I have learned from pervious discussions that replacing the stock MAF sensor is "snake oil" and will usually lead to problems with no performance gains. However, if I replace just the housing ( no screen on the housing) allowing in more air flow (1000 CFM) with the stock sensor will this cause any codes and will I get any gains? I have a 99 coupe with Corsa exhaust, Corsa X pipe, Bassani headers and a Vararam cold air intake, custom tuned.

 

Leave the MAF alone .... period .....

De-screening the Maf will gain you nothing, unless you go to a tuner and spend several hundred dollars to adjust the MAF tables for the altered air flow. Without the tune you may well see the same driveability issues as going to a 3rd party MAF.

For the "phantom" gain .... why bother ????

If the screen is so bad .... why did GM go back to a screened MAF for the C6 up until the 2008 cars ????

 

I've tried both screened and descreened MAF's on my 1997 C5 (with cam, heads, LT, etc) and the screened one runs better (less surging and other drivability issues) with no noticable loss of hp. However, going from a 78mm to a larger 85mm maf might add hp IF that is a restriction in your stock setup. Keep in mind that LT's, intake and exhaust mods like you have are NOT causing the intake to be your restriction.

 

I agree, you would need a new tune to adjust the MAF tables, it is pretty different and will cause issues.

Since you have a '99 have you changed to a LS6 intake?? That would get you a bump over the LS1. Much more than a TB/MAF stuff.

 

Now that I have more time let me explain in more detail why the MAF is NOT an issue ....

The LS1 and LS6 engines are about 350 cubic inch engines (5.7 liters). A cubic foot of air is (12*12*12) which is 1728 cu inches ..... almost exactly 5 times the capacity of the engine. On one revolution of the engine it draws half the rated cubic inches (4 stroke engine) ... 175 cubic inches * 10 = 1750 ..... so to draw in one cubic foot the engine has to rotate ten revolutions.

At redline your engine is running 6000 rpm ..... divide that by 10 .... at redline your engine can only draw about 600 cubic feet per minute.

You can screw with cams, the MAF, the exhaust system ..... but unless you do something to change the "air pumped" by the engine (such as a turbocharger) .... the engine at redline is going to pump about 600 CFM ....... period ... end of story ..... quit dreaming a different MAF is gonna buy you power .....

Leave the MAF alone and if you want serious HP gains look to mods that can increase the amount of air (and therefore fuel) in the cylinder .... turbo/super chargers .... cams that are effective at using fluid dynamics to get more A/F in the cylinder ... boring/stroking the engine ..... whatever.

Screwing with the MAF is about as effective as trying to stop the Titanic from sinking by throwing a deckchair overboard ......

 

Thanks for the advice. I will be leaving the stock MAF as is...

 

I still have not found any data to this date that a going to a 02+ Z06 85mm maf (they have no screens) from a screened 78mm maf will gain you any power, still, I am considering going to the 85mm maf as it will only cost about $50-$60 for the maf and air bridge and $20 for the harness, I am already adding heads and getting a re-tune anyway

 

GREAT POST,GOOD ADVICE,VERY INFORMATIVE,Titantic-deckchair sums it up and got a good chuckle out of me. Concerning MAF I've seen in various posts ,recommendiations to clean MAF, if memory serves me correct GM chassis says no touchy, also they look pretty fragile to me,also their location how could they get dirty ,if dirty do you use spray cleaner they look too fragile to even touch.THANKS!!

 

Yes, auto parts stores sell spray cleaner specifically formulated for cleaning the wires and area of the MAF. I purchased a can from Auto Zone. Some say OK to use brake cleaner, others say not so. I elected to buy the cleaner that is made and sold to do the job.

 

On de-screened mafs I have used a q-tip dipped in alcohol to clean the wires and thermistors. Works well since I can get at it from both sides. If in doubt, you can use a MAF sensor spray cleaner too. It is more plastic "friendly" than brake cleaners, etc

Over time, a bit of "road film" (minute oily aerosols) can eventually get past the air filter and coat the wires and thermistors.

HTH

 

There was a discussion similar to this where a gentleman from LG chimed in on power gains from the various MAF setups. I understand what BlackZ06 is saying, but if a bigger MAF is not needed then a 90mm throttlebody and intake really shouldn't benefit a 346 either (and restricting a 90/90 setup with the 75mm MAF makes no sense). There are many instances of a 90/90 setup making large power gains on an LS1, so there must be some benefit in increasing the flow into the motor.

Now adding an 85mm MAF while retaining a 78mm throttlebody is probably not going to net much. The 78mm TB will simply act as a restriction to the overall flow. You would gain a 3mm flow advantage over the 75mm MAF though.

 

I can see how adding a 85mm maf would not net you any power on a otherwise stock set-up but for the cost (~$80 w/ harness used) I am going to do it only because I plan on getting a 90/90 to go with my heads/cam set-up and everybit of extra CFM will help, if I got 2 whp out of it I am happy.

 

I do exactly the same thing, works like a charm.


JC

 

First, I'd challenge the "90/90 setup making large gains" ...... usually you see people doing a cam, the intake, headers ..... blah blah blah .... all at the same time, and then claiming "I got 25 RWHP from my 90/90 ...."

In this post .....

http://forums.corvetteforum.com/show....php?t=1977400

in post #4, if I'm reading this correctly, Tony is claiming 5 RWHP for the FAST 90/90 ....

In short the two power curves would be a "layover" (exactly the same) from the start of the pull to about 4500 RPM's or so and then the much larger TB starts to show you its stuff and the power curves slowly diverge so that by the low to mid 6000 range you see the full 5 RWHP or so. You may even see more if you buzz the engine closer to 7K but from 6000 and up its a solid 5 RWHP or so over the 78 mm set-up.

(Unfortunately the dyno sheet is no longer available) ....

A properly designed intake manifold has one significant purpose ... it actually helps "push" the A/F mix into the cylinder. In essence (especially at high RPM) the manifold creates a "flow" of A/F mix that has a "momentum" to it ..... so even as the intake valve is starting to close the mixture is "pushed" into the cylinder by the flow of gases behind it ..... think of the mix like a flow of water.

I take two hoses ..... one is 1 inch in diameter, the other is 1 1/2 inches in diameter. I have two identical buckets ..... which one can I fill faster ??? Depends on which hose has the higher rate of flow .... I can push more water through a 1 inch hose using pressure than will dribble through a 1 1/2 inch hose with almost no pressure behind it.

In hoses, as in intakes .... size isn't all that matters.

Also, take a look at the differences between the following engines ...

2004 LS6 5.7L HP=405 @ 6000 rpm .... TQ=400 @ 4800 rpm

2004 L59 5.7L HP=295 @ 5200 rpm .... TQ=330 @ 4000 rpm

The LS6 is, of course, the Z06 engine, the L59 is used in Chevy trucks like the Tahoe.

Both engines use the same block, but by altering the cam and intake manifold (and some other changes ... but these are the main two) they could build two completely different engines.

The LS6 is designed to produce power across the rpm range .... but it is "skewed" to produce the most power at higher rpm. The L59 is "skewed" to deliver power at much lower rpm. It is also biased for more torque than horsepower. The L59 is an ideal truck engine ... lots of pulling power at low rpm and still fuel efficient. Basically the same engine, but by altering cam and intake design you get two different engines.

Neat, huh ???

 

Well the majority of the top horsepower 346 cars are all running ported FAST 90/90's. Here are some gains for you:

http://www.ls1tech.com/forums/showth...hlight=90+fast

http://www.ls1tech.com/forums/showth...hlight=90+fast

http://www.ls1tech.com/forums/showth...hlight=fast+90
*8-10rwhp of this was due to the water pump

I quit about 6 pages in and found those before and after comparisons. I did not link the threads showing a gain vs. the LS2 or links of combinations that included a FAST 90/90. And to be fair not everyone sees a gain. But it's hard to argue when about all the top hp 346 cars are running this setup.