Forced Induction Superchargers | Turbochargers | Intercoolers

Reasons for loss of fuel consumption

Thread Tools
 
Search this Thread
 
Old Jun 20, 2016 | 06:42 AM
  #1  
69-chvl's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (11)
 
Joined: Nov 2009
Posts: 1,621
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Default Reasons for loss of fuel consumption

Something that has me perplexed is why my engine seems to be burning less fuel (in lbs/hr) lately. Usually it burns around ~450 lbs/hr on ~12psi and close to 480-490 at higher boost levels. Yesterday I did a log and I'm only using 396 lbs at 14 psi. Seems like I'm missing a lot of power. Yesterday was hot (about 90*) vs the much cooler temps (around 50-60* ambient) that I did the previous logs so wondering if that has anything to do with it. Or, was also wondering if the "summer" blends of fuel have an impact. Otherwise, car runs really good and clean. This is a stock LQ9 with the LS6 cam, BR7ES's at .022. Timing 11*, IAT's around 100*, spraying a little 50/50 also. Next test will be to shut the 50/50 off to see if its drowning anything. Thanks!!
Reply
Old Jun 20, 2016 | 07:41 AM
  #2  
rotary1307cc's Avatar
8 Second Club
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (5)
 
Joined: Jan 2007
Posts: 2,790
Likes: 123
Default

E85 or?
Reply
Old Jun 20, 2016 | 08:02 AM
  #3  
69-chvl's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (11)
 
Joined: Nov 2009
Posts: 1,621
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Default

93 octane.

And I forgot to add which is probably the reason for less lbs/hr...

I upped the base fuel pressure from 43 to about 53 to see if I could get a better idle...which I actually did. So the DC is now a bit lower up top than before. I figure that total fuel consumption should still remain the same though right?? Maybe someone can explain what I'm missing here as far as how the system calculates fuel flow/consumption.
Reply
Old Jun 20, 2016 | 09:12 AM
  #4  
rotary1307cc's Avatar
8 Second Club
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (5)
 
Joined: Jan 2007
Posts: 2,790
Likes: 123
Default

Yes that is the reason

For fuel consumption in the holley it does not watch and use actual fuel pressure for the computation. It only uses what you have entered into "actual system pressure"

Why the consumption number means fuckall unless the correct number is in there and you actual hold a perfect 1:1 rise on fuel pressure

Start dropping pressure with boost and it will give big time inflated numbers
Reply
Old Jun 20, 2016 | 09:17 AM
  #5  
tblentrprz's Avatar
TECH Fanatic
 
Joined: Feb 2015
Posts: 1,080
Likes: 178
Default

air density from 50F to 90F is approx 10% lower
Reply
Old Jun 20, 2016 | 09:48 AM
  #6  
69-chvl's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (11)
 
Joined: Nov 2009
Posts: 1,621
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Default

Originally Posted by rotary1307cc
Yes that is the reason

For fuel consumption in the holley it does not watch and use actual fuel pressure for the computation. It only uses what you have entered into "actual system pressure"

Why the consumption number means fuckall unless the correct number is in there and you actual hold a perfect 1:1 rise on fuel pressure

Start dropping pressure with boost and it will give big time inflated numbers
Thanks rotary that's what I needed to know. I never updated actual system pressure!
Reply
Old Jun 20, 2016 | 12:15 PM
  #7  
rotary1307cc's Avatar
8 Second Club
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (5)
 
Joined: Jan 2007
Posts: 2,790
Likes: 123
Default

Np man
Reply
Old Jun 21, 2016 | 05:57 AM
  #8  
forcd ind's Avatar
TECH Veteran
15 Year Member
Liked
Loved
Community Favorite
iTrader: (7)
 
Joined: Sep 2007
Posts: 4,188
Likes: 292
From: woodbine, md
Default

I have noticed on my data logs the max. fuel used is
diff (more) than where the overlay (Holley HP) shows it to be.
I am guessing the closed loop comp. adds the diff?
Interesting raising the base pressure and not changing it in the system, something I wouldn't have thought of, and the effect.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Jun 21, 2016 | 06:45 AM
  #9  
69-chvl's Avatar
Thread Starter
TECH Fanatic
15 Year Member
iTrader: (11)
 
Joined: Nov 2009
Posts: 1,621
Likes: 31
From: THORNTON, PA (NEAR PHILLY)
Default

Originally Posted by forcd ind
I have noticed on my data logs the max. fuel used is
diff (more) than where the overlay (Holley HP) shows it to be.
I am guessing the closed loop comp. adds the diff?
Interesting raising the base pressure and not changing it in the system, something I wouldn't have thought of, and the effect.
Yes you have to factor the closed loop compensation into the mix.

I was able to a achieve a slightly better idle going from a 43 psi to 53 psi. Not a nigh/day difference, but noticeable.
Reply
Old Jun 21, 2016 | 12:27 PM
  #10  
rotary1307cc's Avatar
8 Second Club
15 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (5)
 
Joined: Jan 2007
Posts: 2,790
Likes: 123
Default

Move to v4 and fill out the the injector end angle calculator correctly.
Reply




All times are GMT -5. The time now is 10:54 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE