Injectors too big?

[madmikeismad]

1.9 vw tdi
vp37 pump with 12mm dodge pump guts
5x.022 "single stage" injectors
gt35r

Potential problem: Won't build much boost. Mostly cleans up at higher rpms (4k+), and doesn't really make any power. No boost leaks that I can find.

My question: Is it possible the injectors can be too big? I know the pump will only make a certain pressure, so is there a chance that with the injectors being as big as they are, the fuel isn't atomizing correctly and I'm getting an incomplete burn?

I'm going to re-tune it and add some fuel where it's leaning out, but I feel like that might not help. I'd like to rule out the injector size concerns before I completely start over with the tune.

 

[mfsuper90]

We have a 354 perkins with big dual feeds, and below 1500 it will flutter if you floor it, almost like a flooded gas engine until it warms up good, or you ease into it. Roosamaster pump.

I dont remember how big my 8 hole injectors in my 318 perkins are, im thinking 8x.015 or so? With a 12mm VE, and they perform flawlessly.

In my opinion, i dont really think injectors are too big. My first thought would be, Whats your exhaust back pressure vs Boost?

Sounds like the gt35r might have too big of housing making it lazy.

 

[madmikeismad]

We have a 354 perkins with big dual feeds, and below 1500 it will flutter if you floor it, almost like a flooded gas engine until it warms up good, or you ease into it. Roosamaster pump.

I dont remember how big my 8 hole injectors in my 318 perkins are, im thinking 8x.015 or so? With a 12mm VE, and they perform flawlessly.

In my opinion, i dont really think injectors are too big. My first thought would be, Whats your exhaust back pressure vs Boost?

Sounds like the gt35r might have too big of housing making it lazy.

It's a very tiny housing, .63.

Probably zero drive pressure, as boost doesn't get over 5psi before.

This was just a question to weed out any possible problems, in case adding fuel and playing with timing doesn't help. But since it sounds like injectors should be good to go, I'll rule that out right now.

 

[mfsuper90]

Well I'd love to hear Weston or someone with a lot more experience chime in as well.

 

[madmikeismad]

Took it out on some full throttle runs today, didn't make over 4psi and fell on it's face around 3500rpm. Have plenty of fuel through the entire rpm range. Looked through the tune and found that for some reason my timing maps never go over 19*. Not sure how that happened, when stock lets it go up to almost 50. So I'm going to throw the stock timing maps back into it tonight and see how that works out. I'm really hoping this little engine loves timing so much that 19* was just cutting its nuts off.