fuel injectors

[JWMX3]

In January I will be swapping a DE into my gs... and i wanna get the Pre 99' Millenia S fuel injectors... would it be beneficial to ge tthe millenia rails also, or will I have to use the DE rails ?

[Limegreen mx-3]

well i ask my brother on this ? since he is the MX-6 V6 nerd. he said the millina S injecter will fit on the DE fuel rail no mods requied but he said people use them when there running on some kind or FI but can be used on N/A. the S injecter spit out like 280 cc or so i could be wrong vs the 220-230 cc on the DE. hope that helps out laters

Drifter MX-3

brother has a MX-6 V6

[babyblueMX3]

yup you're right...millenia s pre 99 are 280cc and de and ze are 220cc.

btw the 220cc are way more than enough you going to need on a n/a engine...don't need those 280cc if you're staying n/a..so SELL THEM TO ME

[Limegreen mx-3]

I guess my brother does know what he is talking about he is a Veteran on the MX-6 board rbluemx-6. his not as dumb *** he looks.

[JWMX3]

If i come across any of these injectors at a good price I will let ya know babyblue

Thanks for the posts guys

[Limegreen mx-3]

Originally posted by JWMX3:


If i come across any of these injectors at a good price I will let ya know babyblue

Thanks for the posts guys

My brother said thats a good setup if ur going to run with 75 shot.

[TsiMiata]

Why do you need bigger injectors running nitrous? If it's a dry system the extra fuel is added by upping the fuel pressure. If it's a wet system the fuel is added via the fuel jet in the nitrous system. Either way it doesn't matter what size injector your running.

Unless you are going with some kind of stand alone efi setup you'll be doing more harm than good by upping the injector size. The car won't run right at enaything but WOT. Since at every other point the engine will be getting to much fuel.

So not to sound like a jack *** but either your not explaining properly to your brother what is going on or he doesn't know what he's talking about.

[JWMX3]

you'll be doing more harm than good by upping the injector size. The car won't run right at enaything but WOT. Since at every other point the engine will be getting to much fuel.

interesting.... i was told that wwith a 75 wet shot... it would be beneficial to have bigger injectors, better fuel punp, and an adjustable FPR...

Im no expert on fuel systems, so I dont really know who to listen to

[babyblueMX3]

Originally posted by TsiMiata:
Why do you need bigger injectors running nitrous? If it's a dry system the extra fuel is added by upping the fuel pressure.

mmm I'm not a nitrous expert what so ever but the stock injectors can up the fuel pressure to a certain point.but when going pass that point (and I'm sure it is with a 75 shot) you need bigger injectors to keep up with the high fuel pressure..

as far as the wet shot is concerned..nitrous is injected by the nozzle not fuel..you still need to up the fuel pressure..it's the same deal.

I could be wrong tough..I just think this is a logical explaination

[RbluE_MX-6]

Originally posted by TsiMiata:
Why do you need bigger injectors running nitrous?

It's not neccasary to up the injector flow rate on such a setup. But then again 60cc is not much of a difference, oh say compared to any flow rate above 320. And most people start with smaller shots of 50-55 with 190 fuel pumps and stock injectors. The rule of thumb is that the highest shot that would be in the "safe zone" would be half your motors hp atw. Most guys over at PT and mx6.com that are running 75 wet systems have 190 or 255 fuel pumps, adjustable FPR(usually set at 55 psi at idle). Some are running the millenia s injectors. But the consenus is that its not OVERKILL to utilize them in their setups of 55+ shots.

Originally posted by TsiMiata:
If it's a dry system the extra fuel is added by upping the fuel pressure. If it's a wet system the fuel is added via the fuel jet in the nitrous system. Either way it doesn't matter what size injector your running.

Well he is running a wet system.

Originally posted by TsiMiata:
Unless you are going with some kind of stand alone efi setup you'll be doing more harm than good by upping the injector size. The car won't run right at enaything but WOT. Since at every other point the engine will be getting to much fuel.

That's where wonderful things as Fuel Managment Units and adjustable Fuel Pressure regulators come in handy. So that you can find the proper pressure and settings so that you recieve the correct amount of air to fuel. But like I stated earlier, the flow rate of the millenia injectors is ideal for most moderate forced induction setups. For n/a setups, it is overkill. Which is what it seems that you are trying to get at.

Originally posted by TsiMiata:
So not to sound like a jack *** but either your not explaining properly to your brother what is going on or he doesn't know what he's talking about.

With any forced induction setup, its ALWAYS wise to be cautious. You wouldnt want to lean out, cause predetonation, and blow your motor, now would you?

[JWMX3]

Wow.. not bad for a first post, you sound like you kno what your talking about thats for sure... ok i think i will go with the millenia injectors, 190 pump and an adjustable FPR like i was gonna do from the beginning, but maybe ill start of with a 55 shot then move to 65 and eventually 75 (Ill be getting the Zex wet kit

Thanks Babyblue and Rick

btw - welcome to mx3.com

[TsiMiata]

I totally agree with getting a bigger fuel pump. A 190 HP walbro pump is a really good idea especially if going with a dry system.

In this guy's case he wants to put bigger injectors in. The millenia injectors will be adding 27% more fuel all the time if he just puts them in. Thats 27% richer at idle, cruising at 35mph and 27% more fuel at WOT wether you need it or not. This is not the right answer. If you really want to use millenia injeectors properly you need some kind of fuel control to throttle them back when you don't need that extra fuel. An adjustable fuel pressure regulator is not the right answer here. I don't agree with using adjustable fuel pressure regulators to solve WOT fuel problems. Yes upping the fuel pressure will give you extra fuel. The problem is it gives it to you everywhere no matter the rpm, load etc.. Now if the car is lean everywhere than the FPR is a good solution. With most cases though it's just WOT that's the problem. If you tried to lower the fuel pressure to get back to a somewhat stock flow rate you'd have to be at 25psi. Now your injectors are not spraying properly because the fuel pressure is so low.

As far as the nitrous system goes the stock 220cc injectors will support a 75hp increase with 80psi of fuel pressure. That's still well within what the injector can handle.

If you really want to run the millenia injectors you at least need an AFC. An afc run off a map sensor can do a great job of fuel management.

[TsiMiata]

I started thinking about what I said about the dry nitrous setup. I figured the needed fuel pressure increase with the injectors at 80% duty cycle. It dawned on me that the injectors are not at 80% duty cycle except for at wide open thorttle at very high rpm's. I then figured out the fuel pressure needed at various injector duty cycles. I made up a table guessing at injector duty cycles at different rpm's and what kind of fuel pressure it would take to support an additional 75hp. Keep in mind this table is just some arbritrary numbers I made up. It' as close as I could guess things would be in the real world.

RPM Inj.% PSI of fuel for +75hp
1000 10% 700!!!
2000 22% 235
3000 34% 148
4000 46% 115
5000 58% 96
6000 70% 85
7000 82% 78

This gets me wondering... Since a dry system can really only have the correct A/F ratio at one specific injector duty cycle how do the nitrous companies decide what pressure increase is needed? One pressure does not cover the entire rpm band properly. I can also see why they say to not spray at lower rpm's. It's not because your engine won't take it. It's because the mixture will be horribly lean and that will cause the engine to grenade. On our 2.5 engines the A/F mixture can't be right until your over 50% injector duty cycle. The injectors won't work at the fuel pressures above 100psi.

I guess I'm kind of going off topic here.