MAF: 48mm vs 52mm

[Red96LT4]

Can you tell me if there's any advantage to running a larger MAF (52mm) over the stock MAF (48mm) on an otherwise stock LT4? I'm considering installing a Forced Air Induction System as well and would like to get advice on improving the flow of air/fuel. Thanks in advance.

 

[invinceablevett]

I have the forced-air installed and I was wondering if and how much the 52mm. would help.I heard that to get the most performance out of the 52mm. a better cam is needed.....help anyone?

 

[FX GS]

Can you tell me if there's any advantage to running a larger MAF (52mm) over the stock MAF (48mm) on an otherwise stock LT4?

Do you mean MAF or THROTTLE BODY?

 

[Red96LT4]

I am talking about the MAF. I know the TB is 52mm. It's a little strange that they would put a 48mm MAF in front of the TB. Ideas?

 

[Tuna]

I am talking about the MAF. I know the TB is 52mm. It's a little strange that they would put a 48mm MAF in front of the TB. Ideas?

The stock TB on an LT4 is supposed to be 48mm. Do you have a 52 on your LT4?

 

[Red96LT4]

I haven't measured it but to the best of my knowledge, the TB is stock. Is it best to match the size of the MAF and TB?

 

[LT4BUD]

On a stock LT4 the intake manifold has 52mm openings, the throttle body is 48mm, and never heard mention of the MAF size.

What the stock MAF does have is a rather restrictive honeycomb that is used to create laminar airflow. Removing this honeycomb might get you another 5 hp. It is held in place by a snap-ring.

From what I have "heard" I would avoid the aftermarket MAF such as the Granetelli...

Many people have upgraded their throttle body from 48 to 52mm....not sure how much gain on a stock motor...probably in the order of 5 hp....

 

[Red96LT4]

I've contacted the original owner and found out he had the TB milled to 52mm. I would like to leave the cam, heads and exhaust basically stock for now, but am considering a Forced Air system, Hypertech programming, and 160 thermostat. Any experience out there with this type of mod? Reccomendations? Also, I've seen various air foils for the TB, is this mod worth the expense? Thanks.

 

[LT4BUD]

I've contacted the original owner and found out he had the TB milled to 52mm. I would like to leave the cam, heads and exhaust basically stock for now, but am considering a Forced Air system, Hypertech programming, and 160 thermostat. Any experience out there with this type of mod? Reccomendations? Also, I've seen various air foils for the TB, is this mod worth the expense? Thanks.

It has been pretty well proven by many people that air foils are not worth it and don't result in any measureable gains on a stock LT4...Don't waste your money on an air foil.....

Stock programming is pretty good, so unless you have mods you don't gain much of anything by programming...

I think the 160 stat is good investment, plus reprogram the fans to really benefit, but actual power gain are pretty minimal..

 

[Aurora40]

I am talking about the MAF. I know the TB is 52mm. It's a little strange that they would put a 48mm MAF in front of the TB. Ideas?

Forgive me, as I don't owe an LT-4, but I think you might be confused? The TB is 48mm, but what that means is that each of the butterflies in the TB are 48mm in diameter. There are two of them. So they would have the same area as a single 68mm TB. Otherwise, a 48 or 52mm single-butterfly TB would be horrifically small. The MAF, though, is just one round cylider. I would bet it is over 80mm in diameter.

 

[Red96LT4]

I guess I need to start over. I've installed an AO Engineering FA Induction on my LT4. I'm told by the previous owner that the TB has been modified to 52mm. My concern was that the stock MAF would represent a choke point in the air flow and was wondering if it was necessary to change the MAF/MAF housing in order to realize the full benefits of the FA Induction. The engine is stock with the exception of an aftermarket fuel regulator, TB coolant bypass, and Hypertech 160 degree thermostat/programming. Along the same vein, does the accordian-style TB inlet hose create enough turbulence to make it worthwhile replacing it with a smooth surface variant?

Thanks for all the info.

 

[Aurora40]

As a general statement, I'd look at how big the MAF actually is. And how big is the ducting around it. For example, if the MAF is say 90mm or so (~3.5"), and the ducting is the same size and matches it well, I'd probably leave it alone. If you make the MAF wider than the ducting, you may have poorer flow due to poor transitions and turbulence. If the MAF is narrower, maybe it might help to widen it, if for no other reason than to reduce turbulence. A 52mm 'vette TB has the area of a single 74mm TB.

So now, you have to consider if the screen in the MAF really hurts flow, and if so, how much. I personally don't think they are worth it to remove as inaccurate MAF readings aren't gonna help anything. If you figure it decreases flow by 20% (I doubt the screen area is 20% of the total area, though, as the honeycomb is very fine), then you'd need a 92.5mm MAF to flow the same amount of air at the same velocity as it is at the TB (i.e. to have the same flowing area). If you think it's less than 20%, or if you MAF is bigger, etc, then there is probably not much to gain by boring out the MAF.

That smooth ducting stuff seems interesting, but I wonder how well it bends? Your engine will move side-to-side and back-and-forth (mostly side-to-side, though) while your airbox won't. So what happens to that ducting when the engine moves to the side? If it creases or something due to an inability to bend, then that probably hurts flow. But if not, they probably make it a bit less turbulent. Though I imagine the flexed ducting doesn't cause a lot as I imagine air will just flow down the center of it. But heck, I dont' know... I'm just trying to make reasonable guesses.

 

[FX GS]

The stock MAF flows, I believe, 640 CFM. Also, I have the smooth type of ducting and have experienced no problems.

 

[Aurora40]

Well, 350 cu. in. at 6,300 rpm would consume 638 CFM. While I don't know at what pressure, etc the MAF was rated, it sounds like it should be up to the task of feeding an LT-4 at redline.

 

[redc4corvette]

If you are going to replace the maf with the plastic one that mid america has then you might pick up something like a little colder air so you don"t get heat soak.

The engine will improve but it will most likely not be noticable until you hit over about 100 mph.
I did all that to mine but I did not see any diff until higher speeds.
If you remove your screen, on the dyno the engine throws voltage spikes not much to worry about.

 

[Bluewasp]

who sells aftermarket MAFs???

I'm building a 383 and have a 58mm TB.

 

[WhalePirot]

If you remove your screen, on the dyno the engine throws voltage spikes not much to worry about.

I just read, under C-5 solutions in the latest Corvette Fever, a reason for these spikes. In a FI car, the air needs to be smooth for proper measurement of the amount of it passing the MAF; entering the engine. Carbs 'like' turbulence for better mixing of fuel/air, but not injected engines.

The trivial increase in airflow area, risk of ruining the MAF while de-screening, plus the irregular measurement of incoming air would certainly decry this 'mod'.

 

[Vettelt193]

I just read, under C-5 solutions in the latest Corvette Fever, a reason for these spikes. In a FI car, the air needs to be smooth for proper measurement of the amount of it passing the MAF; entering the engine. Carbs 'like' turbulence for better mixing of fuel/air, but not injected engines.

The trivial increase in airflow area, risk of ruining the MAF while de-screening, plus the irregular measurement of incoming air would certainly decry this 'mod'.

I have seen dynos before and after on this mod... C4's benefit from the screens being removed, but not a ton of power is gained (about 4-5HP). F-Body cars actually lose power from it... because there is a bend in the intake before it hits the MAF... so the air is not straight enough to get a good read. either way, for the cost of messing the MAF up, 4-5 HP may not be worth it.