Boosting a 302, use FMU?

[China]

I have a dumb question.

If I want to add boost (probably a turbo) to my 302 (93 mustang GT EFI) about 6-8 psi. Besides the hardware, all I need is the FMU to keep it from throwing codes? Will I have to have a new ECU/ECM that reads boost like imports do?

Technically, I'll need the turbo, plumbings, larger injectors + MAF, FMU and I'm good to go?

[GT408R]

If you have larger injectors (and right MAF) and a larger fuel pump you will not need to use the fmu.
The fmu is designed to be used with stock injectors and fuel pump

[MJN]

China.

The FMU is a crude way of getting extra fuel into the motor under boost. The FMU has a port that is connected to manifold pressure and as the pressure rises it increases the fuel pressure in proportion. There are discs that you can change on the FMU to vary the amount of increase in fuel pressure relative to boost pressure. It is a very basic way of preventing the motor from going lean..... to a point.

Not the cheapest but by far the best and safest way of getting the correct amount of additional fuel into the motor is to use larger injectors and either a matched MAF sensor or chip.

[6243]

Ditch the FMU, put 42# injectors in it, along with a MAF calibrated to 42#, and a 255lph fuel pump. You'll be crazy rich down low, but you WON'T be lean up high, which is safe.

Greg

[MJN]

Originally Posted by gbranham

Ditch the FMU, put 42# injectors in it, along with a MAF calibrated to 42#, and a 255lph fuel pump. You'll be crazy rich down low, but you WON'T be lean up high, which is safe.

Greg

Greg.

I run 42# injectors in mine and it's very nice at idle and part throttle. I still get over 20 mpg on a highway run but I can maintain a very safe 12:1 air fuel ratio across the board at wide open throttle.

[China]

OMG, that is so awesome!! I can't believe it is that simple!?!?

2 more questions:

1) I guess I can just keep the factory fuel pressure regulator?

2) Which one is in the correct order?

Turbo => MAF => T-body

OR

MAF => Turbo => T-body

Thank you so much guys!!

-China

[Bobasaurus]

I run a Lightning MAF, Tweecer on a A9L, and 42LB injectors with 8-9 lbs of Boost. I have had no problems at all running our of fuel.

I run MAF-Vortech-TBody.

Bobby

[MJN]

China.

Most MAF sensors are not boost rated and should not be placed after the turbo however if you are using a metal housing MAF sensor I don't see that it should be a problem. Plastic meters might not be able to handle the boost pressure and the under hood heat and could fail. Arguably the meter should be as close to the intake as possible to be as responsive as possible but in that location after the turbo the air flow could be very turbulent and screw with the meter. I suggest that you PM Wayne Presley and get his opinion he probably has the most experience here on the forum.

[China]

MJN,

You are 100% right. MAF does go AFTER the turbo and close to the t-body. I learned a lot after spending all day on www.turbomustangs.com

Thanks guys!!

-China

[No Tread TommyG]

There are "draw through" which go before boost, and "blow through" which go after, between the turbo and TB.

Just make sure you get the right one : )

[MJN]

Originally Posted by No Tread TommyG

There are "draw through" which go before boost, and "blow through" which go after, between the turbo and TB.

Just make sure you get the right one : )

The meter electronics measure air mass and don't care whether they are before the compressor where they might see anything from ambient pressure to a certain degree of vacuum or after the compressor where they might see less than ambient pressure to boost. They just provide a voltage in proportion to air mass to the EEC where the EEC takes this voltage and looks at the various calibration tables to calculate the required injector pulse width to achieve the desired air fuel ratio. If you have a calibration sheet that came with the meter and a way of programming the EEC such as a TwEECer then you take the meter calibration data and input the transfer function directly into the EEC.

The only differences that I have noted have been in the physical housing design. Meters need to have a retaining 'lip' where the hoses attach otherwise they will blow off under boost. The older 'bullet' meters were like that with no lip and were no good for boost. Also some plastic meters will just not stand up to boost pressure.

I have a run a stock Ford meter under boost and it works fine. I currently have an older Pro-M Univer aluminum meter which was run downstream by the previous owner and now upstream in my set up and it works fine.

Also the difference between a meter sold for a supercharged application and one sold for a normally aspirated application is in the meter calibration relative to the stock transfer function in the Ford EEC. The supercharged meters transfer function is designed to be 'fat' at higher flow values so that under boost it will ensure that the motor does not run lean and risk detonation. This is just fooling the EEC to get the desired results, by far the best way is to change the parameters in the EEC calibration that you want such as air fuel ratio.....