ok heres my question...i plan on using walbro 255lph fuel pump w/550cc injectors and an s-afc....but when do u usually need to upgrade the stock ecu for a new one? at around what power level?

 

550's are simply too big for the stock ECU, no matter what else you strap to it. If you're running that Walbro 255lph pump, then your fuel pressure is going to spike to 60+psi and those 550cc injectors are going to start flowing closer to 680cc because of the pressure rise.

Stock ECU with 440's, an RX7 fuel pump and an S-AFC is good for around 230-240 as-proven by Onpol. Anything higher than that, it's time to get a better piggyback computer of somesort. E-Manage, UniChip, etc...

 

ooo thats good to know before all that gets put in. thanks for the info red

 

So lets say I have my 2002 Elantra {coming soon} I don't want turbo or nitrous, but a fairly decent supercharger sounds interesting. I imagine that the Beta II 2L engine has a smaller fuel pump and injectors than say the 2.4L in the Sonata or the 2.7L V6 has. Would it be possible to use OEM parts from a these larger Hyundai engines to achieve respectable power increases on a supercharged Beta II?
Perhaps I should be more direct: what size of injectors, what ECU, and what size fuel pump would gain me 50hp on the Elantra's engine if supercharged?

EDIT: I think I had a revelation! Alright, you had mentioned that someone should use 440cc injectors, multiplied by 4; that's 1760cc's. So in a 1.8L engine that's overkill right? Since that would be virtually filling the cylinders and you'd have no room for air. I don't know what the 'mix' is on most cars, but if it was 50/50, then 440cc injectors would normally be used on 3.5L engines... That's what I'm thinking anyways. Please correct me if I'm wrong, two thirds of my use of this message board is to learn more about how my car 'works'.
Thanks.

[ November 21, 2002, 08:25 PM: Message edited by: 5years@$400aMonth ]

 

Are you serious? First hole in that theory is that your injectors are measured in cc/min. Your cylinders are measured in cc's. But not moving. If you want to use the formula you are trying to work out figure out how many cc's a minute your engine would pump (dependant on RPM) then divide by how many cc's your injectors supply. Not to mention that you also need to remember the duty cycle on the injectors should not go over 85% and your Ve on the motor will probably peak somewhere around 88%. Then you have to remember that "the mix" for air to fuel is not 50/50. More like 14.7 to 1. So that means 14.7 pounds of air to one pound of fuel. Of course that is usually reserved for cruise conditions and maximum fuel economy. If you're running F/I you probably want it closer to 12.5:1 or 13:1. Sorry if I sound a little harsh here but I bought the supercharged and Maximum Boost books about six months ago and since then I have learned a lot about motors. I think everyone here should go out and buy a copy of these books. Also be sure to pick up Four Stroke Performance Tuning by graham bell. The wealth of information available in these three books alone will keep you busy for months. Once you read them through re-read them. Then continue to read them until you memorize them and know them by heart. **Steps of soapbox**
But all in all if you wanted to supercharge a Beta motor up to around 190 crank (assuming you already have a decent S/C kit, NOT Alpine's) you could probably do it with a bigger fuel pump, RRFPR, and S-AFC to trim it down. Well you also need colder plugs, ignition timing, way to lower static compression (Ie... low compresion pistons, thicker head gasket rolleyes.gif ) ignition timing control, some form of intercooling would be nice also. It's a lot of work to put 50 extra HP in a motor designed to only make 140-ish. Just because Red and Random make it sound easy it's not. it's just that these guys are really good. It's all about how prepared you want to be. I personally like to be informed as possible before I ask questions or get involved in anything this serious. wink

Again sorry for the rant.

[ November 22, 2002, 05:32 AM: Message edited by: Y2KTIBLTD ]

 

Thanks for being straight to the point. I'll take your suggestion and see of I can pick up those books today. I can't visualize exactly what you're talking about, but I do have a slight understanding of what you are talking about.
Thanks again.

 

Let me make it just a bit easier for you to understand:

You are thinking that 440cc injectors, times four, is going to equal 1760cc's of fuel. Well, on a 1.8L motor, that's as much fuel as there is motor!! Where is the room for the air?

Right? smile.gif

The problem you're missing is, 440cc injectors spray 440cc's of fuel per minute. So over one minute at full-opening, all four injectors could spray that much fuel.

But over that one minute, your motor is turning. A 1.8L motor will basically "move" 1.8L of air every two times it rotates. So if you figure your car was idling for that one minute:
800 RPM's, moves 1.8L of air every two revolutions, so it moved 1.8L x 400 = 720,000cc's of air in that minute.

Well, 1700cc's of fuel for 720,000cc's of air in one minute. Now you see why it doesn't completely lock up smile.gif

What Y2K was trying to explain is two things: Number one, the injectors are not always fully "open", so they can spray much less than 440cc's of fuel if the computer tells them too.

He was also trying to convey that the computer generally will try to keep a certain proportion of fuel and air in the motor at all times. Otherwise, if the two are not in correct proportion (too much fuel, or not enough fuel) then you make less horsepower and either make the engine run too hot OR just simply use up more gas than you need.

There's the simplified version smile.gif

 

Amazon dude. They should have everything because that's where I ordered mine from. In fact if you order all three I think they give you a break on the shipping or something. I know they did on me when I bought Four Stroke Performance Tuning, How to read camshafts, and Balancing/Blueprniting an engine. Trust me you can never have enough books to read on the subject. It will make you respect the few guys on here that really know their stuff even more.
Maximum Boost
Supercharged!
Four Stroke Performance Tuning

Here ya go!

EDIT:
Thanks Red. I knew you would do a better job of explaining it than I did. smile.gif

[ November 22, 2002, 07:59 AM: Message edited by: Y2KTIBLTD ]