Thecarfixerguy
Proven Member
- 57
- 20
- Dec 13, 2022
-
Idaho
Before I order parts for my build I'm trying to get well matched parts. So I went down the rabbit hole of calculating my airflow, manifold pressure, and pressure ratio manually. My concern is the pressure ratios seem much higher than the pressure maps I'm seeing for various turbos. I ran calcs for 400HP and 450HP and came up with airflow of 48 Lbs/Min(400HP) and 54 Lbs/min(450HP) with pressure ratios of 3.49 and 3.91 respectively. Am I needing to look at bigger turbos to hit these numbers, and will that kill my spool time?
My goal for the car is a quick spool and fun car to drive around town without hitting felony speeds before the turbo really gets going. I'd be willing to sacrifice a little max HP for a quicker spool.
My thought was if I pick a turbo where 3.5 pressure ratio hits right at the top right of the turbo map I would have the rest of the turbo range for performance at the lower end. Is that a correct assumption?
I attached an image of my homework paper with all the numbers I used for my calcs. Thanks for the help.
My goal for the car is a quick spool and fun car to drive around town without hitting felony speeds before the turbo really gets going. I'd be willing to sacrifice a little max HP for a quicker spool.
My thought was if I pick a turbo where 3.5 pressure ratio hits right at the top right of the turbo map I would have the rest of the turbo range for performance at the lower end. Is that a correct assumption?
I attached an image of my homework paper with all the numbers I used for my calcs. Thanks for the help.
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