Natural Aspirations

What practices does everyone use for tuning for MPG? AFR/EGT/timing etc...With todays gas prices I am sure this can help everyone out.


I have never gotten too brave always keeping my AFR's in the low 15 area and egt's ~ 1350. Leaner mixture requires more timing correct?

0mtber

iTrader: (2)

Simply play around with fueling values at partial throttle on the setup along with, timing, cam angles if it's a kseries etc. There are too many variables to really give a strait answer on what exactly to target. You really need to try to make the most efficient power at partial throttle with the least amount of fuel to achieve the best MPG.

98vtec

I was talking to Marshall (92TypeR) and he explained it to me in this way.

The reason new civics get such good gas mileage is their very lean fuel mixtures. In excess of 20:1. They can get to this point without breaking up because they run pretty advanced ignition at cruising speeds. I had a chance to test this out with my stock h22.

say at 3500 rpm, i was running 34* table timing, unknown actual. The engine would breakup in the high 15's and hesitate. I took what marshall said and added a good bit of advance and it stopped hesitating at those AFR's. I wouldnt put this theory to test anywhere but cruising and light loads, like getting up to speed at a normal pace. From what i got out of it, as long as the engine does not detonate, the higher ignition you run the leaner you can go. take it with a grain of salt but it worked for me. Instead of getting 280-290 miles to the tank, i got around 340-350.

I've also noticed that i get better gas mileage when i dont run closed loop and tune each cell to the proper target afr.

arc_55

esentially you want a steady state or low enertia dyno and lean mixture and advance timing until peak torque is acheived. This as you said should only be done in light load/cruising conditions. I tend to always tune in open loop with rom editors.

imzjustplayin

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by arc_55 &raquo;</TD></TR><TR><TD CLASS="quote"> I tend to always tune in open loop with rom editors.</TD></TR></TABLE>
What do you mean by that?

98vtec

open loop means the ecu is not using the primary o2 sensor to aid in fueling
closed loop means that it is using the o2 sensor.

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">I was talking to Marshall (92TypeR) and he explained it to me in this way.

The reason new civics get such good gas mileage is their very lean fuel mixtures. In excess of 20:1. They can get to this point without breaking up because they run pretty advanced ignition at cruising speeds. I had a chance to test this out with my stock h22.

say at 3500 rpm, i was running 34* table timing, unknown actual. The engine would breakup in the high 15's and hesitate. I took what marshall said and added a good bit of advance and it stopped hesitating at those AFR's. I wouldnt put this theory to test anywhere but cruising and light loads, like getting up to speed at a normal pace. From what i got out of it, as long as the engine does not detonate, the higher ignition you run the leaner you can go. take it with a grain of salt but it worked for me. Instead of getting 280-290 miles to the tank, i got around 340-350.

I've also noticed that i get better gas mileage when i dont run closed loop and tune each cell to the proper target afr.</TD></TR></TABLE>
You only need to add ignition timing up to a certain point. Once you get to a certain level its not gaining you anymore torque by adding more timing.

arc_55

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by imzjustplayin &raquo;</TD></TR><TR><TD CLASS="quote">
What do you mean by that?</TD></TR></TABLE>

yes 98vtec has it right, but this would be in terms of a stock narrow band sensor. If you use a wideband sensor to and tune fuel and compensations such as IAT and ECT and many others then there is no need for enabling the stock narrow band.

baller status

I can get you in the ballpark.

First of all, it's WAY too general to say that Civics run 20:1, because the ONLY two civic motors that do that are the VX and HX. The VX being the D15Z1 and the HX being the D16Y5. These motors were specially designed to be able to run that lean during light loads. Every other Honda motor will tolerate maybe 16:1 under very light load, and that's still pretty impressive.

Also, you can't assume that a leaner mixture always gives you better economy. It does so only under certain conditions, namely cruise. But if you run lean when you're trying to accelerate, even if it's just a slight incline, you use more throttle and you waste fuel. So it's better to grade your load. Up a not so steep hill might start at 14.7. Slight incline but still accelerating will be about 15.5.

So go with this. 14.7 Idle, and get it to Idle as low as you can and still be stable, ie 750 RPM or so. If your motor has the stock cam then shoot for stock spec (Idle tuning is a whole book on it's own). Mild acceleration shoot for 15.5. (Heavier than that acceleration shoot for 14.5 blended down to about 13.2 for heavy acceleration.) From there down go to 16, try going leaner and see if you get a misfire. And like you said, try playing with the timing.

If it's a stock motor, you can run 13.2 under heavy load and RPM and be careful with timing. If it's modified, run maybe 12.5. High load RPM territory is for experienced tuners though.

After your fuel is optimized you can squeeze a little bit more out with timing, but if timing is already close, it really isn't a justified expense. You do exactly as someone previously stated and tune for MBT on a load bearing dyno.

Hybrid96EK

I'm not too sure about you guys, but with these Blox B's in my B18C1 I am not able to "get away" with 14.7 at cruising or idle. The engine will begin to miss periodically. Its not a fan of the leaner mixture under light load. Never had these problems before with other cams however... just something to look out for.

Right now, I get 25mpg with or without the O2 sensor if I drive it the way I like to. That includes several trips a day to 9 grand and about 20 miles total of driving. If I do not rev the **** out of it and stay off the cam for the most part I have seen 26mpg. This is probably 50/50 city highway driving.

98vtec

post a screen shot of your low cam ignition.

Hybrid96EK

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">post a screen shot of your low cam ignition.</TD></TR></TABLE>

98vtec

have you tried adding timing in the idle/cruise columns?

Hybrid96EK

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">have you tried adding timing in the idle/cruise columns?</TD></TR></TABLE>

I have not. Do you think that would help?

98vtec

couldnt give you a definite answer, but it is worth a shot dont you think? You arent gonna grenade your motor or something by advancing the timing a few degrees in those particular areas. If you hear knock, simply let off the gas and take out some timing until it stops knocking. Part throttle has quite a large window for error in ignition timing as the cylinder pressure just isnt high enough to create any knock that would peak enough to cause any damage.

i would try interpolating 1750 RPM - 26" to 14" - 1250 RPM. You've made your ignition idle resolution a little higher into the RPM range than it needs to be.

what is your compression?

can you email me your bin? I'll make the changes that i would make and send it back to you. Doesnt mean what i change will fix the issue, but second opinions are always nice

blakesvtec-at-yahoo.com

Hybrid96EK

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">couldnt give you a definite answer, but it is worth a shot dont you think? You arent gonna grenade your motor or something by advancing the timing a few degrees in those particular areas. If you hear knock, simply let off the gas and take out some timing until it stops knocking. Part throttle has quite a large window for error in ignition timing as the cylinder pressure just isnt high enough to create any knock that would peak enough to cause any damage.

i would try interpolating 1750 RPM - 26" to 14" - 1250 RPM. You've made your ignition idle resolution a little higher into the RPM range than it needs to be.

what is your compression?

can you email me your bin? I'll make the changes that i would make and send it back to you. Doesnt mean what i change will fix the issue, but second opinions are always nice

blakesvtec-at-yahoo.com</TD></TR></TABLE>

Emailed you a copy of the bin. Check it out if you want. Compression is ~11.2:1. Did 176whp with the exhaust and all, 190whp without the exhaust on the dyno. Not really dyno tuned, but street tuned at this point.

98vtec

these are the changes i made:

baller status

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">You've made your ignition idle resolution a little higher into the RPM range than it needs to be.</TD></TR></TABLE>

For real. Mine goes 0, 500, 900. Idles like glass too.

nowtype

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">
You only need to add ignition timing up to a certain point. Once you get to a certain level its not gaining you anymore torque by adding more timing. </TD></TR></TABLE>

Matt, you should know better. He is not adding timing to make more power but to start the ignition event earlier so that complete combustion can occur. Combustion occurs most efficiently(ie read at the minimal timing) at 12-13:1 AFR. Anything richer or leaner requires timing advance as the burn takes longer.

Typically the trick is to run lean AFRs with advanced timing. How lean? Well, that is where it gets tricky. If you run too lean, your engine will lose enough power so that you are increasing loading on the engine to get to the same speed thus making fuel economy go down. Typically in the 15's works pretty well.

civickiller

i get 38-40 mpg with my ls on 87. timing advanced alittle and fuel subtracted.

runs perfect, did 15.0's @ 90

OEM1

For better mileage on Hondata S100/S200/S300 and Kpro cars I've always had good results when I tune the main fuel tables with the close loop on and monitor your short term fuel adjustments. The factory honda stuff works, why not use it?

shemag

If you have the time and patience, and really want good MPG, first the cylinder head needs to come off, all valves need to be inspected/ground in, then checked for leaking. Both inlet and exhaust ports need matching to their respective manifolds (just done a smart car, well missmatched) with out doing this first, all other "Tuning" is a bit of a waste, the gas needs to get in, burnt correctly, then get out again.
rog....

blundar

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OEM1 &raquo;</TD></TR><TR><TD CLASS="quote">For better mileage on Hondata S100/S200/S300 and Kpro cars I've always had good results when I tune the main fuel tables with the close loop on and monitor your short term fuel adjustments. The factory honda stuff works, why not use it?</TD></TR></TABLE>
I don't care what system you are talking about - unless you can control what lambda is targeted (i.e. have a system with a wideband O2 and semi-intelligent feedback) there is always going to be the potential for better fuel economy running the car leaner than stoich if properly tuned.

Over the past years, I have consistently seen better than stock gas mileage from approximately 10% leaner than stoich mixtures below 750mbar load coupled with 2-5 degrees extra timing advance.

inaety

How much MPG can be saved through ECU? Just a stock b16a2

imzjustplayin

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by inaety &raquo;</TD></TR><TR><TD CLASS="quote">How much MPG can be saved through ECU? Just a stock b16a2</TD></TR></TABLE>It requires a culmination of changes and once those changes are made, then the ECU is absolutely crucial but otherwise ECU tuning alone can't do very much at all. Even if you consider Lean-burn, it can't do much because lean burn only works if you've basically shut off one of the valves in order to create swirl in the mixture. With that in mind, I'd say ECU tuning alone on a car that makes 30mpg could be increased to 33mpg.