Gen V 5.3l turbo build - 87 octane and AFM/DOD

[BoomBoomBamaPhD]

So I just looked it up to confirm, but the new dfm system is close to choosing whatever cylinder you want with 17 possible cylinder configurations and all cylinders having the lifters that are electronically controlled through solenoids.

 

For reference:

https://gmauthority.com/blog/gm/general-motors-technology/general-motors-propulsion-technology/general-motors-dynamic-fuel-management-cylinder-deactivation-technology/

 

The control for this system seems very in depth, but I don't see why it couldn't be tuned.

 

I understand this is different from my 2015 engine though.

[shakenfake]

No offense but you just need to chunk all that out the window. Focus on the 2015 AFM.  The driver though does not get to choose. The engine and PCM chooses. The lifters are controlled electronically but it is if they meet certain conditions so hypothetically yes you could edit the conditions. I have never heard of someone doing it though so I could not tell you.

 

You are over thinking this. AFM delete, add turbo, done

[newdude]

12 hours ago, BoomBoomBamaPhD said:

Let me start by saying hey thanks for having me, new here.

I will probably make a build thread for my 15 Silverado separately, but I felt like this discussion needs to happen.

I want to preface this by saying that I am decently versed on the actual theory and thermo of the discussion as I am a current Engineering PhD student studying combustion. I do however lack the physical experience of boosted applications as well as engine tuning.

The two topics to be discussed here are probably highly controversial and I am not looking to start a pissing contest about anything, but rather a tame discussion.

Please let me know if I should split these into two separate posts, but these would be in the same build for me.

 

1. How much boost could I run, or power could I make, while running 87 octane. (5.3L "Eco-boost")

And yes, I realize the disadvantages of 87 in regards to a boosted application, but if Ford can do it stock, I don't see why we couldn't do it aftermarket (and probably better tbh).

But for reference, I am not actually looking for a high HP or drag type build. More a reliable DD that will be used for truck things like towing occasionally, but would like to get as much out of it as possible. (haven't even settled on it needing to be turbo) 

 

2. Can the newer (2015) AFM/DOD be upgraded and/or tuned properly to be reliable and retain the intended advantages that were originally intended, with or without adding boost?

Half of 5.3 is close to 2.7(eco-boost), so I don't see why I couldn't leverage the fuel economy of a turbo "4 cylinder" while having access to the full V8 when wanted.

 

 

87 octane and a turbo?  No.  If you are trying to keep operational costs low, add a flex fuel sensor and tune it for 93 and E85.  E85 will get you 87 octane prices and on top of that make some stout power.

 

You are wasting your time trying to set it up for 87 octane.  You "want to get as much out of it as possible" then you will need 91/93. 

 

AFM.  Turn it off or physically delete it.   

 

 

3 hours ago, BoomBoomBamaPhD said:

Hey thanks for joining the discussion. But from here on out how about everyone try to put some thought and explanation in their answers.

 

Obviously 87 octane can be run in certain boosted applications, aka the Ford Eco-boost. As referenced multiple times in the original post. Though I have already conceded to knowing it is not the most ideal. And with the direct injection of the newer engines I'm pretty sure the only difference fundamentally would be the compression ratio, which I have mentioned being open to changing previously. (Please let me know if there is some other fundamental difference I am missing.)

 

And as for the AFM with boost, do you have a reasoning it can't be done?

I think I have a pretty good idea of how the cylinder deactivation works mechanically, and I wouldn't think it would be effected really at all by boost or cylinder pressures.

 

 

3.5 Ecoboost might be able to run 87 but it pulls some good power out of the tune doing so.  87 is "allowed" for cheap people aka fleets.  

 

 

2 hours ago, pokismoki said:

doesnt LT4 have afm ?

 

 

Yes and no.  All LT4s have the hardware.  In Camaro ZL1, its turned off.  C7 Z06 2015-2019 its active.  

[BoomBoomBamaPhD]

I'm on my way to getting a PhD in mechanical engineering, it's quite literally my job to overthink things haha.

 

"AFM delete, add turbo, done," just honestly isn't helpful in this sort of discussion.

 

I understand how everyone else does it for high power, I'm trying to have a discussion about other ways of doing things.

If what I have suggested doesn't make sense at the end of the discussion then cool, but nothing would ever get figured out if people keep doing what others have already done.

 

Also a side note regarding E85, most people overlook the fact that price per gallon is not the same as price per "energy."

There is a reason E85 tunes usually involve larger injectors, more of it is needed.

[newdude]

Just now, BoomBoomBamaPhD said:

I'm on my way to getting a PhD in mechanical engineering, it's quite literally my job to overthink things haha.

 

"AFM delete, add turbo, done," just honestly isn't helpful in this sort of discussion.

 

I understand how everyone else does it for high power, I'm trying to have a discussion about other ways of doing things.

If what I have suggested doesn't make sense at the end of the discussion then cool, but nothing would ever get figured out if people keep doing what others have already done.

 

Also a side note regarding E85, most people overlook the fact that price per gallon is not the same as price per "energy."

There is a reason E85 tunes usually involve larger injectors, more of it is needed.

 

 

Stock 5.3 injectors handle E85 no problem.  If you need to make serious power, a set of LT4 injectors solves that.  I'm tuned for 93 and E85 naturally aspirated.  Still on stock injectors with zero fueling issues.     

 

All of the AFM delete and add turbo and 93/E85 talk is very helpful as its the best route with the best results.  Go around to LS/LT performance shops, they will take you down the same path.  They will at a minimum turn off AFM but they will probably suggest a delete and a new cam to take advantage of adding boost as well.  

 

If you want AFM active and want a reliable tow rig that can run 87 octane, then leave it stock or sell it and get a diesel.  Not trying to sound mean, but it sounds like you are hung up on wanting low operation costs and high fuel economy which is why you want AFM to remain active and run 87. 

 

E85, I don't think most that use it care about the energy per gallon.  Its more like HP per gallon, especially when you are talking at least near me, $2.89/gal for E and $3.95/gal for 93.  $1 less per gallon, 25-40hp more but a 2-3mpg loss?  I'd take it any day of the week.  

 

My brother had a 2014 Camaro SS and now has a 2019 ZL1.  In his SS, he had headers and a tune with AFM turned off.  After installing all of that, and driving 15,000 miles after the mods, he averaged 14mpg with the way he drove over that distance.  His ZL1, so 6.2 650hp supercharged LT4 which has AFM off from the factory?  16mpg driving it the same way as he drove that SS.  So 200 more HP in a similarly weighed vehicle and he gets 2mpg MORE.  Same 93 octane fuel, both without AFM but the ZL1 is 100% bone stock.    

[BoomBoomBamaPhD]

I'm not really hung up on anything, just trying to figure out what's possible.

 

Everyone knows how to make more power, it's pretty "easy" nowadays.

Most people don't look at efficiency type stuff though, which is a large part of engines that most gearheads don't care about.

And also the versatility is a cool concept to me, disregarding the 87 for now, having a small block v8 that can act like a turbo twin or turbo 4 or 6 or whatever with the newer technology.

[shakenfake]

Yeah gonna disagree with the e85 portion. MPGs ****** the bed. Smiles per mile do go up though! It seems this guy does want something that has some good mileage with turbo so I say stay away from e85. Maybe they aren't so bad on these newer trucks but NBS trucks are like single digits lol

 

Again it will never ever act like a 4 or 6 cylinder because it is not going to ever be in those cylinder configurations when under boost. 

[KARNUT]

The E-85 deal was awesome. I had it on my 14 GMC. The power boost was very  noticeable. My local Kroger store with their card made E-85 1$ per gallon cheaper. The best part I just switched to regular gas for trips. I understand GMs reluctance to continue the option. Getting that close to the 6.2 in horsepower and just changing to reg gas for trips. Probably wasn’t a good thing.  

[BoomBoomBamaPhD]

You're probably right, practically at least, about the not being in boost, but I don't think for the same reason you're portraying.

Assuming we could force the v4 to be on whenever, you would now only be spinning the turbo with the 4 cylinders. I wonder how small of a turbo would be needed to make that practical.

Supercharger would probably still work though, but we won't go Into that here.

[shakenfake]

Oh yeah that is true I hadn't even brought that into account. You'd have to have mini turbos for that one.

[BoomBoomBamaPhD]

3 stage turbo system???

1 for v4

1 for low rpm v8

1 for high rpm v8

Now we are onto something lmfao

[CamGTP]

A 6.2 with very minor bolt on's on E85 is likely over the injector limit. The DI engines can handle a lot leaner air fuel ratio that port fuel injection but even so I'd want larger injectors if more than 100-125 horsepower was added. It would just come down to watching fuel pressure and your injector pulse width.

 

87 octane tends to show knock even without boost. It can be brought down with changing fueling and dropping timing but if you added boost it's just going to make that worse. If you go too low with the commanded air fuel ratio it will start to fuel knock.

 

At a minimum I'd want to run mid grade 89 octane even on low boost levels, like sub 5 psi.

[RJSmithers]

In response to your earlier questions yes it's a stock engine, On3 turbo kit, Tuned on 91 octane as that is the most readily available.

 

I mean they do make variable aspect ratio turbos, you could also use something like a twin scroll turbo/turbine housing but that could make for some interesting exhaust routing

 

Almost anything can be tuned, If it's available on the LT4 engine it should work on our engine. My only real concern would be the firing order and the balance. The AFM system (when mine was active and stock) seemed to cut out before any real load was applied to the engine, I can't imagine it'd be designed to run under boost in 4 cylinder mode. Could maybe be more achievable with the DFM on the newer engines however I'm not sure you'd really want to? Why build boost/power with half the engine when you've got the other 4 cylinders to give you more power. The only reason I'd want to turn my AFM back on is for the fuel efficiency when cruising down the highway. But that's primarily because I incorrectly sized my turbo so I build a little more boost cruising than I'd like. Which brings up another aspect to this, turbo compressor maps are an animal of their own (at least to somebody like me)  and you'd obviously need to be quite dialed on what you choose with that.

 

I'm not saying this isn't achievable, but I'm not sure it'd be entirely worth the amount of effort, unless you're just doing it to say you could.  If you were really dedicated to 87 octane, I'm not sure exactly but a certain company might make a higher grade of 87 than another I know shell 91 is widely regarded as the best 91 octane fuel that's readily available I'm not sure if anybody has a reputation for 87 octane. CamGTP knows considerably more than I do although I'm not sure 89 would totally reduce the engine knock, simply because 89 octane is simply a blend of 91 and 87, all of the lighter ends of the 87 would still be there just to a lesser extent. But you might know more in that regard since your studying combustion I am by no means well versed in the exact differences in octane rating as it applies to combustion nor am I an engine tuner  

 

[BoomBoomBamaPhD]

'So why boost only 4 cylinders?'

Because you could see efficiency improvements regardless of how many cylinders are active. Plus it adds to the versatility of the engine, assuming that you could properly make boost with afm active anyway. Basically like having a turbo 4 truck when focused on eco and a turbo 8 for heavier towing or fun.

But like stated earlier, it has now become an issue of how to properly build boost at 8 and 4 cylinders. 

Depending on which cylinders are cut, twins would be perfect tbh.

 

And theoretically all fuel with the same octane rating should auto-ignite/detonate/knock at the same conditions. And these companies are supposed to be held at pretty high standards chemically, though I would not be surprised to see a couple psi difference of max boost between even two different gas stations of the same brand.

For absolutely perfect octane numbers, race fuel is the best bet as it is made in smaller batches with higher quality control.

[M1ck3y]

Gm designed the engine to be as efficient as possible the way it sits now.

 

If you want an engine with boost, buy an engine designed for boost. Anytime you modify an engine not designed for boost there are any number of trade off's you have to contend with.

 

Essentially your saying you want a power adder but you don't want the added power. Meaning your looking to reduce emissions. Entirely possible for a large corporation that designs and manufacture's automobile's.

 

Cost... it is simply not worth it. But hey, nothing wrong with a project if you've got the time and money. 

 

But you already know all of this