370cc injectors on stock ECU

[AceInHole]

The idea: run 370cc injectors on the stock ECU. Use a custom MAF housing to linearly change the flow/ sensor voltage curve. The idea works on laminar flow equations for fuel injection and mass air flow, so the only thing left is to apply it to 240's (I'm told Mustang owners already do this).

As promised: 370cc injectors on a stock ECU, modded MAF.

Install: the stock injectors were a pain to take out. I think I broke 2 of them (they might still be useable. I'll get another opinion on that before i try selling them tho :p). It turns out one of the 370cc injectors has a small leak, so I'll have to learn a better way to take out injectors other than pliers. Any suggestions?

The modded MAF had to be made out of flexible intake hose and duct tape. On a test run I didn't feel like spending more money on something that I might have to take out anyways, so the intake looks like this:
http://www.engr.uconn.edu/~corrales/240/modded_intake.jpg
REMEMBER THIS IS JUST FOR TESTING!! I KNOW I WILL NOT GAIN ANY PERFORMANCE, AND THIS CRAP WILL NOT LAST LONG!!!

That said, the car runs fine. There's no decrease in performance as far as I can tell. Although I haven't had the chance to take it to redline at WOT, I have done some low RPM WOT runs. Here's one of the pics:
http://www.engr.uconn.edu/~corrales/240/WOT370ccAF.jpg
That pretty much says everything. WOT, reading green on the A/F meter. Who could ask for anything more??

As far as idle, it's perfectly smooth. No fluctiation whatsoever.
I'll check back in with a redline WOT update later, but if it's reading green at WOT at low and mid RPM, i'm sure it'll be fine at high RPM.
Other than that... the only testing to be done is ON BOOST!

P.S. Shut up about the duct tape already. It works.

[sykikchimp]

HOORAY!! he finally did it! Excellent work. What size piping did you use? any plans for what material you are going to use permanatly? maybe you could get a custom intake pipe made. Did you just put the MAF element directly in the tube in the flow of the intake air?

VERY COOL. Talk about CHEAP engine management.

Are you gonna run an AFC to help adjust fuel curve as necesssary with boost?

[sykikchimp]

Shouldn't you get some Vacuum at WOT??

[AceInHole]

at WOT you ideally have no vacuum. Since the throttle plate is completely open, you're getting as much air in as the engine is sucking in. Basically, in the intake manifold you have atmospheric pressure, or 0 vacuum. This neglects vacuum due to flow velocity, but that's pretty much negligible in the intake manifold.

[AceInHole]

Update to the injectors:
I drove my car home from my uncle's garage where I did the install, and everything was working great. After being parked for about an hour, I guess my O-rings corroded or busted or something, because fuel was leaking externally from the #2 injector. After replacing that, I ended up with a really crappy idle that kept dying on me. After another hour of scratching my head and playing with the custom MAF sizing, and searching for where the smoke was coming from (yes SMOKE!!) and thinking I blew my engine, I came to the conclusion that it sounded like a dead cylinder. At this point, I pulled the plugs one at a time, the #1 plug yeilding no change in the crappy idle. Therefore, something was wrong with the #1 cylinder. Checking the spark from the wire near a ground (valve cover) showed the plug was getting power. After pulling the actual injector, I found another corroded O-ring.

What was happeneing was the fuel was leaking through the first injector, giving the other 3 injectors less fuel to work with, less fuel pressure to inject fuel with, and flooding my #1 cylinder, causing a lot of smoke, leaking through yet another leak in my exhaust piping (having a low car yeilds lots of exhaust leaks... lesson #2).

So... lesson learned? Always use new O-rings on used injectors. I'm gonna get a complete set tomorrow before testing further. I'm sure there's still more leaks as the AF gauge isn't cycling when cruising (not accelerating or decelerating) on throttle. The WOT to redline tests that I did after replacing the #1 injector O-ring showed some promise though, pulling hard and showing a barely rich reading on the A/F gauge.... but screwing with so much stuff at once is messing up my system. I'm going to need to re-make my MAF using PVC in the near future and get those O-rings, so when that happens I should get a lot more consistent results.

[DarkRaptor42]

im lost here. What are you hoping to gain in doing this. I read your posts twice and I dont get it. Is this to setup for a turbo or am I really just missing somthing. I like the idea of adapting the MAF. Is that the whole point?

[AceInHole]

Originally posted by DarkRaptor42
im lost here. What are you hoping to gain in doing this. I read your posts twice and I dont get it. Is this to setup for a turbo or am I really just missing somthing. I like the idea of adapting the MAF. Is that the whole point?

The point of this is to allow you to use larger injectors to supply more fuel without having to resort to raising fuel pressure. In a sense, the process could also allow you to control your overall A/F ratio for stock or larger injectors as well.

In my case, I'm setting up the fuel system for a turbo setup.

[sykikchimp]

Originally posted by AceInHole
The point of this is to allow you to use larger injectors to supply more fuel without having to resort to raising fuel pressure. In a sense, the process could also allow you to control your overall A/F ratio for stock or larger injectors as well.

In my case, I'm setting up the fuel system for a turbo setup.

In other words.. you wouldn't need an Aftermarket ECU to run larger injectors that could support more Airflow (like a turbo.)

CHEAP ENGINE MANAGEMENT :D :D

[240racer]

I was looking into this type of thing, I called it bypass air. My question, how did you figure out how to get 37% more air in then the MAF knew about, since that is the only real goal here, that's what the AFC does. I don't see from your picture where the extra air is going. I was just going to make a hole in the intake tube that was a certain size, but my friend and I thought that the air might not flow in there very linearly, so we were a little nervous about the system. He has been using this type of thing a little in his MKIII supra, with mixed results. For one, the way we had it setup, the extra air didn't pass through a filter.

[AceInHole]

Originally posted by 240racer
I was looking into this type of thing, I called it bypass air. My question, how did you figure out how to get 37% more air in then the MAF knew about, since that is the only real goal here, that's what the AFC does. I don't see from your picture where the extra air is going. I was just going to make a hole in the intake tube that was a certain size, but my friend and I thought that the air might not flow in there very linearly, so we were a little nervous about the system. He has been using this type of thing a little in his MKIII supra, with mixed results. For one, the way we had it setup, the extra air didn't pass through a filter.

In case people are wondering about the 37%:
370/270 = 1.37 = 137% more air... stock MAF = 100%, which is 2.5" in diameter, or 1.25" radius.
You want to use a percentage of areas, since:
air flow = Cross Sectional Area x Velocity
Thus:
Modded Air Flow = 1.37 x Stock Air Flow
Since velocity is constant, and area of the MAF = pi x r^2
(pi cancels out)
(r-mod)^2 = 1.37 x (r-stock)^2
or:
r-mod = sqrt(1.37 x (r-stock)^2)
and diameter-mod = 2 x r-mod.
All this comes out to around 2.9"

PVC piping diameter is measured by the outer diameter, so using a thick PVC pipe (schedule-80 in this case) yeilds just about a 2.9" inner diameter.

So... knowing we could use a larger pipe, all that was left was finding a way to shove the MAF sensor in there.

For the test though, I used flexi intake hose, which allowed me to cut and fit "easily". It also allowed me to compress the hose a bit using zip ties to richen the fuel mixture as I went along. The cross section view looks like this right now:
http://www.engr.uconn.edu/~corrales/240/seethruMAF.jpg
This way... the air flows through the original MAF and the outer part as well (hopefully in some close to laminar fashion...).

Later, I'll re-install the MAF into plastic PVC (which I should get today from my gf's uncle who has a bunch at a house he's renovating).

As an update to the MAF... I finally got all the o-rings in and they're not blowing up this time. Initially I was installing the injectors incorrectly... pressing them in using the screw-in caps (just twist them in by hand or with a pair of pliers so they "pop" in). The car runs fine but I get a bit of idle fluctiation when coming to a stop on occasion. If i let it go it usually just settles itself and goes to normal idle (constant).

[Foxcolt]

Kudos! Takes a lot of effort to do what you did! Fookin awesome. If you ever get a chance I'd love to see some voltage readings from the mafs. Modified vs stockie.

Jed

[AceInHole]

yeah... i'd like to see if the voltage readings at idle and WOT are actually lower than stock. Of course... I'd need someone to hook a voltmeter up to their stock MAF to have a comparison. :p

anyways... the project takes less effort than it does trust that your engine won't blow up.... it's gonna take some big balls to test it under boost though :eek:

[Kreator]

Ok i was thinking... What if i run a 1.5" pipe (area = 37% of 2.5" area) that will divide the intake before the maf and join back right after. Will it give the same result?

[uiuc240]

I realize you already have this working....but let me be a skeptic anyway. Given that air, like any fluid, will follow the path of least resistance, how do you know that the proper amounts of air are going to the proper places? This, I think, would be even MORE problematic in the situation Kreator suggests...as the air would probably just jam itself through the 2.5" portion because it would be more direct (rather than going through the 1.5" tube). But maybe not.

Why isn't there a way to just some type of resistor on the MAF so the ECU gets an airflow signal that is lower than it expects to see (thereby sending less fuel)? I'm no EE, so there's no need to flame my possible ignorance. I'm just trying to find an even easier/cleaner way to do this.

Eric

[AceInHole]

Originally posted by uiuc240
I realize you already have this working....but let me be a skeptic anyway. Given that air, like any fluid, will follow the path of least resistance, how do you know that the proper amounts of air are going to the proper places?
That's why I placed the MAF sensor inline with the 3" piping. That's also why I started with a 4" flexible hose, so that I could bring it down as needed. The real problem with this setup is the amount of turbulence in going from the 2.7" air filter inlet to the 3-4" overall MAF area and back to the 2.5" stock intake in such a short distance. When I have the PVC, the section will be longer. Then I'd be able to assume more laminar flow, where frictional losses along the pipe surface would be pretty much negligible and I could assume constant velocity anywhere through the pipe. Thus when it reaches the MAF tube, I can assume it's entering at some constant velocity equal to the air flowing around the MAF tube. In any case, providing a theoretical overall MAF size is just to give an idea of how big a pipe you should use. Some "tuning" in the MAF is given, and once I can get the car onto a dyno with a wideband O2, I can see if I need to make any adjustments.

This, I think, would be even MORE problematic in the situation Kreator suggests...as the air would probably just jam itself through the 2.5" portion because it would be more direct (rather than going through the 1.5" tube). But maybe not.
what i'd be afraid of with Kreator's suggestion is something like a venturi affect, where you have air flowing in one direction, and then air attempting to flow in another direction, causing some vacuum in the smaller pipe (some garden hose attachments for things like siding cleaner work like this, using the vacuum caused by the flowing water on the smaller feed tube perpendicular to the flow). This setup MIGHT work if you could use a Y-pipe like some twin MAF setups... but then you're taking up a bit more room, which might be a problem, or might not.

Why isn't there a way to just some type of resistor on the MAF so the ECU gets an airflow signal that is lower than it expects to see (thereby sending less fuel)? I'm no EE, so there's no need to flame my possible ignorance. I'm just trying to find an even easier/cleaner way to do this.

Eric
If you use a resistor, then the airflow/ voltage curve is changed, but you cut off the end of the voltage curve by not allowing the MAF to send a reading near or at max airflow.
Think of it this way (completely theoretical): if the MAF can send 1 - 5v, and you're cutting off 1v, then at most the MAF can send a 4v reading to the ECU. Here, the ECU tells the injectors to work at something like 60% duty cycle, and no more, since the MAF isn't reading a full 5v to tell the injectors to work any harder. At 60% duty cycle, the new injectors are working as hard as the old ones would have been at say 90% duty cycle, but you're not going to go above that 60%, so you're not getting any more fuel anyways. Basically, you have larger injectors, but you don't get any more fuel than you did before, since you're getting the same amount of air and injecting the same amount of fuel as stock at the MAF's full capacity.
To simplify things even more: the range of airflow of the MAF isn't changed using a resistor (at least, I don't think it is, if the MAF can send say 6v on a 5v scale then it works, but i don't think it can). Using a bypass, you change the airflow linearly by "adding" more air per sent voltage reading.

[uiuc240]

Originally posted by AceInHole

Think of it this way (completely theoretical): if the MAF can send 1 - 5v, and you're cutting off 1v, then at most the MAF can send a 4v reading to the ECU. Here, the ECU tells the injectors to work at something like 60% duty cycle, and no more, since the MAF isn't reading a full 5v to tell the injectors to work any harder. At 60% duty cycle, the new injectors are working as hard as the old ones would have been at say 90% duty cycle, but you're not going to go above that 60%, so you're not getting any more fuel anyways. Basically, you have larger injectors, but you don't get any more fuel than you did before, since you're getting the same amount of air and injecting the same amount of fuel as stock at the MAF's full capacity.


I'm seeing it a different way. For instance, let's say you put *more* air into the system (turbo) and the MAF now reads nearly 5v at WOT (which should get you ...... nevermind.

The more I think about it, the more right you are. Kudos.

Just seems like a weird way to do things (cheating the airflow like that). Is there no other way to do it? BTW, what MAFS are you using? That's not like any KA/SR MAFS I've seen....oh wait, I've never seen an S14 one...is that an S14 MAFS?

What happens if you use a Z32 MAFS and 370cc injectors....???

Eric

[Kreator]

Originally posted by uiuc240
I'm seeing it a different way. For instance, let's say you put *more* air into the system (turbo) and the MAF now reads nearly 5v at WOT (which should get you ...... nevermind.

The more I think about it, the more right you are. Kudos.

Just seems like a weird way to do things (cheating the airflow like that). Is there no other way to do it? BTW, what MAFS are you using? That's not like any KA/SR MAFS I've seen....oh wait, I've never seen an S14 one...is that an S14 MAFS?

What happens if you use a Z32 MAFS and 370cc injectors....???

Eric

Guessing you have to reprogram the ECU with the z32 mafs.

As for going around this, you could put some computer thing in between that would alter the reading based on your setup... but than it's again money....

ace, with the 1.5" pipe though... i don't see how what you are saying is possible with the vacuum stuff. It's all either gonna go one way when the throttle is open, or the other when it's closed.... I don't think the 2.5" pipe is going to suck air out of hte smaller one, reason being the angle would be way too sharp... On the other note, what if u ran 2 differnt pipes, to 2 different filters and only one has maf on it? and then join them before the throttle body (or turbo)? Solves the vacuum problem?

[uiuc240]

Originally posted by Kreator
Guessing you have to reprogram the ECU with the z32 mafs.



Well, I was guessing that too...but just thinking that *maybe* because the Z mafs is for the 370cc injectors (for the turbo), that perhaps by installing both (on a KA), it might work....

Eric

[sykikchimp]

The z32 MAFS produce different voltage's for different flow rates than the KA MAF, so you would indeed need a way to adjust the MAF signal..

Now what I was thinkin.. Use z32 MAF's, and an AFC along with an enlarged pipe to match whatever size injectors you use. The z32 MAF's will become necessary once you are finding the max voltage capabilities of the KA MAFS.

Only thing is, I have no idea what the AFC does with the New voltages to let the OEM ECU know what to do???.. If it takes the reading's and translates them to what the stock MAFS read, then this would work fine b/c it would only add capacity to the system.

[Kreator]

About the z32 mafs.... i was thinking... even if the voltages were relatively same and u could theoriticly make it work, wouldn't the fact that the z mafs is working with 6 injectors and we only have 4 set everythin off anyways?

[240racer]

Originally posted by Kreator
On the other note, what if u ran 2 differnt pipes, to 2 different filters and only one has maf on it? and then join them before the throttle body (or turbo)? Solves the vacuum problem?

this sounds like the most sure plan, but I think what he has is working pretty well. It's definatly nerve racking to boost without a wideband O2 sensor so you know what you are actually getting out of the tailpipe.

[AceInHole]

The original idea was to use a Cobra MAF (appx. twice as large as a stock KA MAF) with 50lb injectors (appx twice as large as stock KA injectors). The person I was talking to when I was thinking about the plan has that setup with a JWT ECU and also has a stock ECU lying around. The only problem would be that the flow/ voltage rate is non-linear, and is different for every MAF (as someone has already stated). The bright idea here was to use the stock MAF and change that linearly by resizing it. You keep the same curve, but over a larger range.

As for the y-pipe with dual filters, one having a MAF.... it would work. Single turbo conversions on twin turbo cars (rb26dett) sometimes use setups like that... although both sides have MAFs. Take away one of the MAFs and it should work the same for a single MAF car. The point of what I was saying about the 1.5" pipe extension off the side was that it'd cause turbulence (especially through the case I tried to describe). Turbulence through the MAF is bad... since the MAF won't be able to get an accurate reading.

What an AFC does is it allows you to change the MAF's voltage by some percent (50% to 150% for the Apexi SAFC) at different points along the curve. This allows you to adapt the curve of a specific MAF to whatever injectors or fuel setup you are using.

[240racer]

My friend tried to do this on his '91 talon by putting the larger 2g MAF and larger 550cc/min inj. (they get 440's stock, jerks) they worked out to be only 10% different I think, but he still had problems with his idle and stuff. I think things go downhill rapidly when you change mafs. That's why I like you're idea best for the budget method. Also, keep in mind that you want the MAF a little ways away from the turbo so you don't get turbulance there either. That would be one problem with the seperate bypass tube, it would most likely come back in close to the turbo and screw stuff up. This of course is after you go turbo. BTW, what turbo are you planning on running?

[AceInHole]

Originally posted by 240racer
Also, keep in mind that you want the MAF a little ways away from the turbo so you don't get turbulance there either. That would be one problem with the seperate bypass tube, it would most likely come back in close to the turbo and screw stuff up.
I'm aware of the distance needed between the turbo and the MAF. I already got an 8" long peice of 3" PVC (schedule-40) to re-make the MAF, so that I can also plumb the other intake lines in between the MAF and turbo. That 8" section will be connected to the turbo using intake flexi-piping.

This of course is after you go turbo. BTW, what turbo are you planning on running?
I've got a TD05 off of Volvo. I'm pretty sure it's just a larger trim TD05 than the ones used on some DSM's. The engine it was used on originally was 2.3L and ran 7.7psi (at least from what I've deduced from the Volvo performance sites). One site described it as being close to a T3/4 hybrid. Hopefully things will work out.