Don Terrill’s Speed-Talk

Customer car: '91 Mustang 5.0, 45K, all-stock (previously)

Fellow comes in with this cherry stock 5.0 wanting us to install headers, gear & shift kit.

Done. Now, he wants to change out his injectors. I asked if he was doing a cam upgrade,

and he said no, but he wanted a "2012 injector & not an OEM '91". He said he'd heard there

is some "latest-greatest" injector made by one of big (Siemens, Bosch, MSD, etc) companies

that has some "revolutionary" spray-pattern, "vastly" superior to his current set. I told him

to bring me some specifics on them, but he has not been back.


I'm not up to the minute on aftermarket EFI goodies. For future reference, does the above

ring a bell as to what injector/what company the kid is referring to? ~ ~ Thanks!

Some newer ford injectors have a dual spray pattern better suited for two intake valves. That would not help his old 5.0

There are newer style injectors from Bosch, among others, that have a slimmer body design and a supposedly better spray pattern and quicker response. The electrical connector on the 5.0 injectors should be the common EV-1, and some new style injectors are available with the old style connector. Most have a later style connector, the EV-6. The connectors can be changed on the stock harness or adapters are readily available. I have not tried them personally, but anecdotal comments on other forums claim smoother operation and possibly better economy?

2seater wrote:
There are newer style injectors from Bosch, among others,
that have a slimmer body design and a supposedly better
spray pattern and quicker response.

The electrical connector on the 5.0 injectors should be the common EV-1,
and some new style injectors are available with the old style connector.

Most have a later style connector, the EV-6.
The connectors can be changed on the stock harness or adapters are readily available.

I have not tried them personally, but anecdotal comments
on other forums claim smoother operation and possibly better economy?

That's pretty much how he described them, i.e., smoother & more-mpg.

Now to translate this into some part #s (& then give him a call w/a quote for parts & labor).

Thanks for these replies! ~

I don't know the flow rate of the existing injectors (guessing at about 19#/hr), but you can check the part # on the side of the injector (if Bosch), should start with 280xxxxx. Cross reference on Stan Weiss site for the flow rate. If this is a Mass Air system the system with adjust if a litte off. If it's a speed density, the injectors will need to be sized fairly accurately. Any good injector vendor should be able to find you a plug in replacement in the new style Bosch. They are supposed to be a disc style rather than pintle style for better wide range pressure atomization.

Yes, the stock Ford injectors on the '91 5.0 were 19#ers.

Thanks very much for the helpful cross-reference to the newer disc-style Bosch units!

The latest style bosch injector gives a much better spray pattern. EV14s are usually multi hole and are a much better injector than the older bosch EV1 pintle design. I have swapped an older engine over to newer style injectors and much better in idle/drivability/tunabillity/economy. When tuning with a programmable ECU I noticed a much wider tuning window where it ran well so easier to tune with also.

The 5.0 Explorers had the 4-hole 19Lb/hr injectors... EV6 body with the stock Fox EV1 connector.
Direct swap for stock Fox body 19's, mechanically speaking anyway...

I'm running these 19's on a n/a 2.3 setup, but don't have any comparisons to make with pintle type injectors.

There is a lot more to a fuel injector than just the flow rate static. There are different battery compensations, different dead times and different flow curves vs. pulse width commanded. When you change to a different technolgy of injector say from a pintle to a 4 hole disc these all change. In general a newer technology will have a greater flow at small pulse widths and a little flatter flow curve so will richen the engine up a bit through the majority of flow ranges. I you only test an injector at a static flow of wide open all this information is lost. Even if a bit richer the saving grace is the ethanol based fuels like E10 commonly sold at the pump really requires a bit more fuel as chemically correct is not 14.7 / 1 anymore much closer to 14.4. I would put it on a chassis dyno for a couple of pulls with a wide band O2 sensor and do again after the injector change and see if air fuel ratio still in the ballpark as well as find out if it is all smoke and mirrors on the upgrade.