Force Truck to Run in 4 Cylinder Mode

[silver billet]

I drove the Sierra with the 4 cyl 2.7 turbo, and was pretty damn impressed.

What doesn't impress me is how its only 2 mpg better in the city (same highway) and only 1 mpg better combined

The 2.7 is a replacement for the N/A 4.3 v6, not the v8s. People like to compare it the v8 and then dump all over the little turbo, but that's really an injustice to the 2.7.

Compare it to the v6, they're both base engines and GM will eventually discontinue the v6 and offer the 2.7 only. It offers more power, more towing, and 25% better MPG than the engine it was designed to replace. It's a great little motor, and I'd take it everytime before the 3.6 pentastar.

Core Metrics	21MY 2.7L I4 L3B Turbo	21MY 4.3L LV3 V6	+/- 2.7L I4 Turbo
Power	310 horsepower	285 horsepower	+25 hp or + 9%
Torque	348 pound-feet	305 pound-feet	+43 lb-ft or +14%
Fuel Economy	20/23/21 mpg	16/21/17 mpg	+4 / +2 / +4 or 25%
Max Trailering	9,600 pounds	7,900 pounds	+1,700 pounds or +22%
Payload	2,070 pounds	2,040 pounds	+30 pounds or +1.5%
0-60 mph	6.8 seconds	7.8 seconds	1 second faster

 

[HSKR R/T]

Empirical evidence over 3 years of daily driving. The ECO light has always, without exception, turned on when the truck goes into MDS (easily heard) and turned off when MDS is disengaged. Again, not one exception.

To my knowledge, this isn’t documented (aside from a great many posts in very old threads on this forum and others).

Note: The misinformation almost always comes from previous or current 4th-gen owners who assume (incorrectly) that 5th-gens work the same way.

I actually turned my light on because it wasn't "easily heard" on my truck. And even now with the Borla ATAK, I have to actually have radio turned almost off and be listening specifically for it to notice any difference when MDS engages. So I can see how some would say it doesn't necessarily only come on with MDS. You say yourself, there is no officially documentation to support either way. So saying it is misinformation, can itslef be misinformation since you says it sjust based on your own personal observations, and what others have posted.

 

[soSincerious]

I never said the 2.7 was the 5.3 replacement, nor did I say anything bad ... infact, I was very impressed with the 4 banger!

Because this thread is about turning an 8 into a 4, I found a direct parallel that I had experience with.

Now, where I did down-talk the 2.7 was in terms of how marginally better the fuel economy is - which is entirely related to this thread.

 

[SpeedyV]

I actually turned my light on because it wasn't "easily heard" on my truck. And even now with the Borla ATAK, I have to actually have radio turned almost off and be listening specifically for it to notice any difference when MDS engages. So I can see how some would say it doesn't necessarily only come on with MDS. You say yourself, there is no officially documentation to support either way. So saying it is misinformation, can itslef be misinformation since you says it sjust based on your own personal observations, and what others have posted.

A long conversation was had a long time ago on this topic. A consensus was reached. Just trying to prevent another hundred posts on the same thing. That horse was dead a long time ago.

 

[User_3336]

A long conversation was had a long time ago on this topic. A consensus was reached. Just trying to prevent another hundred posts on the same thing. That horse was dead a long time ago.

I am surprised this repeated topic got 45 responses (of course, no one uses the search function here). It was by a new user, his first post(I seriously had to laugh at it), and he's never returned. ever feel like you've been trolled. Just some random topic by a newbie to see who will respond. Its happened before. You could just LOCK the thread!

 

[SpeedyV]

I am surprised this repeated topic got 45 responses (of course, no one uses the search function here). It was by a new user, his first post(I seriously had to laugh at it), and he's never returned. ever feel like you've been trolled. Just some random topic by a newbie to see who will respond. Its happened before. You could just LOCK the thread!

But what fun would that be…?

 

[User_3336]

But what fun would that be…?

Well, you did say yourself...."trying to prevent another hundred posts on the same thing", and we're 1/2 way there! LOL

 

[silver billet]

I actually turned my light on because it wasn't "easily heard" on my truck. And even now with the Borla ATAK, I have to actually have radio turned almost off and be listening specifically for it to notice any difference when MDS engages. So I can see how some would say it doesn't necessarily only come on with MDS. You say yourself, there is no officially documentation to support either way. So saying it is misinformation, can itslef be misinformation since you says it sjust based on your own personal observations, and what others have posted.

It's not misinformation. It has been confirmed by many on this forum including myself: in 5th gens, ECO = MDS.

I get what your saying with respect to official documentation, but not everybody needs a whitepaper as proof either. Just try it yourself, run around for a while with TH engaged or use the gear limiter and set it to 8th gear. A months wages says you will never see your little ECO light appear, ever, while you're doing that. But hold your speed steady at 40 mph, then disengage TH or the gear limiter and boom, you will see the little ECO light appear shortly.

 

[silver billet]

I never said the 2.7 was the 5.3 replacement, nor did I say anything bad ... infact, I was very impressed with the 4 banger!

Because this thread is about turning an 8 into a 4, I found a direct parallel that I had experience with.

Now, where I did down-talk the 2.7 was in terms of how marginally better the fuel economy is - which is entirely related to this thread.

But you did compare it to the 5.3 when you referred to the "marginally better fuel economy". All I was saying, is that 25% better economy is not marginal by any stretch, you're simply comparing it to the wrong engine!

 

[soSincerious]

OP wants his 8 to also act as a 4, so that's what I'm using to compare



I'd call 5% marginally better ....

 

[silver billet]

OP wants his 8 to also act as a 4, so that's what I'm using to compare

View attachment 100452

I'd call 5% marginally better ....

If you want to compare 8 vs 4 in the Ram directly, we already know MDS does next to nothing; I get > 23 mpg on the freeway with MDS disabled, so whatever it's doing, it's not much.

And for what its worth, the guys driving the 2.7 on the GM forum seem to report having no trouble beating the EPA ratings either.

 

[Mountain Whiskey]

Well, you did say yourself...."trying to prevent another hundred posts on the same thing", and we're 1/2 way there! LOL

We can make it all the way! Keep the posts coming!

 

[Trooper4]

At 55/60 flat and level I gain 2 to 3. Not a huge gain, but over time it adds up, so, hey, whatever floats your boat.