I have been reading about the performance gains the C5 guys are having with this mod, is it good for LT-1/4s as well? If so can anyone tell me how its done? Thanks. :chevy

 

It is a fairly simple job... All you have to do is remove the maf sensor, an cut the wire mesh screen out.. I would only recommend this if you have a k&n airfilter though.. The screens are there to block any debree (sp?) from hitting the sensor.. The k&n will block anything that might get in its way.. Other than that, your on your way to a few more hp's!! :cheers:

 

I've never seen any proof (dyno/dragstrip runs) that this mods adds any HP to an LT1/4. Some folks have had the engine hunting for the correct idle speed after removing the screen. The key point is the MAF flows over 700 CFM, it's not the bottleneck.

Eric


[Modified by silver & red CE, 10:23 PM 7/8/2002]

 

This issue has been debated quite a bit. Consensus is that it helps on L98's more than LT1/LT4's. Many say that the MAF sensor was improved in the '95, '96 model year over previous years and the single screen in front of the sensor serves primarily to shape air flow in a certain manner before it hits the MAF diodes so that the diodes get an optimum reading with minimal turbulence in the air flow. If you want to try removing for God's sake don't just hack it free of the housing. There is a c-clamp around the perimeter of the screen that holds it in place, either in front or back of the screen. Carefully remove that clamp and it should come out. I would completely disassemble the unit to do it, so as not to risk slipping and destroying one or more of the fragile MAF diodes with whatever tool you use for the job. The clamps that hold the rubber accordian air duct to the MAF unit are easy to take loose but a bear to get reset when you put it back together. I disassembled my MAF only to inspect the diodes for dirt or oil build-up since I run a K&N type filter. Sure enough, the top diode had a light coating of greyish stuff on it. I used a q-tip soaked in mineral spirits to *very gently* clean the three fragile diodes, and a dry q-tip to gently dry them and wipe off any residue from the mineral spirits. I think it is a fairly common problem with the K&N oiled cloth type air filters for the high velocity air flow through the filter to carry with it microscopic particles of oil, which over time get deposited on the tiny diodes of the MAF and cause them to accumulate micro particles of dirt. Anything on the diodes, even the thin oil coating which might not even be visible can reduce the sensitivity of the MAF unit. I believe that the aforementioned air filters tend to do release micro particles/droplets of oil usually when brand new and/or after a cleaning and re-oiling, *especially* if too much oil is applied to the filter after cleaning.

Whew, what a dissertation. Anyhow, might be worth taking your MAF apart to clean the diodes, but if it were me I'd leave the screen installed... :D


[Modified by Lone Ranger, 10:24 PM 7/8/2002]

 

The screen is not there to prevent debris from hitting the diodes. That is why you have an air filter!.
I also have a KN filter, and noticed a little oil on the sensors. I just sprayed a little shot of carb cleaner on them, and wiped out the body of the MAF.

FYI-Don't remove the screen. It is there for a purpose, and the potential gains are not worth the risk. IMHO :flag

 

I would not remove the screen as the above posts correctly state that the screen directs the air to the sensor for an accurate reading. Otherwise the air passing would vortex around the maf. I have never seen proven gains from this mod, and other web sites that show dynos of the mod show absolutely no gain. All you ever hear is how people "think" it makes a difference because the car "feels" better. :rolleyes:

 

silver and red.....what IS the bottle neck?

 

After opening the air filter box and adding a catback exhaust, I'd say it's a toss up between the cam and the exhaust manifolds. Adding long tubes yields ~20 RWHP, adding an LT4 HOT cam adds ~20 RWHP, adding 1.6 rockers adds ~10 RWHP.

Eric

 

"Vortex"? Dude- the screens are either one or two cheapo wire screens, put on the TB to prevent warranty claims when people try to run without a filter- engineering to the lowest denominator. That GM dropped the back screen (saving about $.0001 per unit) demonstrates that there is no validity to claims of air flow improvement; fluid dynamics are pretty sophisticated, and a couple of door screens in the TB aren't the result of numerous SAE papers.

If the engine can utilize the extra air, it will enhance performance- if you put a bigger carb or TB on an engine, it won't make any more power unless the engine needs it- so that is why there is no significant power gain, because 700cfm is plenty for less that 300hp.

Many, if not most, cars with TB's have a screen in their system- Ford didn't put a screen in my Explorer because they wanted to enhance my performance experience..........

I know, I know- but a little flamage is a good thing- lol!!!!!!


[Modified by jcazin, 9:50 AM 7/10/2002]


[Modified by jcazin, 9:51 AM 7/10/2002]

 

"Vortex"??? Yes sir. Air passing through a curved tube will vortex, basic science. I can call it turbulance if you wish. Maybe this can help explain better:

Mass Airflow Sensor

This is more of a warning rather than a modification. The MAF uses hot wires inserted in a known cross sectional area to measure airflow. Higher air velocities will cool the hot wire changing its resistance thereby providing a representative voltage. Many people are suggesting that improved airflow will be gained by cutting the screen out of the MAF. I highly recommend that this NOT be done on F-body vehicles. Most people mistake this screens purpose as preventing debris from hitting the hot wires in the MAF (That is what the air filter is for). Actually the screen is a bank of straightening vanes used to straighten the airflow before passing by the hot wires. Eddies and vortices (turbulence) in the MAF will cause inaccurate readings. Straightening vanes are used in most mass flow measurement situations where 10 diameters of straight upstream conduit is not available. F-bodys intake does not meet this requirement. Straightening vanes are sometimes installed on the downstream side when 5 diameters of straight downstream conduit is not available. An accurate MAF sensor is critical for the engine's fuel/air ratio adjustments.

Here the site: http://www.exicte.com/mods.html. I wouldn't lie to someone or give my opinion if I felt I was clueless on the subject.

 

Allc4lt4's post was exactly correct. The screen has nothing to do with blocking debris. It is there to guarantee straight air flow so that an accurate air velocity can be measured.

My opinion is that the air intake is straight enough that the straightening vanes are not needed. I have heard of people that have experienced hp gains from this mod. The MAF is not a restriction itself, but the vanes due restrict airflow. The question to be answered is if they restrict airlfow more than the air intake, the 48mm TB, the intake manifold or the heads. In my opinion, not fact based, just my intuition, is that the vanes do provide a bottleneck between the air intake and the throttle body. This is the reason I removed my screen. Other people will certainly have separate opinions, and I advise them to use their judgement when modifying your car.

 

It's not gonna help, it's not gonna hurt, It just lets you feel like you've done something to your car, if you're a fidgit like me.

 

I also agree with kkonen's post. Like all mods, everyone has an opinion. I have chosen to leave mine in for now. But GM has removed the MAF screens from the 2002 LS6's for the exact reason kkonen states: the passage is so short and fairly straight enough that the screens may not be needed. They are always used in trucks as the intake passage has turns, and GM used them in the corvette as well.

 

:yesnod: Yep, I am.

If one is careful about it, one could always remove the screen via the c-clamp and try the car out sans screen. If it causes problems, put it back in.

But... I'll probably leave mine in.

 

I yanked it out with no ill results. Can't say that it helped either (never took before/after data).

Since GM finally removed it on the Z06, that tells you the the screen was just some leftover engineering that progressed from one model year to the next, even though it may not have been needed.

 

If you're concerned about the debris issue, just remove the screens, then epoxy a small piece of screen in front of the tube holding the sensor wires.

Best of both worlds; increased airflow AND sensor wire protection.

That's how I've got mine done now.

\Whether removing the screens will improve performance depends on whether your engine needs the additional airflow AND (if it does), if you've tuned to take advantage of the additional airflow.

Since at WOT, the ECM ignores the 02 and other sensor feedback and runs off pre-programmed tables if your PROM is burned on the rich side at WOT, then the additional airflow may correct the condition and give you a few more ponies.

If you're lean at WOT, well now you've got a problem and may have to play with fuel pressure, etc.

I've tried these PROM mods in all their various configurations: Only front screen removed, front and rear screens removed, heat sink fins left installed, heat sink fins removed, screens removed but with small wire screen epoxied over sensor wire tube, ad nauseaum.

I didn't put the car on a chassis dyno after each mod to see the effects, but in around town driving I noticed NO difference. At WOT, though, with everything out (screens and heat sinks) I felt a difference SOP. engine seems a tad stronger at the top of the band.

I've gone through three MAFs, however, with the heat sinks removed, so now I leave them in. I've concluded it's Texas' ambient and engine header heat that cause the short MAF life when the sinks are cut out.

As with most things, when you modify one thing it will call for modifying something else.

Just my thoughts.

Jake



[Modified by JAKE, 3:52 PM 7/10/2002]