what stops people from running 10 to 12 psi???
is it interals or fuel???

its arguable, but i personally think fuel, esp with the star kit. cause HRC ran 17psi before internals actually blew, and that only happened cause they ran lean.


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Actually...I ran 10psi once and my air/fuel was all the way at 1.0!!! And staying strong.

It's the internals that stop people.



Ball Bearing Star Stage II
"Power is nothing without control"

Actually i think its the stock injectors (230cc) !!!!!!!!

LAST EDITED ON 05-May-01 AT 02:15 AM (PST)

Hehe, I have to get in on this one...

(I ran @ 10psi like I was *supposed* to...)

IMO Its the internals... Specifically the POS rings that we have.

See my car was 18% leaned out onthe SAFC and I was getting good O2 voltages (i.e. correct air to fuel ratio), but I STILL blew my engine.

Why? Beacuse the piston rings couldn't take it... It was a gradual thing, with me starting to get blow-by until one day, the blow-by was so great that it blew my camshaft seals out....

Mind you the rings can also get blow due to lean conditions. Another theory is that the injectors CAN deliver the fuel, MOST of the time, but should they run lean for a fraction of a second, that sudden "impact" will screw up the rings. See unfortunately at 100+psi for fuel, things aren't very nice.

I once "accidentally" ran 14-16psi and it was the strongest pull I have ever felt....And nothing happened to the engine (2 months later I blew the rings). I also drag-raced my car every week without fail, and the day that they blew, I had made 19 passes....

Guy
RS_Guy



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Like i said its the STOCK injectors!!
First of all I have not seen fuel pressure over 120psi, and second, even if it could get that high and over you would be risking it with possible injector failure!!

Here's how i see it:
stock injectors 230cc @ 43.5psi
stock injectors 380cc @ 120psi
On the most basic setup (intercooled) @ 10psi you should be somewere around 270bhp. With that said, using the formulas provided on the RC website we would need 442cc's of fuel per injector to provide sufficient fuel for that type of power!!!
So if we need 442cc's of fuel per injector, and the max we can provide is 380cc per injector we are in trouble @ 10psi !!!

I would have to say the maximum boost a stage2 system should ever
see on STOCK injectors is 8psi !!

We do need about 380 cc/min per injector of fuel for that HP. At full boost, our stock injectors are probably at or near 100% duty cycle (contantly open). So that means we are actually getting around 380 cc/min of fuel per injector. The formulas on RC's website take duty cycle into account. Say you put in an 86% duty cycle to be safe and it says you need a 442 cc/min injector to do that. Multiply 442 cc/min by 0.86 (duty cycle) and you get your 380 cc/min of fuel. In short, it takes a bigger injector to put in the same amount of fuel at a lower duty cycle.



Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

So what exactly should be upgraded and needed in order to run strong and with no probs at 10psi?

my question is will an injector above 440cc work with a SAFC? i was told it wouldnt be able to alter the mix enough to compensate??? someone explain

http://www.geocities.com/blue2gnt

440's work fine with a S-AFC. As long as you don't crank up the pressure on them. If you're just running 9 psi boost, you don't need to increase pressure to the injectors at all. 440 cc/min of fuel is plenty. And, from what I've seen, changing the MAP sensor voltage by 40% doesn't necessarily mean the ECU will put in 40% less fuel. You just have to work slowly and find the settings that work best. Its going to take me a while before I get my settings down...can't afford dyno time...assuming that there was a dyno nearby.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Excellent post boostin rs and rienforcemnet by Corbin. I just learned about duty cycle and how injectors work last night. I couldnt have explained it better.

Injectors it is:P



Ball Bearing Star Stage II
"Power is nothing without control"

So it's mainly just the injectors? If so, what size injectors would allow me to run 5psi daily and 10 psi for race? Would the same injectors that would work on the 5psi and 10psi work for me when I'm boosting 12psi? dam......I just confused myself. LOL

The problem we are facing is that the stock injectors have to be cranked to mad fuel pressure just to work with the high levels of boost we want to run. Fuel pumps are rated at certain flow levels at certain fuel pressure levels which degrades the higher you crank the pressure. It works, BUT there are better ways, as in injectors and AFC. If you want the cheapest way, just get some slightly larger injectors that the stock ecu can handle with no help. Something like a 280 or 310, not sure what the actual largest it can handle really is, just speculation. This would allow you to drop you fuel pressure to more reasonable levels and not work your fuel pump to death. The ultimate way is to get some larger injectors -400-500 range imo depending on turbo size and amount of boost you want to run, and a S-AFC to work with, which is what everyone is doing. Just look for what the max boost you want to run is, figure out how much flow on your turbo that is, and then sort out waht size injector is needed to support that. Keep in mind your fuel pump will make a difference too.

MuRiX
97 Eclipse GS HRC Stage II
And a whole lot of other mods...
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sweet! Thanks for the info dude. it's time to get back on the phone and start ordering the S-AFC. Thanks for your help.