BigDogJonx

iTrader: (7)

Alright school me.

I see this one equation that StephenMax put up, but that seems to be incorrect cause if his equation was true, then most people at say 10psi on a 8:1 disc would be pushing like 150+psi. I thought 100+psi was injector lockup.

Now Lets take Hal (hlh0501) who is running his turbo and I remember he was running a stock fuel pump, no addition fuel pumps. Running a 12:1 disc and he was telling me he wasnt overly rich. But what I cant figure out is how the stock fuel pump is enough fuel supply? If it is, then what is the point of a booster or upgraded fuel pump for cars running 6psi or less boost?

Now I know that as we get higher in the disc like 6:1, 8:1, 10:1, 12:1 the amount of fuel that gets pumped is more.

Now the other thing is some people say running 6psi of boost from a turbo requires less fuel than 6psi from a supercharger. Is this true or incorrect? I know 6psi of boost is 6psi of boost no matter how you slice it.

Like I said, school me.

MardiGrasMax

iTrader: (14)

If ya want to do it safe, the school bell just rang, class is in.

If you are going to go over 60psi of fuel pressure, get a boost pump or an intank upgrade.

Dont run the injectors over 90psi, or get larger injectors.

No formula has never matched my actual readings. Put in a larger disc in the FMU than you think you need and take the car to the dyno and tune the air to fuel ratio. Bring the full set of smaller FMU discs with you. Make a run, if its too rich put in a smaller disk. When you get close, but still a little rich, use an air fuel controller (AFC etc) to lean it out and make it perfect. Never use an AFC to add fuel to a bost referenced fuel pressure riser fuel system, its allways safer to pull injector pulse width than add it.

Take it in small steps, all ways error on the safe side, do it right the first time, if you wanna play you gotta pay, if you cant run with the big dogs trade your Honda in. Muuuhahahahahahaha

Spend the money for the parts and dyno tuning or you will end up with a few blown motors and spending allot more.

Y2KevSE

iTrader: (13)

I strongly agree with this statement.

Stephen Max

iTrader: (59)

That equation I quoted was for an estimate of required fuel pressure. The fact that people get by with much lower fuel pressure than that indicates the equation greatly overestimates the fuel pressure required. Please ignore it.

At 10 psi with an 8:1 disk you should be running around 97 psi (Vortech's eqn: fuel pressure = one-half base pressure plus boost times disk ratio, i.e. 17 + 10*8 = 97). Thus no injector lockup at 10 psi (if your injectors are operating normally).

It would be nice if we had a good theoretical basis to predict fuel pressure versus boost, but until we do, we can go on the hard won experience base provided by Mardi and others.

BigDogJonx

iTrader: (7)

Okay understood there. Thanks for the info Matt and Stephen.

But here is a sub question now. It seems this question to me is also why does it not make a difference wheather you are running a turbo or a supercharger?

Take for example a supercharger setup with 6psi, and then a turbo at 6psi, the difference in Whp is like 40 at times. So if they are getting that much more Whp what is the cause? It is purely because the s/c setup is robbing that much HP from the engine?

And other question 6psi from a turbo and 6psi from a s/c to me seems different, since the turbo will be intercooled and most likely colder temp air, that means denser air. Denser air means more air packed in there. So thus wouldnt that require MORE fuel to be burned along with it?

See this is why I confuse myself when all these questions start arising. School me again Matt and Stephen.

Dixit

Nismo87SE

Before comparing SC's to turbos get compressor maps for both and then do the calculations. For example a vortech V2 compressor would make way more power than a T3 turbo. However T3/TO4E might make more power than the same vortech SC mentioned. Basically you'd have to compare compressor maps to determine which would make more power generally. However given the same compressor the turbo would have more midrange torque than a supercharger.