Vossie
#thecrazycruiserman
and the 12HT? 256 too good to be true?
Lets talk Brake Specific Fuel Consumption. (2 Viewers)
- Thread starter dare
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and the 12HT? 256 too good to be true?
~250 g/kwh is about what I'd expect for an older 6 cylinder turbo direct injection. With a better turbo and more power/torque (which dilutes idling losses) I'd expect the 12HT to get down to around 220 g/kwh.
I'm trying to dig out some figures to check these myself. Anyone got a good power/torque reference for these motors?
Vossie
#thecrazycruiserman
ok, thats where i was hoping to be. just dropped a 12HT into my 45 and fuel economy is one of my main reasons.
Soooo a turbo is gonna make the 3B more efficient somehow, right?
Vossie
#thecrazycruiserman
the way i understand it yes. turbo means more air per fuel. more air means more burn. more burn means higher efficiency.
Isn't there an optimal AFR, which my 3B if correctly tuned should already be running at? Adding turbo means more air, which with the addition of more fuel means more power - but at the cost of using more fuel per distance travelled?
Only if you poke it harder.
Best efficiency is as rich as you can run while still burning it all cleanly and quickly. So around 18:1. This only happens at full torque. Rest of the time you're much leaner.
Turbos improve efficiency by about 10%. If you get the right turbo match. The wrong turbo can hurt efficiency.
Vossie
#thecrazycruiserman
thats doesnt sound quite right either... in my old 45 i had a 2H. it gave me real world figures of around 7.5km/L. that sounds too good for an engine with 345
You weren't running at 3500rpm though.
Vossie
#thecrazycruiserman
very good point. so in real world expectations, the efficiency at peak torque also depends on where your peak torque is. eg, in the 2H, your only hitting 3500rpm very rarely. but with the 12HT having peak torque at 2000rpm, your going to be hitting it and sustaining it alot more of the time. so in reality, these two motors should balance out quite a bit? or am i over simplifying it?
GTSSportCoupe
2LTE abuser
The 2H and 12HT trucks in our local landcruiser club deliver some of the best fuel economy of all the Toyota diesels...and I think we have nearly all the non electronic variations. They seem to get around 10l/100km regularly on highway. This on large tires and with a lot of extra weight. Engines are stock and healthy.
Of the commonly matched tried and tested turbo's used in this context, are any likely to hurt efficiency?
How badly matched does a turbo need to be before it hurts fuel efficiency?
An original paddle wheel turbine CT26 is going to hurt efficiency. That's the #1 reason the 1HD-FTE gets better economy than the 1HD-T. It's got a far better turbo.
interesting.
As a hypothetical scenario in simple terms, take a 1hz, and add a stock ct26 from 1hd-t, if all else is the same (same fuel settings etc), is it reasonable to expect the 1hz to be more fuel efficient with the turbo?
My thoughts are that it would be more efficient as you get a more complete fuel burn from the added air intake volume. This would also equate to more power?
For low boost I think you'll gain fuel economy. But at higher boost the BSFC will likely rise back to stock or even get worse due to turbine drive pressure.
With a more efficient turbo, the BSFC will be better across the usable range.
Awesome info. I'd love to see some curves for the 14B-T. I was hoping for better fuel economy and more power out of the 14B-T, but alas 'I poke it harder' so I'm getting about the same fuel economy (maybe a bit less) out of the 14B-T as the 3B-II. I am driving way more aggressive than was ever possible with the 3B-II though.
Thanks,
Dan
Thanks,
Dan
Thank
By far the most understandable article on bsfc I have yet seen. I am looking at getting the 4.5 EFI a little more user-friendly.
Thank you DareOkay so I recently bought a disc off eBay with a bunch of FSMs on it (failnet out here so downloading is impossible). Whilst Toyota don't just tell us the BSFC they do give us the fuel injection volumes near peak torque and with that and the torque figures we can roughly calculate the peak (lowest) brake specific fuel consumption as it occurs near peak torque. All the indirect injection BSFC maps I've seen have BSFC occurring at 75-80% of peak torque so these figures probably don't show the best of them. Direct injected motors on the other hand have the peak at the top of or very close to peak torque, I don't know if this has more to do them them being generally electronically controlled or if it because of the injection difference.
For those who don't know, what is Brake Specific Fuel Consumption? Basically it's a measure of how much power an engine can produce from an amount of fuel, or how efficient the engine is at converting fuel into power. This is of course directly linked with fuel economy, a (numerically) lower BSFC will certainly get more miles out of fuel. It's also inked with power, a more efficient engine will extract more power from its fuel so for example for a given air fuel ratio an engine with a lower BSFC will need less boost than a less efficient one to make the same power or it could be making more power with the same boost.
I haven't seen Toyota BSFCs calculated on mass like this before so hopefully this helps a few people out.
The fuel injection volume charts look like this (pic thanks to lostmarbles). Toyota state all injection volumes as per 200 shots/strokes for one cylinder, though some early manual also give per 1000 shots for all cylinders.
For the numbers I'm picking the model that is "general" market, there's very little (or sometimes no) variation in the volumes between models of the same engine. I'm using the number from the lower end of the range, that might make BSFC a bit optimistic but it's what everyone else does with other motors anyway.
To calculate BSFC (using the VE pump B as an example) we break the cc/200 shots number down to cc/single shot, times that number by the number of shots per revolution (2 for a 4 stroke 4 cylinder), times that by the number of engine revolutions (2200 at peak torque for the B) and then times that by 60 for the number of minutes we're doing those revolutions.
So (9.35/200)x2x2200x60= 12342cc/hour
Then we times that by 0.832 which is how many grams 1cc of diesel weighs.
12342x0.832=10268.544g/hr
We take the torque and rpm figures and calculate power at that rpm.
KW=(191nm x 2200rpm)/9548.8=44.01
10268.544/44.01=233.3g/kw/hr
B (inline/A type pump)
1100/10.0
???
B (rotary/VE pump)
1100 pump rpm/9.35cc/200shots
191nm@2200rpm 44.01kw
10268.544g/hr
233.3g/kw/hr
11B (A)
1100/9.5
???
11b (VE)
1100/200/11.95
???
3B (A)
1100/11.1
217@2000 45.45kw
12190.464 11082.24
243.83
3B-II (VE)
1100/10.85
???
13B (A)
1100/11.2
???
13B-T (A)
1100/13.5
auto 12.8
???
14B (VE)
1100/13.75
700/11.9
Average of those is 900/12.825 which is what I used for the calc, though I think the 14b would be more efficient. Even calc'd at 11.9 it's 236g/kw/hr.
240@1800 45.24
11524.032
254.73
15B-F
900/16.7
1100/17.5
290@2000 60.74
14177.28
233.4
15B-FT
900/13.9
1300/14.4
382@1800 72.01
15005.952
208.4
Note the injection volumes for 15B-F and 15B-FT, that's how they published it but I assumed they put the 15B-FT numbers with the 15B-F and vice versa and calculated it as such.
2H
1100/8.2
1100/1000/255 (all 6 cylinders)
240@2000 50.26
12729.6
253.27
12H-T
1100/11.3
1100/1000/345
315@1800 59.38
15230.592
256.5
1PZ
1200/11.78
230@2600 62.63
19111.872
305.15
1HZ
1100/11.8
285@2200 65.66
19438.848
296.05
1HD-T
1000/11.7
361@1400 52.93
12265.344
231.7
L
1200/7.54
142@???? (assuming 2400) 35.69
10857.6
304.22
2L
1200/9.34
167@2400 41.37
11190.0672
270.48
2L-T
1200/10.4
188@2200 43.31
11421.696
263.7
2L-T-II
1000/13.7
216@2400 54.29
16413.696
302.33
3L
1200/11.6
188@2400 47.25
13897.728
294.13
5L (not 5L-E)
1200/12.18
192@2400 48.26
14592.6144
302.37
1KZ-T (without altitude compensator)
700/14.9
1800/15.3
287@2000 60.11
14876.16
247.48
I think a few of those BFSC numbers are a bit out, some of the pump rpms don't match the peak torque rpms. I've just pulled the torque figures off wikipedia so who know how correct some of those are.
It's not surprising to see the 15B-FT as the most efficient, it's the most advanced engine here. I really thought the 14b would be much better, it don't see any reason for it to be (far) behind the 4BD1 or 4BT. I also don't see why it need almost identical fueling to the 15B-F when the 15b-F is over 10% larger and has a modern 16v head. I thought the 1HZ would be ahead of the 2H but apparently not. It's odd the 1HD has slightly less injection volume than the 1HZ, if the numbers are correct the 1HD is making all that extra power from increased efficiency alone!
@ERNRAM recently showed us some Toyota BSFC curves. I'd really appreciate some higher quality photos or scans!
Observations.
Engines with altitude compensators generally run less fuel, meaning less power(or greater efficiency, but I can't see how that could happen)
Automatic models almost always run more fuel.
China models run less fuel (emissions requirements?)
Just for comparisons sake, here's a few other comparable/relevant motors.
Isuzu 4BD1T 216
Mercedes OM617 245
Cummins 5.9ISB225 203
Mitsubishi 4d34 235
If anyone can post Toyota diesel torque figures or curves, please do.
By far the most understandable article on bsfc I have yet seen. I am looking at getting the 4.5 EFI a little more user-friendly.
