I dunno. I'm starting to think I should get smaller injectors and run higher rail pressure so my idle pulse widths are a bit larger (pulling 1.5's now)..

Here is my combo:

Engine: 357 cid 4-bolt main 1pc rear
Camshaft: Comp Cams CC-306 (230/244, .510/.540, 112lsa 110ctr)
Pistons: SRP-139629 reverse dome, -16cc dish
Rods: SCAT H-BEAM 5.850"
Heads: TrickFlow TFS 23* alum, angle milled to 55cc
Manifold: TPIS Miniram, 58MM BBK Throttle body
Exhaust: Hooker 2149 long tube headers, carsound cat, dual exhaust
Intake: Stock ram air, K&N air filter
Fuel: Walbro 255lph pump
ECM: 1227730 ECM, $8D MAP code
Transmission: 700R4 w/ transgo shift kit, 2800 stall raptor 5x converter
Compression: 10.14:1

I'm running 36# LS1 injectors (the white ones). Starting to think 30's might be better for my combo.

What do you guys think?

-- Joe

 

Sounds reasonable to me, it's looking like my SVO 30's are going to be plenty for me since I donm't run any power adders.

 

Good thing is, I could probably do an even trade with someone whos running boost or NOS. heh

That and MR fuel injectors take 30 seconds to change.

-- Joe

 

I know, that's a real sweet feature on the MR's!!!

 

I have a very similar setup and was running 24# injectors. They were in the low 9ms range at about 5200 rpm, so I just recently installed some 30# SVO injectors. As you say - the MR makes it easy except that I ended up damaging two o-rings where they fit into the fuel rail despite being very careful. Damaged o-rings can leak quite a bit of fuel at 43 psi, so that would be my caution here. Unfortunatley, I don't know yet what base pulse width I have at high rpm. I can report this in the next day or so. I think the 30# will be the correct size. I do like how you can change the injector constant and easily be back in business and the car runs the same as it did before.

 

Have you played with the injector biases, more specifically the min sync pulse width? This setting is critical for a good idle with larger injectors. A while back, I tested several different size injectors, 19,22,24, and 30 lb. As injector size increased, so did the minimum pulse width to open the injector. The 19 lb. injectors were right at 1mS, the 22's were just under 1.1mS and the 30's were at 1.3mS. That is a 30% swing. I did not have a 36 to test although you can test it yourself easily if you have access to an oscilloscope. It doesn't take a fancy setup. Al you need is a simple 555 timer circuit with a driver transistor and potientometer for varying the pulsewidth, a 12V batttery, a regulated air compressor and some hose. Connect the circuit to the injector and connect the compressor to the input side of the injector with a small piece of hose and some hose clamps. You can fill the hose with some fluid if you want to get fanvy. Set the pressure to something reasonable like 40 psi and turn on the circuit starting at a low PW. Slowly increase the PW until the injector starts flowing air (or fluid) and then measure the PW with the scope. This time will be very close, close enough to use as the min sync PW. Just a thought. HTH

 

I've played with them. The problem is actual minimum pw.. 1.5msec is not a reliable pulsewidth IMO. I've had best luck idling with setups in the 2.0msec range.. Maybe i'm being paranoid..

I'd like to get my hands on somebody elses map setup with big cam. My TPS reaction is just plain bad. I don't know if its map resolution causing the problem, or what. Theres almost a second delay in throttle stab.

-- Joe

 

Sounds like an AE vs MAP (or LV8. Don't know what ECM you're running) issue to me. All the more reason to have plenty of injector.

 

$8D..

I dunno. it's weirdness. i'll figure it out when I'm done. I keep taking it apart.

Guess i'll tinker with the 36's for another month or two and make a decision.

-- Joe

 

Alright, I'm curious about the injector bias thing. In TunerPro 165/6E there is a constant called Minimum Enrich Async Pulse Width and its set to 1.69 ms. I currently idle with about a 2.2 ms pulse width. What happens if I change the constant in TunerPro from 1.69 ms up or down?

 

I don't think Minimum Enrich Async Pulse Width is an injector bias in 6E.

For 8d it would be the low PW off set table at $840B.
There's also a single fire PW setting & the batt volts offset table.
If you do some digging, you might find Traxion's AE comments from his MR setup. All I remember of it was that he used 200% of aujp but not which tables he did it to. I used 1.7 applied to AXCN tables for the current MR bin on a 6sd 383 30lb setup I'm helping on. It has a slightly bigger cam than yours. But the 1600-2400 VE came out at 96/125 on the second chip so the extra richness may have covered up any AE defecits. I've also heard from guys with smaller cams that the LT1 tables work well.

 

Also, for AE, make sure your MAP sensor is on its own port to the the manifold. Don't share it with anything, not even the FPR. Also make sure the tube to it is as short as possible, and make sure the tube is not too soft. That can cause a lot of lag and turn a small AE problem into a big AE problem.

When you get to big cam and big injectors, it's time to consider some kind of sequential conversion, if you want to get better idle. Not mandatory, but life is easier with it.

 

In another thread, I was mentioning how much i'd love to run a 93-95 LT1 ecm. If I could get it to work with a hei dizzy i'd repin in the quickness. Then i'd get sequential, EFI with cyl trim, etc.

-- Joe