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NoDOHC · 08-13-2010, 09:33 PM

If I can afford the dyno time, I would love to document a full BSFC curve. This issue with this is that drivetrain loss is a little funny at lower throttles (manifold pressures), as some of it drops with load (bearing and gear resistance) and some is fixed (windage and oil displacement). Still, this curve would be more useful than an actual engine BSFC curve to develop optimal mileage gearing....

More data would be awesome here, as I would not consider the number from a single engine a representative sample.

The data is easy to get, simply datalog injector on-time and engine speed during a dyno run and compare the graphs. You should have fuel pressure and manifold pressure to be really accurate.

With enough data, we could develop compression ratio comparisons (which should show lower BSFC with higher compression). Porting comparisons, aspiration comparisions, AFR comparisons (mostly done already by Kenichi Yamamoto) and ignition timing comparisons.

I wish I owned a dyno sometimes, I would get a lot more data if it didn't cost me $60 per hour to collect it.

08-13-2010, 09:33 PM	#14
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	If I can afford the dyno time, I would love to document a full BSFC curve. This issue with this is that drivetrain loss is a little funny at lower throttles (manifold pressures), as some of it drops with load (bearing and gear resistance) and some is fixed (windage and oil displacement). Still, this curve would be more useful than an actual engine BSFC curve to develop optimal mileage gearing.... More data would be awesome here, as I would not consider the number from a single engine a representative sample. The data is easy to get, simply datalog injector on-time and engine speed during a dyno run and compare the graphs. You should have fuel pressure and manifold pressure to be really accurate. With enough data, we could develop compression ratio comparisons (which should show lower BSFC with higher compression). Porting comparisons, aspiration comparisions, AFR comparisons (mostly done already by Kenichi Yamamoto) and ignition timing comparisons. I wish I owned a dyno sometimes, I would get a lot more data if it didn't cost me $60 per hour to collect it. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)