Tec 1 - Injector Requirements

[rvanderpyl]

Anyone know what kind of injectors a Electromotive Tec 1 requires? From the doc's it seems like it wants peak and hold type, but are they low or high resistance? The Electromotive site lists both types and I am wondering if that is because you use low resistance type for sequential/multi-port and high resistance for throttle body single/dual injector setups.

[stlrj]

Here's what the search button turned up:
Alternative Fuel Injectors

[rvanderpyl]

That applies to the standard Porsche injectors, this is for the aftermarket Electromotive controller.

[rvanderpyl]

Bump

[Paul Thomas]

www.clewett.com

Richard is the man and will gladly help.

[TimT]

I recall having to use high impedance injectors with Tec1.
Later Tecs you can use either high or low impedance, depending whether you batch fire or sequential fire the injectors.

A quick call tod Electromotive Tech line couldn't hurt..

BTW good luck tuning the Tec1.. when we tuned them it always brought on a few more gray hairs

[Wayne 962]

Originally posted by TimT
BTW good luck tuning the Tec1.. when we tuned them it always brought on a few more gray hairs

Right-o. From what I gather, the Tec3r is worth the upgrade...

-Wayne

[beepbeep]

Peak & hold injectors are always low-impedance. Most of the time, you can attach high-impedance injectors to peak & hold driver. It works fine (albeit withoput peak & hold functionality).

Peak & hold are not used exclusivly for sequential/port injection, they are used when injectors are big and require precise timint to be able to attain decent idle.

With other words, imagine having six 100cc injectors on a engine that needs 3cc to idle. Pulse-width ratio to achieve idle on that engine would be 3%. Now imagine same engine fitted with gigantic turbocharger and six 1000cc injectors. They would be able to support lot's of horsepower but engine will still need just 3cc to idle. Pulse-width ratio @ idle would be 0.3%.

Hi-impedance injectors are lazy and have typical opening current of around 1A. They are not precise at small pulse widths. Having six 1000cc hi-impedance injectors trying to inject 3cc at idle will almost certainly result in failure. One of them might inject 6cc, other 2cc, third 4cc etc. In such case only solution is to richen everything up until the least common nominator goes over 3cc. You get a bad idle, bad emissions etc.

Peak& hold injectors are typically triggered by 4A (four times as much current) and then kept open with 1A. With other words, four times as much energy is used to slam the pintle open, which helps a lot when it comes to achieving decent idle on motor fitted with big injectors.

They are generally better but require more complicated driver circuitry.

Most "big" injectors (>25lb/hr) are of peak & hold type.


Other than that, most naturally aspirated engines with cylinder volumes less than 0.6L per cylinder have specific power that doesn't require big / peak & hold injectors.