A 1:1 boost referanced regulator? The stocker does the same thing right ? It's preasure referanced right ? Isn't it also 1;1 ? So why one over the other I just got my 50 lb racetronix injectors ( any good ?)

 

The stock FPR is vacuum referenced.

 

Yes, the stock fuel press. reg. is 1:1. Your 50#/hr injectors will always act like 50#/hr injectors under any amount of boost.

You are cutting it real close on injectors using a double fire batch ECM (stock Camaro). I have 42#/hr injectors with a 216@.050", 110* LSA cam (-4 * overlap at .050", LT1 intake on a 350ci. The injectors are at 1.8ms at the injector (not what the ALDL reports...1.2ms) at idle and part throttle cruise. If you get much lower than this with your high-z injectors the idle could be tricky to tune. It is possible. Just giving you a heads up that it will take some time to tune the low RPM VE tables.

You will here people say that 60#/hr high-z work fine with double fire batch ECMs. Ask what CI and cam they have because it is usually in the 400ci area and 244@.050" cams that run rich at idle.

 

I appreciate the heads up . I always indout about this stuff too late ... I JUST got my 749 here in the mail .....hopeing i can make it run well enough for me to stomach the idiocyncracies (sp lol )

 

The 749 ECM has two injector drivers where as the 730 only has one. The 749 has the capability to do alternate bank fire. Instead of firing all the injectors twice per engine cycle (720* crank degrees), it could fire each 4cyl bank every other time. The 749 ECM could do this........but the $58 code that runs that ECM doesn't have the capability. If it did the 50#/hr injectors would be easier to tune at low pulsewidths (idle/part throttle).
I think you will be OK with the 50#/hr high-z units. Take your time and run it rich at first and slowly creep down on the injector pulsewidths.

I once was playing with the $58 code to make it do alternate bank fire, but the more I read the code I disliked it. The new ECM project is to use the 427 ECM out of a mid-90s truck that was originally TBI. People at DIY PROM are already using it with TPI port injection setups. This ECM is more easily adapted to alternate bank fire. I have some 55#/hr low-Z injectors sitting that will eventually go in along with the 427 ECM. Oh, and the 427 ECM will control a 4L60E or 4L80E with just a code change.

 

aside from all the technical stuff that i dont understand completely....boost referenced regulator is for those running super/turbochargers. it rises 1 psi of fuel pressure per 1 psi of boost over the base FP.

 

Also, since you went with high-Z injectors you didn't need that 749 ECM. A 730 ECM (cheaper) would have done the same job. The ONLY advantage of the 749 ECM is that it will operate with low-Z injectors and high-z injectors. It is all about how you wire it at the ECM connector. With your stock wiring it should already be setup for high-Z injectors. A lot of people buy 749 ECMs and don't really need it.

That info. is fact. I have had both of those ECMs apart and verified what they have for chips in them. Actually, with my car and no AIR, TCC, EGR........I could run the $8D and the $58 code in the 730 ECM without any wiring changes. It was a simple chip burn to switch from the Camaro code and Sy/Ty code.

 

I apreciate all this . I just figured that the 749 was kinda the best way to go about it untill I go FAST ( wayyyy down the road) . I just got the pinouts ( thanx to you know who ) ...so hopefully I can get that in and working correctly

 

I'm running lowZ 55 lb Siemens injectors with an Acceleronics injector driver box, and they're pretty much maxed at 600 rwhp.

Anyways - if the stock rails and fpr flow enough for you without being a bottleneck, then use it. An aftermarket 1:1 afpr lets you adjust the base fuel pressure if you need a little more than the injectors can provide on standard pressure (but the increased pressure will decrease the pump flow). In my case, I needed the aftermarket since I was no longer running the stock fuel rails.

 

thanx man . I had no idea that the fuel rails would be an issue . I only plan on haveing a max of 650 hp ( crank) Thats with everything up to par ... ECM , intercooler ( probably different shrotblock aswell ) ...as I only have forged flatops in it for now . Untill I get stuff up to par ...I would be happy running around at about 6-7 psi . I think I am keeping my stock injecotrs in it too for this season ( only running at 4 psi ) . But at least I will have the parts for the later bump in psi .


Did you see the pics I had up of my smogg modifications to the headers ?