Supercharger Math
Thread Starter
Racer
Joined: Aug 2000
Posts: 491
Likes: 0
From: Houston, Texas
Supercharger Math
I had some time to kill at work so I crunched a few numbers for a supercharged motor. These results were calculated using engineering equations (not made up.)
The first thing I calculated was how the outlet temps (after the S/C) changed with boost (air inlet of 80F). (The result is the minimum temp, in practice it will be higher because the inefficiencies of the supercharger.)
The next result shows how horsepower output changes with boost if your engine can support the flow numbers and horsepower was directly proportional to airflow.. These results take into account the higher outlet temps and power required to turn over the supercharger (with eff. of 80%)
The last thing I wanted to see was the volumetric flow rate before and after the S/C and what the MAF would be reading.
These are all theoretical results.
[Modified by Red94Vette, 3:41 PM 6/11/2002]
The first thing I calculated was how the outlet temps (after the S/C) changed with boost (air inlet of 80F). (The result is the minimum temp, in practice it will be higher because the inefficiencies of the supercharger.)
The next result shows how horsepower output changes with boost if your engine can support the flow numbers and horsepower was directly proportional to airflow.. These results take into account the higher outlet temps and power required to turn over the supercharger (with eff. of 80%)
The last thing I wanted to see was the volumetric flow rate before and after the S/C and what the MAF would be reading.
These are all theoretical results.
[Modified by Red94Vette, 3:41 PM 6/11/2002]
Thread Starter
Racer
Joined: Aug 2000
Posts: 491
Likes: 0
From: Houston, Texas
Re: Supercharger Math (Coupe89)
:lol: I knew that was coming..
The intercooler would be easy to slip in there. All I would need is the heat transfer coeff., the surface area, and the resistance (pressure drop) of the intercooler.
:hat
The intercooler would be easy to slip in there. All I would need is the heat transfer coeff., the surface area, and the resistance (pressure drop) of the intercooler.
:hat
Thread Starter
Racer
Joined: Aug 2000
Posts: 491
Likes: 0
From: Houston, Texas
Re: Supercharger Math (GRX)
:eek:
Well H2O injection could be modeled. You see when water changes from liquid to gas it absorbs a set amount of energy called "latent heat". So, however much H2O you inject you could turn it into a vapor and reduce the air temps by performing an energy balance on the air.
Heat removed = (mass of air) * (heat capacity) * (change in temp)
The heat removed term will be equal to the latent heat of water * the injection rate.
:lol: :conehead
Well H2O injection could be modeled. You see when water changes from liquid to gas it absorbs a set amount of energy called "latent heat". So, however much H2O you inject you could turn it into a vapor and reduce the air temps by performing an energy balance on the air.
Heat removed = (mass of air) * (heat capacity) * (change in temp)
The heat removed term will be equal to the latent heat of water * the injection rate.
:lol: :conehead
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Thread Starter
Racer
Joined: Aug 2000
Posts: 491
Likes: 0
From: Houston, Texas
Re: Supercharger Math (johndezman)
Well the horsepower results is a little pointless becase I just based it off of more airflow = more horsepower. If that were true you would see the gains I predicted for a 350. Now in real life, not only will your airflow increase but also your effective compression ratio will be raised and this will give some more power in addition to more airflow.
I think the point of this math was to show how the air gets heated as it passes through the S/C. It's also interesting to notice how the compressed and heated CFM (outlet on the S/C) is back down to N/A motor numbers. Even though more air is there (mass) with the S/C the CFM after the S/C is around the same as a N/A. That's why you turn about the same RPM with the same heads/cam compared to a S/C motor.
:seeya
I think the point of this math was to show how the air gets heated as it passes through the S/C. It's also interesting to notice how the compressed and heated CFM (outlet on the S/C) is back down to N/A motor numbers. Even though more air is there (mass) with the S/C the CFM after the S/C is around the same as a N/A. That's why you turn about the same RPM with the same heads/cam compared to a S/C motor.
:seeya
