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Discussion Starter #1
Ok guys...should be here at the end of the week...we'll see what happens....

Nader dynoed on a wideband...ran perfectly till about 5000rpm, at about 14:1 and then went FULL rich up to 7500rpm, at some points down to about 12.1 or so

So go figure, all this talk about me needing AT LEAST 24lb....

Weird, but hey, thats what happened, so im going with that, once installed, im hitting the dyno with wideband and tuning the fuel with either an apex or the mafafterburner

NO CHIP TUNING FOR ME...sorry, i dont believe in that **** yet...(not including REAL custom chips obveously)
 

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Err... this setup got to 14:1 at 5000rpm and that's good?
 

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Originally posted by P-51:
Err... this setup got to 14:1 at 5000rpm and that's good?
<font size="2" face="Verdana, Arial">Our experience has shown that 13.9:1-14.2:1 A/F on a naturally aspirated car yields the best power numbers. We hooked up one of the Pro-M fuel caliberators and leaned down the mix just a hair and gained 3-4 hp and the equivalent torque up top.
 

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Discussion Starter #4
Originally posted by P-51:
Err... this setup got to 14:1 at 5000rpm and that's good?
<font size="2" face="Verdana, Arial">P51.....up to about 4500-5000 rpm...it was a constant 13.9-14.1 then it went rich up to 7500rpm

Why is this bad????? I do remember that on a NA car 13.5-14.0 is best for power, and i think its PLENTY to run safely....

But the weird thing is that it stayed good on the lowend, and then dipped rich....kinda weird, and DEFIES ALL THE MATH that everyone has done as far as what injectors will support what power...

It was stated IMPOSSIBLE to suppoer 170whp with 20lb injectors...but look at the results, its actually RICH>.....WTF is going on??
 

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Is that 14:1 A/F reading through the cats or without them?

We don't like to see anything richer than 13.7 for a naturally aspirated engine that is going to see more than 1/4 mile at a time full throttle. We like 13.4 as a nice target for our road race Focus.
 

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Discussion Starter #6
no cats...\

and i think you mean you dont like to run LEANER than 13.7?????

Yeas, i would like to have mid 13's on the topend, but is it bad to run 14.0 under 5000rpm? Its not as crucial there is it to have the extra fuel? It does make for much nicer torque leaner down low
 

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Yes, we don't want to run leaner than 13.7. My bad.

Sorry if this is basic, but I'll review quickly.

The theoretically correct chemical mixture of air to fuel (stoichiometric [spelling?]) is not what you want for optimum power, because the fuel never mixes perfectly with all of the air. What you do is run a little extra fuel to make sure that you have enough fuel to burn all of the oxygen that is present. How much extra fuel depends somewhat on how well the fuel is mixed with the air. The big car manufacturers are working on high swirl combustion chambers to mix the fuel better so they can run leaner and cleaner. They want as little unburned fuel in the exhaust as possible for emissions reasons. For us trying to make horsepower, we are more concerned with making sure we burn all the air in the combustion chamber, so we add a little fuel to make sure all of the air is used.

Adding increasingly more fuel cools the combustion chamber. (So will running extremely lean.) We want to add enough fuel to make sure all the fuel is burned and cool the chamber enough to avoid detonation, without adding so much fuel that we cool the combustion process enough to decrease power. For a typical naturally aspirated engine, A/F ratios in the low 13's work good. For typical low/moderate boost super/turbo-charged engines A/F ratios in the mid/high 12's are good.

[ 10-18-2002, 08:01 AM: Message edited by: techguy ]
 

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Originally posted by nazthug:

Yeas, i would like to have mid 13's on the topend, but is it bad to run 14.0 under 5000rpm? Its not as crucial there is it to have the extra fuel? It does make for much nicer torque leaner down low
<font size="2" face="Verdana, Arial">You will probably get the most power at a slightly leaner setting than is “safe” for the street. The Dynojet inertia dyno doesn’t load the engine as heavily as a 4th gear pull on the street. You might be OK at 14.0 below 5,000 rpm just because you aren't making enough power yet to create the heat to start detonation. It will depend on the timing curve and the shape of the combustion chamber, among other things. I’m not the expert on this. You might want to get some more opinions from the engine gurus out there.

A related side story:
When you fly small airplanes you have to adjust the fuel mixture to match the air density of the altitude you are flying at. You do this by reading the exhaust temperature off the EGT gauge and turning a knob on the dash that controls the mixture. First you turn the knob until you get the hottest possible EGT reading. Then if you want the best POWER, you turn the knob to richen the mixture until the EGT is 75 degrees colder (richer) than peak temperature. This makes sure all of the AIR is burned. If you want the best FUEL ECONOMY, you turn the knob the other way, to lean the mixture until the EGT is 25 degrees colder (leaner) than peak temperature. This makes sure all of the FUEL is burned.
 

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Techguy, you're an asset to Steeda! You might even be able to defend Steeda's honor on Corner-Carvers.com


Naz, I think in the 14's is a little lean. I would be aiming for 13.5:1 if I were you. Sure, leaning out for maximum power will make you a hero on the dyno, but on the track, you're going to be a zero.


I don't think the engine will take that for extended periods of time. If you ever go lapping, once the engine gets hot, you're too close to the ragged edge of detonation to be safe.

Sure, you'll make the best power like that... but not for long.
 

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Discussion Starter #10
is it as bad to run a bit leaner down low as it is up high?

For example, i will be shooting for 13.5 on the top end, but can i go a bit leaner down low for mor torque, say 14.0???

Or is it just as dangerous to go leaner down low as it is up high?

Im gonna be strapin on to the dyno/wideband with a mafterburner soon and tuning it to perfection, i really like that product.

Then it will be time to SOMEHOW add some timing, i wish it were easier than with a chip, cause those things are a headache
 

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It's probably worse down low than up top!

At lower rpm, you will have more cylinder fill, higher peak cylinder pressures, etc... The point which is one of the most prone to detonation is the point of peak torque.

That is the point of peak cylinder fill, peak cylinder pressure.

Above that RPM, not only are the cylinders filling less, but there is less time for the precursors of detonation to form.
 

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Correct me if I'm wrong, but peak torque occurs when peak cylinder pressure occurs. Detonation at peak torque will be just as destructive as detonation at peak power.
 
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What type of wide band are you using? If you are using the DynoJet attachment that sticks in the tailpipe, then it is about 1/2 a point off - leaner. If you are getting readings of 14:1, then you are actually 13.5 - 13.6
 

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Techguy: Yes, peak torque is at the point of peak cylinder pressure.

Detonation at that point, or any other point is destructive. But detonation at that point is more LIKELY to occur, because the cylinder fill is greater, thus more pressure, hotter combustion, etc...

Fastrax: Not having seen the Dynojet system, how far in the exhaust pipe does it go? Doesn't the amount of oxygen contamination get reduced as you stick the probe further up the pipe? After a foot or so, I'd figure there is no more contamination for the ambient air. Doesn't that probe go up the pipe? Or just clip to the rim?
 

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Discussion Starter #15
Originally posted by FastraxTurbo:
What type of wide band are you using? If you are using the DynoJet attachment that sticks in the tailpipe, then it is about 1/2 a point off - leaner. If you are getting readings of 14:1, then you are actually 13.5 - 13.6
<font size="2" face="Verdana, Arial">REALLY?

Damn, i never even knew...

Its gonna be on a wideband on a dynojet, going in the exhuast pippe

I can also use a MOTEC that actually replaces the 02 sensor, but you cant datalog it, just read it as it appears...so i guess i can just check it as long as it stays below 1, we know its richer than 14.7

But i like the datalog of the regular widebands on the dynoes, because you can look at the graph and tune accordingly you know?

So will it help to stick it farther in jon or what? So what should i tune for on a dynojet where it just goes in the tailpipe? ANd should i stick it in farther?

Im gonna get either the mafterburner or the APEXi afc to do the tuning, although i like the mafterburner software, it seems a bit easier, has 2 settings for OPEN LOOP and CLOSED LOOP

Unless you think the apex would work better...

Im gonna be swapping out cams first, going with something a bit bigger, but still as good on the torque and down low, CUSTOM SPECS, so like tom, i wont be saying what they will be
, but after some testing, we found a pretty nice combo for 170whp+ under 7000rpm and still a flat torque curve from 3000 rpm on, with peaks in the 150ft/lb+
 
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