Injection Modes And Control Technology .

[discopotato03]

Over from the Wolf/PFC/Motec Autronic thread .

I've always been interseted in the specifics of EFI evolution and what developed from motorsport than can benefit us on the street .

My fist EFI setup was non factory using a now ancient Haltech E6 on an L series 4 . It was batch fire only so not very sophisticated but it worked reasonably well - compared to a pair of Webers . Electronics aside the batch injection I think was a simple way to get injectors of limited size to inject twice in the four stroke cycle . I was reading up on sequential injection but could not really get those around me to see any positives

from it . To me it seemed logical to inject once and have some say in the injector close timing but the rally heads were not interested in low speed performance . They were saying that sequential needed larger injectors to get it all in with one burst and that the timing was not important .

My next victim was an FJTurbo motor and an Autronic SMC which is sequential . After using the std injectors I convinced myself I needed larger ones and fitted modified Bosch (403) 500cc squirters . Luckily I knew someone else that had a similar spec engine so I had maps to a least make it run . I like my engines to idle well and be crisp at low speeds so I spent a lot of time mucking around with injection timing and ignition timing to get it to behave itself . My engine had no idle bypass motor/solenoid just the "dumbell" style valve with the electrically heated bi-metalic strip . I was saving the SMC's single PWM output for a boost control valve . Both of these engines were MAP load sensed .

By the way I did prove that injection timing made very noticable differences to how well sequential injection runs . The SCM allows you to time the injection anywhere in the 720 deg cycle (360 x 2 for four stroke cycle) and from best to worst was quite a variation . Those injectors were probably similar to the Mazda RX5 T being large single pintel valve and I'm told more of a squirt than a spray .

So this leads into injector types and from what I've seen many performance cars use high current or low resistance injectors of high flow capacity . I gather these need the resistor unit like GTR's and std FJ20's use but not being an electronics expert I'm not sure how that bit works . The other things I'd like to know about are the peak and hold vs saturated systems and about high performance read high speed injector drivers in the ECU itself . Now I havn't used a Wolf so I should not slag it but is the fact of the matter cost with boxes that don't support sequential injecton or motorsport standard injector drivers ?

One would imagine that Apexi had a fair idea that we may be using giant - compared to std - injectors so their drivers would have to be to a high standard to cope .

Some years back I found an article on what GM in the US did to their Gen 3 era ECU to make a competition version for their road racing Corvett . I think it was in Race Car Magazine and got lost somehow . If anyone has the article I'd like to read it again . Anyhow the ECU from memory was beefed up to take the heat and vibration plus mods to non std drivers and whatever the gadgets are that do the counting business for injection and ignition . I think whatever was driving the coils was beefed up too .

Cheers A .

[RB30-POWER]

haha,

so was there a question anywhere in that or were you just having a general ramble?