Small gas engine with poor FMIC

[Dust]

Been looking at a Chevy Cruze, as the diesels in the area are higher than I want to go. It's a 1.4L with small turbo, and FMIC behind A/C condenser. The car suffers from timing pull in hot weather due to bad flow through heated FMIC.

I could use the .3mm check valve nozzles i already have. I would like to run at low IDC, but would also like, if possible, to use a larger nozzle for normal operation.

I have a lowest flow FAV, so I think the hardware is there, but wondering if the HFS-3/4/6 can run at low flow, but only failsafe when the big nozzle and 4 DP nozzles are flowing?

[rotrex]

"I have a lowest flow FAV, so I think the hardware is there, but wondering if the HFS-3/4/6 can run at low flow, but only failsafe when the big nozzle and 4 DP nozzles are flowing?"

I don't understand that statement?

For say 200HP and less, 4x 0,3mm nozzles right behind the injectors (from engine perspective) is likely all you need for "normal" WOT operation. Doubling this flow with a 5th bigger nozzle is only useful if you run a lot of boost, say 15PSI and higher.
Dual stage injection is not really needed in your case IMHO. The FAV will take care of the flow control.

[Dust]

Originally Posted by rotrex

"I have a lowest flow FAV, so I think the hardware is there,

There are 4 different sizes of FAV
239B, 240, 241, and 242. Richard shipped me an FAV with lower flow.

I don't understand that statement?

I would like to use the Aquamist failsafe to trip boost down to wastegate pressure, but don't want to worry about it when I am spraying while rolling down the highway and pulling vacuum. Just when I am in boost. Big nozzle might not be the best word to use, but a boost nozzle instead of only the direct port nozzles.

For say 200HP and less, 4x 0,3mm nozzles right behind the injectors (from engine perspective) is likely all you need for "normal" WOT operation. Doubling this flow with a 5th bigger nozzle is only useful if you run a lot of boost, say 15PSI and higher.
Dual stage injection is not really needed in your case IMHO. The FAV will take care of the flow control.

Boost when tuned is usually 20-22 psi.

[rotrex]

Ok, usually you do not spray at all unless you apply significant boost.
There is little benefit spraying at say 0-10PSI cruising along except making your methanol supplier happy.
At this high boost level you really can take advantage of water injection. 4x 0.3mm nozzles flow some 300ml/min at 10 bar. (pls check the number form current charts, this is form memory). Rule of thump is 1.5ml/HP. So this would about fit.
As with 22PSI you'll push the OEM TC really hard. In this case the engine might benefit from pre compression injection.
What are your current IATs after the FMIC?

If you can freely tune ignition timing and your current tune is knock limited by high intake air temperatures, you could push things further by injecting more water meth than those 300ml/min.

[Dust]

The point of part throttle injection is two fold. First, as mentioned in my low flow diesel thread, to increase MPG, and second, to decrease heat soak based power reduction. The Cruze has a small FMIC mounted between the AC condenser and radiator. Many complain about severe lack of power in stop and go traffic. If this is an "octane", or timing pull due to knocking problem, spraying at low IDC can be helpful at direct port locations. If it is a software problem that pulls timing everywhere, then the spray can still be useful, but not in the direct port location. Nozzle would have to go before the TMAP.

[rotrex]

the stop and go issues come from the intake air correction of the ignition timing.
usually this is helped by fans running across the IC.
sounds like you should relocated the IC.
spraying at loads connected to city stop and go will cause issues with the water condensing everywhere as there is hardly any air flow. Direct port will not have that issue, but require you to map the ECU to take advantage of that, i.e. accept more timing at high intake air temperatures.
it also won't improve MPG at cruise speed unless you map it to run super lean with loads of ignition advance, e.g. an AFR of 20:1 plus water. Not worth the trouble.
Do you have full access to the ECU and can map it?
if you just substitute methanol for petrol, you save fuel, but use more methanol. With the cheap gas in the US, you won't save money.
Relocating the IC to see cold air will improve MPGs and help with the city driving.
I'd do this and add water meth under mid to high boost.