BTW The one I picked up is a BEGI 2025

Thanks

Pobs

 

thats not the super fancier one.

 

Thanks!

 

Five years? Impressive.

 

poops

 

You can count that high ?!!!

 

3 year bump this time.
I'm either missing something in the equations for fuel injectors, or there's some errors.

When calculating fuel pressure at the rail, it seems that 48 is added in seemingly randomly.

becomes this:

8*6 is 48, so where'd that other 48 come from to get 96 ?

This is done further down, using a 12:1 ratio. It's shown as being added in, but still not explained where it comes from.

Another thing I'm not following.

The 265cc is for the 1.8L injectors. But in the next section, 203cc is used:

Is this a typo and supposed to be 230cc for the 1.6L injectors ? If so, the rest of the math is off. 1.65 x 230cc = 379.5cc, not 334.

Someone please shed some light here because I'm totally confused.

 

Will reply tomorrow when I'm not drunk, remind me

 

From the same post: At 6psi with a 8:1 ratio FMU we will have about 96psi of fuel @ the rail. We will use that to find an injector that will flow 360cc at 96psi.

96 = 96psi at the rail.




from the same post: So the 1.8 injectors will be less than 80% duty cycle at 6psi of boost with 96psi of fuel pressure to reach 160rwhp. But what if we add more fuel pressure. Remember that calculation was with a 8:1 ratio. The most aggressive ratio is 12:1. Let's see how that would effect a 1.6L injector:



from the same post: So the 1.8 injectors will be less than 80% duty cycle at 6psi of boost with 96psi of fuel pressure to reach 160rwhp. But what if we add more fuel pressure. Remember that calculation was with a 8:1 ratio. The most aggressive ratio is 12:1. Let's see how that would effect a 1.6L injector:

seems you missed reading some lines of text which answered all your questions.

 

But how'd you get 96 ? If we're using the 8:1 ratio, and 6psi of boost, 6*8=48, not 96. How do we get from 48 to 96 ? Where's the other 48 coming from ?

Earlier in that post, you say the 1.6L injector is 230cc, but in your calculations you use 203cc.

The 203 should be 230, right ? If that's the case, and it's just a typo, that line of math is off.

I read all the lines, and had 2 other people read them too. There's something missing in here, the numbers don't add up, and the 3 of us couldn't figure out why.

 

the base fuel pressure at 0psi.

if fuel pressure is 48psi at 0psi, then you add 48psi due to the 8:1 FMU, youll be at 96psi of fuel.
The oem regulator is 1:1, so you'll only be be at 56psi without the FMU at 8psi of boost.



legit typo. should be 230cc. the math is not off technically.

[used to be gospel they were 203cc injectors, must have requoted that without thinking when i typed that up]





none of this really matters cause you should just buy large injectors and run a MS and not worry about this 1989 way to fuel your car.

 

Ok this makes sense. I thought it might be something similar, but wasn't sure.



Gotcha. Again, just trying to make sure.



Haha that's the plan, if I go this route. My friend will be selling his 91 soon, and I've always wanted to do a turbo build. I'm just trying to get as much research done as I can and see if it's something I want to tackle or not.

Thanks for clearing that up, I appreciate it.

 

I realize this is an old thread, but in reading the wiki and the thread this branches off from, I read that the 99-00 fuel pump system is returnless and that the 255lphp pump was required. I bought one of these, but I'm reading a bunch of stuff now about how the 190lphp pump is likely more than adequate since the 255 puts out too much fuel and runs rich too often. Is that accurate? Or is that information outdated since it was targeted to older injectors?