Blackbear Performance Review

[Geotrash]

If you have a bidirectional scanner and use the mfr's codes by VIN (not generic OBD) is there a fuel composition or alcohol content value, or a reset function?

I do (hp tuners and a tech 2) and I’ll plug them in and find out. Not sure if a tech 2 will work with this rig.

 

[Fless]

So it’s been interesting. I’ve been doing a good bit of “general” maintenance (will post in the 3500 thread I have) but VIN lookup at the parts store has the question about flex fuel or non-flex fuel engine. I believe my truck to be non-flex as it was a fleet vehicle and came with a sticker “GASOLINE ONLY”.

I do not have a factory sticker indicating anything else.

That's pretty conclusive that it's not a FF system.

 

[Geotrash]

If you have a bidirectional scanner and use the mfr's codes by VIN (not generic OBD) is there a fuel composition or alcohol content value, or a reset function?

So here's what I found with HP Tuners, using their scanner app. Alcohol content was not a default channel for the app's home screen, but I was able to add it and then scan the ECU to see if there was any data available there. Sure enough, there is. Now I don't know if it's a calculated value based on O2 sensor data, or an actual hardware sensor value, but at least the ECU is capturing alcohol content data as a percentage. And the value seems plausible. Note, the ignition was on but the engine wasn't running for the screenshot below.

 

[Fless]

So here's what I found with HP Tuners, using their scanner app. Alcohol content was not a default channel for the app's home screen, but I was able to add it and then scan the ECU to see if there was any data available there. Sure enough, there is. Now I don't know if it's a calculated value based on O2 sensor data, or an actual hardware sensor value, but at least the ECU is capturing alcohol content data as a percentage. And the value seems plausible. Note, the ignition was on but the engine wasn't running for the screenshot below.

View attachment 444783

I can't imagine that there is a physical sensor on it, so I would bet it's a calculated percentage. They dropped the physical sensor from the GMT800s around 2005 or so.

 

[Geotrash]

I can't imagine that there is a physical sensor on it, so I would bet it's a calculated percentage. They dropped the physical sensor from the GMT800s around 2005 or so.

Thanks, Steve. I think you’re right about not having a physical sensor, but I guess the question is still open as to whether or not it’s actually a stealth flex fuel truck.

 

[Fless]

Curiously, gmauthority says it's FF:

https://gmauthority.com/blog/gm/gm-engines/l96/

I would be inclined to do a little test with some E85 -- know your fuel trims with E10 first, then maybe mix 1/3 E85 (probably E50 or E70 at the pump) with 2/3 gas and see 1) if the STFTs go way positive, or settle down to a good value and 2) see what HP Tuners reads for alcohol content. And not a full fillup, just less than 1/2 a tank if it becomes an issue.

EDIT: I take that back, didn't read the fine print. Article says FF in the Savanna and Express only.

 

[mikeyss]

Curiously, gmauthority says it's FF:

https://gmauthority.com/blog/gm/gm-engines/l96/

I would be inclined to do a little test with some E85 -- know your fuel trims with E10 first, then maybe mix 1/3 E85 (probably E50 or E70 at the pump) with 2/3 gas and see 1) if the STFTs go way positive, or settle down to a good value and 2) see what HP Tuners reads for alcohol content. And not a full fillup, just less than 1/2 a tank if it becomes an issue.

EDIT: I take that back, didn't read the fine print. Article says FF in the Savanna and Express only.

It's odd that this article says the L96 has cathedral port heads, but those came with the 823 rec port heads.

 

[Bigburb3500]

What is the physical difference between a FF and non-FF engine? Maybe a dumb question but I’m wondering if the “stealth” feature is there but the difference could be injectors or something else buried deep into the truck.
Maybe?

 

[Fless]

What is the physical difference between a FF and non-FF engine? Maybe a dumb question but I’m wondering if the “stealth” feature is there but the difference could be injectors or something else buried deep into the truck.
Maybe?

As I understand it from a GMT800 perspective, larger fuel injectors, a fuel pump that can pump more volume, and an E85 fuel table in the ECM. I'd be curious what others think the differences could be.

 

[mountie]

I gotta do the Blackbear ( I keep considering it)......
Making a right turn from a light ( get ahead of oncoming traffic driving over the speed limit).....
( Screw them... they're speeding )... I have good acceleration, but the '05 Yukon is confused, with "how much throttle / gear it should be in".
It's like the ECM doesn't think fast enough......

 

[Bigburb3500]

I gotta do the Blackbear ( I keep considering it)......
Making a right turn from a light ( get ahead of oncoming traffic driving over the speed limit).....
( Screw them... they're speeding )... I have good acceleration, but the '05 Yukon is confused, with "how much throttle / gear it should be in".
It's like the ECM doesn't think fast enough......

Blackbear fixes this. Or at least it made my 2018 think like a German with an American V8. Zah-right-gear is POWERBAND!!!

 

[Bigburb3500]

Also, quick update from a week of driving. No MPG gain to be seen yet… might be about .3MPG less right now. Slight mix of me THROUGHLY testing the new tune or some long idle times (maybe both), but without a doubt they have greatly improved the drivability of the truck.

Thoroughly recommend them! I also got a Blackbear Performance sticker, it adds 10hp and 20lbtq by applying it the truck. Trust me, but you can only verify this claim if you purchase their tune.

 

[Bigburb3500]

Update: MPG does not seem to be getting “better.” But I think I have figured out why and it’s not my driving habit.

With 4.10 gears and the 6L90 trans the truck cruises at 70MPH running about 2k RPM. This dips the economy pretty substantially, but running anything lower than 2k RPM the truck gets MUCH better MPG. I see nearly 18MPG at 45-65MPH.

I do not have the $$ but thinking a 8L90 or 10L90 swap would bring that final drive ratio down to improve highway cruising. I cannot complain that much as I did not buy my truck for efficiency purposes and the driveability of the truck is SO much better. That makes it worth the trade-off.

 

[mountie]

Update: MPG does not seem to be getting “better.” But I think I have figured out why and it’s not my driving habit.

With 4.10 gears and the 6L90 trans the truck cruises at 70MPH running about 2k RPM. This dips the economy pretty substantially, but running anything lower than 2k RPM the truck gets MUCH better MPG. I see nearly 18MPG at 45-65MPH.

I do not have the $$ but thinking a 8L90 or 10L90 swap would bring that final drive ratio down to improve highway cruising. I cannot complain that much as I did not buy my truck for efficiency purposes and the driveability of the truck is SO much better. That makes it worth the trade-off.

Add an inch to your tire diameter??

 

[Bigburb3500]

Add an inch to your tire diameter??

Thinking about this as well. My “issue” is I just got new tires when I bought the truck 6mo ago so hard to rationalize that at this point. Used tire shops gave me pennies on the dollar for them and they are the new BFG KO3s (btw they are GREAT tires).

 

[mountie]

Thinking about this as well. My “issue” is I just got new tires when I bought the truck 6mo ago so hard to rationalize that at this point. Used tire shops gave me pennies on the dollar for them and they are the new BFG KO3s (btw they are GREAT tires).

Yea.. I get that... No point to swap out your tires to save a little on gas $.. Then blow more money on tire $.

 

[Bigburb3500]

Yea.. I get that... No point to swap out your tires to save a little on gas $.. Then blow more money on tire $.

I do want bigger tires as I’m love that look but do not know how big I can go until I start needing spacer and what not. I want to keep the stock rims (or maybe upgrade to something else - sticking with the 18”) and keep same stance, aka no wheel poke or anything.
I will consider it when I run thru these tires tho.

 

[Bigburb3500]

Update on Blackbear Performance tune:
We are about 1month into driving the truck daily to-from the office. I am sorry to report that fuel mileage has dropped about 1MPG since the tune (about 800miles in at this point). I have ZERO regrets about it. The trans shifts much more confidently and the truck pulls a lot harder thru all the gears. GM did these trucks a disservice by limiting so much of them for emission purposes. The truck is “safer” now because it is much less confused what gear to grab and there is less hesitation in the throttle response. No more order-and-waiting for a downshift, it’s near immediate.

As my previous post suggests, eventually I would like bigger tires but I love the truck. Maybe a 10-speed conversion + supercharger will be on order… that might make this truck perfect and improve the MPGs I see.

Let me know if you have any questions.