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MetroMPG 03-19-2008 12:00 AM

The BSFC chart thread (post 'em if you got 'em)
Had a suggestion to post BSFC charts for various vehicles in one place. If you've got one, post it in this thread. I'll add an index in this first post if it gets long.

Geo/Suzuki 1.0L SI engine

Thanks to tasdrouille who posted a link to a fuzzy - and the only - bsfc chart I've yet seen for the Suzuki/Geo 1.0L, non-XFi engine (judging by power rating):

The original, fuzzy image:

Cleaned up image. Note: I "best guessed" a few digits:

Note that peak torque for this engine is listed as:

Torque(lb/ft) @ RPM: 58 @ 3,300 (Non-XFi Models, XFi not listed - source)

And 58 lb/ft = 78.6 Nm (calculator)

Straight-3 03-19-2008 02:28 AM

What I'm getting: Driving at WOT from about 2600 to 3600 rpm will yeild the minimum fuel used for power produced.

What I'm wondern: Why is there so much data on the graph? Like islands instead of just a line, theres seems to be 8-10 points plotted for every rpm from 1100 to 5000.

Straight-3 03-19-2008 02:51 AM

Wait a sec... the aliens were just communicating with my brain... Each line is just fuel consumption for a given torque and rpm, throttle position is not represented on this graph. I think.

cfg83 03-19-2008 04:20 AM

1 Attachment(s)
Hello -

Here's one for my Saturn 1.9 liter DOHC engine :

Attachment 469

I got it from here :

Fuzzy Pareto Frontiers in Multidisciplinary System Architecture Analysis


tasdrouille 03-19-2008 08:17 AM

Here's one illustrating NA vs Turbocharged for a given engine. It clearly shows how a turbocharger can lead to better FE as you can downsize the engine and get the same power output, but you extend the bsfc sweet spot to lower loads vs the bigger engine.

MetroMPG 03-19-2008 08:43 AM


Originally Posted by cfg83 (Post 15008)
Here's one for my Saturn 1.9 liter DOHC engine

cfg, do you know what the line is at the top of your chart with the points marked on it? The original Geo engine chart appears to have a similar line.

jwxr7 03-19-2008 09:08 AM

Here is a chart for a 2001 GM vortech 4.3l v-6. It shows both, the truck and marine applications.

Brake Specific Fuel Consumption
The engine brake specific fuel consumption (bsfc) shall be as follows:
1. The engines nominal brake specific fuel consumption point on a W.O.T. curve is shown in
table 6.3 -I.
2. The engine nominal specific fuel consumption shown in table 7.3 -I are for an operating range
between peak torque and maximum power at full load.
3. The engines best part throttle bsfc (on a fuel map) is shown in table 7.3 -I.

Table 6.3 L35 V6 4.3L Engine BSFC

rpm truck marine units
800 0.529 0.495 lb./BHP-Hr
1200 0.521 0.478 lb./BHP-Hr
1600 0.484 0.481 lb./BHP-Hr
2000 0.470 0.471 lb./BHP-Hr
2400 0.471 0.466 lb./BHP-Hr
2800 0.469 0.472 lb./BHP-Hr
3200 0.478 0.458 lb./BHP-Hr
3600 0.483 0.452 lb./BHP-Hr
4000 0.500 0.460 lb./BHP-Hr
4400 0.525 0.479 lb./BHP-Hr
4800 0.532 0.506 lb./BHP-Hr
5200 0.556 0.550 lb./BHP-Hr

cfg83 03-19-2008 06:10 PM

MetroMPG -


Originally Posted by MetroMPG (Post 15018)
cfg, do you know what the line is at the top of your chart with the points marked on it? The original Geo engine chart appears to have a similar line.

Nope, I don't speak BSFC. It's just a topo-map to me. I'm sure someone else will pipe up and say what it is.


tasdrouille 03-19-2008 06:50 PM

I always thought it was simply the torque curve at WOT through the whole range. I could be mistaken though.

boxchain 03-20-2008 12:37 AM

I agree that those look like torque curves...

So this is a load vs speed graph that maps fuel/power gradients :D ...the way I'm reading them is that the sweet spot for acceleration is about 1/2 to 2/3 throttle (y-axis...load really) at 1500-3500 rpm, depending on what your torque curve looks like.

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