5th injector

[phastalon]

has anyone here tried this? we set one up on a shelby daytona and ran 26 psi on the stock fuel system, i was thinking about upgrading my pump and maybe trying another injector instead of four new ones

[v413nc3]

I have an article on a 1000hp skyline that runs 4 660's and 2 1000s as "secondaries"... it has a real nice advantage of letting you have the gas you need available at WOT and still really easy tuneability and driveability at less than full power...

[phastalon]

yeah what we did is we got a cold start injector of a jetta from a junkyard and put it in the intake line and added a valve to it that was hooked up to the battery and where we tapped for the boost gauge and when it sensed 15 psi it would complete the circuit supply fuel to the injector worked quit nice and ive always been a fan of the backyard setup:)

[hoffman]

i know Rau used to run 8, 550cc injectors. 4 on the rail and 4 tapped in to the mani runners.

[erik]

Originally posted by hoffmangsx
i know Rau used to run 8, 550cc injectors. 4 on the rail and 4 tapped in to the mani runners.
--
...you said, "...used to..." what does he run now? I wonder if he has proven a new and improved way. ... I don't want a chance for my mani to detonate due to unspent gas in the mani. I wonder how this is controlled. You'd want to put those puppies as close to the intake of the head as possible. right? .. ever heard that an aerosol, spray can of something flammable, sprayed at a lit match can chase the stream to it's source and blow up the can? Couldn't that happen here too? this could lead to loss of power, or worse blow up your intake to bits.
I would think atomization is key to full gas use and control. If the car is tuned right and the injectors are large enough and controllable throughout the bandwidth then the afc should be able to the job with the main 4. no?

[phastalon]

the afc can do just a fine job with the four the reason im considering it is because i can go to a junkyard and pull a cold start injector of an old vw or saab and get the switch to control it for like 30 bucks or i can buy 4 new injectors and an afc. i plan on going to a full standalon system but for now i want more boost for cheap

[v413nc3]

As a wise person once told me, people who own DSM's are poor... LMAO :) I believe the theory of it was used for very very LARGE fuel flow... you run a secondary fuel rail and flip on those injectors when boost is above a safe area where your smaller injectors run into pre-det range... that way the small injectors are easy as cake to tune and you still get the benefit of HUGE injection... the 1000hp Skyline I'm speaking of has twin T66's I believe, I'll check the article later... 6 660cc's and 2 1000cc's so basically it's like running 6 826cc injectors... the whole point being that smaller injectors have better spray patters at low fuel flow than larger ones do, so you can retain better fuel econ at partial throttle with all the benefits of WOT power... As far as adding additionals because you simply don't want to go purchase larger ones... I'm gonna have to go with the SPEND THE MONEY theory :)

[303Racing]

FINALLY something I can reply to!!!:D

There are a TON of race cars that use 8 injectors. (2 per cylinder)

Alignment of the secondary injectors isn’t as important as the primary injectors. Secondary injectors aren't used until the system has achieved a high rate of air flow. 2 injectors per cylinder is a very solid set up. One nice thing about it is that you can keep you daily drivability of your car. If you run 440cc stock and use 440cc as a secondary you at 880cc and you have that 880cc only when you need it. Gas mileage is better tuning is easier and truthfully it is cheaper than a standalone w/ real large injectors.

Using a single injector isn’t as good as using one extra per cylinder. The problem is that you are going to have a hard time getting equal distribution of the fuel to the cylinders. Remember that the manifold is designed to flow air only. Ideally you need one extra injector for each cylinder.

>I don't want a chance for my mani
>to detonate due to unspent gas in the mani

Your valves are closed on the ignition stroke. They open and take in the air/fuel then close and then the air/fuel are compressed and then the boom. Your injector, stock and/or secondary should not be spraying during that specific cylinders ignition. It's like this, your stocker’s fire like normal but when you reach a certain point (rpm, load, Throttle position, and boost) the secondary fires along w/ the stocker adding more fuel.

>You'd want to put those puppies
>as close to the intake of the head
>as possible. right?

Yep as close as you can get them. 2 or 3" up from the stockers is perfectly fine.

>ever heard that an aerosol, spray
>can of something flammable, sprayed
>at a lit match can chase the stream
>to it's source and blow up the can?
>Couldn't that happen here too?

No because the secondaries aren’t fired until high boost and the valve is closed and the injector isn’t firing during ignition.

You can control the secondaries a variety of ways.

Here are a few:

http://www.034efi.com/034SupECU.html (so far the best I have seen, used by a TON of turboed 2gnt's)

http://www.sdsefi.com/eic.html (I know one guy who uses this and likes it a lot)

Eric I am building my 8 injector set up soon, I will show you how it all works. It is really easy and a good affordable method to add a LARGE amount of fuel.

Rau used it, may still but he has a new rwd car and I don’t know all what he us running now. I think I read some place that Shepard used 8 injectors (might be thinking of Rau) HRC uses it on there 9 second neon, a TON of drag Hondas use it as well. It isn’t a very new method of adding fuel.

[303Racing]

Originally posted by v413nc3
As a wise person once told me, people who own DSM's are poor... LMAO :) I believe the theory of it was used for very very LARGE fuel flow... you run a secondary fuel rail and flip on those injectors when boost is above a safe area where your smaller injectors run into pre-det range... that way the small injectors are easy as cake to tune and you still get the benefit of HUGE injection... the 1000hp Skyline I'm speaking of has twin T66's I believe, I'll check the article later... 6 660cc's and 2 1000cc's so basically it's like running 6 826cc injectors... the whole point being that smaller injectors have better spray patters at low fuel flow than larger ones do, so you can retain better fuel econ at partial throttle with all the benefits of WOT power... As far as adding additionals because you simply don't want to go purchase larger ones... I'm gonna have to go with the SPEND THE MONEY theory :)

Exactly, well put.

I am going to use stock injectors 235cc (remember 420a) as my primary and my 625cc as my secondary injectors. Keeping my DFI and using it to control my secondary injectors. Basically I am tired of the suck ass fuel econ that I get w/ the 625’s and the standalone. (I don’t boost all that often anymore)

[v413nc3]

Originally posted by 303Racing


>I don't want a chance for my mani
>to detonate due to unspent gas in the mani

Your valves are closed on the ignition stroke. They open and take in the air/fuel then close and then the air/fuel are compressed and then the boom. Your injector, stock and/or secondary should not be spraying during that specific cylinders ignition. It's like this, your stocker’s fire like normal but when you reach a certain point (rpm, load, Throttle position, and boost) the secondary fires along w/ the stocker adding more fuel.



Carburated vehciles dump gas in before the intake mani, the whole system was designed so that the air/gas mixture was safe during detonation.

Personally I'm going with 4 1000cc's which are sitting downstairs next to my new manifold... the reason for this is because of the tuneability I'll have with the AEM... if it turns out to be rough then what I will do is the double with 2 sets of 550's... the 1000's were only $420 anyway...

[SnwNRcktRder]

yup '303Racing', I think I am going with this setup, seems like a pretty good idea!! Keep the gas mileage and tunability, and still have good flow when you need it! How can you go wrong with this setup? :rolleyes: Yes, I bet standalone has some pro's, but I can't really think of any big cons for the 2nd fuel rail, and 2nd set of injectors setup....if anyone has some other thoughts of some pros and cons on this topic, let's hear it!!