..for now anyway...

I've spent hours reading the stickies and I'm still not done, but I do have something I'd like to pick your brains about before I get going.

I'm building an engine for my truck, it's at the machine shop right now. I will be using TBI from an '87 350 truck, 1227747. The engine is going to be bored .030", stroked to 3.75" (383) and the compression ratio is being raised to 9.52:1. I am using a fairly mild Comp Xtreme Fuel Injection camshaft, part number 12-365-4 and 180cc Dart Iron Eagle cylinder heads. The exhaust system is a true dual system with flowmaster mufflers and dynomax headers. There are no emission control devices on this vehicle at all as it is off-road use only (literally).

My question is, how bad do you guys think this engine is going to run on the stock programming? Am I going to have to dive into the world of PROM programming before I'll even get this thing to run? I'm hoping that since the cam is so mild, it will idle fairly smooth without any modificiations, but I am not sure.

I've made several phone calls to people trying to figure out what kind of software and equipment to buy in order to tune this thing after it is installed. There is also a wealth of knowledge available on this forum about that very subject. The only problem with it is that they all suggest something different, or several different things.

I know about engine tuning, I know how to jet a carb, change a distributor curve, etc.k, and I do know/understand that the fuel and engine load requirements for my new engine, which should make 335 HP, is vastly different from the engine that this injection system came from, which made 210. That is why I'm slightly nervous about this entire thing.

I need to know enough information to get a baseline, or at least start somewhere so that I can ensure this engine is going to run, and not run so lean as to get very hot as soon as I get it running. How do I get started?

 

It'll be using different areas of the fuel map do to the manifold vac readings in the manifold being so different. It might run, but that's about it.

Hope springs eternal......
Often that's about all it does. <sigh>

If you understand tuning, and all the principles involved, then it's no different then a dist/carb set-up.. It's just that you don't get your feet wet, by having to change carb jets. <G>

Fire it up and see where you are!.
Nothing's going to melt down in 3-5 seconds of running at idle. This is also where a Wide Band is a great tuning tool...

 

FWIW, mine was barely driveable. I also use the EBL now, enourmous difference in tuning ability. When I first fired my engine up, I used a crab to get it broken in. Then after some miles I put the tbi on it with the stock 7747 ECM. (wiring was already run). I used the 350 TBI w/ 55 lb'ers, stock FP, and it barley ran. Needless to say I didn't drive it till I could burn a few chips. Just to get the BPW and some timing issues squared away.

 

I am curious to find out if I will need larger injectors. It seems somewhat far-fetched that the stock 350 injectors will support 335 HP. I would imagine that step one to enrichening the mixture is going to be turning up the fuel pressure/adjusting it, so I'm going to get an adjustable fuel pressure regulator right now.

This isn't a roller cam engine, it needs to be broken in the first time it runs. I don't have any intention of trying that with a carburator, either.

I will have to do more research about this wide band O2. I've seen it mentioned all over here, but I haven't researched what it'd take to buy one. Since I'm way over budget, I may be using the seat of pants and plug reading method for the time being.

The cam I'm using only has 40 degrees of overlap so I'm really hoping that will help it run halfway decent right out of the box. Am I completely off on this?

With an adjustable fuel pressure regulator, am I going to be able to get enough fuel out of the stock injectors to support 335 HP or am I going to need bigger ones? Every place I talk to, in an attempt to get info just wants to sell me something...but I really want to know what is good before I buy everything. I can't believe how many different people/places are selling products for this EFI. It's insane...it' just makes it so difficult to get straight answers as to what works and what doesn't when everyone is running something different.

 

An '87 350 TBI will be running 61#/hr injectors at the stock fuel pressure. To support 335 HP only need to crank up the presure to 28-30 psi. Will need to use a port injection fuel pump. TBI pumps don't go that high.

GM sells a direct fit regulator that runs at 30 psi. It is for the '94 - '95 BBC trucks. P/N 17113079

RBob.

 

Just a thought, but is 28-30 PSI beyond what is going to idle?

Is it advisable to install this fuel pressure regulator prior to firing the engine off at all? I need to tell the computer that my 61 lb/hr injectors are 100 lb/hr injectors now, don't I?

I guess my question is, what will I need to fire/break in the engine, and then what will I need to maximize performance?

Do any of you guys run 30 psi of fuel pressure?

Is it a possibility to ask someone if they have a baseline .bin program that one could edit around here or is that against the rules? I am starting to think that I bit off way more than I could chew as it's going to take some pretty drastic modification to force this EFI to feed this engine. It seems that there is a lot of grey area and not many straight answers as to exactly where to start. I'm new to efi, and new to trying to run EFI on modified engines. I've spent the last week reading and it's very overwhelming.

Once I get rolling, I'll be good. I just have to get this pig to run and then I can modify whatever is necessary to make it run better (even if it's only trial and error). Either way, I don't want to melt down my new motor so I need to ensure that it's not running way too lean.

 

I'd just like to thank you guys for the help you've given me so far. It's going to take me a while to get this going (which I know) but I really appreciate this site for sharing their experiences with these EFI systems.

 

If you the TPI in tank pump, (are you using an in tank pump), That will support the higher pressure you need to feed the motor. I have an engine similar to the VORTEC 330hp motor, but it should be making some more, and I use a BBC TBI w/90pph injector, with a vacuum adjustable fuel pressure regulator. It is set for 26 psi max. All that and my VE table are still at 98 % at 100 kpa and 5600 RPM. If you use the injectors you have now, and crank up the fuel pressure, you will need to adjust the BPW in the bin so the VE tables aren't too rich. Then you adjust the VE tables from there. I'm sure there are more who will chime in here, as i am reletively new to this also.

BTW, I am using a COMP XFI cam also, but it is not a roller cam motor.

 

Mine isn't a roller cam either, it's hydraulic flat tappet.

You're still at 98% even with 90 lb/hr injectors? Damn!! I really hope I'm not trashing my performance by putting this EFI system on this engine.

The vacuum controlled fuel pressure regulators are discontinued, unfortunately.

I was considering 75 lb injectors in the stock TBI and working from there....but now I'm not so sure if yours is still on the lean side with 90 lb injectors @ 26 psi.

 

Do some searching, you might find a TBI guy near you.
Do some digging on the TBI setup also. There's people supporting 400 or so HP with them.

 

It's not on the lean side, I could up the BPW and make the VE % lower, it's just I am persistant on using the VAFPR, cause I already have it. I could also change the spring and add 2 more PSI of FP, bringing me to 28, or I could go to 30, which would make a difference. Since my LC-1 wide band o2 took a crap again, I am on hold. Before it broke, I was running open loop tuning the VE tables, got them really smooth, the Wb read 14.7 during most cruising, a slight drop during AE in acceleration, and a good 12.7 afr in PE mode. I also had no problem when I used the n2o. There are ways for me to get more fuel, I am just now getting a good hang of the tuning. So I am easing into the changes. Also, my injector dc% isn't high during 5500rpm in PE either, maybe 55-60%. So I'm not close to static. They were kissing about 80% when I stabbed the throttle and I was getting a whole lot of AE, but a short conversation with RBob got me straitened out.

 

You're near me! If I ask you nicely, can you help me tune my truck?

Of course I need to know what injectors I'll have to start with, of course.

 

I know very little about TBI code. But there are several around here that do.
I also just moved here so I need to finish unpacking. Only reason I'm on the boards is because I hurt my back.....
61's run at 30 psi comes out to about 96lbs/hr. For 335hp and 85% dc, I get 98 lbs/hr. So your real close at 30psi.

The calcs are NA lbs/hr= (hp*.5/DC)/# injectors- use .6 for boost
New Lbs/hr = old Lbs/hr * sqroot(NewFP/OldFP)

I'd be happy to help you in 2-3 weeks though. My tuning stuff can be a bit difficult to get to work with a 747 or so I've read. I'm a 7730 guy.

 

If I'm lucky, it'll be in the truck by then, but no guarantees....the engine is still at the machine shop currently, they just bored the block today.

If you're willing to help, I'm willing to take whatever help you'll give me. If I need to swap fuel pumps to get the necessary fuel pressure to make it run right, that's fine.

This truck is off road use only and I'd have to trailer it down to your place, but if you're willing to spend a few hours working with me and my truck to at least get a baseline from where I can work, I'd greatly appreciate it.

 

You had asked about cam break in. I would use the stock TBI unit at the low stock pressure. If you can swing a regular old 2bbl carb, that too is a good choice for cam break in. The key being something that needs the least amount of attention while the cam breaks in.

Don't forget a can of GM EOS added to the oil, or use a good diesel oil such as Rotella. Todays car oils don't have enough zinc for flat tappet cams.

RBob.

 

Rotella is a good choice, I use it in my Cummins powered Dodge. I'll have to try it in this engine, too.

Thanks for the help, everyone. Fast355 has been talking to me via PM. Once I can get a hold of Craig Moates, I'll be ordering a programmer.

 

I use the penzoil diesal 15w-40, or Royal purple, depends on what i can find. As RBob said, flat tappets need the zinc