Injector types and high HP/displacement.

[Brad-ManQ45]

I'm putting this question in this forum, because I don't think it belongs in the Fuel Delivery forum.

 

I am asking if anyone has experience with the 2 or more of the 3 basic injector types in a high hp/displacement turbo'dengine.

 

From what I have been able to gather, the disk type injector seems to be inclined toward opening/closing faster, therefore making them what would appear to be the injector type of choice for small displacement high boost engines. I am assuming the fuel injecton system has enough resolution to make use of them in order to provide a good idle (not rich).

 

Has anyone tried 550cc injectors of the disk type (Rochester/Lucas) and one of the other pintle or ball type injectors that can share their experience?

 

Thanks

[Tony D]

Check out JeffP's recent experiences. He is using a GM style (lucas?) injector, I don't think it's pintile style, and he seems to be having some issues with pulsewidth resolution. Get with him on what current status is, he did dyno runs this past monday, and this is where it manifested itself...

He's in "troubleshooting mode" right now!

[Brad-ManQ45]

Saw that last night before I created this thread.

 

I think his problem is the ECU not having enough resolution (300zxt).

 

He hasn't stated what his A/R is at idle.

 

Large iknjectors for the cylinder size present a problem, not only at idle, but off idle as well. If the ECU doesn't have enough resolution, you have problems.

 

What I am trying to determine is at what size does idle become a problem maintaining a 14.7 a/f ratio, and does the injector type have an affect.

 

Once again, from what I've read, the disc type injector is supposed to be the quickest in terms of opening/closing, so I am looking for empiracle evidence to support this.

 

I didn't want to put this in the MS forum, although the MS Extra Hi-res code and MSII should have the resolution to provide a valid platform for such a test.

[Tony D]

Oh, Jeff's AFR with his 720CC/Min injectos is variable with the ECU from 20:1 to richer than 10:1. When he was starting the runs and doing low load maps, the he had the idle at 14.7:1, and the L-Engine doesn't like that at all I had him drop the mix to 13/13.5:1, and the idle smoothed right out.

 

So with the Z31 ECU and 720CC injectors the resolution is not a problem at idle. Just keep in mind that Nissan had "idle enrichment" that went away once the L-Engines came off-idle. At idle speed they always liked to run rich, and at 14.7:1 will be very erratic comparatively to one at 13.5:1

 

Like you mention the MS forum (and the MSEFI Forum) has a lot of duscussion about pulsewidths. Usually idle pulsewidth control becomes a problem on stuff larger than 1000 cc/min. Injector opening time and all that rot starts to close in with those big honkers. They just get dribbly and sloppy...

[Brad-ManQ45]

if it can idle properly, then it is definitely not the injectors causing the problem - it is as I suspected - not enough resolution or the tuner ain't gettin' the 300ZXT maps/settings right.

 

I personally wouldn't even fool with the mass air conversion with the 300

zxt stuff. It's gonna be MS for me!

[speeder]

I use 780cc Delphi Disc-type injectors in my 3.0l L with Electromotive Tec2. Supposedly the disc types have a better pattern and are less suseptible to clogging than the pintle types. The low impedence injectors such as Delphi and Lucas do exhibit faster opening and closing speeds, (when used with a compatible ECU that has peak-and-hold drivers) which make them the best choice when using 550s or bigger.

 

I can idle at 15:1 or so - but have found that most L motors like 13.8-14:1 for a smooth idle.

 

Previously I had Lucas 550s from RC engineering (also low impedence, disc-types) and had absolutely no problems with idle/low speed running.

 

You should be fine resolution-wise with the Megasquirt(Version 3.0 with PWM) and disc-type 550s.

 

Cheap, good injectors are here: http://racetronix.com

 

The secret to idle tuning with big injectors is to pull timing in the idle regions of your map.

[RTz]

When he was starting the runs and doing low load maps, the he had the idle at 14.7:1, and the L-Engine doesn't like that at all I had him drop the mix to 13/13.5:1, and the idle smoothed right out.

 

 

I can back this up. Of any of the L-powered cars I've messed with, they don't like a 14.7 idle. I typically find best idle between 13 and 13.3.

[spork]

My buddy is running 4 1600cc injectors on his 2.2L running through an sds for control and has zero idle issues. They're bosch injectors (not the pintle type). That had me impressed. We figured we were going to have to bump up the idle speed to keep this thing running, but it runs smooth and doesn't load up on fuel. I'll be putting the same stlye injectors on my car when I upgrade.

[jgkurz]

I use 780cc Delphi Disc-type injectors in my 3.0l L with Electromotive Tec2. Supposedly the disc types have a better pattern and are less suseptible to clogging than the pintle types. The low impedence injectors such as Delphi and Lucas do exhibit faster opening and closing speeds, (when used with a compatible ECU that has peak-and-hold drivers) which make them the best choice when using 550s or bigger.

 

I can idle at 15:1 or so - but have found that most L motors like 13.8-14:1 for a smooth idle.

 

Previously I had Lucas 550s from RC engineering (also low impedence, disc-types) and had absolutely no problems with idle/low speed running.

 

You should be fine resolution-wise with the Megasquirt(Version 3.0 with PWM) and disc-type 550s.

 

Cheap, good injectors are here: http://racetronix.com

 

The secret to idle tuning with big injectors is to pull timing in the idle regions of your map.

 

Rick is right on with this. I currently use the RC 550cc Pintle style low impedance injectors. I think they are the same 11mm injectors found on DSM's. Over the years I have worked hard to fine tune my idle quality. I run 15 degrees of initial advance, 38 psi idle fuel pressure, Idle PW of 1.71ms, minimum injector PW of 1.1ms, 14 in vacuum and with the O2 sensor on it will idle decent @ 14.2 - 14.5AFR. If I richen it up slightly into the high 13's it will smooth out a bit more. The issue I still have is a lean idle once the injectors get heat soaked. If I restart the car after sitting for a few minutes in the summer the idle AFR will be about 15.5:1 until the injectors get cool fuel flowing through them again. BTW, This is just me shade tree mechanic diagnosis. : )

[RTz]

The issue I still have is a lean idle once the injectors get heat soaked.

 

John,

 

Have you made any effort to cool them off externally to verify that this is whats actually happening?

 

It might also be interesting to see check the resistance of the injector during this time?

[Brad-ManQ45]

I have purchased 4 peak & hold injector boards and all the components - enough to do 2 V8 projects. One set of boards will be for the ZXT. I'll go ahead and assemble all 4 driver circuits so that if one goes down I can switch to another.

 

I was actuaslly thinking that I would go with the 72 lb injectors if I could get them in the 11mm size.

 

Thanks for verifying what I believe JefP's problem is. After the posts about the same size injectors causing no problems, it can only be a lack of resolution in the early 200 ECU causing the problem, unless of course JWT doesn't know what its' doing when programming it - which I doubt.

[Tony D]

Jeff stopped by this morning to raid my parts bin for his wiring harness so he can build his test stand, later he called me and said he picked up some Bosch 720CC units from Lance at Pantera Specialists and had gotten them installed into the car and went out for some testing. These are the pintile style units. He said idle quality improved IMMEDIATELY , and the car was running slightly richer than with the Ring & Disc MSD units JWT sold him for the setup---this was a straight swap from what he had to the new style injectors.

By his one run in second gear, he says now the car is behaving much more linearly in regards to the VQ Table and etc. It gets pig rich on the top end, so maybe he was having an injector problem.

 

"That was another $700 down the drain" was one of his comments. Genteel company dictates I not repeat some of the more spicy comments in regards to these initial findings!

 

LOL!

[dapiper]

Speeder is right on. I had the blue top 450cc Bosch pintle style on a batch fire ECU (squirts every crank rev) L28 custom turbo (mid turbo grind, 14"Hg at 800 RPM idle) and had no probs with idle in the 13:1 range. Then upgraded to PL9-550 Lucas RC disc style inj and could not idle above 11:1.

 

Then switched ECU to sequential and was able to turn idle down to 14:1 easily.

 

Nevertheless, idle quality not as good as b4, so checked pattern full open and observed narrow like garden hose with large drops. The disc is recessed in the nozzle which contributes to narrow pattern. Russ acknowledged that these inj designed for racing where narrow pattern is desirable.