stock injectors

[Lil Freek]

How much boost can i push from stock injectors?
probably a dumb format for a questions... any of the below can be answered

What can the stock injectors hold (safely) in terms of power:
whp
boost
??

I'm looking to run 8psi daily and 10psi for fun.
properly tuned, i'm hoping for 200whp daily and like 225whp for fun.

should i beef up the injectors? I'd rather just get 440's than add more injectors, though.

[pdhaudio83]

what are you planning on managing the 440s with?

[Lil Freek]

I'm not 100%.. but can't i use the MPI to manage them?

[bluebyuwrx]

If anyone is interested I have a pair of wrx injectors...........just pm me

[pdhaudio83]

what size?

[Lil Freek]

isn't there another thread recently started about tossing shit like this into another person's thread?

[pdhaudio83]

Sorry, Lilfreek- people just randomly remember things and if they dont post them sometimes they forget- to help answer your question more, the stock injectors will prolly do 200-215whp, or like 12psi before things get dangerous.

Personally, I'd tell you to let a standalone control the injectors if you are using a bigger size for the primary (if you used stock for the primary, and added some secondary ones to the pipes, I'd say try the MPI) but I'm not sure how great the MPI works if you control bigger primary injectors with it...

[Lil Freek]

doesn't Focus use the MPI for his 8 injectors?
i'm not going to do standalone

maybe i'll just top out at 8psi for now

[NSNMotorsports]

I'm not 100%.. but can't i use the MPI to manage them?

Only if they are run as a pre-TB injector... getting them to work at the primary sites may be doable if they are the right impedance... but will be a HUGE pain in the ass to get to work well, if at all.

Stock injectors are 280cc... so you can find calculators all over the net that will tell you how much effective displacement and horse and so forth you can get out of them.

[NSNMotorsports]

doesn't Focus use the MPI for his 8 injectors?
i'm not going to do standalone

maybe i'll just top out at 8psi for now

You can fire a second rail as a grouping if you want... same as a pre-TB injectors.

[Ken@ProtegeGarage]

kooldino uses his mpi to run a pair of extra injectors if i recall correctly.

for me the 4 stock injectors were maxed at 8 psi according to my haltech's tuning software.

[bluebyuwrx]

Well I thought that maybe the thread starter may be interested in his quest for more horsepower, and since I have no use for them I figured Id offer them up. Since my cars injectors flow as much as the STi injectors Im all set :)

[brealmp3]

well from my readings, the regular protege injectors are the same as the msp injectors correct? i know a guy here with an msp and the mpi on stock injectors running 11psi making close to 210whp and that was with an ok tune... he has done some retuning and seems to be making more power, but hasn't been back to the dyno. so if we have the same injectors, and ken i remember saying that the regular protege fuel pump was the same as the msp, i don't see why you would need larger injectors as long as you get a good tune.

[NSNMotorsports]

yeah, injectors are the same on both the MSP and the proteges.

[BRIAN MP5T]

well from my readings, the regular protege injectors are the same as the msp injectors correct? i know a guy here with an msp and the mpi on stock injectors running 11psi making close to 210whp and that was with an ok tune... he has done some retuning and seems to be making more power, but hasn't been back to the dyno. so if we have the same injectors, and ken i remember saying that the regular protege fuel pump was the same as the msp, i don't see why you would need larger injectors as long as you get a good tune.


for me the 4 stock injectors were maxed at 8 psi according to my haltech's tuning software.

I agree with you on that, when I ran the P5 at 6 Psi without the EIC-2, I noticed it was simply not able to keep up with what I would call a "Safe Fuel Mix"

Personally, Peeps that simply add a MBC to an MSP with a stcok fuel system are simply fucking themselves, eventually it will fail and if not they are still wearing the engine much quicker.

Fuel must be addressed IMO before the MBC goes on, even a cheap FMU.

That plus a decent FMIC and a set of mounts. I see the MSP running 2 Psi higher than stock, safely on stock injectors.

[atticus1398]

ouch Brian, that seems awfully conservative. i am currently boosting 13-15psi w/ unichip(for about a year now). we will see what my AFRs are once i install my w/b. i have 440ccs and a perrin fuel rail waiting to go in. not sure yet if i will go with microtech or just get the unichip retuned. unichip can be tuned to control extra injectors or bigger primaries.

[BRIAN MP5T]

Conservative with the stock ECU?

Flow and Control are an issue.

[Lil Freek]

but i'm using the MPI which will assist in my fuel dumping.

i might get a new fuel rail, though....

[BRIAN MP5T]

but i'm using the MPI which will assist in my fuel dumping.

i might get a new fuel rail, though....

Fuel Pump

[Lil Freek]

yeah.. i suppose i'll have to get a walbro.

it's not hard to replace in protege, is it?

[BRIAN MP5T]

No, Under the back Seat.

[Bigg Tim]

You can control the larger injectors with the MPI, but they will be in batch mode like the Haltech uses. They will have to be the same impedence as the stock injectors like NSN said. You could leave the stockers in place and run xtra injectors and retain teh stock drivability.

The stock pump can handle well over 300whp, so replacing it now is not necessary.

[BRIAN MP5T]

You can control the larger injectors with the MPI, but they will be in batch mode like the Haltech uses. They will have to be the same impedence as the stock injectors like NSN said. You could leave the stockers in place and run xtra injectors and retain teh stock drivability.


That is basically what I'm doing with the EIC-2.

The stock injectors do the "thing" until the car goes past -1 Vac

[Peepsalot]

Well I was just looking it up and apparently our injector size is 285cc/min

I've tried a couple equations I found, and the amount of horsepower you can get out of them just isn't adding up. I am getting very low numbers. Does anyone know what the psi of the stock fuel system is?

There is a calc at the bottom of this page: http://www.stealth316.com/2-air-fuel-flow.htm
And it comes up with a max hp of 153, using a BSFC of .6 and IDC of 85

I tried another equation from a book of mine, and it is telling me that they are good for only 173hp at 85% duty cycle. I'm pretty sure this is supposed to be crank horsepower btw.

This seems to go against real world dyno proof, so I'm not sure what to think right now. Either the rating of 285cc is not correct, or not measured at the standard 43psi, or our car's fuel pressure is higher than 43psi. Or the laws of mathematics have changed.

[pdhaudio83]

The stock pump can handle well over 300whp, so replacing it now is not necessary.

Just totally curious. I really am rooting for this to be right, but other people have said that it is weak.

For me, I am running stock pump with 440s, and people say its a big risk.

Do you know other people that use the stock pump for their large fuel needs?

[Mr.Win]

Honestly though pat... i think your gettting to the point where a bigger fuel pump with a constant 12V might be a good idea.

As for you lil freek, You can push the injector for a lil bit with a 12:1 vortech FMU, the spray pattern will be altered but you should get all the fuel you need. That or purchase an extra injector set up.

[NSNMotorsports]

85% is just "safe".. you can get away with around 95% in some cases...

we definitely do not have gigger than 285 based on the manual.

You are using a really rough BFSC:

0.32-0.38 Two-stroke diesel engines

0.37-0.44 Fuel injected four-stroke gasoline aircraft engines

0.40-0.48 Fuel injected four-stroke gasoline automobile engines

0.43-0.48 Carburetted four-stroke gasoline aircraft engines

0.48-0.60 Carburetted four-stroke automobile engines

0.55+ Two stroke gasoline engines

0.55-0.70 Four-stroke aircraft engine takeoff fuel flows




Well I was just looking it up and apparently our injector size is 285cc/min

I've tried a couple equations I found, and the amount of horsepower you can get out of them just isn't adding up. I am getting very low numbers. Does anyone know what the psi of the stock fuel system is?

There is a calc at the bottom of this page: http://www.stealth316.com/2-air-fuel-flow.htm
And it comes up with a max hp of 153, using a BSFC of .6 and IDC of 85

I tried another equation from a book of mine, and it is telling me that they are good for only 173hp at 85% duty cycle. I'm pretty sure this is supposed to be crank horsepower btw.

This seems to go against real world dyno proof, so I'm not sure what to think right now. Either the rating of 285cc is not correct, or not measured at the standard 43psi, or our car's fuel pressure is higher than 43psi. Or the laws of mathematics have changed.

[Peepsalot]

Ok, well, that is what the page recommend for turbocharged engines, so I just went with that. Maybe ours are more efficient. Even so, using BSFC of .4, it seems like our injectors start to be out of the "safe area" at around 230bhp, which would be near 200whp I think. Or does that BSFC account for drivetrain loss as well?

[NSNMotorsports]

I think the BFSC compensates for the drivetrain as you usually calculate it based on actual gasoline used... a turbo engine is technically more efficient than a normal engine... so I would think going around .4-.45 would be accurate.

[CasopoliS]

I know someone on MSpro was running 440's with the DSM AFC, but I have not heard long term results. Don't think the pump was upgraded.

So... all the pros out there...
what is the verdict on the stock MSP pump? Is it big enough to feed aux injectors / bigger injectors? Is a drop-in needed? I have heard both ways on this and would like to discuss it.

[Bigg Tim]

Just totally curious. I really am rooting for this to be right, but other people have said that it is weak.

For me, I am running stock pump with 440s, and people say its a big risk.

Do you know other people that use the stock pump for their large fuel needs?

Dean made over 330whp with the stock injectors and pump, plus two 440's pre-TB, and he had fuel left over. How much higher, will be found out by you since you are running more boost and power. Fastlane is around 300whp with plenty of room left over also. I don't know the IDC's of the sotckers or the xtra injectors, but I can't see them being too high.

You are only running 440's, so maybe you might need more injector to hit the limits of the stock pump, who know's? Let us know when you hit the wall and if it is an injector wall or pump wall.

[pdhaudio83]

I can tell you now, its an injector wall. My IDCs have hit about 95-97% under certain conditions.

If I were to upgrade to 550cc's, I'd HAVE to retune, and if I am doing that, I MIGHT as well upgrade the pump.

[Bigg Tim]

I can tell you now, its an injector wall. My IDCs have hit about 95-97% under certain conditions.

If I were to upgrade to 550cc's, I'd HAVE to retune, and if I am doing that, I MIGHT as well upgrade the pump.

I can see it being an injector wall because you are at 1760cc's total, Dean had 2000cc's total. I think you are probably right about the pump though, it has to be close to the limit.