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Old 04-07-2022, 02:34 PM   #1 (permalink)
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2022 BRZ or GR86, BSFC charts

Has anyone seen or know of a source for BSFC chart for the 2.4l boxer engine in these cars.

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Old 05-07-2022, 11:38 AM   #2 (permalink)
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Don't worry about BSFC charts, just use the highest gear you can before the next gear down shows better mpg on the display.

If it's out of academic curiosity, the BSFC chart should look nearly identical to the old FA20, which should look like a 2GR-FSE but with slightly poorer low rpm efficiency. When I had a FR-S back in 2015, the mpg really tanked as you went below 2000rpm in 6th gear, which is expected because the cam profiles are high lift high duration.

The new 2.4 is paired with the same gearing AFAIK so I would expect that you want to shift slightly earlier than the 2.0 because there's more displacement.
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Old 08-21-2022, 12:17 AM   #3 (permalink)
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Quote:
Originally Posted by serialk11r View Post
Don't worry about BSFC charts, just use the highest gear you can before the next gear down shows better mpg on the display.

If it's out of academic curiosity, the BSFC chart should look nearly identical to the old FA20, which should look like a 2GR-FSE but with slightly poorer low rpm efficiency. When I had a FR-S back in 2015, the mpg really tanked as you went below 2000rpm in 6th gear, which is expected because the cam profiles are high lift high duration.

The new 2.4 is paired with the same gearing AFAIK so I would expect that you want to shift slightly earlier than the 2.0 because there's more displacement.
The upshift indicator on the BRZ wants you to upshift at 1800 rpm, which is ridiculously low. The mileage on this really benefits from being in a high gear quickly. RPMs, even at light throttle, kill the mileage.
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Old 08-21-2022, 03:09 AM   #4 (permalink)
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Quote:
Originally Posted by Mcgiiver View Post
The upshift indicator on the BRZ wants you to upshift at 1800 rpm, which is ridiculously low. The mileage on this really benefits from being in a high gear quickly. RPMs, even at light throttle, kill the mileage.
This has been my experience with every car I've owned. My MX-5 suggests shifts at around the same point, with the next gear typically landing me somewhere around 1300rpm. It'll get 50mpg+ if driven that way without stop and go.

BSFC islands are almost always wider than they are tall, on the chart, suggesting it's almost never a good idea to hold onto a gear when you have another gear you can shift into and not shake the car to pieces.
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Old 08-21-2022, 06:55 AM   #5 (permalink)
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Quote:
Originally Posted by Mcgiiver View Post
The upshift indicator on the BRZ wants you to upshift at 1800 rpm, which is ridiculously low. The mileage on this really benefits from being in a high gear quickly. RPMs, even at light throttle, kill the mileage.
It does, but you need really good control of your right foot if you are to shift up at 1800rpm. The engine efficiency is really poor down there. It actually LOST mpg in 6th gear below 1500rpm compared to going faster.

I remember doing calculations for the enrichment threshold mpg in each gear, I remapped the throttle so it was easier to control, and I learned to drive only at stoichiometric AFR. I would typically get 42mpg "highway" using some pulse and glide, and about 25 in traffic. The car isn't particularly fast as is so I usually accelerated to 3000rpm and then dropped to neutral or the highest possible gear asap.
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Old 08-21-2022, 09:18 AM   #6 (permalink)
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Quote:
Originally Posted by serialk11r View Post
It does, but you need really good control of your right foot if you are to shift up at 1800rpm. The engine efficiency is really poor down there. It actually LOST mpg in 6th gear below 1500rpm compared to going faster.

I remember doing calculations for the enrichment threshold mpg in each gear, I remapped the throttle so it was easier to control, and I learned to drive only at stoichiometric AFR. I would typically get 42mpg "highway" using some pulse and glide, and about 25 in traffic. The car isn't particularly fast as is so I usually accelerated to 3000rpm and then dropped to neutral or the highest possible gear asap.
My BRZ is a 2022, 2.4 l engine. I was pleasantly surprised that the DFCO comes back on at a low 1000 rpm, I think. At least that's what it feels like to me.

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