Fuel 101

[growguy]

i must be missing the point then. what is the significance of having a fpr if it dosent increase power. theone has one i read on his post in the member's section, but i guess what im asking is how you would get more power though a walbro fuel pump / fpr.

injectors or a fuel rail mabye? i am a newbie with regards to fuel

[Fearit22]

Well just think of it like this ... it doesn't add more power, but it gives you the capable to have more power. For example you couldn't run a turbo @ 25 psi on stock fuel rail, injectors, and pump because none of those things could flow efficiently or fast enough to supply you with you fuel you need. Unless you have upgraded to a turbo or very large shot of nitrous you really don't need new injectors or a fuel pump. The fuel rail is only necessary if you are running a wet nitrous kit (it has a slot for the nitrous) or if you have a very, very powerful engine. If you get new injectors it's probably a good idea to upgrade the stock fuel pump too. Basically you don't need any of this unless your car is pretty heavily modified.

[MRX]

i believe its the 1st gen dsm injectors you want ( not sure of tranny type tho...not even sure if they change) . They are the blue top ones however. You'll need to get the o-rings for the our stock injectors and just bore them out slightly. The dsm injectors almost work but its a tight squeeze for them to get into the o-rings. We use stock o-rings because the outer edge naturally fits the intake manifold...imagine that lol Anyways i'm in disagreeance with the run as lean as possible assuming there is no detonation or pinging of any sort. I think it'd be best to let a dyno prove what fuel pressure would yield the best power. But the point of the fpr (only raised a couple of psi) is to make the fuel and air mix better with the mist effect. It may in fact add more fuel but i did say its best to be left on a dyno or an egt gauge (which i still won't get into because i don't want the controversy) but if someone wants me to explain egt's (exhaust gas temperature gauges) i'd be more than happy. More power through a fuel pump and fpr depends on your current mods ( please state them). Its just the process of using the correct amount of fuel with the increased in coming air. Its definately not the first mod you should look into but rather the third or fourth. Even if it doesn't yield gains right away you WILL need them if you plan on modding your engine be it forced inducted or N/A.

[Fearit22]

From what I've seen and heard from everyone, running as lean as you can safely will yield the best power results. Unless your injectors are malfunctioning then increasing the fuel pressure wouldn't make much of a difference. That is how injectors are supposed to work ... they spray out a mist and the only reason they wouldn't is if they were dirty/clogged at all and that could be fixed by some good fuel injector cleaner. Putting out more fuel wouldn't help at all if there isn't enough air for it to properly combust. That just makes you lose power and is why your car will be shooting out black smoke when it's running rich. Either way you shouldn't be messing with any of that stuff without taking it to a dyno. Don't adjust your fuel pressure or anything without doing it on a dyno because I don't know of anyone who can do it without one and get it right ... it's just not a good idea.

[MRX]

fearit22 and I are on the same page then and we both say DYNO IT. There are some wicked pros out there that have done countless setups and know how to tune without dynos (still recommened) but it'd still be better to tune on a dyno...besides aren't you curious. I'd say tell the techs to play around with the fuel pressure and see what results you find. As for the dyno being far away...make it happen

[Fearit22]

Yeah, it's not something you skimp out on. Running rich won't really hurt anything, but if you run it too lean then good bye engine. Just leave it to pros that know how to tune it.

[growguy]

thanks for clarifying that. i was seriously confused with some posts here. until my engine is heavily modified work on the fuel system is not nessasary.

[MRX]

Originally posted by growguy
thanks for clarifying that. i was seriously confused with some posts here. until my engine is heavily modified work on the fuel system is not nessasary.

i'll take the liberty of confusing you a bit more. The fpr would be the only thing you'd want with a mild n/a setup (couple of bolt-ons). The fpr not only raises it can also lower fuel pressure which in fearit's theries would cause less fuel to be injected thus causing a slightly leaner a/f ratio correct? Well in keeping with his theories leaner means a bit more power. ponder that

yet i still remain firm that playing around with it would tell a different story

[ZigenBallZ]

You can gain decent results from just using the butt dyno... but of course you can really fine tune it on a dyno.... and I don't know how much it costs where you guys live but I can't blow $100+ just to tune my fpr...

Anyways... there are some blatant misconceoptions in this thread... You can do damage by running too much fuel.... washing out the rings is what it's called...

If your fuel pump is in good condition it should have no trouble holding up to 220-240 hp... a lot of guys are getting these 255lph fuel pumps and wonderinf why they have problems and such.... that's way more than anything you could ever need unless you are running something crazy.... 190lph is also more than you could need... check out this link since he went to all the trouble to do the research...Fuel Pump Test

and I/H/E leans out the mix slightly to begin with so there would be no reason to turn the FP down... fuel mods do help after doing air mods like I/H/E... it's the next logical step to take...

Fearit is right... you do want to run at the edge of being lean on an N/A setup to make the most power possible... as close as you can get without detonating... so you usually have to run a very slight buffer zone to avoid certain problems but that was right on target...hence the "as close as you can get"...



I find it amusing that some people are wanting to run certain parts just because they saw them on someone else's car without really knowing why.... doesn't anyone search for stuff anymore...I don't say that to single anyone out or be a dick... but that's the worst reason I've seen yet for wanting a part...

[MRX]

I think i miss understood fearit. I thought he was talking about a FI setup. It was the buffer zone i was trying to describe. Fearit's words translated to me as run as close to detonation as possible without touching it...thats too close for my comfort which is why i was trying to say keep a buffer zone just in case some freak accident happens you stand less of a chance of blowing the motor. He may be correct for an n/a setup but for FI setups we need that buffer. As for the rich thing i was only talking about running rich within reason. If you run rich enough to wet your spark plugs your engine may not start with out u drying them out. If you wash the pistons you should just be ashamed of yourself. And yea $100 is alot so its not commonly done.

Lets start a quick mod list for fuel additions...that should help clear some confusion. Concentrating on getting air in and out as fast as possible and efficiently here on an n/a setup in order:

intake
headers
exhaust
fpr<-----add fuel
ignition upgrade (spark plugs and wires don't really count)
ported and polished head and head job (valves)
port matched manifolds
bored out tb
fuel pump<adding more fuel
ignition upgrade
ecu trickery with upgrades to ignition to balance everything out

Tell me how u guys like that "to do" chart

I'm gonna have to agree with zigen on the horsepower thing because h22 cb7's don't switch out their fuel pump until slightly modded. Does the horsepower coincide with the need for a fuel pump tho? I would think it would have more to do with the cfm's the head flowed.

[Fearit22]

Well I was pretty much implying running rich within reason. If you are running rich enough to do that you shouldn't be anywhere near a car to begin with. There is one thing I wasn't completely sure on.... Will having a cam make you run leaner or richer? I thought it would make you run leaner because it's flowing more air, but someone else told me differently. I think your list is missing one very important thing. No ignition upgrades. All that fuel and air isn't going to help if you aren't burning it efficiently. I would recommend adding a msd ignition, blaster coil (whatever the hell they are called), better ignition wires, and some new plugs. I had a question about the ported and polished head also.... They have to completely take apart your engine to do that right?

[MRX]

I was concentrating on getting air in and out as fast as possible on the previous post. I didn't want to get into how engines make power i was just focusing on air and fuel ( however i did add in ignition upgrades at the end), regardless its been edited. For P&P's they just have to take off the head and the manifolds. It'd just be taking off everything you would normally take off if u were doing a head gasket change. The cam thing would be more depend on the cam you bought. Different cams for different applications as u already know. FI cams close the valves a bit sooner i believe and n/a cams keep them open a bit longer. I think it'd depend on the application but that was a great question and has got me thinking...i like this thread lol I'm still at a stalemate on if it'd affect the a/f ratio tho.

[ZigenBallZ]

Both of you guys mentioned everything elsewhere...so you guys had it right.... it's just keeping track of the details and the exact topic....

FI is not my forte by any means but I do know that the target mixture is waaay different for an FI setup... you want richer mixtures...


I would differ about the order of some the of things on your list but looks good IMO...

Ignition would be the next logical step after air and fuel upgrades... it's a touchy subject though... some say stock is good for so much power but then they turn around and upgrade other unnecc things like fuel pump and cite something like I might need it one way... That rationale always confused me but whatever....

<edit> DOH! forgot the part about cams, it's not really as simple as running lean or rich with them... They generally change the dynamics of the intake and exhaust charge... and change the use of the fluid dynamics in the head... so depending on what the full, exact specs are of the cam you are running they might be able to use air and fuel more efficiently or differently but there are a lot of other factors to take into consideration.... IMO I don't think it could be described as running lean or rich with a new cam/s because so many other things are altered...and would be totally dependent on how the cam in question interacts with other modifications as well as what your static cr is at along with how it affects the dynamic cr and also minute design differences can affect things.... It just too broad of a thing to say yes or no either way while speaking in general concept terms like these...It really would have to be applied specifically to a particular setup and engine....but midnite touched on some of the general differences between cams more suited to FI and N/A...
I have recently been informed that I suck at explaining things so if someone else wants to explain it a little better....have at it... <edit>

and as far as porting and polishing a head.... nope, not the whole motor or anything just the head...you could slap it on a bone stock bottom end if you so desired...

Good discussion though guys....some good info and good points were brought up....

and I apologize to growguy...Didn't mean to come off that rude or harsh since you were just wanting to know before actually doing it... but I would strongly suggest doing a bit more research into the parts you're looking at just so you understand what they are doing, how they help and why....

[MRX]

just found more info on the zdyne.com site.

Does the factory forced induction car have a rising rate regulator?
Hell no! Stock injectors (above about 60psi) can stick open or leak. Add the fact that injectors "give up" at high pressures - the point of diminishing return - more pressure does not equate to more fuel flow. Our tests (which you can duplicate on your own car using an electrically isolated fuel pressure gauge on your dash), showed that most (the typical round black one) RRRs DO NOT HAVE A RISING RATE. It is an on/off switch where the "rate" simply specifies the on ramp slope. Worse yet, was seeing that it simply did nothing until about 2-3 psi boost! Note that there are a few expensive regulators that function a bit better, but the high pressures are still hurting your factory injectors. Nor will such a configuration ever approach the adjustability of a large injectors/3D tune system.

[MRX]

just found this from various sources online.

AS THE RELATIVE AMOUNT OF FUEL IN THE MIXTURE DECREASES ( A LEANER MIXTURE ) THE A/F RATIO VALUE BECOMES LARGER. AS THE PROPORTION OF FUEL BECOMES GREATER ( A RICHER MIXTURE ) THE A/F RATIO VALUE BECOMES SMALLER.

A/F RATIO COMMENT

9.0:1 BLACK SMOKE (NO POWER)

11.5:1 RICH BEST TORQUE @ WOT

12.2:1 SAFE BEST POWER @ WOT

13.3:1 LEAN BEST TORQUE @ WOT

14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )

15.5:1 LEAN CRUISE

16.5:1 BEST FUEL ECONOMY (EXCEPT FOR HONDA MOTOR COMPANY)

18.0:1 CARBURETED LEAN LIMIT (EXCEPT FOR HONDA MOTOR COMPANY)

22.0:1 EFI LEAN LIMIT

The ideal A/F ratio is expressed in pounds weight of air and fuel. You want to be a little rich, to make sure there is plenty of fuel for the available air, 12.5:1 seems to be a good place to be. Anything richer and exhaust temps go down and so does power.