2 Injectors per cylinder?

[Imp558]

Okay, so I was tearing down my L36 for recycling and was curious about some interchangability and found something I thought was pretty neat. Had thought before it may be possible to put L67 heads on and L36 and end up with 2 injectors per cylinder like an LT5. The intake manifold could use some clearancing around the injector ports in the heads but this would mechanically bolt up and line up well. If I remember correctly there used to be an adapter plate to put a SC on a l36 LIM, that could be the makings of a bitchin' boosted/wet nitrous setup.

[Philbo Baggins]

If that were made to work it would be fuckin awesome

[Imp558]

It fits, I had bolts in it. I suppose the second set of injectors could be run off a PWM circuit that turns on with the nitrous.

[RobertISaar]

controlled intelligently, they could be a rather interesting possible advantage in certain situations.

 

what all plans did you have in mind?

[no1kicker]

Using a L36 LIM with L67 heads is common when people go turbo. If you wanted to use two sets of injectors you could probably wire the injector connectors together so they both open at the same time. But now you need two fuel rails. To me it doesn't seem very practical.

[Imp558]

My initial thought was to wire the injectors in paralell like an LT5, but a PWM that could be varied could drive a bank of MOSFETS and run them with nitrous, dial the PWM rate in at the dyno or by watching wideband O2. These could even be methanol injection points. I'm not terribly interested in taking a project like that on right now, maybe my next engine, but it looked damn cool so I posted my findings. Would there be a benefit to running 2 smaller injectors, like reduced reaction times and more accurate fueling?

[RobertISaar]

the way the LT5 runs them is that only 1 set of injectors are used in most situations. when the secondary intake tracts open up, the secondary injectors come online. since the PCM controls all of this, it knows exactly when this is happening and what to do about it, namely, the BPW is dialed back to account for the increased amount of fuel that would be flowing due to the secondary injectors running off of the primary signals. the way the PCM enables the secondaries is that there is a "injector driver box" located externally from the PCM and the code switches a relay driver and the injector driver box uses a solid-state relay to get around the time delay that would be present with an electromagnetic one.

 

neat(useless in this situation) fact: almost all of the hardware necessary to do this is already present inside the MPFI 88-94 60V6 PCMs. of course, the code isn't present from the factory, but it could be patched in.

 

anyways, two smaller injectors that equal the flow of one larger one that are active at the same time will be open for roughly the same amount of time.... no real benefit. if the PCM commanded them intelligently(like the LT5), you could run a fatter BPW at idle and reduce any kind of "large injector at idle" problems. how you would do this with the OBD2 PCMs, i wouldn't know, i can't look at 68332 assembly without feeling dumb. there were some OBD2 PCMs that still used 6811 processors(96-99 northstars, 96-97 LT1, some saturns), but none were used on any 60 or 90V6 applications in the US. australian 3800s used them until 2001 or so?

 

in any case, i don't think i would be of much use if you're using an OBD2 PCM.

 

otherwise.... for "standalone" usage, like adding in fuel needed for wet nitrous, that could certainly be done and done well as long as you have something setup to control them as such. keep in mind that you WILL need everything to be dialed in perfectly BEFORE N20 is added.... and afterwards, should the PCM cut fuel flow for any reason at all, if the nitrous is flowing, you WILL experience extreme lean conditions, since N20 will still be being added and some fuel is being injected, but not at a correct proportion, since the fuel charge that would have covered the naturally aspirated air isn't present, but the fuel charge for the oxygen added by the N20 is.