Contour Enthusiasts Group Archives Forums Modifications Duratec Performance 65mm Mustang TB installed!

So I'm gonna assume that an aftermarket mustang throttle bodie would work. I was thinking that the flow characteristics of something like a Accufab 65mm TB would be better than trying to shave here and shave there to get maximum flow from the stock ones. I can get the Accufab at wholesale as well as the BBK just wondering. Whats your folks thoughts...Mahalo

Great you threw on a GT TB, but what gains will you have? 2.5L, vs. 4.6/5.0, wont this acutally hurt performance opening up your AIR inlet so much?

Good luck with it.

Yeah...

What about letting in all that un-metered air? (2 K&N Breathers)

The unmetered air is NO different to having the bigger MAF, but at $30 for the mod it is way cheaper than buying a 80mm MAF. Because essentially a bigger MAF lets in more air than the computer thinks the engine is getting. This is due to the fact that the calcs for the airflow in the fuel tables within the program in the ECU are setup for a 75mm orifice in the MAF.
I am getting a A/F meter in the next few days, but I am sure that the leaning out is nowhere near any dangerous levels.
I apologise to those who where waiting for replies from me in the last few days, but I was in a work-run course so I was out of the office and away form my computer.
As for performance increase, I have stated the results twice already and if you can't read, then I am not going to repeat myself again. :rolleyes:

Sorry Aussie, I'm gonna have to disagree with you on this point. Technically speaking, a bigger MAF only serves to report an ultimately higher amount of air flow to the pcm. With the same amount of air going through both mafs, the value they report to the pcm should be the same.

dan

Yes, it is different. The larger MAF still MUST have the correct ratio of flow over the wires as the stock MAF, that's why just any old MAF will not do. The 80mm Ford MAF just happens to be close enough to work, the 75mm and 73mm aftermarket MAFs are calibrated by their respective companies. I'm glad your breathers work for your combination and you're more than likely in the safe range of fuel mixture as the MIL will trip for dangerous lean trim levels, but the two mods are not compareable. Also, thanks for the write up on the TB, very nice pics too.

Well I diasagree with your ideas purely due to these facts:
That ECU is CALIBRATED for a certain orifice size in the ECU, i.e for "x" m/s the ECU will inject "y" litres of fuel, and as you may know flowrate, Q=A.v, where A is the cross sectional area, and v is the velocity of the air passing through the cross sectional area measured, at any given point in time. Thus for the point you stated, i.e a fixed volume of air which is dictated by the volume of air induced by the engine per 720° the crank turns (lets assume 100% v.e., therefore 2.5L of air), the velocity will be lower through the large diameter MAF than that of a smaller ID MAF. And therefore the MAF will report a lower velocity to the ECU, which in turn makes the ECU think that less air is entering the engine and thus the ECU REDUCES the amount of fuel injected into the engine for that volume of air, thus increasing the A/F ratio (leaner).

Again, incorrect. What you state would be true IF the MAF sampling tube size were fixed. With a larger MAF size on equal size engines, the larger size MAF will also have a larger sampling tube size, or just smoother flowing sampling tube to send the correct signal. The sampling tube MUST do this to "read" the same volume of slower moving air as the smaller MAF's, faster moving air within the sampling tube. The entire MAF size is not even known by the ECU.

If it were a fixed volume of air at 100%, we wouldn't need a MAF. I know you stated it just to make the math easy, but it also negates your point. One of the main reasons to get a larger MAF is to unrestrict air flow, thereby increasing the volume of air ingested. This is exactly why some people don't see any improvements by changing the MAF as the MAF isn't always the restriction in the air flow.

Anyway, I see your point. You just missed a few variables in there...

I agree with you if in fact that sampling tube is indeed larger. And truthfully I haven't seen the internals to the larger MAF (80mm etc) to see if the sampling tubes were bigger. I assumed that the sampling tube diameter was the same and just the body diameter varied.

Stazi, brad's right. btw, if I read your post correctly (I read it quickly) you basically described a speed-density system, not a Mass Airflow system.