guitarjunkie28

dynojet

it was about 8 degrees warmer today, but that won't be a big difference.

ranger4277

Somebody get this man a laptop! I'd donate one if I had a spare.

Snoochie

Anyone in the area wanting to help us out and lending us a laptop would be more than appreciated. I'll buy some beers and lunch if one of you comes out. If not I just gotta go buy one which is less money towards my car so it's up to you guys hehe.

guitarjunkie28

well, after much thought, i've found the perfect way to eat up all that extra gas...

what we've got here is a t66...guranteed to eat any quantity of fuel you can throw at it!!!

guitarjunkie28

long tube manifold, a big hole in the hood, DI-rect ram air intake (you'll need it to spool that thing). we won't measure at what rpm the turbo spools, rather what vehicle speed. full boost by 90 mph...LMAO

it'll be like a ram jet effect :p

the sick thing is i'm debating on whether or not to put that monstrosity on my fd...it'll either be that or a gt 35/40r.

Ajax

Hehe.. I think that's a little bit overkill at this point, lol.

Map wise, how does the T66 compare to a GT35? Anyone got the compressor maps?

Ajax

RX8-TX

First of all: I don kno nuttin'!

Then, let me throw this out there:

1. You increased flow on the intake side.
2. You increased flow on the exhaust side.
3. At increased flow, you'd expect more air to flow through the motor, which is fine.
a. Did the porting really increased flow? would be my first question.
b. If it did, why in the heck is the ECU overcompensating so much? if it gets its feedback from the WO2 sensor while in open loop, it should still be shooting for what the stock maps indicate (unless, the stock maps have a data table with preset injector duty cycles for a given MAF...but that would make it go leaner, so discard the last sentence!) -Is the WO2 sensor functioning correctly?
c. If the MAF sees extra air going through, it'll 'suggest' extra fuel be dumped as well. Could turbulence on the intake (or things alike) be responsible for the rich condition?

Just throwing some things out there.
Oh, yeah! Did I remember to say, I don kno nuttin'?

Having said all that, you are not that far from my a/f. Just a whole point :D

guitarjunkie28

well it doesn't even look at the o2 sensor when it's in open loop. you could take it out and **** on it and the computer wouldn't care.

i may or may not be correct on this, but here's what i'm thinking--

the MAF sensor is calibrated to have a particular amount of resistance @ a particular amount of airflow. i don't know if this motor/computer/maf setup was ever tested with airflow this high from the factory, so maybe it's some kind of fail-safe...run pig-rich when it sees extra airflow?

OR

i've heard of maf voltage on a stock motor being somewhere around 4.5-4.6 volts...that's already close to the top of a 5 volt reference...

take your shitty boom box and turn it up to 5. sounds ok, right?
turn it to 7 or 8... starting to break up right?
ok, now turn that thing to 11. what does your music sound like? the spice girls start to sound like ozzy and rob zombie on crack.
so i think it may be possible that we just reached that top area-where things start to get garbled.

so why don't turbo cars do this--after all, they go through more air than an n/a car.
good question--but they've all been tuned.
i'd like to see someone run 1-3 psi through a stock computer to try to duplicate the kind of extra airflow we're getting from the porting and see what the computer does.

at this point, i could actually unplug 2 of the injectors and probably still be too rich.

so someone bring a laptop and we'll tune this thing. snoochie's buyin' the beer :D

Ajax

Mass airflow sensors output a voltage proportional to the amount of airflow passing through it. Whether or not it increases or decreases dependent on airflow would be dependent on the wiring. Differences in MAF sensors could account for a lot of the differences in stock cars.

From looking at MAF sensors for chemical operations, it looks like the increase in voltage with airflow, but again, that's dependent on the sensor itself. The operation range and tolerance is what we're going to be looking at as I bet the MAF sensor won't output more than a certain voltage and we'll definitely see Hysteresis.

RX8-TX

My bad....your are absolutely right!

RX8-TX

The MAF is an exposed wire, which is conducting a certain current. The electrical current is producing heat. When air flows past it, it cools it down. Then the ECU adusts the current to maintain the MAF at a certain temperature. The current difference, I believe, is what is being measured -and used to determine airflow.

guitarjunkie28

i'm wondering if the new velocity of the air is cooling the wire too much--throwing off the reading.

RX8-TX

Like you said, going outside of its operating range? But then, what about TC'd cars? The MAF doesn't see the additional air going in? -like I said: I don kno nuttin '

BTW, if the operating range of the MAF is exceeded, no level of tuning is going to solve it.

guitarjunkie28

if the operating range is exceeded, it'll be easier to tune. you'd have constant voltage, so all you'd have to do is tune based off of rpm...piece of cake

it when you're getting near the edge that's hard. but then again, we could be wrong on all of this.

Ajax

I doubt it's reading current but probably reading voltage over a known resistor. It makes little logical sense to read current. It's not exactly a wire either. It's a film of some kind strapped to a single or dual whetstone bridge acting as a variable resistor across which voltage is read.
Different voltages are mapped to different amounts of airflow.

RX8-TX

I just know that to generate heat through a resistor, you have to have a closed circuit. In a closed circuit you could read either the Voltage differential between 2 ends of a resistor, or the current circulating through it. You have a fixed variable (R), the MAF's wire (film or conductor..doesn't make a difference for this purpose). And yes, you would have to vary voltage in order to alter the current, thus varying power consumption, thus varying heat generation.

Now, consider what happens is the resistance of the 'film' is so minimal that the voltage drop between the 2 extremes is minimal as well. Again, you could be right, I just DNN.

Edit: you are most likely right...
http://www.allfordmustangs.com/Detailed/583.shtml :o

guitarjunkie28

all the hot wire maf sensors i've heard of bsically heat a coil or small element-which has calibrated resistance depending on the temperature of the thing.
the more air that psses by, the cooler it gets, the less resistance it has.

so the computer either reads the amount of voltage, or the amount of current needed to keep the voltage.

anyone know if this is a current or voltage based reading on the rx8?

Ajax

Voltage and always voltage.

Almost every electrical system reads voltage. Current = dangerous. Quantifying current by using voltage = safe.

guitarjunkie28

i think some fords use a current type, but i'd have to double check.

Ajax

They all develop current, but they should output voltage. I don't see any reason output current. That's just silly. 90ma will kill a human being, whereas 10,000 volts wont even make you twitch if the current is low enough.

RX8-TX

For some reason, I am pretty sure that there are certain sensors and microcontrolers that indeed use current input & output signals. I guess it all depends on the application -motor brake control and some other industrial related things come to mind.

That's playing with the definition. A 10,000 volt differential between 2 points will do nothing at all if the circuit resistance is high enough to warrant an open circuit. The moment you have current circulating, you've closed the circuit, and you are in fact toasted.

But, the higher the power differential, the more prone electrons are to jump from one place to the other, so you would REALLY have to be insulated to prevent your body from closing the circuit.

Oh, wait! this isn't Richard's thread. GuitarJunkie, sorry to hijack. Thought you needed more pages! :o

Ajax

There definitely are devices that work on current IO signals, but most logic devices work off of voltage where some threshold voltage is set to be high and interpretted as a logical 1.

Anyway, it has to do with sensitivity.

Since even 1 amp is dangerous, you need to use a smaller value. So you'd say milli or even micro-amps, but then you're talking about extremely high resolution on your device just for safety, whereas with voltage, you can use larger scales like 1.65, 3.3, 5 and so on for your thresholds. The difference between .00001 and .00002 is a lot smaller than the difference between 3.3 and 3.4 and therefore a lot more expensive to implement.

guitarjunkie28

richard is snoochie, i'm dave

cretinx

GT3540R on my RX-7 spooled up too fast! Full boost by 3000 rpm.

We've got about 1500 more rpm in the powerband to play with
Get the GT42R, you'll see full boost by 4000 and it won't matter cuz you'll have another 5500 to play with.