Its funny how you make some simple statements and people derive other observations that have nothing to do with what I said. I would think it a more intelligent observation that GM deleted the MAF when they needed to reach a higher performance level.

At best the screen is a redundant protection they found could be deleted in favor of airflow. Speed density tuners have shown 20+ rwhp deleting the MAF all together. The LS3 deletes the screen too and has no air flow straightening issues.

In your case deleting it wasn't worth it. I think that to be a subjective view even if it was made by Dave or Julio.

Now, since I didn't say GM purposely worsened performance by using a screen I will now clarify what I did say since I am being led down the misquote road again:

1- THERE ARE APPLICATIONS WHERE REMOVING THE SCREEN OR GOING TO A BIGGER DIAMETER MAF WILL MAKE A SUBSTANTIAL DIFFERENCE; Even though yours wouldnt gain much as per cartek. I seriously doubt any real max effort stroker motor would use a GM maf anyway.

2- I believe the new LS3 uses the same LS7 unit....no screen. A screen isn't needed on any corvette. My car is proof that it can and does work fine with the screen deleted.

3- My last point is that the removal of the screen can and has been successfully tuned in properly so I disagree with the gloom and doom know it alls that say it cant work and that it will kill performance. It isn't needed for air flow straightening as prooved on the C5z and C6 2008 LS3 and the LS7. I deleted it and it works fine. I have spoken with other max effort motor owners and they said it was such a big restriction that the screen needed to be removed or a bigger MAF installed altogether.

I never commented on it being a great power mod and never will. Stay with what I did say and stop bringing new things in to confuse the issue. I numbered them above and they are the facts.

If you have an issue with what I actually said please show where my statements didn't hold true.

 

This is the Halltech MAF housing that uses the MAF from the LS7 and LS3.
It has zero laminar airflow issues. Somehow the air still makes it into the engine. Imagine that. The lingenfelter unit is basically the same. Both come with software upgrades needed to make it work.

 

 

I did not run the calcs on those MAF's, I imagine they would be different since the air flow is different in those engines...You state there are zero laminar issues, do you have the Reynolds number info to back up your statement? I would imagine as long as you are in a stable flow regeim or pass though all three regimes in a predictable manner, or with software enhancements, there would be no problems....

The problem I looked at was specific to the LS2, and the problem is at idle. I am thinking the screen serves to fix problems encountered in the idle range....

 

Killer Bee from Halltech is a very good solution but not cheap! I've had one installed for about 4 months now and NO problems!

 

My LS2 has no idle problems and no screen.

No, I didnt run calcs on any engine. I modded them in the real world time and time again without any of the issues you speak of. So what makes the desk/chair race man right and me wrong. I have multiple cars to prove it. The LS2 has no issues with idle with a calibrated MAF using a C5 Z06 scale as used by the screenless MAF (same part number in that car). I have an LS2 and have never had any idle issues and the screen serves no part in the idle on my car since it isnt there. I can assure you my car scans perfect and runs perfect as doens every car I have tuned and removed the screen on.

Having a theory or math correct rarely makes you an authority on fast cars....building a fast car does and thats it. I did this mod and it works without any of the issues you and your calculations state will occur. Sit in your chair and type away on theory and calculations to show why my car does what it does. 600rwhp with all my mods and it creeps along at 7 mph in a parking lot at idle in gear without bucking.

By the way, I am a licensed math teacher and seriously doubt you can show me a model that covers all the variables nec to prove anything. The software is where the issues and fix are and thats where I addressed it; MAF tables:high and low frequency.

 

One of the biggest problems I have with this forum is too much conjecture and too little scientific evidence to back up the conjecture.

When the MAF screen was removed when I first got the car it picked up 3 hp on a stock engine. After 11 years, three different engines, literally another 1000 dyno passes, dozens upon dozens runs at the track and a bunch of street racing, I've not had any issues at all and would do it again in a heartbeat IF it showed up on the dyno as an inprovement.

We all have seen GM sandbagging in the past and that includes the current LS7. The exhaust valves are too small on the heads holding back performance. Why did GM not put larger exhaust valves in?? Perhaps they didn't have to.

Why did GM put the screen here? How about someone from GM answering it so we know exactly why but the sky will not fall on anyones head if they do happen to remove it.

 

So I take it you have no backup, that's ok just admit it and keep the personal attacks to a minimum, they are unbecoming of you, as a..... teacher...

And you are right, from your low tech post, there is nothing I can tell you that you don't already think you know.....

 

The MAF screen removal is worth 2 HP, but ONLY if you retune the MAF tables to compensate for the missed airflow. Spin Monster is correct. The only issue with removing the screen is the occasional lean code, if the MAF tables are left stock. Look at GMs tables for the 2001 Z06 (MAF with screen) and compare them to the 2002 Z06 (No screen) and you get the idea.

The screen is a laminar flow honeycomb which helps straighten the airflow to the wire pickups on the Delphi MAF.

If you really want some additional airflow, we have the answer. Halltech now has a conversion package, which allows use of the LS7 MAF and the LS7 Killer Bee AAIS on the LS2. Not cheap, and the MAF tables MUST be reprogrammed. We can do that by emailTUNE or mail order tuning, but we will also make the MAF table available free of charge to any local tuner.


The above Nylon 7 MAF is bonded to our Killer Bee as a one piece unit on the Killer Bee AAIS:
Order: http://www.corvettec5.com/store/?pag...ae2675c9cb237d

I recommend the Vette-Air Cold Air Mod along with our system for the best of both worlds.



Jim

 

If I had a Z06, I would run without a screen. Since I don't have a Z06, and I don't have a stroker, and I don't run a cam or aftermarket heads, I will leave my screen in.

If someone can post repeatable dyno results OR repeatable track results, I might change my mind. Until then, no thanks.

 

The 2008 base model doesnt have a screen either now from the factory. I agree with what you mean though. If you have a stock or near stock car the airflow requirements are met.....but that isnt what i posted about. I said you can remove the screen without issue if you tune the change in.

I have scans sir. They are from actual cars (not fictional armchair day dreams) that show an airflow restriction. I have no back-up?? You simply scan a big power car and if the MAP shows too low a reading (99 is optimum) you have an restriction. But what some take as a personal attack, others take as info to build on. Sorry it wasnt clear enough for you. My comment of being a teacher was to show I can hang with anyone on advanced math, not as you say to make personal attacks.

If you need to observe a heavily modded H/C car with a need for more front end air flow I can e-mail such a scan to you for use with your copy of HPtuners as real data that shows your incomplete model to be incorrect in some applications. No, I'm definitely not the be-all-end-all of tuners but I have tuned a few and can use real world data scanned from a car and get a MAF to work without a screen. I know at least one of every size LS engine running without a screen and there is no issue with how they run (OR IDLE). Please show me a car that doesnt idle when you remove the screen and tune for it that runs when you have the screen in place. I have never seen it. Have you? If so, let them know I will tune the car for free if they pay the travle costs.

Low tech You may wish to search to see what kind of low tech posts I make. I only post in this section. Cams, heads, intakes, headers....I did it. When you have actual cars to back up those theories, feel free to post. My experience is posted all over this forum and the people I did the work for have had ZERO to complain about......especially the price.

For the record I have no animosity toward you and wish you the best.



The purpose for my post was to state that a screen can be removed and the car tuned to run properly without issues and provide additional air flow for the guy that needs it. I never recommended it for the stock or near stock guy; I said that here:


Once again NOW QUOTE ME:

If you need additional airflow, you CAN remove the screen with no adverse affects but it will require a retune of the MAF table so the additional airflow isnt read as a lean condition.

So for the record I made no comment on it adding power to a stock or near stock car and I never said anyone should do it. I just said it can be done without adverse affects.



Jim/Halltech...thanks for taking the time to state the facts and I love the MAF you have there. It also has the benefit of not being made of heat soak metals. Nice product.

 

GM also sells trucks with short enginebays, meaning aircleaners are
left or right. the bents before the MAF will squirl the flow.
The Z06 MAF is a complete airduct MAF unit and i guess you will not
find that in any other GM Car. So for me a C6 is using more platform
parts than a Z06.
A PCM can handle a removed sreeen in closed loop, cos the O2 sensors will tell -->more Air,but during WTO it will run a little lean, so atleast you have to take care of PE. Since a C6 has 2 new Operating
system (2005 and 2006 E38 ?) the expected airflow might be set in calulated tables like VE.This is different from LS1 and could be a reason why some don't see a difference.
A big problem here is that many who will in to tune a new car, will
do a complete job, with airbox, exhaust ...you know better,
so a small mod like this will be hard to separate.
The reason why i would be careful is that the screen can sit quite
hard and its in the end a sensible piece.
(Its colder these days, have fun ...)

 

I was not dissing you for your education, I just had trouble with you being a teacher yet you seem unwilling to explore new things or learn from others. I am sure I can learn from you, I expected the same curtousy in return.



For the record, I have no animosity towards you either.

I dabble in "aremchair" hydraulics on things like the LS2 because it is something I love to do. I go to my day job and do it for real, solving far more complicated hydraulics problems than this and get paid really well to do so considering it is something I love to do.

That being said, you know HOW to affect change through the removal of the screen, I seek to understand the WHY. To help people answer their own questions, understanding why the screen is there is important.

It does not straighten flow, it is a very inefficient device to do that, so that cannot be the reason for it and there are other pronounced ways to straighten flow without the pressure loss of the screen. It can impart change to the velocity profile of the air stream. This makes sense considering when you look at the Re number and it would be a very efficient device for this purpose.

Why would GM put it there? I would think when faced with a issue like this, the effect on one car is small, possible altered emissions at idle, maybe an inability to control the engine during these transitional conditions. I would focus on emissions and I say this because GM has produced 10's of throusands of C6 vettes and a small imbalance that leads to changed idle emissions can be scaled across all these vehicles and present a major issue with respect to total emissions from the fleet.

Why did they use a screen and not a software change? The best way to deal with a hydraulic condition is to not let it happen. The screen manipulates the flow across the three flow regimes and specifically the laminar regime in a static manner. A software change only deals with the hydraulic condition after it occurs. So it tends to solve the symptoms, not the problem. Unstable flow across the flow regimes in by nature unpredictable and makes predictable software code unable to handle it under all conditions.

I still believe from my research that the screen is an idle device. Removing it will improve performance beyond idle, as you are indicating. I will also not be needed if you increase air flow to the engine through various mods like forced induction, as the flow volume will move the Re out of the transitional regime area. I also believe that you will not notice the screen missing at idle performance, no bucking, no stalled starts. I conclude this from the emperical data others posted here from actually trying it and returning their performance information.

Again, understanding the WHY allows people to make more informed decisions on thier particular ideas of leaving it or removing it.

Now, if I had the time to run a CFD model on the intake like I do on other work issues, that would trump all, but like a mechanic, I like to keep my work life at home simple and will stick to armchair analysis since this is simple problem....

Happy trails....

 

I trust Jim Hall, so if he says it's worth 2 HP IF you also reprogram the tables, then I'm convinced. I also respect Spin's opinions and real-world experience.

However, since my engine is pretty much stock (just have LG headers), I still plan to leave my MAF screen as is.

 

And the only thing I was saying in this thread was that I can remove the screen from ANY vehicle's MAF (trucks included with short intake tracts) and get it to run 100%.

Idle issues and people saying it will run bad are what I was debunking.

I didnt say it was worth it.

I didnt quote any gains from it other than a car that scans less than 99kps MAP needs to have less front airflow restriction.