[matthewx]

I did a search for secondary injection and couldn't find anything, so I am posting this question. I have noticed in Caledit that there appears to be a setting for multiple injectors. It appears that it may be possible to set up secondary injectors with something similar to this:

Set the low slope at the usual 1.15-1.2 times the primary injector size and have a simple add-on controller lock out the secondary injectors during low slope conditions. Set the injector breakpoint high enough to avoid ordinary driving conditions (Assuming you don't enjoy burning tires every chance you get....) but low enough that the primary injectors haven't reached a high duty cycle. Have your controller activate the secondary injectors just as the breakpoint is crossed.

The benefits of making a usable secondary injection system are numerous. Firstly, less expensive injectors could be used (Two sets of 24's are probably cheaper than one set of 50's). Secondly, the engine would run much better in the low speed area, but still have lots of capacity (And you can always add a third set) for higher speeds.

Does this sound possible ? Is the approach right, or should I try a different means of doing secondary injection ? Has anyone here done a Tweecer tune using secondary injection ? Does Caledit have a way to change the number of injectors based on the injector breakpoint (Or some other speed/load activated means) or is the number of injectors setpoint always the same number of injectors throughout the entire operating range ?

Appreciate the help on this one. Look forward to hearing back on this one.

Matthew
tune to up When the

[Daggar]

Pardon my ignorance if this is a stupid question.

Where are you going to get a set of heads/intake that provide for two injectors per cylinder? Are we talking about a Mustang?

[matthewx]

The inserts are available and they can be welded into the intake. Also, a spacer between the throttle body can have the holes drilled in it. Rails are available from Aeromotive as well that can be assembled.

Matthew

[Dale McPeters]

Matthew,

Drop a note on the Yahoo TwEECer list for Daniel R. Nicoson as he has ben working on a secoundary injector dirver that should drive 8 extra injector....

Here is the link to his website.

http://www.myo-p.com/

[matthewx]

Thanks Dale. I finally got that Mass Air Converted 1988 F-150 datalogging and running pretty good. Once I get my Mass Air meter connector back, I hope to take it in for an emissions test. Had to put the connector on another vehicle that the Mass Air meter went out on. Waiting on the new meter to get here.

Matthew

[DrDirt]

The benefits of making a usable secondary injection system are numerous. Firstly, less expensive injectors could be used (Two sets of 24's are probably cheaper than one set of 50's). Secondly, the engine would run much better in the low speed area, but still have lots of capacity (And you can always add a third set) for higher speeds.

I doubt that by the time you assembled all the hardware necessary to run 2 sets of 24# injectors would cost less than 1 set of 50# injectors. You would need 4 rails, extra fittings and hoses, the inserts and the labor to install the inserts.

On the surface it would appear that the engine might run better on the low end with the smaller injectors...I assume you're talking about the problems associated with low pulsewidths but if you were running 16 24# injectors, you would have to cut their pulsewidth in half compared to only 8 24# injectors and you'd be right back to the small pulsewidth problems. Maybe I'm missing something.

[Dale McPeters]

The other injectors can be triggered to come on later they do not have to be used at all times. The GM guy's have been doing this for years....
Works very well if the car is tuned correctly. Also the cost may not be that bad if he has another set of injectors already.......and can fabricate things himself.

[incon_331_twinturbos]

I think he's saying that the secondary injectors would not fire until a later time when needed...ie. WOT...doh, didn't see your post Dale...(edit)

[fireguy50]

the 5.4L in the new GT has 16 injectors.
might be able to order parts at the dealer

[matthewx]

Idea is to use some extra injectors I have. As with the rest of this system, I will be doing the work (As much as possible) instead of buying off the shelf. One possibility to this is to use a 302 rail for the secondary injectors since it is narrower than the 408 I am running. Idea is to maximize low end torque and operate on the street at a slow cruising speed (Say 1100 RPM @ 60 mph) so just dumping large injectors in isn't a good option for this setup. To compensate for the low RPM redline (Say 6250 Max), I am using cubes and high boost, and adding an underdrive (That can also shift to direct drive for the slow cruise speed I am targeting) to allow great launch off the line while maintaining a bit of fuel economy as well. Big injectors would kill any possibility of this thing working well at the slow cruising speeds I am targeting.

Matthew

[DrDirt]

Owwww, that all makes my head hurt! I'm having enough troubles getting 8 injectors to fire at the right time and with the right amount of fuel. :D Good luck with the project. I hope you can get it working and still have more hair left than I have right now.

[matthewx]

You are correct to say this will be a challenge. I half expect that I may not be able to pull this off. Probably what I will do is to borrow a big set to give me a good baseline for what I should be able to get out of my engine from an all out quarter mile run. Then I will try the secondary setup with the knowledge of what I should be able to run so I know which way to tune the tip-in and/or amount of fuel.

I just posted this mainly to see if anyone else has tried this and if the Tweecer has a way to provide a way to load trigger this. The merits of this may or may not materialize, but it would be a lot easier for me to pull this off if I can borrow someone's tune.

Matthew

[rockin_rick]

What strategy are you running? Please add your engine specs to your signature, as stuff like this matters with the tweecer. Please add at least year, cid, induction (S/C, T/C, NA, etc), inj size, calibration code, tranny, etc.

I doubt that there is controls in the eec to 'enable' secondary injectors. It would sure make your job easier, though.

IMO, I think that your easiest method would to have a secondary injector controller that both sets of injectors were ran off of. The EEC's inj outputs would be inputs to the controller (not driving any injectors), and the controller would determine when to spray both sets, and how much PW each gets.

I'm imagining setting up the EEC to see the total inj size of both sets. Say you are running 2 sets of 24's, then the inj slopes would be setup for 48lb-ers. Then at low PWs, the controller takes the outputted PW, and converts it into a PW for just one set, while the secondary are off. With the two 24 sets example, the controller would double the PW output to the primary set, for the given EEC PW output. Once that set gets to 80%DC (or whatever) (while the EEC is outputting say 40%), then clip that set to 80% and start sending PW to the secondary. Then the secondary set will build PW.

Of course, you could add more complex logic so that when the primary set hits 80%, then on the next cycle, back the primary down to like 60%, so that you can hit the secondary with like 20%, to avoid small PW on the secondary.

I've never heard of such a device existing....

Rick

[matthewx]

Rockin Rick, it sounds like you may have kicked this around a bit yourself. Sort of the path I was thinking of, but your method is a bit more sophisticated (And probably better) than mine. I have heard that on EEC-IV's, pin 27 (60 pin computer) can be made to be an output. Really be interesting if that pin could be triggered by duty cycle.... Wouldn't help on mine since I will probably be using an EEC-V, but if a similar pin can be programmed that way on a 1995 AODE style EEC, it would really make this easy.

Is there a pin on the EEC-V's similar to this ? If so, I'd like to hear about it. It would be good to see if another pin can be made into an input (Detonation sensor comes immediately to mind for me). If anyone knows about that, I'd like to hear about that as well.

Matthew