ok, i would have thought that this would have been discussed a million times already, yet searches for "max boost," "most boost," "how much boost," "highest boost," "stage 2 boost," etc, yield no results.

can someone please point me to a post that discusses (or debates) the maximum boost levels that can be run on an HRC stage 2 with built internals (stage 3 i suppose). i ordered the FMIC tonight, and it seems as though hahn ships the stage 2's with a 9psi wg actuator because of the fact that most people are on stock internals. surely the weakest link in the motor after the internals isnt going to still limit me to 9psi?

Stock injectors will pretty much max out at 7 psi. At that amount of boost you're running close to or over 100 psi of fuel.

The Hahn Stage II actuator is set to 9psi but you'll only see about 7psi running it through their FMIC. Even with proper fueling I would not run over 7-8psi of boost on stock internals. However, as stated above, 7-8 psi of boost is pretty much maxing out your stock injectors.

Edit: I said "pretty much" too damn much...

not stock internals

if youve got a built bottom end in there, why not shell out the extra 200 bucks for some upgraded injectors? www.exileracing.com sells injectors for good prices plus the owner is a respected member of the board.

thats the next thing on the list...however, im worried about running larger ones on the cartech regulator. correct me if im wrong, but the 440s CAN be run without an SAFC right? i can feasibly change the injectors and regulator soon enough, but an AFC and the accompanying tuning and install is way off. i'd like to run 15psi right now. can i do it with 440s and a SFMU WITHOUT having a fucked idle?

Originally posted by Uberingram
Stock injectors will pretty much max out at 7 psi. At that amount of boost you're running close to or over 100 psi of fuel.

Thats interesting. I was able to run 11lbs of boost on stock injectors. 110psi of fuel pressure, the injectors were screaming, but they did it. I think 7psi is not accurate. Sorry to disagree with you, but I really think that if you couldn't run 10lbs, then HRC wouldn't say you could AND people would actually say this. These days people say don't run more than 10lbs of boost with stock bottom end and stock injectors.

a point on the cartech
i just got a recalibration kit for mine
to go along with the 270cc injectors
craig at hahn said that with respect to the fuel
as long as my engine can handle it
my injectors with the recal kit is good to 10psi on stock compression

Originally posted by baxsom
...with the recal kit is good to 10psi on stock compression

stock compression, or stock internals?

and james, when you were stage 3, what size injectors and boost level did you upgrade to first (not familiar with your setup now). did you go to 440s and 15psi? if so were you using an AFC or not at the time? next week i can install the FMIC, the week after i could purchase and install the SFMU and the week after that i could get new injectors. however thats about as far as i can, or am willing, to go at this point. i still need to get the exhaust dump installed, new suspension, throttle body, brakes and motor mounts before going into any electronic engine management or tuning (AFC, wideband, ignition, etc). i think the question has been raised several times before, but without browsing through literally hours of pages, can i run 15psi on an SFMU and 440s while retaining a decent idle. (contrary to the above, i am not really planning on using the stock injectors for very long).

Originally posted by cyan

Originally posted by baxsom ...with the recal kit is good to 10psi on stock compression

stock compression, or stock internals? and james, when you were stage 3, what size injectors and boost level did you upgrade to first (not familiar with your setup now). did you go to 440s and 15psi? if so were you using an AFC or not at the time? next week i can install the FMIC, the week after i could purchase and install the SFMU and the week after that i could get new injectors. however thats about as far as i can, or am willing, to go at this point. i still need to get the exhaust dump installed, new suspension, throttle body, brakes and motor mounts before going into any electronic engine management or tuning (AFC, wideband, ignition, etc). i think the question has been raised several times before, but without browsing through literally hours of pages, can i run 15psi on an SFMU and 440s while retaining a decent idle. (contrary to the above, i am not really planning on using the stock injectors for very long).

i had stock injectors.. running 10lbs of boost all day long.
bumped up to 310cc injectors.. build the motor.. ran 13lbs of boost
bumped to 440cc injectors.. started running up to 21lbs of boost
bumped to portfueler....... now its just sillyness

i have never used an AFC.

if you install 440cc injectors you need to turn your idle pressure down to 20psi.. its low.. the car acts a little funny and you are rich, but it does work and there isn't much point on spending money on the AFC. granted you will be running rich, but rich is better than lean.

with 440s and the SFMU set at 15-20 psi idle FP, i assumed the idle would be pretty bumpy and i knew it would be pretty rich, but if you were to install an AFC is it possible to use the AFC to control idle fuel pressure but keep it away from boost fuel pressures? im not too familiar with that unit...id like to be able to get a decent idle but not have a device screwing with something thats going to cause it to advance timing.

the part where im getting confused is this:

1) some people are using 440s and an SFMU at 10psi idle and are fine. others are using the above setup at 20psi and are also fine...is there really enough variation of other factors that could cause both of the above idle FPs to be acceptable?

2) others are posting all kinds of different spring/disc combos to achieve the proper idle and static pressures. is there some sort of majority concensus on which spring and disc to use or what? i've seen so many different combos that i cant remember what is best...ive heard all of this stuff before, but cant keep it organized in my head.

Originally posted by cyan
with 440s and the SFMU set at 15-20 psi idle FP, i assumed the idle would be pretty bumpy and i knew it would be pretty rich, but if you were to install an AFC is it possible to use the AFC to control idle fuel pressure but keep it away from boost fuel pressures? im not too familiar with that unit...id like to be able to get a decent idle but not have a device screwing with something thats going to cause it to advance timing. the part where im getting confused is this: 1) some people are using 440s and an SFMU at 10psi idle and are fine. others are using the above setup at 20psi and are also fine...is there really enough variation of other factors that could cause both of the above idle FPs to be acceptable? 2) others are posting all kinds of different spring/disc combos to achieve the proper idle and static pressures. is there some sort of majority concensus on which spring and disc to use or what? i've seen so many different combos that i cant remember what is best...ive heard all of this stuff before, but cant keep it organized in my head.

the afc will not control the idle fuel pressure, it simply changes when the injectors open and for how long to lean or richen the system. all cars are different, therefore some settings work best for some and others are different.

for 440cc injectors, i used the 2.72" ring/disc and the short, dark spring. i was able to achieve low pressure and could tune decently well.

So, to answer your question, the answer is yes. But, my question to you is, why are you so set on the 440's if you're worried about idle? Why not just get 310's, run it with the SFMU, and when you have the money later, get bigger injectors and SAFC. You can always sell used 310's on this board.

whats the boost limit for 310s?

what about using 36lb injectors? is or is not a happy medium between 310s and 440s. 36lbs is what, 370cc?

Originally posted by cyan
whats the boost limit for 310s? what about using 36lb injectors? is or is not a happy medium between 310s and 440s. 36lbs is what, 370cc?

310cc will take you to about 13lbs of boost.

36lb injectors will take you to about 15lbs of boost. not much difference.

go with the 440cc injectors right off the bat and dont waste money like i did.

seems as though the most popular route (440s and SFMU) is the most popular for a reason.

if not using an SAFC, don't the injectors run at 100% duty cycle?

I'm selling my Accel 40lb injectors if you want them.
I used them w/ my SFMU. Worked well, but freerev sucked even with an AFC. Set at like 21 or 22psi. I didn't want to make it any lower.

I have a set of 1000cc low impedance injectors ready to be installed along w/ an Aeromotive and the MS.

To answer your question, I would not recommend using the stock injectors at all with boost. My EGTs started gettin' goofy around 6 lbs. I tend to fix things before they fuck up, though.

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

What's the maximum PSI you can run on stock injectors? Nobody knows because nobody's been stupid enough to push the limits of a $3000 built engine when they could just replace a $150 part.

If you want a number, 7-10psi tuned RIGHT. Use a wideband. Pray.

Go higher if you want, it's your money.

Originally posted by HiOnPSI
I have a set of 1000cc low impedance injectors ready to be installed along w/ an Aeromotive and the MS.

Woah isnt that overkill? Or does the MS handle idle that well on such huge injectors? I still need to figure out what set to get myself...

It is a bit overkill on the 1000cc injectors. Im not sure the spray pattern will be great at idle, but at any other load they will work great.

Cyan I would recomend against using an AFC, it does wacky things to your timing, and you can get a MS from mrslick for $300 (almost the cost of an AFC) and it will run your car much better than any rising rate regulator ever will.

Bottom line is:
You need to decide on a good fuel solution, either a SFMU and large injectors/portfueler/8 injector or the MS system or some other alternitive.

YES you can run 10psi on stock injectors. I did this for over a year with a cartech regulator. Is it wise, NO. Would I do it again. NO.

stock compression, or stock internals?

to answer the question completely
both

i consider the fact that my compression is lower than stock to be a safety zone
so whenever i talk to hahn about limits
i always ask about stock compression limits
then i know i am ok

I had no problem running 10psi on my stock bottom end with stock fuel system, but I live at 5000ft+ over sea level so my air charge is less dense. My cartech FMU was maxxed out at about 110psi. I wouldn't reccomend it though unless you have an in-dash fuel pessure gauge because if you loose even a little pressure at 10psi even on upgraded internals you could do some damage. My ex-man on my old 1G got majorly warped because I was running way lean, then one of my turbo studs cracked and I had a terrible exhaust leak.

we're going to see how well it handles those injectors :)

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

sigh...

it's time for a megasquirt or 8-injector i guess then. it will probably be cheaper to go with the MS & some 40 or 48# injectors than 440s/SFMU/SAFC anyway.

in the meantime i may be interested in getting some injectors. i dont want to go with 440s though. i want something that i can get a guaranteed good idle from, yet will still boost to 15psi with fuel pressures below 100psi. 330s? 370s? i wonder. any thoughts?

310's are relatively cheap and got me into the 13's...plus the car runs pretty much like stock.

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

how much boost were you running with 310s and what spring/disc combo did you have in the sfmu (if using one) at the time?

10 lbs, and the gay ass cartech, and 12:1. i think i ran a 13.8

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

12:1? on the cartech?

cartch has recalibration rings and discs
that put it at 12:1
havent checked mine on a wideband yet
but that is what craig at hahn told me the kit would meter at

nah, 12:1 meaning 12psi fuel pressure increase for every 1lb of boost

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

OOOHHHH

never mind that then
with the recal kit
hahn told me that at 8psi of boost i should be seeing from 85-90psi fuel pressure
so whatever that works into
from a starting fuel pressure of 45

sounds about right. Hell, I ran those 440s on a 12:1 and i was maxing out fuel pressure...still got 10:1 flatlined AFR

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!

i understand the 12:1 ratio and what it means in relation to the pressure...my question is, if you were boosting 10psi on a 12:1 regulator, your boost fuel pressures would have been over 120psi. are you sure you were running them that high?

Yes, it just maxes out pressure..roughly 110psi or so.

Jon

1997 Eclipse RS
1998 Dodge Dakota Sport
12.671 @ 111.660 1.586 60' 5/28/04

www.haiokuracing.com

shaun> i'm sayin', bro!