Narrow and Broad band O2 sensors and open vs closed loop systems

[pbanders]

You make a good point, lapuwali, regarding tuning. But if that's the goal, then there is no substitute for dyno tuning, and there, you'll likely have access to a shop-quality 5-gas analyzer, making the need for the NB or WB O2 sensor moot.

[pbanders]

Here's a cost comparison that might be interesting:

Purpose: Performance tuning of FI system across all load ranges, engine speeds, and running condition.

Alternative #1: Build WBO2 sensor and use G-Tech in-car tuner for performance measurements

WBO2 Sensor w/Interface: ~$300
G-Tech: ~$115
Total: ~$415

Advantages: You own it, can use it any time, simple to operate.

Disadvantages: Limited accuracy of A/F measurement, uncalibrated, limited accuracy of performance data, difficult to fully exercise car across all engine speed and load conditions safely on the road.

Alternative #2: Take car to dyno facility for tuning

3 hours dyno time: ~$450 to $600 (maybe less)

Advantages: Calibrated 5-gas analysis, independent torque and power measurement, full engine speed and load range available (depends on dyno setup), safe environment for testing.

Disadvantages: You don't own it, so if you do iterative testing, will require more dyno time ($), cooling can be an issue.

[lapuwali]

It's true that a dyno will allow you to acheive good tuning more quickly than an on-the-road method. If just tuning for power, a gas analyser isn't even required, it just makes the job easier. Without one, you're just reduce to more trials and more errors until you acheive best power. But you'll get there, eventually.

You can tune something on the road, too. Given that no dyno ever gives a true picture of driving conditions (they aren't very good at handling drivability issues, for example), you're going to do some on the road tuning, anyway. Having an analyser in the car will, like the dyno, simplify the job. A solid-state device like the WBO2 stuff is also less likely to suffer from calibration drift.

As for costs, the WB02 stuff will be a good bit cheaper in 5 years, the dyno route will (at best) cost about the same. I'd venture that an off-the-shelf WB setup will sell for under $200 within a year. The G-Tech you can eliminate, as the Innovate box will log RPM and time, which allows you to derive real-world at-the- wheels HP over RPM over mixture curves. The devices the Megasquirt boys are concocting will allow similar functionality in kit form.

[klatinn]

Hi,

There's one other thing to consider:

5-Gas analyzer reaction time: ~7-10 seconds.
WB reaction time: ~100-300 milliseconds.

(reaction times are give for settling to final steady result)
Because of the reaction time tuning with a 5-gas is out on an inertial dyno or on street acceleration runs.

Regards

[pbanders]

Good discussion!