MAF question for the blower guys

[trueSHO]

I plan on running 9psi, 12 at the very most with my S-trim, I'm wondering which would be a better MAF to go with... The Lightning 80mm or 90mm? I can just make a junkyard run and pull one off a lightning or find one on ebay, correct? Also, am i correct in saying I need a harness from another car, (obd-II???) which cars can I find the harness?

 

[yamahaSHO]

The Lightning 80mm MAF is all you will need. You're most likely not going to find one in the junk yard. If you want to get one for $50-$70 shipped, make a "WTB" ad at www.nloc.net.

You will need to pull an OBD-II MAF harness, cut the old SHO/OBD-I out, and solder the new one in. I suggest lengthening the harness a few inches at a minimum.

 

[trueSHO]

Thanks Jason, where can I find an OBD-II harness, any specific vehicles?

 

[yamahaSHO]

You should be able to find one in the junk yard off of a Ford 96+ vehicle.

When soldering in place, the wires are a straight though design, the colors will match up. If you look closely, the power and ground wires are thicker on your SHO connector. I followed this accordingly when I lengthened my wires.


BTW, the MAF you are looking for is an 80mm from a 99-00 Lightning.

 

[trueSHO]

perfect, just the info I was looking for, thanks again

 

[SHO Dude]

The Lightning 80mm MAF is all you will need. You're most likely not going to find one in the junk yard. If you want to get one for $50-$70 shipped, make a "WTB" ad at www.nloc.net.

You will need to pull an OBD-II MAF harness, cut the old SHO/OBD-I out, and solder the new one in. I suggest lengthening the harness a few inches at a minimum.

My car put 325hp on the ground with a max of 8.6psi. I'm running a 80mm Lightning MAF. It peged at about 6900rpm. I'll be switching to the 90mm Lightning unit before I make the next pull. There's a good 300rpm more power there with enough MAF resolution.

Go with at least a 90mm Lightning unit and 42lb injectors...and the right tuning.

 

[yamahaSHO]

I could not peg the MAF on 12-13 PSI at 900 ft altitude at 75 degrees and 381whp. As far as injectors, I'd go with a minimum of 44lbs.

 

[Sh03d]

Another question, Why are some of you guys running your MAF on the sucking side and some are running on the blowing side? Personal preference?

 

[yamahaSHO]

The MAF will meter air better on the vacuum side of the blower vs after the blower (blow-through). I was running mine before the blower (as was Terry) but neither of us could tune out the rich condition under engine deceleration. In fact, coasting down hills in gear would actually cause the computer to stop learning KAM values.

Now that Terry and I have our MAF's on the blow-through side, the car will lean out when off the throttle but bucks under engine deceleration and idle. I've taken a break from this crap.

 

[SHOMurph]

The MAF will meter air better on the vacuum side of the blower vs after the blower (blow-through). I was running mine before the blower (as was Terry) but neither of us could tune out the rich condition under engine deceleration. In fact, coasting down hills in gear would actually cause the computer to stop learning KAM values.

Now that Terry and I have our MAF's on the blow-through side, the car will lean out when off the throttle but bucks under engine deceleration and idle. I've taken a break from this crap.

so Jason you are finding that the cars will run better with the MAF after the blower?

Tony and I are about to start planning my rebuild and was curious.

 

[twr]

Murph,

My car was ******* the WBO2 under decel above 3k rpm. I tried a slew of different tips and tricks get rid of it to no avail.

 

[SHOMurph]

Murph,

My car was ******* the WBO2 under decel above 3k rpm. I tried a slew of different tips and tricks get rid of it to no avail.

hmmm I might have to try to place the MAF after the intercooler post blower/pre throttle body.

 

[yamahaSHO]

Actually, the car runs better with the MAF before the blower. The only thing is the SHO Shop piping is so large and the BOV is so poorly placed that boosted air pressurizes in the piping and oscillates causing an oscillating rich condition under engine deceleration.

The tune does not stay as consistent with normal and WOT driving with the MAF after the blower. I've thought about moving the MAF back before the blower and try to figure another way out to cut fuel when I'm off the throttle.

 

[SHOMurph]

Actually, the car runs better with the MAF before the blower. The only thing is the SHO Shop piping is so large and the BOV is so poorly placed that boosted air pressurizes in the piping and oscillates causing an oscillating rich condition under engine deceleration.

The tune does not stay as consistent with normal and WOT driving with the MAF after the blower. I've thought about moving the MAF back before the blower and try to figure another way out to cut fuel when I'm off the throttle.

Should the BOV be placed closer to the throttle body?

just playing devil's advocate.

 

[yamahaSHO]

Having the BOV near the TB would be optimal. A larger BOV or a larger ****** (the SHO Shop ****** has a smaller opening than the BOV) would also help. With the MAF before the blower, you'll also have to vent all the air from the BOV back into the intake just before the blower. Best results would be to angle the air towards the blower.

I've thought of doing all this but just ran out of time and energy. I have the MAF in the SS location just for that reason. There will probably be some trial and error and the piping may still prove to be a little too large.

 

[Toolman]

FWIW, I vent all my air into the atmosphere with pre-turbo MAF. No real problems. And that was with the old LPM. I really think this Tweecer thing will be da BOMB! I am very happy with the results so far. I have yet to datalog a session, but after two tries the WOT and part throttle WB's are quite nice, and I can actually begin to remember what the car was like. Also, having the BOV vent to atmosphere sounds SOOO cool!

 

[yamahaSHO]

Venting the BOV to atmoshphere with the MAF pre-blower is easier to do with a turbo. Once you close the TB, your turbo is not getting flow on the exhaust side causing the intake impeller to slow down. A supercharger is a different story, when you're trying to keep the motor in it's powerband and keeping it at a high RPM, a supercharger is still spinning VERY fast.

In short, the turbo stops forcing in air where the supercharger is still trying to (because it is mechanically driven by the motor), therefore you're pulling air past the MAF still. You'd think the computer would see that the TB is closed and cut the fuel, but that's not the case.

 

[Toolman]

Yeah, which is why you should ditch the Vortech and get a TURBO!!! YEE HAW! j/k, but not really

 

[SHOMurph]

Yeah, which is why you should ditch the Vortech and get a TURBO!!! YEE HAW! j/k, but not really

Its called SUPER....for a reason!

 

[Axianator]

When discussing MAF placement issues on a forced induction setup, one must remember that a blow-through MAF should not be used in place of a draw-through MAF (or vice-versa). Doing so could result in driveability problems like the ones that Jason, Terry and others have experienced (barring the BOV placement and over-pressurization problems that Jason already mentioned).

FWIW, I will likely run a draw-through Lightning 80mm MAF with my shaft-driven blower setup.