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Forced Induction Turbochargers and Superchargers..Got Boost?

vq35de light load crusing a/f ratio

Old Mar 23, 2012 | 11:26 AM
  #21  
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Originally Posted by str8dum1
never seen a real increase in mpg from going from stoich to >stoich lean burn

i think the real gain in mpgs is more based on ign timing and injector firing angles...
by injector angle do you mean pulse timing? do standalones let you change that?
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Old Mar 23, 2012 | 11:35 AM
  #22  
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^ I think the answer to your question is yes, for the Haltech, map allows I think up to 720 degrees. The terminology used is firing angle though as str8dum1 stated.

Here is what I have from a Haltech engineer on that tuning element:

The Injector firing angle is the angle at which the injector will SHUT after the injection even has occured (relitive to a full camshaft revolution). The injection angle depends on things such as camshaft profile, intake manifold design, fuel type, injector location as well as other external factors.

Injection angle is also used in certain applications to cool in the inlet valves.
When tuning the end of injection angle (with the exception of above) you want to make sure all injected fuel is taken in by the motor and not "blown" back up the inlet manifold. (Look on Youtube for old F1 engine dyno tests to see the fuel spraying all over the place)

In practice the easiest way to do this is by tuning your engine to a known AFR. Next, adjust the injector firing angle until the engine becomes as rich as possible, now we know that the engine is burning the maximum amount of injected fuel. Do this for each RPM site you require.

You will notice that the engine will be slightly more responsive at lower RPM with the correct injection angle.

Please note, if the engine is not tuned to accpetable mixtures (rich and lean spots all over the place) that injection angle will not make much of a diffrence and you should spend more time on the tune.

Last edited by rcdash; Mar 23, 2012 at 11:36 AM.
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Old Mar 23, 2012 | 12:05 PM
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be interesting to know what the stock firing angles are.

If I could get good gas mileage with the stock injectors/ecu than I should be able to replicate that with my big injectors/standalone. Something isnt the same.

Not much to choose from since AFR's, rpm range, tps, engine temp, and vacuum levels were the same. could only be:
cam timing
ign timing
injector angle

Last edited by str8dum1; Mar 23, 2012 at 12:07 PM.
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Old Mar 23, 2012 | 12:09 PM
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^ what about decel cut?
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Old Mar 23, 2012 | 12:35 PM
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Originally Posted by str8dum1
be interesting to know what the stock firing angles are.

If I could get good gas mileage with the stock injectors/ecu than I should be able to replicate that with my big injectors/standalone. Something isnt the same.

Not much to choose from since AFR's, rpm range, tps, engine temp, and vacuum levels were the same. could only be:
cam timing
ign timing
injector angle
I'll harass hal/dustin when I get my ecu re-flashed and see if they have any light to shed on the topic.

This is a pretty interesting video I saw a while back, pretty related I suppose, and vinny ten has his credentials:
http://www.youtube.com/watch?v=tys6M_5Z_uk
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Old Mar 23, 2012 | 06:01 PM
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thats the slowest refresh of an AFR gauge i've ever seen.
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Old Mar 26, 2012 | 06:22 AM
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Mine is also at around 14.7 and I get 18-22 while cruising on the highway.
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Old Mar 27, 2012 | 04:49 PM
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Originally Posted by Gingervitis526
Mine is also at around 14.7 and I get 18-22 while cruising on the highway.
Wow I'm getting about 28mpg on the highway at 75 with my greddy twins. I'm in sixth gear at 3000 rpms and not making boost yet and the car does answer. I swear. I couldn't believe it the same highway before turbos I was getting 23mpg
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Old Mar 28, 2012 | 08:46 AM
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you can drive 550miles on 1 tank of gas. pretty solid. i sure cant, nor do i care if i could
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Old Mar 28, 2012 | 12:47 PM
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Originally Posted by str8dum1
you can drive 550miles on 1 tank of gas. pretty solid. i sure cant, nor do i care if i could
im in the same boat lol. freeway cruising im lucky to break 15 i get like 200-250 miles on a tank (about 12-14 gallons)
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Old Mar 28, 2012 | 12:55 PM
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I get >26 mpg staying out of boost and shifting at 2krpm. It's rare I actually do that though.
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Old Apr 1, 2012 | 07:43 AM
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Originally Posted by Gdoser
Wow I'm getting about 28mpg on the highway at 75 with my greddy twins. I'm in sixth gear at 3000 rpms and not making boost yet and the car does answer. I swear. I couldn't believe it the same highway before turbos I was getting 23mpg
Hope you aren't basing it on the computer tea out for mpg. As soon as you change tires, fuel pressure, or injectors it's completely inaccurate. You have to put fuel in, drive for a tank, see how much you used by filling up again and then calculating it based on how many miles driven.

I can drive downhill on almost no throttle with my large injectors and it says I'm gettin 40mpg. It's based on pulse width which is considerably smaller with large injectors than with the oem stock injectors.

On that note with pump I average 26mpg per tank (calculated). I have been getting 19mpg per tank with e85 now.
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Old Apr 1, 2012 | 07:50 AM
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Originally Posted by str8dum1
be interesting to know what the stock firing angles are.

If I could get good gas mileage with the stock injectors/ecu than I should be able to replicate that with my big injectors/standalone. Something isnt the same.

Not much to choose from since AFR's, rpm range, tps, engine temp, and vacuum levels were the same. could only be:
cam timing
ign timing
injector angle
You forgot the most important factor: drive style. As much as people don't want to admit when hp is upgraded and new goodies are on the car they tend to drive harder. Everyone says "no way, blah blah blah" but under normal daily driving instill remained same calculated mpg per tank through all my upgrades as I was stock. That's because I drive sensibly as a daily driver. Indot count the tanks that I'm tuning or racing on.

Same thing with my ex. We bought a Milan with the 4 banger. She said it was horrible on gas mileage and was getting 25ish mpg. I decided to drive it for a week and averaged upper 30 mpg. She drives like a moron and drag races from stoplight to stoplight. She also loves to sit in the car on the phone while the engine is running. Driver mod needs to be performed.
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Old Apr 1, 2012 | 05:02 PM
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Originally Posted by binder
You forgot the most important factor: drive style. As much as people don't want to admit when hp is upgraded and new goodies are on the car they tend to drive harder. Everyone says "no way, blah blah blah" but under normal daily driving instill remained same calculated mpg per tank through all my upgrades as I was stock. That's because I drive sensibly as a daily driver. Indot count the tanks that I'm tuning or racing on.

Same thing with my ex. We bought a Milan with the 4 banger. She said it was horrible on gas mileage and was getting 25ish mpg. I decided to drive it for a week and averaged upper 30 mpg. She drives like a moron and drag races from stoplight to stoplight. She also loves to sit in the car on the phone while the engine is running. Driver mod needs to be performed.
Same thing here... wife gets 16mph avg at best in the minivan... if I reset the MPG's and drive it for a day around town I'm 22+ easily. She's not complaining about the mpg's though... she is well aware of being a leadfoot.
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