i've searched and have been reading up on this for a while and im tring to get a good understanding on everything for a turbo.

my goal is to run 9psi on stock internals by summer and i want to try to part together my own kit.

i know that adding more fuel is a big thing and some people put on the FMU for this. i've been hearing people putting on higher injectors for their fuel. which is better? and say i had injectors ( 450cc), an AEM fuel rail, a new fuel pump(is that the FMU?)(what brands do you suggest and what rate), and an SAFC... would that be enough to tune the fuel so i wouldn't run lean?

also, on the wastegate. i was looking at one and it said it had a 7 lb. spring or something like that. does that mean it is only good for 7 lbs of boost? or what. what kind would you suggest i get so i can run 9 pounds.

and one more thing. which exhaust manifold is best? the steel or cast iron? does one tend to crack easier or are they both fine?

sorry if these questions seem stupid

 

try here as well if you haven't already:

http://www.honda-tech.com/zeroforum?id=16

 

that 7lb spring in the wastegate is the default psi. meaning if your boost controller fails or something you'll just be boosting the 7lbs.

thats how i understand it anyways :thinking:

 

The fuel injection system works on a basic principle of a fuel map. The map is a 2D chart based on RPM and MAP sensor voltage (the amount of air coming into the engine). Each cell on the chart corresponds to a fuel injector duty cycle value. This is represented as a percentage of the maximum amount of time that the injector can be open. The longer the injector opens, the more fuel goes into the motor. The fuel map only has MAP sensor values up to atmospheric pressure, and no higher because it doesn't need to read boost.

FMU means "Fuel Management Unit." It's actually called a boost sensitive rising-rate fuel pressure regulator. It works by sensing your boost level and raising your fuel pressure by a certain amount for each pound of boost, for example a 6:1 FMU will add 6 psi of fuel pressure for each psi of boost. It can work but a problem you run into is that the stock fuel pump can't flow enough fuel at high fuel pressure to keep up.

When you use an FMU, you have to use a check valve to bleed boost away from the MAP sensor. If the MAP sensor sends a signal to the ECU that indicates boost, the ECU will go into a limp mode. So the ECU sends the maximum fuel amount (as a duty cycle value) for that given RPM, and the FMU bumps the fuel pressure up to pick up the slack where the ECU leaves off. It ain't exactly elegant but it'll work.

A better solution is to use an AFC and 450 cc/min injectors. AFCs work by changing the voltage sent to the MAP sensor input of the ECU. So if you use the AFC to dial back the MAP signal by 40%, the ECU can receive all of the signals from the MAP sensor without thinking that it sees boost. It sends a duty cycle signal to the injectors that is 40% less than what is actually needed, but since the 450 cc/min injectors flow more for the same given signal, they "multiply" the signal back up to the needed amount of fuel. Relatively simple and it keeps the ECU in the loop.

 

that makes sense. i got some more questions

i have a friend that is getting rid of his 370 cc/min injectors because he said he needs bigger. should i buy those or just buy some 450 cc/min? and the ones that you get out of an eclipse, do those fit or do you need to buy something to make them compatable?

is a fuel rail necessary or a waste of money?

 

It's better to get the 450's since it gives you some more headroom with the tuning, especially if you're going to be running 9 psi. You can use injectors from a DSM if you get the right injector clips and the injector resistor box out of an '88-'91 Honda that has fuel injection. The reason you need the box is because the DSM injectors are a different impedance than the newer stock Honda ones, but with the resistor box it will make them the proper resistance. It's a good idea when putting in used DSM injectors to send them off to RC Engineering to be cleaned and flow balanced. Alternatively you can just buy some RC 440 cc/min injectors that will plug right up.

The AEM fuel rail isn't exactly necessary when running the high flow injectors.

I also forgot to answer a couple questions from your original post.

You should stick with a cast iron exhaust manifold. They have the disadvantage of placing the wastegate port on only one runner but they are a bunch more durable than the tubular manifolds.

If a wastegate has a 7 psi spring that means it is set to limit boost to 7 psi. You can replace the spring with one set to a higher boost level or you can get a boost controller (in which case it doesn't matter what the spring is as long as it's lower than the boost level you want). A TurboXS manual boost controller can work just fine with the only catch being that if you drive up and down into high altitude areas it can spike boost. But unless you live near mountains or something it's not an inssue. Otherwise if you want an electronic one, the GReddy Profec B can be found on ebay for pretty cheap and will work nicely.

Also you should try and get a Tial wastegate instead of the Turbonetics Deltagate that normally is included with the turbo kits out there.