Knife-edged Maf Foil

BlackJack · 05-22-2005, 10:04 PM

Today I got bored and decided to pull the MAF, punch the screen and see how much better the flow was. While I was in there, I decided to whip out the old file set and knife-edge the foil, match port both halves of the MAF since there was one hell of a ridge where the halves met, and otherwise polish out the inside from all the rough spots and irregularities in the surfaces.

At the same time, I decided to add in the 180 t-stat I've been staring at for the last week, and also put in the Water Wetter since the coolant was getting flushed anyhow.

Temp needle used to ride about 1/8 inch above the centerline on the factory gauge, now it rides 1/8 inch below after giving it a good solid half hour riding around to be sure.

I honestly have to say, I can feel a slight bit more pull on acceleration. Not to a great degree, but just enough to make it feel it was worth just that little bit of effort.

The MAF foil was actually very blunt before I started, so I can see how it actually gave just a hair better flow by running a knife-edge.

jabartram · 05-23-2005, 12:24 AM

the cooler engine temp gives the little extra pull. and the screen in the MAF is actually designed to straighten the airflow past the MAF.

BlackJack · 05-23-2005, 01:26 AM

good point, but I've heard both sides....that the screen restricts the flow just a little on the one hand, and on the other, it helps stabilize the flow for the sensors on the other hand. I dont know, I got a little more pull out of it now, so I guess I'm ok, but that's probably more from the knife-edge and thermostat/coolant changeover than removing the screen.

-Alero- · 05-23-2005, 02:50 AM

hmmm how tuff was that 1780 t stat install? i need to do mine

05-23-2005, 03:57 AM

Put your screen back in! you MAF need it to read correctly!
And a 180 degree TS is only going to help if you seeing knock due to heat, witch next to stock 3400's dont have an issue with.

BlackJack · 05-23-2005, 06:34 AM

hmm, difficulty level......took about half hour tops. Hard part is doing the squeeze to reach behind the crossover. Basically I already had the MAF out when I did it, so that gave me a little better visibility below the throttlebody. Basically just removed upper radiator hose from the housing, and the reservoir return line (hard line on top of housing), put a 1/2 or 13mm socket w/extension on the upper left bolt, and had to hand wrench the lower right one 1/4 turn at a time since I couldn't get a socket on it. If your crossover is easy to remove I recommend doing that to save scars.

BlackJack · 05-23-2005, 06:39 AM

Quote:

Originally posted by Blackrider@May 23 2005, 01:57 AM
Put your screen back in! you MAF need it to read correctly!
And a 180 degree TS is only going to help if you seeing knock due to heat, witch next to stock 3400's dont have an issue with.

Quoted post

I understand about the MAF, but the 180 TS actually helps in most situations. Especially during the summer. My temps are running markedly cooler, and I'm feeling just a TAD more hp. This makes sense, otherwise, why would we use a CAI? Because cooler air temp = higher density = more hp.

-Alero- · 05-23-2005, 06:33 PM

a CAI is actually just tricking your computer to deliver more fuel.

the IAT see's that the air is a cooler temperature, so it says to the PCM "hey deliver more fuel so we can stay warm" so it delivers mroe fuel, etc. etc.

the colder air that is inhaled instantly turns into hot air right around the TB, because the EGR has heated up the UIM so much that the cold air, heats up so fast.

BlackJack · 05-23-2005, 08:37 PM

but by starting at a lower temperature coming in, it doesn't raise as much coming through the uim, so the density of the mixture is higher since it's at a cooler temperature, and gives a bit more oomph when the cylinder hits. Remember, the velocity of the air rushing through the intake system at WOT is fast enough so that the heat transfer isn't that significant. Now if you slow down the speed of air flow, it has more time to heat up.

-Alero- · 05-24-2005, 02:16 AM

well put.

05-25-2005, 01:07 PM

Quote:

Originally posted by Blackrider@May 23 2005, 07:57 AM
Put your screen back in! you MAF need it to read correctly!
And a 180 degree TS is only going to help if you seeing knock due to heat, witch next to stock 3400's dont have an issue with.

Quoted post

Then explain why the Pro-M or the Granatelli or the any aftermarket performance MAF companies DON'T have screens...........I was told by my dealership one time with my old car when I sucked some water in that the MAF screen helps REDUCE (not prevent) water from getting in....that's it...it isnt needed at all. I have mine out on my alero and NEVER had a problem and now i have the pro-m and still NO problems

05-25-2005, 02:51 PM

You need the screen in the stock MAF. Maybe an aftermarket one is designed to not need a screen, I don't know. But the stock one does need it. I mean, I'm sure a car dealer knows more about engines than anyone with an engineering degree, so go ahead and listen to him.

BlackJack · 05-25-2005, 09:04 PM

Quote:

Originally posted by misslindseysue@May 25 2005, 12:51 PM
You need the screen in the stock MAF. Maybe an aftermarket one is designed to not need a screen, I don't know. But the stock one does need it. I mean, I'm sure a car dealer knows more about engines than anyone with an engineering degree, so go ahead and listen to him.

Quoted post

You raise an interesting point, no doubt. However, I have not seen any reduction in power (actually an increase from the polishing to a VERY minor degree) or mileage since doing so, and no unusual evidence of running either rich or lean from the plugs, and it was necessary to remove it in order for me to polish the inside. I'll just chalk it up to a fluke that it had no marked effect and just leave mine out until I see some other adverse effect.

My understanding is that it's purpose is to "straighten out" the flow of air prior to it passing the wires. This I can understand would be needed using the stock airbox since it's so close to the MAF, and the air being very turbulent after passing through an irregular shaped corrigated tube. However with a CAI, I think the air has plenty of time to stabilize in a very smooth passage prior to passing through the MAF, and therefore may not be necessary to use a screen in that respect.

Additionally, I have seen no difference in the appearance of a "performance" MAF, other than larger diameter, being knife-edged already, and polished. I thought it's main purpose being "performance" was just generally higher flow?

I respect the opinion of engineers, dont get me wrong. I just wonder if this is one of those exceptions?