MrDude_1

so i was at a friends house thumbing thru some mags, talking about car stuff when i looked at the new ford GT motor, and started thinking about their fuel solution... (they have two injectors per cyl)


that got me thinking... big injectors are big money... and big injectors, because of the very short pulse width, arnt the best at idling and low power (off boost) driving.


so i started thinking of possible ways to run 16 injectors.
the actual manifold isnt a problem. but how can i control them?



if i run 2 ECMs, i can have one zeroed out except when the boost starts to rise past a specific amount at or near WOT.. then it can help the primary ECM.... the primary will add fuel until the injectors are almost static.. then it will just hold it there and the 2nd ECM will do the additional fueling.

benifit to this is i can run off 8 and then feed in the second injectors as needed.... but getting the two to merge flawlessly could be a challange. i THINK this is how the superfueler for TPI works, but i never looked that far into it.


the other option is to beef up the injector driver board so that it can run all of the injectors. i could get my fueling easily, and keep everything else the same... but that would make it just like if i used larger injectors... not solving the idle problem.



keep in mind, this would only apply to a heavily boosted motor that needed that much fuel.

comments/suggestions/ideas?

dimented24x7

iTrader: (2)

I *think* the ecms that have dual injector drivers could drive 16 high impedence injectors. Couldnt vary them sequentially, though. theyd all eb on at once.

Grumpy

ZR1s ran 16 injectors years, ago.
They used flapper door on the intake to shorten the tract lenght and then turned on a relay to power up the additional 8 injectors. Just rant the additonal ones at the same PW as the first 8.
With 60PPH injectors being available, would make for 8x60x90%DCx.5BSFC= ~860 HP, at a BSFC of .5. With a stock ecm.
I have a set of 60 PPH injectors in my lil v6 and it idles at 800 RPM in gear, with a DC of about .8 msec..
~$55 a pop they're a pretty good deal. Thou with their popularity they may have gone up, since I got mine.

And if you want to spend $90 a piece even larger saturated, 90PPH, and I think 120PPH are to soon be on the market, and that' about the break even point for new using 2 instead of one, if your buying new.
The old P+H 83 PPH injectors on a Syclone with swapped drivers in the ecm, needs the idle cranked up to like 900, to get the idle/DC to line up. In a v8 that'd be close to 1,200 HP.

Max_Maro92

Okay now I'm sure I will get flamed and called a crossbreeder but here goes anyway. I did a great amount of research into this area due to the fact I didn't want to give up my off boost drivability. Being that I was in the parts business for years I have had to cater to all different crowds. I finnally decided on a unit similar to this from HKS
http://www.hksusa.com/products/?id=638[/URL]
I found an HKS AIC III on ebay for a good price so that's what I ran. Read up on this unit, it can control high and low impedance injectors (up to 8 I believe) with a fully programmable enrichment curve (based on boost and RPM). Now before some of you go and yell "****" take a look at some of the products that the high end japanese manufacturers offer. Looking for a good boost controller or blow off/recirculation valve? companies like HKS, BLITZ, APEX-I, and GREDDY offer some fantastic products. Anyway just a thought I am happy with the results but if you would rather have something else you can also check out the paxta-map fuel controller, or the SDS injector controller. I don't feel that either of these units are as good as the HKS but having alot of choices never hurt.
-Mike

Grumpy

Nice post, wrong board

Your probably right thou, at 1,000 HP there might be some advantages to using aftermarket ecms/ controllers, for some people.

MrDude_1

how did this work? at a specific time, the ECM grounded a relay, and the relay connected the 2nd set of injectors to the same signal as the first 8?

Grumpy

The ecm supplies a ground path for the injectors.
All 16 were wired to the ecm.
Under normal driving power was supplied to 8 of them. When under heavy load, then the relay turned on, and supplied power to the other 8.
Might want to try running this sort of set-up on an ecm bench first if your not going to use the ZR1 ecm to verify it can handle the load.

Are you going over ~800 HP?.

JPrevost

***cough*** 9th injector ***cough***
More fuel, cooler intake, easily compensated for, no crowded intake runners cluttered with 2 fuel rails and complicated controls.
Motorcycle's like the Honda CBR600RR run 2 sets of injectors. I haven't gotten a chance to look at the controls but I bet it's a dual stage type system. Just looking at the RPM range of a little motorcycle engine just boggles the mind, 1000rpm to 14000rpm ... fun stuff on a dyno (until they break ).

83 Crossfire TA

iTrader: (2)

I really don’t see why this should be that hard on a map setup… just wire the injectors to be triggered with the first set (use a mosfet driver triggered by the first driver circuit) that has one side of the circuit interrupted by a pressure switch (I don’t know how accurate/repeatable a hobbs switch is, it may have to be a small circuit that triggers at whatever map voltage) and then just scale the tables back at that point by the ammout of your fuel delivery increase and you’re done, for example, if you’ve got 2 sets of 36pph injectors and the pressure switch set to come on at 0psig then you’d just scale the table to 50% past 100kpa).

The trick would be to adjust the setup so that it’s seamless. It would be much nicer if you could trigger the second set of injectors with the ECM, that way both would be controlled by the same source, but I’m not sure if you could get one of the outputs to trigger every time you reach a specific pressure, maybe the EGR or AIR?

Grumpy, any thoughts on what could be used to trigger the second circuit? How did the ZR1 do it?

FWIW, I don't think that this would be worth doing to save money, since by the time you get done with 2 sets of decent injectors, 2 fuel rails, all the plumbing... you'll have spent more then you would have for low Z injectors and an appropritate driver if you're up to that much fangling to start with.

83 Crossfire TA

iTrader: (2)

Huh, on second thought, I’d imagine the seamless part would end up a bit of a hassle, since I’m sure that the ECM interpolates between points and there would probably be a pretty big slope between the points where you turn on the second set…

I think I know someone that played with this… I’ll have to ask him what he did…

Grumpy

A long about the time, that you need additonal injectors, there's generally some serious HP involved.
Most of the cars I've been in at that HP level, don't spend alot of time being modulated between 40->100% throttle. So the seamless part isn't a real big deal.

I've played with Hobbs switches for the 7th injector, and Alky injection on the GN, and it seems OK. The second fuel pump also runs off a Hobbs switch.

Given a high resolution VE map, say 17x17, and an ecm controlled output, I'd venture a guess, you could get the transistion real smooth. IMO, having say the Hobbs turn on the A/C request to activate a BPC change might be effective.

83 Crossfire TA

iTrader: (2)

It could happen, land speed car, enough HP + limited traction. I’ve been wondering how to get rid of the 255mph limit in most ECM’s, I suppose that you could scale your VSS to read 50% or something… hum, take a lot of HP to push an f-body 255…

The pump is not a big deal, but the injector is… I guess that it’s not as picky as I expected it to be.

749 I guess? The only MAP stuff that I’ve been tinkering with so far is the 808 stuff, which seems to be limited to a 9x17 map… I wish I knew how to stretch it to 17x17 or so, since the map resolution gets pretty thin with a 2 bar and only 9 columns. I don’t think that 3 bar would work at all.

That was my original point.

What’s a BPC (sorry, still a big time ecm noob)? A/C request, as in the AC pressure switch used to trigger the fans?

va454ss

iTrader: (1)

https://www.thirdgen.org/techbb2/sho...&highlight=BPC

Does this help?

83 Crossfire TA

iTrader: (2)

I’m not sure if it does… how do you get the ECM to change a constant it’s using for a calculation while running? And why would you need a hobbs switch to tell it when?