Hacked MAF???

[WDRacing]

OK, I know I'm already a certified genious....heh, but I'm not familiar with the term hacked MAF. I know it obviously has somthing to do with altering your MAF housing or signal. I would just like to know exactly what is involved and what you expect from doing the alteration. Thanks...

WD

[MaxType 240]

Here's the theory posted by Brian (aka Orion):

"Your MAF sensor assumes a certain cross-sectional area of the tube it's in, which on an S14 is about 2.5" ID.

If you change that area, it's reads incorrectly by the % change.

So make the cross sectional area 37% bigger (about 2.9" ID) and increase the injector size by the same amount (go from stock 270cc to 370cc = ~37% increase) and it even itself out (kinda).

In a nutshell: You put ~37% more fuel in the motor, and sneak ~37% more air past the MAF sensor, and things are once again in check, and your computer is none-the-wiser."

I'm a fellow Fresh Alloy member but I've noticed the technical discussions getting better here. Considering you're die-hard on building a super KA, check out some stories here:

400HP KAs

Read through the pescky SR young ones & you'll find info from highly revered pioneers like TY, Jay, others. There's a ton of wealth there & it's always good to forum hop to see what's the latest. Run a search for KA turbo & watch out...

Jesse

[WDRacing]

OK, thats what I was thinking. There's a really easy way to do this without destroying your MAF sensor. Guys have been doing it for years. Its also alot easier to tune with.

You simply add a small intake pipe after the MAF sensor with a filter on it. Does the same damn thing. Plus you can alter the size of the hole you make. Just make the hole a little bigger each time until you get your idle stable.

Oh and the SR boys don't worry me......

[:: orion ::]

Jesse -

Thanks for posting that...

WDRacing -

The only issues I see (after much debate on FA) are:

1) The amount of air that would pass through the filter on the bypass tube*could* vary if the filter was dirty

2) How can you gaurantee (or approximate) that the size of the bypass you use will be appropriate for the injector size...i.e. how do you calculate it?

With a hacked MAF, it's easy b/c you increase the cross sectional are as described and your very close to an exact compensation. That, and all the air comes from the same source, so no variation.

Later - Brian

[:: orion ::]

Here's a picture of mine...not pretty, but very functional:



I used exhaust tubing, 2.875" ID, which is .05" smaller than the theoretical *ideal* pipe inner diameter.

I'm gonna fab a new one soon, with a welded box to house the element just to make it look better.

Later - Brian

[WDRacing]

Well, this is how I would do it. Since I'm a seat of the pants tuner and don't mind blowing up a few motors in the namesake of cheap hp. I always use an AF meter and a accurate knock sensor to assist me in all my tuning. So I would install some new injectors, we'll go with 370cc's for now. Then I'll drill a hole in the air pipe aft of the MAF. I'll start with a 1/2 hole. Fire up the car, watch for knock and af while I take her for a full boost sprint up the block. Then I'll either increase or decrease the size of the whole. After finding the right size, I tig or JB weld a tube there an fasten on a nice valve cover air filter. Bam.....all done. Probably take me 2 hours. Another huge bonus for people like me is the NO math thing...lol. Where are you located Bri??

WD

[GatorS14]

hey brian,do you still meet up thursday nights over on archer road?I might show up tonight.I came out there a while back.I had the black S14 w/the red &black advans.Nice to see you're boostin'(I like them dyno numbers!)

[:: orion ::]

Where are you located Bri???

Gainesville, FL

And while I'm a fan of seat of the pants tuning, the fact still remains that you couldn;t be 100% sure that the bypass would always pull the same amount of air...

i.e. say you set up a bypass tube and the A/Fs look good. Then you clean your air filter, and the path of least resistance for the incoming air is now more through the filter - You run really rich. Or quite the opposite, you install and tune, but over a few months your filter gets dirty - The path of least resistance is now more through the bypass - say it gave 37% more air before, but with a dirty filter you get 45% more through there b/c it's easier to pull air from the bypass = too lean and blown motor.

Only way this could work IMO is if you used a bigass filter with a oval mounting plate and plumbed the bypass back into that - So the air had to come through the same filter no matter which path it took, and there would be MUCH less deviation/variation.

Anyway, that's my take. We've debated this a bunch and the only way anyone has decided it's safe to run a bypass is if you run a Y pipe with two MAF sensors - One plugged in, one not. Then use injectors twice as big. Install new filters at the same time, and clean regulary to insure the split is even.

Later - Brian

[:: orion ::]

hey brian,do you still meet up thursday nights over on archer road? I might show up tonight...

Cool...I'm there every Thursday to run the meeting.

And now I'm running an intercooler and 8psi - It's MUCH faster.

Later

[gogeeta13]

The bigger question becomes, what exactly is changing on the MAF signal wires back to the ecu. It seems with a simple stamp circuit or serial laptop we should be able to emulate or modulate the MAFs output signal.

[AceInhole]

The bigger question becomes, what exactly is changing on the MAF signal wires back to the ecu. It seems with a simple stamp circuit or serial laptop we should be able to emulate or modulate the MAFs output signal.

people do it all the time with piggyback controllers. Apexi makes a good one called the S-AFC II.

Quote » We've debated this a bunch and the only way anyone has decided it's safe to run a bypass is if you run a Y pipe with two MAF sensors - One plugged in, one not.[/quote]Just because a name brand tunder does that (forgot which, actually) doesn't meanit's the best. Isn't that only because the car (Skyline??) has two MAFS on it, and its for a single turbo conversion???I keep thinking about the "what ifs", like what if there's turbulence in the Y section that causes uneven flow through the MAFS? What if one filter is placed in a "better" position to take in air, giving the disadvantaged filter slightly less air to flow through?? STuff like that......

Anyways, I think it's fairly safe to say the way that we did it (hacking the original MAF) is a safe bet, as it's been working thus far and through a lot of boost and abuse.

[:: orion ::]

Yeah...I picked up a spare (wrecked) S14 yesteday, and will put the motor in my car before August (don't like the piston slap I'm getting now), so I flogged the HELL out of my car last night to se how the hacked MAF liked 8psi - Several 20-120mph and 30-140mph rolls next to an EVO VIII - He won the first one (got the jump) and I was about a car length ahead at ~140 (5800 in 5th gear) for the second good race. And then a bunch of other playing around - Car took a beating an liked it!!!

I fell more comfortable endorsing the hacked MAF now that I have REALLY put it through it's paces...I had auto-xed with it 3-4 times already, and some drag racing, but no real long, extended pulls or abuse.

Later - Brian

[slw240sx]

correct me if im wrong im new to all the inovations and progress you guys are making with the KA -ts but isnt the hacked maf, just like a Z32 maf? i mean for all that hassle wouldnt it just be easier to get the SAFc you guys are using them right? and just program in a z32maf and tune for bigger inejctors? please inform me !

[:: orion ::]

No...

Z32 MAF is used on an SR typically as an upgrade b/c the stock MAF is tiny and runs out of voltage somewhere...so your HP is limited by the MAF.

The reason to use the KA MAF in a bigger tube is that it compensates for bigger injectors WITHOUT the need for an AFC or ECU upgrade.

If you stock injectors, you could make 200rwhp on a KA. With 370s, you can make about 260-275rwhp...but you can't just drop 'em in. Most the time people just upgrade thier ECU or tune the airflow via an AFC - This makes it so you don't have to do that...it's a $100 fuel upgrade - Buy the injectors, hack the MAF, and you're set.

And before someone asks...NO, you can't just swap a 3" Z32 MAF onto a KA and use 370cc injectors and have it work out perfectly b/c the Z32 MAF has a different voltage curve than the KA MAF, making them NOT interchangable.

Later - Brian

[silviaNE]

You should by a few mafs and build some hacked mafs to sell. I bet if you made a nice mount for the maf to pipe, you could sell them.

[:: orion ::]

I'm working on making a nice looking 'case' for the S14 MAF internals - basically just a 3" exhaust pipe with a 3" square mount on the top where you could just drop in you S14 MAF internals (the sensor) with a little epoxy and be done.

If it's not to time consuming I may make a few and sell 'em...we'll see.

Later - Brian

[silviaNE]

let me know, sounds good.

[WDRacing]

Actually, I was thinking the same thing. Sell some nice MAFS along with the turbine kits. I'll have to use somthing a tad bit better then electrical tape though....heh.

WD

[silviaNE]

hey WD, all great minds think alike.

[AceInhole]

hmm... i don't think mine looks too bad. just a lot of JB Weld

[:: orion ::]

Yeah...the tape was a necessity b/c the setup was initially a blow thru MAF, and it leaked heavily even with LOTS of epoxy.

And now, I don't really care how it looks, but someday it will be much nicer.

Later

[slw240sx]

cool, thanks for explaining that too me it made much more sense ! ill continue to read up on this and absorb as much info as possible , i may soon build a Kadet

[I am Technoman]

I like the KA because its just a nasty a$$ torgue beast!And I think in the near future the KA will hit 700WHP!

[zeardux]

what about a sohc s13 mafs, is it possiablr to hack this one considering its a pull thru type? because if so then im going to try it when i go turbo

[:: orion ::]

No one has hacked a S13 MAF - The SOHC and DOHC are similar in design/function, but not identical to an S14 MAF.

It could be done I'd guess, but it would take more work, and trial and error to find out the right size tube to use...

Later - Brian

[Flamereka]

So all I do is get a 3" pipe diameter drill a hole in it and mount the stock S14 maf on the pipe then I can drop in the 370cc injectors and it will compensate for the additional fuel?

thanks in advance

[:: orion ::]

Yes, and you'll be the third to try it.

If it works for you, great.

Mine is perfect...AceInHole had to change the pipe diameter (smaller) to get a proper A/F ratio.

And you need to make sure the pipe ID isn't more than 2.9" - Most 3" exhaust tubing is 2.875" ID, and that works out quite nicely...

But this is untested - Proceed at your own risk - And know that AceInHole and I have had other issues that blew our original KAs...seriously doubt it had anything to do with the Hacked MAF, but...???

Late - Brian

[TomsMR2]

couldnt you use a smaller than ideal pipe for the hack, and lower fuel pressure accordingly? seems safer, as initially you'd be running rich. id imagine you can turn down the fuel pressure a few psi's safely if needed.

[detforme]

you have to increase it by a cross sectional are ie. pi*r^2. otherwise yoour sneaking a lot more aair through, it will result in a lean condition.

[TrunkMonkey]

No one has hacked a S13 MAF - The SOHC and DOHC are similar in design/function, but not identical to an S14 MAF.

It could be done I'd guess, but it would take more work, and trial and error to find out the right size tube to use...

Later - Brian

silly question...are the s13 and s14 DOHC mafs the same?

-demetrius