Changed 383 TBI to BBC Injectors - Looking for direction...

[Chewy1576]

I went for a long drive yesterday and logged a bunch of data running with cleaned up 5.7L injectors (55 #/hr). I know it was running lean and I hoped a new EP381 fuel pump would help with that. After getting back home and looking over the log, it's still running lean. Today I changed the injectors out for a set of the early 7.4L injectors (90 #/hr) just to see what would happen and logged some more data. Not surprisingly, now it is running rich. I have attached the ADX and XDL files to look over.

So here is where I am at - I am working on getting the equipment to start doing my own tuning. I have been in contact with Blueprint Engines to get a copy of the .bin file used to make the chip that came with my engine, but no word if they are going to give it up yet. I'm looking for some guidance on where to start tuning this beast. Once I have the 1228747 ECM modded for the new chip, is it better to begin tuning with the 5.7L injectors and try to add fuel, or leave the 7.4L injectors and try to remove fuel? Or would you start with the stock .bin (Mine was AKWH) and start from scratch? I am using the stock small block TB and it's sensors. I would like to avoid switching to a big block TB to keep from having to remove the intake and have it bored out for the bigger TB.

[Roadknee]

Looking at the datalog with the 5.7 injectors it looks to be lean by about 14%. I think it would run pretty good if you reinstalled the small injectors and increased fuel pressure about 30%. If you're currently running the stock spring fuel pressure regulator spring, try an 18 psi spring.

It's definitely pig rich on the big block injectors. BLM's are buried at 105. Some of the cells are close because the O2 does occasionally cross count.

If you don't plan to rev the 383 above 4,000 rpm I think you can get by with the small injectors with increased fuel pressure. Otherwise use the large injectors and adjust the injector constant in the Bin.

If Blueprint Engines won't cut loose with the Bin, you should be able to read the chip they provided you once you get your chip reading/burning hardware.

[Chewy1576]

Looking at the datalog with the 5.7 injectors it looks to be lean by about 14%. I think it would run pretty good if you reinstalled the small injectors and increased fuel pressure about 30%. If you're currently running the stock spring fuel pressure regulator spring, try an 18 psi spring.

It's definitely pig rich on the big block injectors. BLM's are buried at 105. Some of the cells are close because the O2 does occasionally cross count.

If you don't plan to rev the 383 above 4,000 rpm I think you can get by with the small injectors with increased fuel pressure. Otherwise use the large injectors and adjust the injector constant in the Bin.

If Blueprint Engines won't cut loose with the Bin, you should be able to read the chip they provided you once you get your chip reading/burning hardware.

Hey thanks for looking those logs over. I am already running an 18 lb spring in the FPR. I haven't hooked up a gauge yet, but with a fresh higher output pump, new filter, rebuilt FPR with new spring, and cleaned injectors, I feel like I can safely assume that there is 18 psi. I'm thinking about changing that out to an adjustable one for more control over the fuel pressure though. I'm just worried about maxing out the 5.7L injectors, where the 7.4L injectors will be well under their operating limit, with overhead for later mods. I noticed the BLM value buried at 105, and the INT value not much higher. While generating the datalog with the 7.4L injectors tonight, I burned a 1/8 tank of fuel in a 10 mile commute home from work!

I was doing some long accelerations and I don't think 4K will be seen very much, if at all. The dyno sheet from Blueprint that came with the engine says the torque peaks at 405 lb/ft at under 3000 rpm, so 4000 is really unlikely.

I was thinking the same thing, if they don't give up the bin, I can just read it from the chip in the ECM now and keep it in a box somewhere for warranty reasons if anything happens. The Product Specialist I was talking with created a support record and I am waiting to hear from a Support Specialist about it. Hopefully they hand over the bin file and let me tune it myself instead of trying to do a mail order tune. Just looking for a good starting point as a beginner to tuning from someone with experience. I feel like I could start from a stock AKWH bin and get it running pretty well, but if they have done a lot of the homework already, why "reinvent the wheel"?

[Roadknee]

I didn't realize you were already at 18 psi (should verify with a gauge though). Since you already have the BB injectors, might as well run them. You could try them with the stock spring. I think the tune would still be rich, but the BLMs should move off 105 and it will probably run pretty good.

[brian617]

Used one of those "18psi" springs with the same pump your'e running and all it could muster was 17psi before it coil bound. Never assume, hard to tune with unknowns.

[Chewy1576]

I didn't realize you were already at 18 psi (should verify with a gauge though). Since you already have the BB injectors, might as well run them. You could try them with the stock spring. I think the tune would still be rich, but the BLMs should move off 105 and it will probably run pretty good.

I think my plan of attack will be trying to tune with the 90 lb/hr injectors. I ordered the Burn 2 and hardware to install the chip last night. Should be here sometime next week.

Used one of those "18psi" springs with the same pump your'e running and all it could muster was 17psi before it coil bound. Never assume, hard to tune with unknowns.

To both of your points, I will find a gauge and see what my FP is really at.