Went on the dyno this weekend...

[Kooldino]

At 14psi, I put down 250 WHP @ ~5K RPM.

I ran 94 octane.

I would have put down more, but after 5K RPM, i reach the voltage limit of the MAF and it freaks out on me.

250whp is swell and all, but what bugged me is that I couldn't make power after 5K RPM due to the fact that my MAF freaked (says my OBD - II tool) due to the fact that it reached it's maximum voltage (4.8v?).

So in short, it kinda sucks that I can't rev my car out.

I'm currently working on the problem.


Without further delay...

http://www.dynojet.com/viewer/RunViewer7.0.1.0.zip

(to view the attached dyno runs)

[Kooldino]

Run 6

[Kooldino]

7...

(goddamit...Sorry! The administrator has specified that users can only post one message every 30 seconds.)

[Kooldino]

8....

[gt40]

not bad for a liitle motor.
you'll have to get larger injectors and a recalibrated MAF.
yes it will max out at just under 5.0 volts.

what size have you got now for injectors?

[Kooldino]

right now I have 4 stock 280cc injectors
and two additional 480cc injectors before the throttle body (which only come on under boost)

I eventually want to run 8 staged injectors.

About the MAF - I'm actually just going to cap it so it doesn't ever send the MAF overload error, and from there tune my additional injectors by watching my wideband. Fun times.

[Elie]

What type of car you have?

[gt40]

quick calculations show you got enough injector for about 325hp.
the only limiting factor then is you are pinning the MAF due to air flow.
I had the same problem on mine about 5800 rpm, and data logs showed it was basically hitting the end of it's usefull calibration (about 390 hp) - I was missing the last 1500 rpm of useful range.
My only solution was to get a recalibrated MAF.

what do you mean by 'capping' it? I've never heard that term. are you referring to blocking the small opening on the sample tube?
If you do this you would really be affecting driveability (untill your computer builds up a new fuel table) and probably give you unpredictable results.

[Brian R.]

Now I understand what the "dino" in "Kooldino" refers to.

Shouldn't it be Kooldyno?

[Dilitante1]

Just overclock the MAF

[Kooldino]

Originally posted by gt40
quick calculations show you got enough injector for about 325hp.

chp or whp?

I calculated all of this like a year ago, but I don't have the equations off hand. In STOCK form, the BSFC of my motor was a .6. So be pessimistic, assume a .6 still, and use that in your calculation.

the only limiting factor then is you are pinning the MAF due to air flow.
I had the same problem on mine about 5800 rpm, and data logs showed it was basically hitting the end of it's usefull calibration (about 390 hp) - I was missing the last 1500 rpm of useful range.
My only solution was to get a recalibrated MAF.

I actually have a reclibrated MAF sitting in the garage. But then I'd have to retune my ENTIRE fuel map, instead of just the top end.

what do you mean by 'capping' it? I've never heard that term. are you referring to blocking the small opening on the sample tube?
If you do this you would really be affecting driveability (untill your computer builds up a new fuel table) and probably give you unpredictable results.

No, what I'm going to do is this:

right now:
MAF ---> ECU

after mod:

MAF ---> DEVICE ---> ECU

As you know, when the ECU sees a MAF voltage of let's say...greater than 4.9v or it freaks out and cuts all power.

IF the device gets an input of less than or equal to 4.9v, it will output the same voltage.


ELSE IF the device gets an input of GREATER than 4.9v (so 4.91v, for example), it will simply output 4.9v to the ECU so that the ECU doesn't freak.

An example of such a device would be the VC2 (http://www.splitsec.com/products/clamps.htm)

Fortunately, I may not have to buy the VC2, because supposedly my piggyback can do the same thing.

So I know what you're going to say next:

"How do you know how to tune it once it hits the limit of 4.9v?"

Well, now that the ECU is happy getting a signal from the "MAF" that's within a sane range, it continues to fire the stock injectors. If I overloaded the MAF, the ECU would freak and pull fuel (and timing?).

Luckily, I have stand alone control of my two additional 480cc injectors.

More luckily, I have a wideband O2 sensor.

So while after say...5K RPM (or whatever the RPM is at which point I'm capping the MAF), I won't know how much air is entering the motor, I can make an educated guess and add the proper amount of fuel for that with my big injectors. I'll probably try to keep my guess a bit on the rich side for safety.

Then I just do a test pull and watch my wideband. I make the necessary adjustments, wash, rinse, repeat. Until of course, I get to my target A:F ratio. Then I'm golden.

[Kooldino]

Originally posted by Brian R.
Now I understand what the "dino" in "Kooldino" refers to.

Shouldn't it be Kooldyno?

Haha, nah "Dino" is just a nickname for my real name (Dana).

[Kooldino]

Originally posted by Elie
What type of car you have?

http://forums.murc.ws/showthread.php?s=&threadid=48250&highlight=wing+mazda

[Tjalfe]

the device sounds like a zener diode

[Kooldino]

Yeah, acording to my calculation based on the forumula on http://www.rceng.com/technical.htm , I'm limited at 331hp with my current setup, assuming a BSFC of .6 (which is worse than it probably actually is at this point).