ok this is gonna sound stupid but how much fuel can a stock fuel injector push out?

like if i got a fuel pressure reg. and just put the fuel up on that .. will it work for more fuel?

can i use 93 octane gas safely?

or the gas thats not unleaded but the other kind forgot that it was called HAHA

thanks


oo and to let u know why im asking about the fuel injectors and the 93 fuel

i have an intake, 2.5 inch exhaust, high flow cat, about to get heads p&p, cams, vavle work, throttle body , umm idk what else but all motor?

so just wondering if the fuel will help with the air and @!#$?

ooo and when i got my high flow cat on and exhaust , my engine light is on and it is talking about the sensor right by the cat (if u know what i mean ) maybe ill ahve to put my code on here so maybe someone can tell me how to help that

Yes. Octane (In America at least) is a average of the combo of Research-octane (Estimated in a lab) and Motor-octane (Measured in a single-cylinder variable-compression engine) divided by two. The result is a calculation of knock-resistance. How does this play to your engine? Simple: Take whatever your engine's (static) compression is (It's usually listed in a book) and move the decimal point one place to the right. You now have the minimum required octane for your engine to run upon that'll prevent knock. No need to increase fuel pressure above the factory recommended specs or anything. And no... it won't ruin your injectors.

As for the arguement of spark-knock (Yeah, I knew you guys would bring that up), if your engine still exhibits knock under heavy loads (full- or part-throttle cruising or acceleration (especially on a hot, dry day while in traffic), while climbing a hill...) then go with the next level up of octane gasoline commonly available to you until spark-knock is no longer exhibited.

BTW: The other fuel (I think you mean) is leaded (Contains tetra-ethyline lead), which was once known as Regular. It hasn't been made available to the general motoring public since '88, as it was phased-out (And no longer really needed for pre-'72 or even pre-catalytic-convertor cars ('75-on), since they al pretty much weren't on the road anymore) because on the environmental & biological hazzards it carried (Lead=poison). Plus, leaded fuel plugs-up & kills catalytic convertors if used in a car with one.

And for your MIL thrown by your post-cat EGOS, that's the PCM relaying the message that the catalytic convertor you installed isn't working effectively (Not cleaning the unburned hydrocarbons) enough. And since you related it to a fuel question, running a higher than realistically necessary octane fuel won't help it go away.


Go beyond the "bolt-on".

ok thanks man....

so how can i fix the engine fit?

ool and the code is o2 sensor heater cuircut manlfunction (bank 1 sensor 2)


oo and the fuel thing i was just wanting alittle more fuel because of the air that i have ( with the cams and stuff)

Quote:


How does this play to your engine? Simple: Take whatever your engine's (static) compression is (It's usually listed in a book) and move the decimal point one place to the right. You now have the minimum required octane for your engine to run upon that'll prevent knock

I don't agree with this. You're telling me that my 9.7:1 requires 97 octane to run without knock? And that the Eco (10:1) requires 100 octane? That the turbo eco car (9.2:1) requires 92 octane?





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Shifted wrote:

Quote:


How does this play to your engine? Simple: Take whatever your engine's (static) compression is (It's usually listed in a book) and move the decimal point one place to the right. You now have the minimum required octane for your engine to run upon that'll prevent knock

I don't agree with this. You're telling me that my 9.7:1 requires 97 octane to run without knock? And that the Eco (10:1) requires 100 octane? That the turbo eco car (9.2:1) requires 92 octane?

that's what i was going to say. there are plenty of 12:1 compression (static) running on pump gas (93 octane) without problems with knock.



87 Firebird
All stock...........lol.

My, many negative responses. But I can remedy that...

As you put the engine together, you start getting into things that effect the actual compression produced. This is called dynamic-compression. How that works is like this:

Got a short rod with a long stroke? It goes up because it effects port velocity, which draws in more air at lower engine speeds. Same with high-velocity port design.

Got an aluminum head? It goes down because aluminum is a 'Softer" metal, and actually absorbs some of the pressure. Rule of thumb is that with aluminum heads you can run up to a full point more static-compression than you would with iron heads, and still run the same octane.

How are the chambers shaped? This is something that few ever consider in relation to octane tolerance, as that alone can really effect it. Too many sharp edges & overall shape of the combustion area can really drive it up.

Is it force-induction? Well, since more air is going to be in the cylinder with it, as opposed to naturally-aspirated, it will go up... much like with high-velocity ports on a N/A engine (DUH!).

What's the cam timing & profile like? This alone can seriously effect dynamic-compression, as larger overlap areas & long duration (At low engine speeds) can reduce what the dynamic-compession will be... As those who've installed too-larger of cam can tell you.

Basically, what I gave last time was a rule of thumb to follow (For N/A engines, of course!). If you run F/I, more octane is better. but to learn what your minimum requirement will be in those cases, you basically work backwards (Start with the highest you can get, them go with increasingly lower ratings until it exhibits knock during typical operation). And engine tuning has a considerable effect too. Since most reading this have a electronic enigne management, which typically includes a knock-sensor, I'm willing to bet that the ECM picks up on any knock that occurs & dials the timing back from whatever the programed curve is until it doesn't see it anymore, which would allow a reasonably lower octane than what's ideal to be used. So there's something of a safety-net there.

But... going to far can indeed effect disasterous results. An middle-aged woman whom delivery of a '87 Turbo Lebaron & then ran 87-octane in it comes to mind... She got lucky & only the ECM needed replacement (Guess it had a nervous breakdown from rying to compensate) and the dealer tech told her to run only Shell SU2000 (Premium unleaded, what the engine was tuned on from the factory, and the best commonly available unleaded fuel around at the time) and she hadn't a problem since. Much worse could occur, thou... So don't push it!

And Chris, as for the need for more fuel... Just invest in the necessary tuning stuff & spend some time remapping the curve.



Go beyond the "bolt-on".

ok so if i got a fuel pressure reg. and tuned it on my stock injectors ....

my question is how much pressure is the stock injectors running?

how much can they hold on?

The book says it's supposed to operate at 41-47psi. The max it can handle...? Anyone?


Go beyond the "bolt-on".

41-47 psi ? ok so what is the max?

so i have a 2002 2.2L ohv engine so waht would i set the fuel pressure reg at?

To be honest, I never really investigated that. But to be safe, I wouldn't go much above that. 51psi max, I say.


Go beyond the "bolt-on".

ok well i prolly wouldnt go over 51 psi ...

what would happen if i did haha just wondering?

why do you want more fuel?

Get a wideband so you know what the engine wants and aren't guessing

what i would recommend doing is spending some time on a dyno and/or using a wideband O2 sensor to see how much more (if any) fuel you really need. There are also simple calculations you could do based on horsepower, brake specific fuel consumption, duty cycle, and the amount of injectors that can accurately tell you how much fuel you need. Then it's as easy as finding out how much you can produce based on the stock injectors and stock fuel pressure, and you will know a very close approximation of how well the stock fuel system is keeping up. My guess is you really don't need much more fuel.

And to nickelin dimer, good write up on dynamic compression. many people seem to forget that an engine in operation isn't as simple as spinning it over and calculating the difference in volume. i'm currently working on an E85 small engine kit for a school design project with toro, and effective compression ratios are becoming very important to understand and apply via cam timing.



87 Firebird
All stock...........lol.

Thank, Blackbird & Rand... I was about to tell Chris exactly the same, once I had computer time (I share mine with to others).

And Randizzle... Given that most small engines (Outside of 2-strokes) are L-head (Valve-in-block), I can tell you that even the static seen on the ones for non-race duty are staggeringly low (Try 7.8:1). And they won't respond well to just pouring higher octane fuel into them. I've done it, on an old lawn-tractor w/rebuilt engine. It'd start, then run briefly & die. You might want to consider looking into jr.-dragster parts for it, if you can. The compression seen by just the head change alone is amazing.

Now... Back to the show!


Go beyond the "bolt-on".