Prelude 345's is it enough?

[Likklekilla]

I am running prelude 345's in my car now. Currently running 7psi car runs ok with HKS AFR and ungraded walbro pump i would like to know if that setup is enough to run 9psi daily? Just curios b/c i notice most people use the 440's. Just want a little reassurance b4 i go up in boost.

Can someone explain to me how an AFC works?

And when i add percentage fuel at a certain RPM wat exactly are u doing?

[kommon_sense]

Yeah, 345cc should be fine. Most go with 450 because you can get the dsm injectors for cheap.

[kyosoeg6]

im not sure what 345injectors max out at but 450's max out at about 10.8 - 11.0lbs of boost.for your car to run very good u have to get somebody who knows how to tune,or u can do a lot of research.it is best to get big injectors and trim them down with a vafc or hondata than to have stock injectors and raise the settings.there is sumthing called a duty cycle that dramatically improves or damages the injectors life and the way the fuel burns.

[kommon_sense]

You sized injectors based on hp, not necessarily amount of boost. Also 10lbs of boost on a d-series should be around 200whp. 450cc should not be anywhere near maxing out at that level. A set of 310cc would get the job done @200, but you would be pushing it.

THink about this. A mildly modded b18c1 can probably put down 160whp and still be fine on the stock 240cc injectors. So surely 450cc can handle way more than 200whp assuming the same duty cycle and same fuel pressure.

http://www.honda-tech.com/zerothread?id=373764


Injector size info
-------------------------------------------------------------------------------
You can go with any size injector that meets your HP goal with a standalone. And as long as you aren't running the injectors at really high duty cycles you are fine too.

Here is something I posted up on po.com a while back, it tells us what the various HP limit is for a injector size. The HP numbers are for stock fuel pressure, and 100% injector duty cycle, I suspect that they are a bit off so dont use it as a solution to your problem. I would still take the injector size and ask around to see if they are the right size.

EDIT: by raising the fuel pressure you can get more fuel from the injectors, and remember since the HP numbers are for 100% duty cycle, you should select the next highest sized injector for you HP goal.

270cc = 187 HP
310cc = 214 HP
320cc = 220 HP
370cc = 256 HP
400cc = 277 HP
440cc = 304 HP
450cc = 311 HP
500cc = 346 HP
550cc = 380 HP
600cc = 415 HP
650cc = 450 HP
800cc = 554 HP
880cc = 609 HP


I believe these hp numbers are at the wheel. However there are sites out there that show you how to calculate the correct sized injector for your setup.

[Likklekilla]

Thank u so much guys for clearing me head up.

Can someone explain to me how an AFC works?

And when i add percentage fuel at a certain RPM wat exactly are u doing?

[kommon_sense]

AFC is a piggyback on the stock ECU. It allows you to adjust the fuel curve in 500rpm increments. I think that you can adjust +/- 30% of thatever the ECU is sending. IIRC, this adjustment just changes the duty cycle on the injectors so that they are active longer or shorter, depending on the adjustment. So in the end, the AFC just lets you add and take away fuel as needed.

Now, when running an AFC, you have to program it to adjust the fuel correctly. You can't just do this in your driveway (Unless you have a wideband O2 and an air/fuel guage). You will most likely have to take it to a shop to get the right settings programmed for your engine.

[oscarmayer]

actually it really depends onthe car. i ran 270's on my car and hit 220 wheel power w/o issues and 10 lbs of boost. later i wanted mroe so i got a hondata nd 440's and then hit 250 wheel power on 14 bls of boost. so again each motor is different.

I'ld say his 345's are good for about 250 wheel power or so.

[Dr.Boost]

actually it really depends onthe car. i ran 270's on my car and hit 220 wheel power w/o issues and 10 lbs of boost. later i wanted mroe so i got a hondata nd 440's and then hit 250 wheel power on 14 bls of boost. so again each motor is different.

I'ld say his 345's are good for about 250 wheel power or so.

Are you talking about running an FMU? Of course that will work with stock injectors if you raise the fuel pressure 120+psi, but we are talking about doing this halfway safe. :? I wouldn't run 345's with an AFC because even if it supplied enough fuel, it probably won't scale the MAP far enough back to prevent it from throwing a CEL. People use 450cc injectors for a reason, not just because they are cheap and widely available. They are near perfect for running 10psi with an AFC.

Also, the AFC scales from +50/-50.

[Likklekilla]

Correct me if i am wrong, but when u put in bigger injectors like maybe preludes or 440's wouldn't you have to lean out the mixture with an AFC for the car to run properly b/c under "normal conditions" it would run too rich. About the preludes with AFC or AFR. Please explain the statement

"I wouldn't run 345's with an AFC because even if it supplied enough fuel, it probably won't scale the MAP far enough back to prevent it from throwing a CEL."

What do you mean by it won't smale the MAP for enough back?

And the SAFC scales -30/+30 not 50, not sure about the SAFC II.