BSFC and me.

ENafziger said:
I can't mention the specific engine, but this is data from an in-line 6 cylinder turbocharged common rail diesel, of around 14L displacement. Values obviously aren't accurate for a 5.9 cummins, but trends are.

View attachment 27664

--Eric
Click to expand...
That's quite interesting. The BHP follows BSFC. Cyl1 Pres follows BTRQ. Why does torque act as a ratio of BMEP? I suspect I need to google something.

Code: 
Mode 	Engine 	BTRQ 	BHP 	BMEP 	BSFC 	Cyl1. Pres. 
SET 	rpm 	Nm 	HP 	Bar 	kg/kWhr Bar 
Idle 	600	45	4	0.44	0.73	47.21
A25 	1242	533	93	5.23	0.22	79.47
A50 	1243	1066	186	10.46	0.2	107.92
A75 	1243	1599	279	15.69	0.19	141.26
A100 	1243	2132	372	20.92	0.19	172.42
B25 	1518	521	111	5.11	0.24	89.8
B50 	1521	1042	223	10.22	0.2	126.79
B75 	1521	1563	334	15.33	0.19	158.72
B100 	1521	2084	445	20.45	0.19	181.43
C25 	1794	448	113	4.4	0.29	87.82
C50 	1800	896	226	8.79	0.24	113.59
C75 	1800	1344	340	13.19	0.22	137.35
C100 	1800	1792	453	17.58	0.22	165.22
 
Digging up a (slightly) older thread....anyone have any more info from competition-style engines? I did some math and came up with .40 at full power based on pump cc/rpm/hp from a VE pump truck that cleans up the smoke pretty well. I think OEM stuff can hit lower numbers like .2 to .3 but modified engines become less efficient because they're not designed for the rpm/turbo setup they need to break their factory 200-400-ish ratings.
 
I dunno if I am way off base here, but I've also been using this to check out turbo selection....if the engine we're talking about uses 183.755 lb of fuel per hour, then it uses about 3.06lb per minute.....

I've been led to believe that a Cummins engine cleans up at around a 17:1 air/fuel ratio, so that means a turbo that flows 52lb/min would be needed to keep things smoke free...which would be in the low 60mm-ish range at peak efficency levels.
 
JQmile said:
I dunno if I am way off base here, but I've also been using this to check out turbo selection....if the engine we're talking about uses 183.755 lb of fuel per hour, then it uses about 3.06lb per minute.....

I've been led to believe that a Cummins engine cleans up at around a 17:1 air/fuel ratio, so that means a turbo that flows 52lb/min would be needed to keep things smoke free...which would be in the low 60mm-ish range at peak efficency levels.
Click to expand...

I've always read the smoke threshold was around 20-22:1 But I can't back that up. It seems to work for turbo calculations though $.02
 
Hmmm...Banks website says 22:1....

But I also know by talking to 'em that you can push it richer than that if your engine is designed for it (heads, cam, injectors, etc.)

I used 17:1 because I have a feeling there probably isn't too much power to be gained after that, and most people are willing to live with a little haze....
 
Usually fuel is cheaper than air, and drivability is usually better with smaller turbos, so I think most people would prefer to be on the smokier side
 
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