Anybody have BSFC d16y7? (96-00 civic dx lx)

[hayden55]

Anybody have a chart or done testing to see what the d16y7 likes? I just go a scan gauge today so I'd like to start playing with driving techniques and see if i notice any differences.
From what i've seen it looks to be 60% load from 1750-2250?

[California98Civic]

Originally Posted by hayden55

Anybody have a chart or done testing to see what the d16y7 likes? I just go a scan gauge today so I'd like to start playing with driving techniques and see if i notice any differences.
From what i've seen it looks to be 60% load from 1750-2250?

I learned from watching PaleMelanesian (a member of this forum). He had a 96 DX and now has a Fit. I have a 98 DX. For 5 years I have been driving almost every day to work: 75% to max 80% load, 1500 or 1700 to 2000 or 2200 rpm.

My best tank ever was 70mph. PaleMelanesian got at least 90 once and regularly got 80.

Hope that helps...

james

[Ecky]

The only Honda BSFC chart I have is from the Insight's 3 cylinder, which appears to have heritage from the D-series:




If I were to guess, I'd say peak BSFC happens at closer to 2750-3250RPM on that motor, because of the cam profile, and probably at slightly higher load, closer to 70-80%.

[California98Civic]

Originally Posted by Ecky

... If I were to guess, I'd say peak BSFC happens at closer to 2750-3250RPM on that motor, because of the cam profile, and probably at slightly higher load, closer to 70-80%.

I love your interpretation of the Gen 1 Insight map. I totally agree about the heritage thing. The 2000 Insight was launched in the last year of the 6th Gen Civic (96-00), and lots of engine and trnasmission features were similar. You can see it really clearly in the FSMs. But I can't agree about your RPM recommendation. Why so high? In my experience (and PaleMelanesian's) ... it would suggest, as this map does, that 1500 to 2200 RPMs is the best range. And we drove it at 75% load. 3000+ rpms seems like screaming it.

[Ecky]

Take it with a grain of salt, but here's my reasoning:

The Insight's ECA1 is a VTEC(-e) motor, which opens the second intake valve wider after VTEC engagement, which is somewhere between 2500 and 3200RPM depending on load. This gives the engine two torque curves, one that peaks somewhere between 2000RPM and VTEC engagement, and another that peaks at around 4800RPM.

The D16Y7 is a non-VTEC motor, and its torque peaks around 4600RPM, because it has only one cam profile. The cam profile that it has is a compromise between low RPM torque and high RPM torque, which I would imagine would shift BSFC up the RPM band a bit.

Peak BSFC is generally not at peak torque, but there is a relation. Low-RPM combustion efficiency is improved in the ECA1 due to a swirl effect caused by asymmetric opening of intake valves. I can't imagine peak BSFC being at the same RPM in the Y7, so it's more a question of how far up the RPM band it moves.

[serialk11r]

The tricky part about using the Insight chart is that lean burn creates that first 215 island, which the Civic doesn't have. However the 250g/kWh point a bit above 80Nm is probably the approximate peak efficiency point at stoichiometric.

That said I wouldn't worry about what rpm to accelerate at; when you accelerate hard at low rpm, the engine is less efficient but the "pulse" takes longer, reducing your car's variation in speed. Just pulse in the top gear, it's easier.

[Ecky]

I don't think that includes lean burn, based on my understanding of how it works.

[California98Civic]

Originally Posted by Ecky

I don't think that includes lean burn, based on my understanding of how it works.

I agree with you. That map is normal engine function, not lean burn. Lean burn only engages in light throttle conditions, as I understand it.

Originally Posted by serialk11r

... I wouldn't worry about what rpm to accelerate at; when you accelerate hard at low rpm, the engine is less efficient but the "pulse" takes longer, reducing your car's variation in speed. Just pulse in the top gear, it's easier.

I don't agree with this one. On the map above, the Insight engine clearly produces 60 Nm torque more efficiently at 2000 rpm than at 3000 or 4000 rpm. If the Sixth Gen Civic the OP has is similar, then it too is more efficient at 2000rpm.

[serialk11r]

Originally Posted by Ecky

I don't think that includes lean burn, based on my understanding of how it works.

215g/kWh is extraordinarily low for gasoline. That's a thermal efficiency of 38.7%, which only a few of the most modern powerplants can match.

230-240g/kWh is the correct range for peak efficiency of a MPFI engine with typical compression ratio.

It's lean burn.

[Ecky]

I'm aware of how low it is, and I'm still inclined to believe the chart is for stoichiometric combustion, because you can't get that kind of torque with lean burn in the Insight. Peak torque (WoT) in LB is somewhere closer to 50Nm, making that impossible. Any higher and it's necessarily stoich.

Edit: FWIW Honda has since built several engines that exceed the thermal efficiency of the ECA1. The 2.0L Atkinson cycle engine in the 2014 Accord hybrid is claimed to be the most efficient engine ever put into a production car.