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Old 05-17-2019, 11:07 AM   #101 (permalink)
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The load is much higher in the first scenario. Load drives injector duty cycle, just as rpm does. The way a forced inducted vehicle behaves, especially one on E85, is drastically different than a N/A vehicle. We are ignoring too many important variables.

I think there is too much generalization going on to argue this. Everyone should post up a data log or two to prove their point.
you know what is way fuckin' easier? Drive at 55mph and record your fuel consumption, then drive at 70mph and record your fuel consumption. Same vehicle, as near as possible same weight.

IF your fuel used per mile driven is lower at 55mph than 70mph, your entire system is more efficient in terms of GPM at the higher speed.

it could then be reasonably stated that you simply have more motor than required to drive 55mph at maximum efficiency
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Old 05-17-2019, 11:14 AM   #102 (permalink)
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it could then be reasonably stated that you simply have more motor than required to drive 55mph at maximum efficiency
Ok, let's play your game for a sec.


So what is this mythical and magical "motor" size needed to achieve max efficiency @ 55mph? Inquiring minds want to know.
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Old 05-17-2019, 11:19 AM   #103 (permalink)
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Drive at 55mph and record your fuel consumption . . .
When I drive that slow, you know it's hard to steer.
And I can't get get my car out of second gear.
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Old 05-17-2019, 11:20 AM   #104 (permalink)
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Ok, let's play your game for a sec.


So what is this mythical and magical "motor" size needed to achieve max efficiency @ 55mph? Inquiring minds want to know.
you would need to know what your load is at that speed.

then you would need to cruise around some VE/BSFC maps until you find the thing that is making that power required at the lowest fuel consumption.

it would not be the same motor that you would want to get you up to that speed or over a hill at that speed or with a trailer at that speed
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Old 05-17-2019, 11:57 AM   #105 (permalink)
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no engine burns less fuel by opening the throttle plate further
but what if your engine runs with the throttle plate open at all times, all the way?

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^^This. and NO engine burns less fuel with an increased aero load (higher speed). But those two facts seem irrelevant here
but what happens when we start talking about fuel efficiency strategies?

I know that as soon as my car thinks about downshifting it also comes out of it's ultra hot cruise mode.
The water pump spins up, the thermostat opens and the motor instantly drops 20C.

so isn't it posible that in this advanced age of fuel injection, that running an engine at a steady steady and speed may allow an OEM to achieve efficiency gains that are simply more than mechanical, and use temperature and lean burn strategies at higher, known and anticipated loads?
I don't know.
and I don't know what the fuck the germans do all in there, but crazy shit happens with multiple thermostat/cooling maps and the afrs going dumb lean while you're cruising in 6th gear with the converter locked.
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Old 05-17-2019, 12:15 PM   #106 (permalink)
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no engine burns less fuel by opening the throttle plate further
Technically wrong for part throttle operation of VVT engines, engines with AFM, external EGR, or the small number of lean burn engines.

At the same RPM and torque, a VVT SI engine can alter valve timing to hit the requested torque at low loads so that the throttle plate can be opened further, raising MAP, and reducing pumping work.

AFM makes the remaining cylinders have to run at a higher MEP allowing a higher MAP.

External cooled EGR reduces torque at part throttle loads allowing a higher MAP.

With throttle by wire, it has become much easier to do this stuff without the driver thinking the engine is "doggy on the highway" because their foot is almost on the floor.

We're talking single digit percent or low teens gains in bsfc here, and the oem is going to optimize it at all speed/loads, not reserve "the good tune" that triples bsfc for 75mph vs 55mph.
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Old 05-17-2019, 12:28 PM   #107 (permalink)
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you would need to know what your load is at that speed.

then you would need to cruise around some VE/BSFC maps until you find the thing that is making that power required at the lowest fuel consumption.

it would not be the same motor that you would want to get you up to that speed or over a hill at that speed or with a trailer at that speed
So, suddenly it isn't so simple?

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and I don't know what the fuck the germans do all in there, but crazy shit happens with multiple thermostat/cooling maps and the afrs going dumb lean while you're cruising in 6th gear with the converter locked.
Probably DFCO (or some form of it) coming into play. Stock N/A Ford tunes do it too, AFR 20:1 or greater in no load, off throttle cruise

Ford strategies can also enrich AFR to protect emissions/exhaust components as well on the opposite end of the spectrum.

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Originally Posted by [email protected] View Post
Technically wrong for part throttle operation of VVT engines, engines with AFM, external EGR, or the small number of lean burn engines.

At the same RPM and torque, a VVT SI engine can alter valve timing to hit the requested torque at low loads so that the throttle plate can be opened further, raising MAP, and reducing pumping work.

AFM makes the remaining cylinders have to run at a higher MEP allowing a higher MAP.

External cooled EGR reduces torque at part throttle loads allowing a higher MAP.

With throttle by wire, it has become much easier to do this stuff without the driver thinking the engine is "doggy on the highway" because their foot is almost on the floor.

We're talking single digit percent or low teens gains in bsfc here, and the oem is going to optimize it at all speed/loads, not reserve "the good tune" that triples bsfc for 75mph vs 55mph.
Now you've done it! You are going to make heads explode with all this logic and information
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Old 05-17-2019, 12:29 PM   #108 (permalink)
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but what if your engine runs with the throttle plate open at all times, all the way?



but what happens when we start talking about fuel efficiency strategies?

I know that as soon as my car thinks about downshifting it also comes out of it's ultra hot cruise mode.
The water pump spins up, the thermostat opens and the motor instantly drops 20C.

so isn't it posible that in this advanced age of fuel injection, that running an engine at a steady steady and speed may allow an OEM to achieve efficiency gains that are simply more than mechanical, and use temperature and lean burn strategies at higher, known and anticipated loads?
I don't know.
and I don't know what the fuck the germans do all in there, but crazy shit happens with multiple thermostat/cooling maps and the afrs going dumb lean while you're cruising in 6th gear with the converter locked.
More load on an engine will increase the mass flow rate/time it's burning fuel, but depending on where it is on a bsfc map can often reduce the mass of fuel per crankshaft energy. Just because it's running more efficiently on a bsfc basis, doesn't mean it's using less fuel on a time or mpg basis.

Hotter block temps reduce thermal loss to the coolant improving bsfc, that's why they do that. But again it's a small gain compared to the extra energy required to run 75mph vs 55mph.

Are you sure it's running lean cruise? U.S. market vehicle? What year?

Even the best lean cruise strategy is only going to be in the single digits or teens of bsfc improvement and it isn't common because of the after treatment needs. VVT and externally cooled EGR is what you'll likely start seeing and gives almost as good of results.
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Old 05-17-2019, 12:31 PM   #109 (permalink)
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my engine doesn't even use the throttle body. It's simply redundant to the valvetronic in case it fails so you can still control the throttle.
all intake air control is done with timing and lift.
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Old 05-17-2019, 12:35 PM   #110 (permalink)
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So, suddenly it isn't so simple?

but the point still stands that many vehicle/engine combos (even overbears) are more fuel efficient at higher speeds than other combinations and it is often a direct side effect of having an engine oversized for whatever the target happens to be

I get better MPG with my BBC unloaded at 75mph than 55mph because I have too much engine for efficiently running 55mph, despite the substantial increase in aero load with speed and pumping loss with RPM

I get worse MPG at same with my 4cyl 2rz at 75mph than 55mph because it don't have enough engine to make up the difference in pumping loss with RPM and substantial aero load with speed while remaining efficient.

the 2rz, with substantial efficiency reduction and in a lighter load vehicle, still nets a higher MPG at 75mph than the BBC.

hook a loaded trailer and get GCVW of both systems to the same and the BBC can/will/does net better MPG than the 2RZ


the point is, a blanket statement of "you can't get better MPG with increased MPH because you will use more fuel" is, like almost all blanket statements, bullshit
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Old 05-17-2019, 12:35 PM   #111 (permalink)
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my engine doesn't even use the throttle body. It's simply redundant to the valvetronic in case it fails so you can still control the throttle.
all intake air control is done with timing and lift.
Toyota Valvematic system is the same I believe.
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Old 05-17-2019, 12:36 PM   #112 (permalink)
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Technically wrong for part throttle operation of VVT engines, engines with AFM, external EGR, or the small number of lean burn engines.

At the same RPM and torque, a VVT SI engine can alter valve timing to hit the requested torque at low loads so that the throttle plate can be opened further, raising MAP, and reducing pumping work.

AFM makes the remaining cylinders have to run at a higher MEP allowing a higher MAP.

External cooled EGR reduces torque at part throttle loads allowing a higher MAP.

With throttle by wire, it has become much easier to do this stuff without the driver thinking the engine is "doggy on the highway" because their foot is almost on the floor.

We're talking single digit percent or low teens gains in bsfc here, and the oem is going to optimize it at all speed/loads, not reserve "the good tune" that triples bsfc for 75mph vs 55mph.
Quote:
Originally Posted by [email protected] View Post
More load on an engine will increase the mass flow rate/time it's burning fuel, but depending on where it is on a bsfc map can often reduce the mass of fuel per crankshaft energy. Just because it's running more efficiently on a bsfc basis, doesn't mean it's using less fuel on a time or mpg basis.

Hotter block temps reduce thermal loss to the coolant improving bsfc, that's why they do that. But again it's a small gain compared to the extra energy required to run 75mph vs 55mph.

Are you sure it's running lean cruise? U.S. market vehicle? What year?

Even the best lean cruise strategy is only going to be in the single digits or teens of bsfc improvement and it isn't common because of the after treatment needs. VVT and externally cooled EGR is what you'll likely start seeing and gives almost as good of results.
I'm just quietly laughing to myself that Overbear says out one side of his mouth that his tune is fuckered up but says out the other that you don't know shit about FI.
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Old 05-17-2019, 12:43 PM   #113 (permalink)
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More load on an engine will increase the mass flow rate/time it's burning fuel, but depending on where it is on a bsfc map can often reduce the mass of fuel per crankshaft energy. Just because it's running more efficiently on a bsfc basis, doesn't mean it's using less fuel on a time or mpg basis.

Hotter block temps reduce thermal loss to the coolant improving bsfc, that's why they do that. But again it's a small gain compared to the extra energy required to run 75mph vs 55mph.

Are you sure it's running lean cruise? U.S. market vehicle? What year?

Even the best lean cruise strategy is only going to be in the single digits or teens of bsfc improvement and it isn't common because of the after treatment needs. VVT and externally cooled EGR is what you'll likely start seeing and gives almost as good of results.
it's an 08 328, with a 330 manifold and a factory US market 130 set of parameters in the DME to control the variable intake runner shit that makes the 330 have the extra torque and power.

when on the cruise control at 70mph on the flats, the dme reports like 16:1 afr.
so not a full on like 20:1 lean burn crazy deal. but definitely leaner than not in cruise mode.
it pretty routinely dips to the 13's everywhere else.

I may be wrong. It may be complete placebo, or maybe the instantaneous gauge on the dash lies at interstate speeds to make me feel better.

I'm not expert, and I dn't know what goes on in there exactly, only that it seems as though the difference between 55 and 70 mph is either absolutely nil, or it does better at 70.
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Old 05-17-2019, 12:45 PM   #114 (permalink)
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Yall know it has a lot more to do with fatigue, than jackoff claiming theres no benefit besides burning more fuel, right?
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Old 05-17-2019, 04:49 PM   #115 (permalink)
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but what if your engine runs with the throttle plate open at all times, all the way?
I shoulda offered my mom's couch back then

Then we wouldn't be having this conversation
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Old 05-17-2019, 04:56 PM   #116 (permalink)
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Technically wrong for part throttle operation of VVT engines, engines with AFM, external EGR, or the small number of lean burn engines.
I was debating adding that sort of shit in there, but decided nah, pirate couldn't possibly get that pedantic, we all realize that nobody cares about all the wizardry that's come into the mainstream in the last 10 years (fuck you manche, yours was an outlier when it came out )

but nope, fuck me right?
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Old 05-17-2019, 05:46 PM   #117 (permalink)
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pirate couldn't possibly get that pedantic




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Old 05-17-2019, 10:30 PM   #118 (permalink)
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BLAH BLAH BLAH
my BIG block is BIG likes going 75 not 55
my shitty little 'yota motor is small 2rz and goes slow

BLAH BLAH BLAH:
got it....


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Old 05-18-2019, 07:16 AM   #119 (permalink)
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I was debating adding that sort of shit in there, but decided nah, pirate couldn't possibly get that pedantic, we all realize that nobody cares about all the wizardry that's come into the mainstream in the last 10 years (fuck you manche, yours was an outlier when it came out )

but nope, fuck me right?
yes indeed, fuck you




but isn't all this newfound wizardry the norm now? fucking GDI. Even econo shitbox kias are direct injection and shit now.

I'm glad I'm in on the last port injected BMW motor.
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Old 05-18-2019, 07:53 AM   #120 (permalink)
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wat?

It just means his tune sucks or there is a hole in the gas tank
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Originally Posted by FlexyTJ View Post
^^This. and NO engine burns less fuel with an increased aero load (higher speed). But those two facts seem irrelevant here
Quote:
Originally Posted by FlexyTJ View Post
The load is much higher in the first scenario. Load drives injector duty cycle, just as rpm does. The way a forced inducted vehicle behaves, especially one on E85, is drastically different than a N/A vehicle. We are ignoring too many important variables.

I think there is too much generalization going on to argue this. Everyone should post up a data log or two to prove their point.




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got it....


good to see that you have finally come around to the concept of "too much motor"


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