James, I'm not saying you are an ***, but you aren't being nice either. It doesn't hurt to tell me nicely that I might also want a non-ported/stock one too because of tuning and what not. But none the less this has been a good learning experience for me.

ShibbyZ

 

Ya it will help you out if you want to port your heads or something. Now you know what your doing. And i was being an *** im sorry i had just go home from work.

 

Oh ya and just a good idea, thoroghly research something before you jump into it and you can save yourself wasted time along down the road. Not that i always do that

 

Yeah, fwiw, not only does porting the maf ruin the calibration and make it impossible to tune correctly, it is terribly inconsistent from run to run.

With a stock screened maf we have made over 500rwhp naturally aspirated, and over 800rwhp turbocharged.

The -BEST- maf is stock. Untouched.

 

I did research this, I even stated I went to the library I believe. If I didn't then I'm saying it now. I found a book saying and i quote, "then grab your hacksaw, your 200 mile an hour tape and get busy." It's refering to the MAF sensor fins. The book is Chevrolet Fuel Injection but Motorbooks. The book is for TPI cars but the MAF and TPI concept are identical to an LT1. The page number is 143 towards the bottom closest to the spline if you would like to check it out for yourself. I did do my research and found nothing wrong until I read "caliberation" that someone posted. Other then that I thought, hey, they sell ported MAFs, this book is saying do it, and I haven't heard anyone say no, so why not. That's my explaination of why I went ahead and ported it.


ShibbyZ

 

The ebay link is for a b-body MAF which is smaller which just goes to prove the level or lack of knowledge by some in this thread.
A tune is relatively cheap as $50 from reputable and well respected forum vendors and not only can it correct AFR but can optimize timing and many other parameters especially shift points and TC lockup in A4 cars this makes a huge drivability difference even on a stock car.
The TPI system was not as refined as the LT1 system and the MAFs not as good mand likely smaller, a lot of the info easily available in print and such is about selling something in the case of that book they were just selling the book full of "cheap and easy" ways to "make power", a forum like this is an infinetely better source than something like that or a magazine. Off the top of my head the only books I would recommend for smallblock Chevy modding would be by Dave Vizard I am sure there are a limited number of other but he is the man.

A ported MAF is inacurrate and is reporting faulty info to the pcm period.
As someone said earlier the only people who defend this are the ones who made the mistake of doing it already. You want to do a good tune for it and it will likely take dyno time which is big money and could have optomized the AFR with the stock sensor more easily getting the same power for less money and doing it more consistently.
Do a search here and you will consistently find that the knowledgable guys all say keep it stock and I will take the word of someone with a proven fast car over a book anyday.

 

You are completely wrong. The 3rd Gen MAF engines used an MAF made by Bosch. It had a single-wire heater, an annular ring that controlled the stability of the air flow across the wire, cooling fins that projected into the air path to help cool the electronics (they had a single heat related failure while testing the MAF in Death Valley), and there were metal screens (very similar to window screen) on BOTH the inlet and outlet of the MAF. It also required a "burn-off" circuit to clean the single wire off on shutdown.

That Bosch sensor, used in the 3rd Gens, was extremely unreliable, and flowed very poorly. It was VERY possible to improve the flow capacity of the sensor (assuming your engine was making enough HP to need more air than the stocker) by removing both the inlet and outlet screens, and grinding down the cooling fins that blocked the air flow. The output signal of the Bosch sensor is variable voltage.

That MAF has nothing - zero- nada - in common with the MAF sensor used on the LT1. The LT1 MAF is made by GM, has only an inlet side paper/foil composite honeycomb air straightener (not a screen) and NO internal cooling fins. It uses a flat wire element that uses thin-film technology, and does not require the burn-off circuit. It does have a dividing wall to help stabilize the air flow and keep it uniform. The output signal is a varying frequency.

The LT1 MAF sensor will flow about 50% more than the 3rd Gen Bosch unit at any given pressure depression. It doesn't need to be any larger on a stock engine, or even a healthy bolt-on or heads and cam engine.

The screen is not there for debris, as some have already pointed out. It is there to provide a uniform air velocity across the full face area of the sensor. The wires can only touch a small sample of the air, so the calculation of mass flow has to be based on an assumption regarding the uniformity of flow across the full face area. Disturb the flow distribution, and you destroy the calibration that is programmed into the PCM in the form of a table of frequency (Hz) vs. mass air flow (grams/second). Throw off the calibration, and the PCM no longer can match the fuel flow correctly to the air flow, forcing the long term fuel corrections to try and compensate over the range of RPM and engine load (MAP) that the 18 cells are defined to represent.

 

Injuneer, thank you very much for straightening out my big mistake and you also did it kindly. I'm also now looking for a stock MAF.

 

Lesson learned, I guess. Years of "research" have been done on this board. You should have come here first.

I followed the masses years ago, when I did not know better. What do I have on my car now? A stock MAF.

 

With or without screen?

 

A stock MAF has a screen. That's what I have.

 

I always used the stock MAF, with the screen intact... at least when I still had an MAF

http://cjcfo.fbody.com/members/injun...B/N2ONozzl.jpg

 

STock = Screen.

Shibby, Don't fret. You'll be fine. Leave it and don't worry about it. Its not that big of a deal. I gotta say that you did a good job porting. It looks machined. Yes, it makes it harder to tune and its not a great mod. However, it probably won't hurt anything. Burn some rubber .

Don't take these posts too personal. Most of use were in the same position (including myself) and hacked the heck out of our MAF before we knew better .

Ryan

 

I never really took a lot of these post seriously unless it was hard fact. But now I do feel better knowing other people have done something or the same thing to their MAFs. And for it being machined...I don't know about that, I just used a drill press with a metal chipping drill bit, then smoothed it out with my dremel. Pretty novice in my opinion, but that's another reason why I hacked at it, to learn, and learn I did! No better way to learn then first hand.

 

So how bad is it to take out your screen, is the calibration totally whacked out from that one "mod" to the maf?! My screen was out when I bought my car, should I look for a new "stock" maf to replace the one on my car with?! Thanks--

EDIT: am I getting worse gas mileage with this being done or what?!