to go to it this year..( Feb 6-7-8th ).. Are you going?
A friend, drives a Funny Car ( Dave Richards ) is driving there as part of the **** teams
( Why the heck, is the "S**G" Equipment word bad?? )

That's my father's birthday. I remember you going last year! Will have to see what day(s) we're celebrating his birthday as we get closer. I've also been trying to get to the Alafia Springs Rendezvous for about 13 years now. It's always been on his birthday weekend but last year they moved it to January.

 

[mountie]

That's my father's birthday. I remember you going last year! Will have to see what day(s) we're celebrating his birthday as we get closer. I've also been trying to get to the Alafia Springs Rendezvous for about 13 years now. It's always been on his birthday weekend but last year they moved it to January.

My B-Day is few days after it.... Last year a funny car made the fastest run in history ( 341.68 mph )

 

[Marky Dissod]

... think we're going to switch her over to E85 for the winter.

What is the actual ethanol %age during the winter over there? In NYC it stays under 55% til March or so.