Tech-2 Fun

[swathdiver]

Took the Yukon out for a run and took a Snapshot of the Transmission Data to record the engine torque and some other things. Once home, I played the Snapshot on the Tech-2 back at my desk, hooked up to shore power, and plotted the data on an excel spreadsheet. Decided to use only the 1st gear data even though peak torque occurred in 2nd to get the data started down low, at just over 1000 rpms. Anyway, I was able to make this nice little power graph for the 5.3 LC9 and will do it again with the Sierra's 6.2 L9H soon. Fun stuff.

You guys with Tech-2s can do this too with the help of Excel as well.



She's a little down on power with the leaky intake gaskets, that'll get taken care of before January ends. That's the plan anyway!

 

[Dantheman1540]

Any idea what factors it uses to calculate this? I have an Ultra Gauge 2 and it has an "Instant Horse Power meter" Where it tells you exactly how much power your supposedly making in real-time. I never really used it because I figured it was total BS but was always curious what it factors in.

 

[swathdiver]

Any idea what factors it uses to calculate this? I have an Ultra Gauge 2 and it has an "Instant Horse Power meter" Where it tells you exactly how much power your supposedly making in real-time. I never really used it because I figured it was total BS but was always curious what it factors in.

I don't know. Since it's in the transmission section, I reckon it comes from the drivetrain torque calculations and force applied to the wheels depending on load and speed, maybe.

The horsepower number, figured mathematically from Torque and engine rpms, is basically spot on with the Rear Wheel Horsepower through the traps in the quarter mile.

 

[Dantheman1540]

I don't know. Since it's in the transmission section, I reckon it comes from the drivetrain torque calculations and force applied to the wheels depending on load and speed, maybe.

The horsepower number, figured mathematically from Torque and engine rpms, is basically spot on with the Rear Wheel Horsepower through the traps in the quarter mile.

That's impressive that it's spot on! I might have to try it in the Tahoe and see what it comes up with if it has that option. I think I remember seeing it as an option on my Tacoma which uses a similar system to the GMT900 torque-based calculation junk that I don't understand because I only speak GMT800. It would be really cool if it was something people could use to better guesstimate their power levels.

 

[mrpeterclark]

Took the Yukon out for a run and took a Snapshot of the Transmission Data to record the engine torque and some other things. Once home, I played the Snapshot on the Tech-2 back at my desk, hooked up to shore power, and plotted the data on an excel spreadsheet. Decided to use only the 1st gear data even though peak torque occurred in 2nd to get the data started down low, at just over 1000 rpms. Anyway, I was able to make this nice little power graph for the 5.3 LC9 and will do it again with the Sierra's 6.2 L9H soon. Fun stuff.

You guys with Tech-2s can do this too with the help of Excel as well.

View attachment 359822

She's a little down on power with the leaky intake gaskets, that'll get taken care of before January ends. That's the plan anyway!

That's pretty cool. Maybe I don't have torque problem like I've been thinking. Maybe it's horsepower.... I've noticed on inclines or when towing (only like 2K lbs) (especially at altitude or from a standstill) I have ZERO umph. I was in the mountains this weekend and just struggling up a steep dirt road in second gear going 20 with it floored. If I wanted to mainain any speed, I had to shift into first and just wind it up which kinda sucks. Any thoughts? I got stuck in Ouray last year and COULD NOT back up a steep hill or get a wheel to slip at all (That was probably 12K ft elevation). Maybe only having 50-75 hp (less at altitude) is the issue. (6.2 6L80) Anything to gain down low out of a tune?

 

[swathdiver]

That's pretty cool. Maybe I don't have torque problem like I've been thinking. Maybe it's horsepower.... I've noticed on inclines or when towing (only like 2K lbs) (especially at altitude or from a standstill) I have ZERO umph. I was in the mountains this weekend and just struggling up a steep dirt road in second gear going 20 with it floored. If I wanted to mainain any speed, I had to shift into first and just wind it up which kinda sucks. Any thoughts? I got stuck in Ouray last year and COULD NOT back up a steep hill or get a wheel to slip at all (That was probably 12K ft elevation). Maybe only having 50-75 hp (less at altitude) is the issue. (6.2 6L80) Anything to gain down low out of a tune?

I wouldn't think so with a 6.2. Consider doing a compression test and find out how to see if the cam lobes are worn out. Don't know the answer to your last but know you'd definitely benefit from gears since you are running 33s and have all that overlanding gear on board. Still AWD?

 

[mrpeterclark]

I wouldn't think so with a 6.2. Consider doing a compression test and find out how to see if the cam lobes are worn out. Don't know the answer to your last but know you'd definitely benefit from gears since you are running 33s and have all that overlanding gear on board. Still AWD?

I'll do that. I've got gears on the list. Need to time them with installing 35s. I don't think 33s is a huge source of my problem as that is only about 3% bigger than stock. I do have a lot of extra weight though. I do have a persistent timing advance code that I haven't been able to sort. I'd love your opinion on rebuilding vs a reman/ new crate engine. I know it's coming in the not too distant future with almost 250K on the clock. I don't want to repeat the nightmares I had with my transmission rebuild. Trans is new now.
It is still AWD. I'd like to do a 2 speed swap at some point, but haven't figured out yet if I can make it electronic shifting vs having to go manual.

 

[swathdiver]

I'll do that. I've got gears on the list. Need to time them with installing 35s. I don't think 33s is a huge source of my problem as that is only about 3% bigger than stock. I do have a lot of extra weight though. I do have a persistent timing advance code that I haven't been able to sort. I'd love your opinion on rebuilding vs a reman/ new crate engine. I know it's coming in the not too distant future with almost 250K on the clock. I don't want to repeat the nightmares I had with my transmission rebuild. Trans is new now.
It is still AWD. I'd like to do a 2 speed swap at some point, but haven't figured out yet if I can make it electronic shifting vs having to go manual.

That timing issue may be your problem then, solve that first and see if the torque comes back.

A new turn key engine would be cool but don't think there are any left. Goodwrench Remans may be hard to come by. I've always rebuilt my engines when it was time and was fortunate in that I did not need a new block or heads, etc. That was a long time ago and am actually looking forward to either rebuilding the 5.3 or getting a 6.2, rebuilding that and put it into the truck.

Right, the gearing is not a big issue either by itself.

 

[mrpeterclark]

That timing issue may be your problem then, solve that first and see if the torque comes back.

A new turn key engine would be cool but don't think there are any left. Goodwrench Remans may be hard to come by. I've always rebuilt my engines when it was time and was fortunate in that I did not need a new block or heads, etc. That was a long time ago and am actually looking forward to either rebuilding the 5.3 or getting a 6.2, rebuilding that and put it into the truck.

Right, the gearing is not a big issue either by itself.

I got it into the shop before my trip to have them look into oil pressure/ pickup tube issues and do a compression test. They said that they didn't see anything indicating any oil pressure problems. It was due for an oil change when I had it in the shop so it had older oil in it. Compression was good, and thy think it is probably a flattened cam. On my recent 2500+ mile trip I would periodically get low oil pressure warnings after long hot drives when I would pull in to stop and oil pressure would drop really low at idle. I was loosing almost a quart of oil every tank gas. I would top it off and it would be ok, but the oil pressure was never stellar other than when the oil was JUST replaced and engine running cool. I don't think that I'm burning oil (and it doesn't make sense if compression is good) or if I'm just loosing it out of my front main seal? The quote they gave to replace the cam/ timing chain etc etc seemed really high to me (over $7K). I guess it's really a full top end re-build, pulling the heads etc.
I'd love some thoughts on if I should have it rebuilt (and to what extent) or swap with a reman (haven't gotten that price back yet). I'm would love to do it myself, but I don't know when/ if I'll have time for that. The good local engine rebuilder moved out of state and most shops don't do rebuilds any more. It seems like it would be pretty comparable to swap over the parts to a long block as tearing down and replacing everything. Anyone recently pay for a fresh motor or rebuild?