The BSFC chart thread (post 'em if you got 'em)

[ever_green]

some more charts from honda

2.2L honda vtec FB22 (1993 accord)


1.5L honda vtec (CRX vxi)


1.6L honda sohc ZC vtec


1.8L honda sohc i-vtec (2006 140hp civic)


i-vtec operating range for each valve timing, if anyone here knows japanese can you translate this:


from honda:

[Switching to valve timing for the cruise condition]
over 10km / h: vehicle speed,
1,000 rpm to 3,500 rpm: Engine
speed over 3-gear transmission

[superchow]

Originally Posted by ever_green

some more charts from honda

i-vtec operating range for each valve timing, if anyone here knows japanese can you translate this:


from honda:

Now if we could have BSFC curves for partial loads... I know, I know, never satisfied!

See article below:

Technical Overview of Honda's new R18 i-VTEC Implementation

[ever_green]

Originally Posted by superchow

Now if we could have BSFC curves for partial loads... I know, I know, never satisfied!

See article below:

Technical Overview of Honda's new R18 i-VTEC Implementation

for most modern engines the BSFC sweetspot (RPM) is the same in partial load as in WOT. Here is a WOT BSFC chart for a 2.2L DOHC vtec engine:



here is the partial load BSFC (2.2L DOHC vtec):



Unlike i-VTEC engines, VTEC engines are easier to understand because high lift cams are engaged at a specific rpm (In this case it's 5800 rpm). On an i-VTEC engine it can happen anywhere above 1000rpm. Note the effect VTEC has on BSFC in the chart above. So we must avoid high speed valve lift in order to save fuel. This means that with our typical 1.8L i-VTEC honda engines we should get into 4th gear as soon as possible with moderate loads. The theory of high loads low RPM does not apply to i-VTEC or any other variable valve lift system as it might engage the high lift valve mechanism. I have noticed that some people here pursue lugging methods to achieve good MPGs. On older engines this might be fine aside from the damage it does to their engines, but on a modern variable valve lift equipped powertrain it is counter productive. it's really easy to engage high lift cams below 2000rpm as honda engines have serious lack of torque below that speed.

[ausias]

i did the same calculations with almst the same values and i'm going to make this chnage on my 1.9 Tdi AHF 81 Kw engine.
with spanish diesel price I think i would pay the change in about 29.000 to 47.000 kms (depending if i sell my gear to some 1.8T owner).

My cd it/s around 0.25 (i'm planning going to 0.21 ) but i have my new 205/55/16 michelin energy saver+ tires with european label roll resistance B (6.5 to 7.7 kg force/Tone), wet grip A
I 'will coment the results on the forum

Originally Posted by Deezler

No problem Dave. Thought more folks might chime in... guess no one cares, haha. Either that or I just nerded out hardcore.
Traffic on this site has been a bit slow since sub $2 gas came back, sadly. (gas tax NOW!)

Well I said I would post up my gear swap calculations, so here they are.

Available options for my TDI are 0.681 and 0.658 5th gear ratio sets. (Stock is 0.755). I have also been considering a set of 205/60/16 tires (3% more circumference vs the stock size of 205/55/16).
The combination of the .681 gear and the 205/60/16 tires is almost exactly equal to the effective overall gear ratio as the .658 gear set, btw.

So whereas we could place a mph scale atop the former graph since our gear ratio was unchanging, we can no longer do this. Instead, trusting that our aerodynamic and rolling resistance is constant at a given speed, despite the vehicle gearing situation, we can interpret vehicle speed as a constant power requirement. (e.g. the blue lines from before). So below I plotted 72.5 mph = 24.3 HP, and for a Cd of 0.27, 72.5 mph = 22.2 HP.



The green dot is our starting point. Changing the gear ratio with a .681 ratio 5th, and the 205/60/16 tires, we move from 2496 rpm at 72.5 mph in stock form down to 2189 rpm, along the 24.3 HP line. Finally I again looked at a coefficient of drag reduction down to 0.27, sticking with the new overall gear ratio. Estimating the BSFC for each point, these are my results:

mph rpm load(kW) BSFC est gal/h mpg
stock gear & tire 72.5 2496 18.11 263.0 1.480 48.98
0.681 gear 72.5 2251 18.11 248.5 1.399 51.84
0.658 gear 72.5 2175 18.11 243.0 1.368 53.01
205/60/16 tire only 72.5 2427 18.11 260.0 1.463 49.54
.681 and 205/60/16 72.5 2189 18.11 244.0 1.373 52.79
Cd=0.27 .681, 205/60 72.5 2189 16.54 248.0 1.275 56.87


So, I'm sold. I think I'll actually stick with the stock tire size and grab a .658 5th gear! I may not ever recoup the entire cost of the gear swap ($350 - sale of stock gear = ~$200). But the reduction in engine noise, wear, and fuel consumption are all worth money to me.

edit: stupid table formats never hold up during posting.

[ausias]

Originally Posted by MetroMPG

Roll your own: a few years ago we had a member who was working on a method of converting data logged from the OBD-II interface into a BSFC map. I had a look ... but couldn't find the thread I'm remembering.

I tried several times and with the data logged from OBDII it is not possible (always get constant factors conversions i.e mg/stroke to torque). you need accurate accelaeration data, drag, rolling resitance, wind, a flat road or accurate slope, etc. or some engine direct torque measuring or Roller dynamometer bank like a MAHA, etc.
and C02 accurate emissions will be a best way than OBDII data (Carbone are alway from fuel, 140 g of C02 means 4.5 L of diesel burned).
enigenes does'nt measure injection quantity, we pressume that for guetting 3.6 mg/stroke we apply 1.35 V to the injectors or pum, etc. OBDII data really talks about voltages being applied or measured (MAF, etc.)

Air metering is right if you dont change your air intake,i.e.

You obtain l/h in obdii data from fuel consumption (liters/hour) = rpm x IQ x conversion factor.

I think from Air Flow or Air mass you can get data (scangauge does it?) about meaasured Volumetric Efficiency (assuming nothing changed in air intake).
You always need a way of measuring real work and real fuel consumption to obatain BSFC map, i think.

[ever_green]

this is a for a caterpillar 7.2L 6cyl engine making peak torque of 550ft-lbs at 1000rpm and 125hp at 2000rpm. interesting thing about it is it takes measurements at different gears!

[Sven7]

Recently found this one- straight from an original brochure. Honda S800

The original size image I found wasn't much clearer, so you're not missing much. In a 10,000 RPM engine, the prime FE spot is just below 4,000. Supposedly also did 100mph and 35mpg. The race cars sound great, too.

[RH77]

Originally Posted by ever_green

some more charts from honda

Nice finds! Where were you able to find these? I'm still in search of the B18B1's map... I'd settle for a K24A2 map as well.

Thanks in Advance...

RH77

[ever_green]

Originally Posted by RH77

Nice finds! Where were you able to find these? I'm still in search of the B18B1's map... I'd settle for a K24A2 map as well.

Thanks in Advance...

RH77

got some of them from honda's offical (japanese) factbook website. The rest I got it from honda though articles and other stuff back when I was a student.

for B18B


I have tons of these stuff on my PC, but I don't have access to it now. I will try to find one for K24. I can tell you that k24 sweet spot is also up around 3000rpm. Wide open throttle induces enrichment, quick change in accelerator pedal induces enrichment too. So avoid those things and you will be good on gas mileage.

[WD40]

ever green: the one you list as 1.8L honda sohc i-vtec (2006 140hp civic)
is the same one that tom o shows for the VX
http://www.thelic.org/users/tomo/CivicVXdyno.jpg
what I really want to know is how to understand what its showing.
Can someone explain how to read it?
thanks Dennis