Dan Martin

Has anyone done a dyno on a stock TSX with an air/fuel ratio plot? Stock or modified, I'm just curious...

vwong

Yes, I have. Like I said in the other post, I didn't get a printout of my dyno, but I got ALL the data (including the A/F ratio) from the dyno. I can plot it when I get home tonight.

Dan Martin

It's just purely out of curiosity. If you don't feel like plotting it, what were the highs and lows and at what RPM did they happen?

CGTSX2004

iTrader: (1)

This would be most useful if Hondata releases the K-Pro...

vwong

Here is the A/F ratio graph for my stock (engine wise) TSX. I'm posting the dyno as well.

Dan Martin

Thanks Vincent!

It would be interesting to see how the hondata reflash compares to that.

JTso

iTrader: (2)

Wow! the stock A/F is pretty rich around 4000 rpm. I wonder what the "modified" Hondata A/F looks like...

vwong

Ok...I have to admit. I'm a at this A/F ratio thing (I'm more of a suspension, wheels/tires guy ). What is consider rich and what is consider lean?

CGTSX2004

iTrader: (1)

Rich means that there is more fuel (thus A/F ratio is lower) and lean is when there is less fuel (thus A/F ratio is higher).

Dan Martin

14.64 is the stoichiometric ratio meaning that it's the theoretically perfect mix of gasoline and air to achieve complete combustion. Higher ratios indicate a lean condition (more air than fuel). Often engines are tuned a little on the rich side (13.5 to 14.5 for NA or 12.5 to 13.5 for forced induction engines) during WOT runs. When you're under light load or idling it's not uncommon for engines to be tuned lean (sometimes as high as 16 or 17:1) for increased mileage and emissions reasons.

AZTSX

wait so this is a stock dyno correct? And you got a max HP of 185.9 and tq of 158.2? Isnt that kinda high considering stoke got 184.6 hp and 151.1 tq? I was jw not trying to be an ass or anything

Dan Martin

This run was on a Dynopak dyno which reads about 10hp higher than a dynajet.

vwong

Mine was dyno'd on a Dynapack, while Stoke was probably on a Dynojet. Dynapack is known to read about 10hp more than a Dynojet, however the dyno's on the Dynapack are repeatable within couple of hp.

BTW, thanks Dan for the detail explanation. Reading your explanation reminds me of the Internal Combustion Engine class I took back in college. But I have forgotten most of it already.

jlukja

So, if I'm reading the plot correctly, the TSX burns 6.5% more fuel (14.4 vs. 15.5) at 2000RPM than at 1800RPM? Does that translate into gas mileage being 6.5% better?

Dan Martin

This AFR chart only measures the ratio under WOT and full load. There are other mappings for cruising speeds so there's not much point to gathering fuel efficency info off this chart.

AZTSX

thanks for the clarification

jlukja

Gotcha. Thanks Dan.

vwong

Here's another question from the . What would happen if I lean out the A/F mixture at WOT? OTOH, what would happen if I add more fuel at WOT?

When I was at Church's place to dyno my Prelude, he said something about my Prelude running a bit lean. But when I compare the A/F ratio graphs between my Prelude and TSX, my Prelude is already running a bit richer than the TSX.

Dan Martin

Do you have a fuel management system on your Prelude?

vwong

No, but Church recommended me to get an adj. FPR. what it would do?

Dan Martin

I'm not familiar with the use of FPRs for NA engines so I really don't know what they'll do. Usually with a FI engine, an adjustable fuel pressure regulator is used to increase fuel flow when it senses boost. There's a little vacuum line on the top of the regulator that actuates the flow rate.

Maybe Johnny could shed some light on this for you.

JTso

iTrader: (2)

The adjustable FPR increases fuel based on load condition via a vacuum line to the intake manifold. When vacuum is high, like during idle or cruising speed, the build-in pressure spring is overcome by the vacuum source and certain amount of fuel is allowed to return back to the fuel tank from the fuel rail. When the vacuum is low, like during acceleration or WOT, the pressure spring is pressed down against the diaphragm forcing more fuel to stay inside the fuel rail causing fuel pressure to go up. The adjustable FPR allows you to adjust the tension of the pressure spring. However, the adjustmet affects the entire rpm range and not just where you need it. Therefore, you might correct certain lean area of the rpm range but cause another area to be rich.

Dan Martin

So it functions the same way I guess. It definitely sounds like you want a programable ECU Vincent.

vwong

Can't do, not allowed in STX class. When my Prelude becomes the dedicated track car, then I'll consider.

So is it more fuel, more power; or less fuel, more power?

JTso

iTrader: (2)

This is what an adjustable FPR looks like with a custom mount. Note the adjustment screw on top.



This is what a programmable ECU can do to the A/F during WOT.

Dan Martin

That's mighty impressive JTso. It's ruler-flat throughout the run.

Couple questions:
Is datalogging optional or standard on the K-Pro? Do you need a standalone wideband O2 controller or can the K-Pro use a wideband sensor instead of the OEM narrowband?

JTso

iTrader: (2)

The K-pro comes standard with the K-Manage software, which allows tuning and datalogging. I believe the TSX primary O2 sensor is already a wideband sensor, but not sure if the K-pro is able to use it for proper tunning or not.