1650cc injector and pump/e85 question

[jrohner]

Originally Posted by Kracka

I'm guessing that must be it; or maybe 100% IDC as logged by the ECU is what they feel the ideal maximum to be? It seems like anywhere above ~115% and fueling issues begin to occur.

Is it that way with evo's also? So on some cars 115% is actually around 100% maybe, and some are even more off?

I don't really see why mitsu didn't go by IDC's for fuel cut instead of airflow (or in addition to), maybe it is because the IDC's aren't accurate; although I guess you could use fuel cut to prevent overboosting if you set it just a little higher than the max airflow you'd ever see.

[Shane@DBPerformance]

IDC in programs like Evoscan and the DSM dataloggers is just a calculated value. The Mitsu ECUs don't seem to keep track of true IDC like a standalone, so the calculated values are often off by a decent amount. When injectors go from real 99% to real 100%, there is usually a bigger than 1% jump in fueling because the injectors are no longer closing at all, so the opening/closing times are taken out of of mix and the injectors are just spraying full bore all the time. It is often easy to spot on a dyno chart with A/F ratio readings. A flat A/F will all of a sudden go 3-6% richer and then the A/Fs will start leaning out in a linear fashion with more RPMs, assuming the power isn't drastically changing.

[Kracka]

Originally Posted by ecoli

It is often easy to spot on a dyno chart with A/F ratio readings. A flat A/F will all of a sudden go 3-6% richer and then the A/Fs will start leaning out in a linear fashion with more RPMs, assuming the power isn't drastically changing.

This is exactly what happened on my Evo IX when EvoScan was showing 119.5% IDC with my stock injectors.

[C3L1CA]

Sorry to kind of go off topic, but now I'm kind of curious about power levels on a single set of 1600s.

http://www.dsmtuners.com/forums/151228044-post7.html

In that post Chris says they stopped at 600awhp because they maxed out a single set of 1600s. Given that was on e98, but can are you really going to gain much more power without knocking with e85?

Has anybody else heard of people maxing out 1600s before and what kind of power they were putting down?

[blackrosenova400]

Find the BSFC of e85 and you will have a good guess as too how much e85 you need for a specific amount of power.

[Shane@DBPerformance]

The difference between running a car at 11.5:1 versus 12.5:1 will also drastically change how much power you can make on X injector. That 8% could be 25-60whp worth of fuel depending on the power of the car.

[Archertsi]

I see it was sorta mentioned but how the fuel is getting to the 1600's is also huge. Fuel pumps and the size of your lines greatly effect injector duty cycle.

With my 1600's, walboro pump and stock lines on E70, I was running lean at 5k rpms and 17lbs of boost. I knew the pump just wasn't supplying enough fuel, but just for kicks I mounted a fuel pressure gauge where I could see it while driving. The 1600's were opening up so much under boost that fuel pressure was actually dropping off.

My point, how much fuel you feed to these injectors, like any other, will greatley effect how much they can supply to the engine. That's probabley why some are running out of injector and others are not.

Then throw in whatever AFR and whatever blend of fuel you are runnning . . . it all adds up.

[asshanson]

So would bigger lines help in that scenario of the pressure dropping off? Or would a second pump help more?

I was having ridiculous high IDC on my 1600s for the power I was making, in a few weeks when it's warmer I'll have my fuel pressure gauge installed (on a-pillar) and can see if the same thing is happening for me.

[Shane@DBPerformance]

Usually a single pump maxes before the stock lines. You could get to a point where you have more pump than lines and fuel pressure would drop because the lines or fuel filter have become the restriction.

[Archertsi]

I guess it depends on your set up I think. If stock lines with a walboro and 1600's is dropping off at 40 lbs/min, I would try a bigger pump. Then lines next. 1600's have gone allot farther than 400 whp with E, but they had bigger fuel supply. That tells me that the injectors are not getting the fuel that they are capable of supplying.