I'm running a wiring harness from an 88 chevy van. It was originally 5.7L, 700R4 w/ a 1227747 brain box. There are 2 things that puzzle me....
First, I read somewhere that the 7747 units didn't operate an air pump, but my wiring setup from the van HAS an airpump.
Second, my bin is AKAH, at least that's what's on the label on the ECM. DIY-EFI.org does not list this Bin under the 7747 section. They list other similiar ones, but not this. Do I have an odd-ball Bin/emissions setup?
I'm going to be tuning in the spring and am looking at which Bin to start with right now. The motor's a 406 w/ a 454 TB & 80# injectors. My gut tells me to start with the Bin I have (which will be difficult because I want to use the PROMinator).

Does anybody have any suggestions about which Bin to start with? Another year 5.7LBin? 7.4L Bin? What about the air pump? I don't think I can use a 7.4L Bin because of the tranny.
I'm open to all suggestions.

Mike

 

'7747 supports an air pump, doesn't support canister purge. I usually recommend to start with a bin where the tranny matches: auto or stick. Everything else is up for grabs.

RBob.

 

I suggest you start with a 454 bin, alot of the parameters are already set up for the bigger injectors your running, then tune from there. Keep us updated on how it goes, thats a pretty big engine for TBI.

 

Thanks for the suggestions. Right now (until it was put away for winter) it was running on an all stock 350 TB setup w/ no computer tuning. I know I can get more out of it though.

Mike

 

Mike,

What psi are you running those 80#rs at? I have a 350 with the 80# and 15.5psi seems to be providing enough fuel. But a 406 should need quite a bit more.

 

I don't have the 80's in there yet. It's still running on whatever came in a 350 TB at 13 psi. I know I'm losing a lot by doing this, hence I'm changing to 80#'s. Part of what I'm trying to figure out is what press. to run the new (80#) injectors at. I was thinkin about going with somewhere around 20psi and modifying the BPW constant to get it close enough for tuning. Let me know what you think.
-Mike

 

So far I only know you've got a 406ci, a 7747 ecm, and 80# injectors still not on the engine . You're goint to have to tell me a lot more than that to give you any direction.
Because of the bore I'd go with a 7.4L bin, they came with both auto and manuals.
I'm with RBob though (no suprise), just get a bin that has the correct trans and then setup the bin based on your combo. Cam, heads, intake, exhaust, and vehicle weight are high priority. You can come up with a decent VE curve based on the assumed (or baselined) torque curve of your (or a VERY similar) engine.
Then give the ecm a bpw that is conservative (tells the ecm the injector is smaller than it really is). That way you should be safe side rich, adjust the bpw to get it to run well at part throttle, then adjust VE table to get it to idle. The WOT stuff is last. I also recommend putting big injectors and big fuel pressure on anything making more than 300hp. I wish I could just calculate the injector size and fuel pressure you "need" but that depends on too many variables (engine quench being of high importance, which I can't measure easily).
If you've got some big port heads and a healthy cam I'd start with about 20psi of fuel pressure. The only good thing about having a 400 block is that it doesn't "rev" like a shorter stroke engine. This means you can make just as much average horsepower with a mild cam and low revs than you can with a big cam and high revs... high revs mean TBI injectors NEED to flow a lot of fuel to support the engine. Example; a 300hp 454bbc redline at 4500rpm has 8.3 ms of time to fire the injector (longer time more fuel). A 327 making 300hp at 7000rpm only has 4.2ms to fire the injectors. If the engine efficiency is identical you would need a much larger injector for that 327 since it hasn't the same amount of time to flow fuel. The reason I said if the engines have the same efficiencly is because that way the amount of fuel is closely proportional to the amount of horsepower.

 

SB406,

In addition to the fine advice both Jon and Rbob gave you, let me also suggest investing in a WBO2. I went through the task of getting my PT tune just right only to find out my WOT was very lean due to insufficient FP. Start out rich as Jon has suggested. At worst that means new plugs. With a WB, you'll see where the WOT AFR is and what pressure you'll need to get there with the injectors you have. With a 406, I'd start with the 90's not 80#.
Once you've roughed in the right FP for WOT operation, you can start tuning PT etc. I've been tuning for 4 years and just now got a WB after much "haranguing" from Bruce, Jon, RBob et al. You know what? They were absolutely right. One additional positive about the WB is the data rate. 30frames/sec v 1.5frames from the 7747 ALDL. BIG DIFFERENCE. I did in 2-3 scans what it would take me 10-20 before. Not to mention I don't need to drive as far.
Best tuning money you'll spend. Almost don't need a scantool. Almost. Now if only you could get spark counts on WB dataloggers along with the other data.

 

The engine isn't anything trick. I'm running 350 vortec heads w/ steam holes added for the 400. The exhaust manifolds are from a 350 truck w/ 2 1/4 dual exhaust (no cats). The intake is a '95 big truck 350 TBI intake, which is currently being machined out to 2" bores to accomodate the '90/'91 454 TB. The cam is a slight RV cam. It's a good torque motor. But the reason I'm changin things is because around 95 MPH in O.D. I feel a lag in power. With 3.08's in the rear and a 700R4, I should be doin a buck forty easy without hesitation. Anyway, that's my setup. It's not real crazy and it's not a drag car. It's a nice cruiser that I want peppy enough to beat my buddy's built 302 Ford Fairlane (hehe) with some fuel economy. I intend to use the Prominator, so I can have a couple Bin setups for fuel economy and/or rompin on it.

I still have a question about which Bin to start with because I don't think the 454 ever had a 700R4 behind it, only a THM400. Should I start with a 350/700R4 Bin and add 454/THM values? Also, I see both the 454 and 350 Bins have a BPW constant of 134/135. Whats up with that? I'm pretty sure I'll want to lower that, right?

Edit: Upon looking at both 454 and 350 Bins, I've noticed significant differences in the VE table and others....Since I'll be using the Prominator, Does anybody advocate using a 350 Bin on one selection and a 454 Bin on another and switch back & forth to see which is better to start from? Or should I stick to one thing at a time?

Thanks,
Mike