05-13-2022, 07:16 AM | #1 |
Drives: 2017 Camaro SS 50th Anniversary Join Date: Apr 2021
Location: Missouri
Posts: 929
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Airflow lbs/min on FI vs NA relationship to hp
Im just theoretically speaking here. I know its a just an approximation.
Reputable tuners have said 1 lb/min airflow = 10 hp. That is assuming your tune is perfect with spark, afr, etc... i gravitate to 1 lb/min = 9 hp because im a pessimist. Regardless of the exact ratio, if you have a forced induction system consuming, for example, a max of 60 lbs/min and an NA engine consuming the same max 60 lbs/min. Would they be making the same peak power at the flywheel? Do you have to account for the supercharger drag? Or does it somehow just magically work out in the airflow numbers?
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2017 50th Anniversary Edition | P1X Stage 2
DSX Aux Low Side | LT4 high side | Flex Fuel TooHighPsi Port Injection (installed & tuning) CircleD 3K Stall | QA1 CF Driveshaft Forgestar F14 Drag 17x10 NT555R2 305/45/17 Rear Forgestar F14 18x8 NT555G2 235/50/18 Front 10.84@131 w/4.13" pulley ??.??@??? w/3.7" pulley (installed & tuning) |
05-13-2022, 07:46 AM | #2 | |
Drives: 2019 Camaro Z-28 Join Date: Jul 2010
Location: Dallas
Posts: 1,484
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Quote:
GREAT QUESTION!!! One of the best if not the BEST forced induction shop in the country is AMP. They produce 1000+ HP cars like the were SKITTLES candy primarily utilizing modifed STOCK blowers, MAGNUSON, and PROCHARGERS. I was told by their tuner that at full BOOST, an F1X can take over 100HP just to turn the blower assembly especially on some of the higher HP builds that are running over 30 pounds of boost. This is commonly referred to parasitic losses. As the boost level goes up, those losses increase. And as we all know, the MORE you compress air the HOTTER it gets hence the need for intercoolers to help control that. The intake air temperature of a naturally aspirated engine is MUCH cooler than the intake temperature of a BOOSTED engine. All other things being equal, cooler air is of course MORE dense allowing you to burn MORE fuel and thus produce MORE power.
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05-13-2022, 08:14 AM | #3 | |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
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Quote:
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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05-13-2022, 08:18 AM | #4 |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
Posts: 6,799
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The problem with using MAF lb/min to calculate HP is that the MAF maxes @ 86lb/min even though it may have plenty of ceiling in HZ.
I have setup a custom Math's parameter for HP in HPt using the PID 50408 x 50070 / 5252. It gives you fairly accurate HP reading if your VT tables are close.
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2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
05-13-2022, 10:57 AM | #5 | |
Drives: 2017 Camaro SS 50th Anniversary Join Date: Apr 2021
Location: Missouri
Posts: 929
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Quote:
__________________
2017 50th Anniversary Edition | P1X Stage 2
DSX Aux Low Side | LT4 high side | Flex Fuel TooHighPsi Port Injection (installed & tuning) CircleD 3K Stall | QA1 CF Driveshaft Forgestar F14 Drag 17x10 NT555R2 305/45/17 Rear Forgestar F14 18x8 NT555G2 235/50/18 Front 10.84@131 w/4.13" pulley ??.??@??? w/3.7" pulley (installed & tuning) |
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05-13-2022, 11:10 AM | #6 | |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,749
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Quote:
__________________
2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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05-13-2022, 11:33 AM | #7 | |
Drives: 2016 1SS NFG A8 Join Date: Aug 2017
Location: 46804
Posts: 6,799
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Quote:
__________________
2016 NFG 1SS A8
Options-2SS Leather/NPP Perf. mods-Whipple 2.9/Fuel System/Flex Fuel/103mm TB/Rotofab Big Gulp/Cat Deletes/Corsa NPP Per. times- 10.5 @ 137 w/ 1.8 60ft Full weight on 20's 1200DA |
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05-13-2022, 03:48 PM | #8 |
Drives: like an old lady Join Date: Jun 2012
Location: indiana
Posts: 2,396
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my car shows 45-48 lb/min. m6, made 441, trapped 125 on drag wheels @ 3900 lb raceweight & 900' da.
i think it would take considerably more lb/min in a blower car to equal the performance.
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05-13-2022, 05:58 PM | #9 |
Drives: 2017 Camaro SS 50th Anniversary Join Date: Apr 2021
Location: Missouri
Posts: 929
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441 wheel should be around 490 crank, so that correlates well with 48 lbs/min.
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2017 50th Anniversary Edition | P1X Stage 2
DSX Aux Low Side | LT4 high side | Flex Fuel TooHighPsi Port Injection (installed & tuning) CircleD 3K Stall | QA1 CF Driveshaft Forgestar F14 Drag 17x10 NT555R2 305/45/17 Rear Forgestar F14 18x8 NT555G2 235/50/18 Front 10.84@131 w/4.13" pulley ??.??@??? w/3.7" pulley (installed & tuning) |
05-14-2022, 05:24 AM | #10 | |
Drives: 2017 Camaro 1SS Join Date: Aug 2016
Location: NH
Posts: 1,692
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05-14-2022, 06:26 AM | #11 |
Drives: like an old lady Join Date: Jun 2012
Location: indiana
Posts: 2,396
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i really don't understand the lb/min reading. it has basically read the same thing despite the car picking up power and mph. i never put much stock in it tbh. i also wonder how weather would affect the reading.
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05-14-2022, 07:14 AM | #12 | |
Drives: 2017 Camaro SS 50th Anniversary Join Date: Apr 2021
Location: Missouri
Posts: 929
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Quote:
In reality there is a maximum amout of hp you can make given a certain mass of air. To make more hp you have to add more fuel, and to burn that effectively you have to have more air. So in a loose way, the lbs/min defines the MAX power you can make. If your power is increasing but airflow lbs/min stays the same... it means you are more effectively using the air and fuel you always had. This doesnt account for cams and other things that can drastically change airflow characteristics... its just an approximation. At some point i want to make back to back runs under the same conditions with one run at 5 to 10 degrees less spark timing to see if the airflow is more about cam/displacement/rpm/etc (the physical air pump) vs actual power. Is suspect its more about the former... meaning just an indication how much air you can consume. Making the power is more about using it effectively.
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2017 50th Anniversary Edition | P1X Stage 2
DSX Aux Low Side | LT4 high side | Flex Fuel TooHighPsi Port Injection (installed & tuning) CircleD 3K Stall | QA1 CF Driveshaft Forgestar F14 Drag 17x10 NT555R2 305/45/17 Rear Forgestar F14 18x8 NT555G2 235/50/18 Front 10.84@131 w/4.13" pulley ??.??@??? w/3.7" pulley (installed & tuning) |
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05-14-2022, 08:02 AM | #13 |
Drives: 2018 Camaro ZL1 A10 Join Date: Feb 2022
Location: Dubai, UAE
Posts: 63
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05-14-2022, 08:14 AM | #14 |
Drives: 2017 Camaro 2SS A8 Join Date: Aug 2018
Location: Petersham MA
Posts: 4,749
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That’s the one I’ve been using for the past couple of years. I think it’s MAF blended with VVE airflow, but since VVE is mostly ignored at higher RPM, I’m thinking it’s mostly MAF at that point. I was 113 lb/min on my 927 WHP dyno pull so I think it’s reasonably accurate.
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150
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