Motor Mods vs. SD Capacity

S

silver70

New member
Okay guys... I went through the intro section, already, and received encouragement to post my question, even though it has, probably, been beaten to death. Also, yes... I searched. I was sent here from another forum by one of your members because I asked a, somewhat, technical question in that forum and received "dodgy" answers, at best. A lot of, "Sure... go ahead and run it. You'll be fine." responses with no confident/technical/verifiable support information. The person who sent me here said this was THE place for SD tuning and resource information. So, here I am. Hope ya'll like to read...

First off, I don't own a Lightning. Sorry. I do, however, own a 1988 Bronco, 5.0L, AOD, and completely stock. Engine's rated at 185HP/270TQ in stock form. Unacceptable, IMO, for a 5,500 lb. truck. I have a machine-shop-fresh 5.0L HO (+.020") with these goodies:

- F3ZE-AA GT40 heads (with thermactor ports) milled to 58cc chambers and 1.6 RR

- Comp Cams XE258HR-14 (spec link: http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1446&sb=2)

- Full-length headers with Magnaflow flow-through cat

I am retaining the stock intake because it flows sufficiently due to the extended runners and the entire emissions/thermactor system because I, absolutely, need to pass emissions. Also, this is my DD 22 miles to work and 22 back home 6 days a week.

Estimated power after mods: ~240HP/300TQ (please let me know if I'm over/under-estimating).

The power band will be moved, about, 1k RPM higher than stock. The torque converter is being matched to the new power band and I'm overhauling the tranny with a CP valve body with adjustable WOT shift points, new servos, 2" OD band upgrade, and the usual performance bands/clutches. Also, 4.56 gears out back, if any of this matters.

My questions:

1.) Can the STOCK SD system/fuel map handle this new flow rate and power, acceptably, without any modifications/tuning/chips and maintain it's current driveability without any, noticeable, problems?

2.) Why?

3.) Stock injectors are 19lb. Do I need to go to 24lb.?

4.) Why? (with BSFC at .50, injector duty cycle at 85%, 39 PSI stock rating I figure I can support ~260HP with 19lb injectors, but, I could be wrong)

5.) If I can "get by" with the stock SD set-up, will I lose out on power if I don't tune or get a chip?

Please feel free to be as technical with your responses as you can. If I don't understand terminology or aspects of your response, I will look it up. I want to learn how my system works, not just that it will or won't work. The FI book I have by Steve Probst seems to be geared more towards MAF and has minimal info on the capabilities of SD. It can't be as crappy as I'm led to believe.

Thanks for your time and patience.

Eric
 
I don't think a motor with different heads and cam will run perfect without some kind of tuning. Your not going to be able to just swap injectors (with great results) without some way to adjust for them.

Why do you not want to tune it?
 
Tuning isn't that bad. Lots of guys here to help you do it.

Fwiw, when I bought my L it had 19 lb injectors, TF heads, cammotion cam, edlebrock intake, no egr equip, long tubes, full 3" exhaust .030 overbore ect. It "ran" with stock injectors with no tune, But not very well. It sputtered at idle (that could have been due to a bad map sensor tho, I'll never know for sure, long story).

Your bronco will prolly "run" without a tune, but at a minimum you will leave power and some drivability on the table. With all the work your doing I don't know why spending a couple hundred bucks picking up a tuner ( heck there's a used TwEECer in the classifieds right now) is a big deal.
 
Honestly you should be perfectly fine. The only thing that would give you any fits is the cam and it is pretty tame looking at the specs. You should be fine with the stock 19lb injectors also. It may run a tad lean at WOT but a small bump in base fuel pressure would take care of that.
 
I'm not a "tech" person, per-se. Mechanicals I handle fine and have learned from some of the best. I build my own drivetrains, actually, and grew up around street cars. I can blue-print an engine, modify a valve body, and set up diffs. However, I've never been able to wrap my head around electronics. I just want to understand my system a little better and if something goes wrong, know where to look first.

It would seem that I'm not adding that much power, but, I've been led to believe that the stock SD programming is very limited in what it can compensate for. Pretty much, I want to take the stock configuration as far as possible without driveability issues. Besides, it seems when people start fiddling with tuners, they can't stop and are, constantly, changing this and tweeking that to get it "just right." The time some people invest in, just, learning programming basics is beyond my level of commitment for a DD, given that these are the only changes I will ever make to this vehicle. I'm not looking for another race car that, constantly, needs babysitting and tuning. I, already, have one of those. :D

This build needs to stay conservative and simple.

Thanks,
Eric
 
You should be fine with that intended mod list.... But it would be so easy for you to go a different route as you don't have an electronically controlled trans. If you are a mechanical guy then go carb... If you want a better injection system then go pull the mass air system off a 5.0 mustang that is a manual. Easiest swap ever.
 
You think people with tuners are always fiddling with them and trying to get things just right the carb guys are no different. They fiddle with their carbs, distributor advance and timing adjustments probably just as much. It's in out nature to tinker/adjust our rides in a never ending quest to make it perfect and have something to do.
 
shaunditty said:
You think people with tuners are always fiddling with them and trying to get things just right the carb guys are no different. They fiddle with their carbs, distributor advance and timing adjustments probably just as much. It's in out nature to tinker/adjust our rides in a never ending quest to make it perfect and have something to do.
Click to expand...

I agree, and even we you do get it perfect you always go back wondering if you can get it any better! Never ends
 
Please don't mis-understand... I, very much, respect a tuner's ability and didn't mean to offend anyone. However, I have a street car that I, constantly, tinker with ('70 Maverick) and I just want a little more power out of my DD (the Bronco). After these mods to give it a little more a**, I just want to focus on routine maintenance. I have had many vehicles in the past and have, usually, ended up trying to take them too far to the point where they become impractical.

I, just, want to keep this mod simple and effective. I work a lot and need a reliable driver that handles the off-road when I go exploring, or, at the very least, be able to get out its own way on city streets. I put 33's on the BKO and it's become gutless. I'm adding fabbed bumpers in the near future and that will, significantly, increase the weight.

Thanks guys,
Eric
 
If you added 33's and is now lost power you should also consider re-gearing to compensate for it. My buddy's truck couldn't pull OD until he geared it. What's your gears 3:55's. go 4:10's and get your power back.

- - - Updated - - -

Yeah what oilwell said... Lol
 
He mentioned re gearing to 456's fellers. That will help for sure. I'll bet you will be just fine with a set of heads, the small cam u mentioned and exhaust. I'd bet with those changes and the gears you'll be happier for sure. I'd try it without a tune. You should be able to run 24 lb injectors with no tune as well.

If it doesn't run just the way you want after a couple of days/weeks of getting around in it, spend a could hundo and get a tuner. I was just saying that a good tune is always best, but you will most likely be happy without it if all your doing it putting around on some trails and going back n forth to the old grind.
 
Thanks guys. The 4.56's are for TQ multiplication because the 302 was never designed to be a low-RPM motor. Doesn't have the crank throw for that. It was based on the 289 platform to compete in 5.0L road races. Ford, simply, turned it into their "utility" motor. Put it in everything and made gear-train mods to compensate.

Stock gears are 3.55. The 4.56's are for trail encounters. 4.10's would be, about 50-100 RPM over stock final drive. 4.56's will put me at, approximately 200-300 RPM over stock. As mentioned, the tranny's getting modded to match. However, I need the HP numbers to compete in the old grind. 20+ miles of freeway, at 65+ MPH, in the rush-hour blue-collar commute can become taxing for a heavy truck with an inadequate motor. Especially when merging on short on-ramps and in the mountain passes on long road trips. 302's perform better in a higher power band. I just wanna make sure I have a little more than "enough" when it comes to output.

As mentioned, this will not be an ongoing endeavor. I am making the mods listed and that's it. Afterwards, I'm hoping maintenance will be my only concern. However, I don't want to open another "can of worms" with the ECU if I do this. Anyone have any hard numbers they can throw at me for fuel map limitations? Just how close am I to having a problem? How far can I go?

Thanks again,
Eric
 
Your basically just putting a small cam in there..... the heads are a stock variation. You will be fine. Put the parts on and forget about it. get a wideband though to make sure your air fuel is good.
 
He mentioned 4.56s and a bunch of other stuff to negate them. Just regear and leave the rest alone. The problem isn't power, it's torque. The 302 is never going to make enough torque to get the job done. All you can do with it is spin it higher, which requires even more gear. If it's going to do the job with motor it needs a roots blower.
 
Okay... I get what everyone is saying: "Sure, go ahead and run it... you'll be fine." (please refer back to post #1, first paragraph)

I can appreciate the fact that everyone says this WILL work. However, I need to know why, based on quantifiable reasoning... i.e. hard numbers, tables, figures, or points-of-view from an engineering perspective.

When I asked my grandfather, once, why the grass was green and not some other color, he responded, "just because, that's how it is." Later, in high-school Biology, I learned it was because of the interrelation between chlorophyll and photosynthesis.

We have established the grass is, indeed, green. Now, I'd like to take Biology lessons. :D

Does anyone have, or, know where I can find the stock VE tables programmed into the EEC-IV for my application?

Thanks much for the input guys. Your time is appreciated. I hope this post didn't come off as sarcastic. It was not meant to be. I am, genuinely, grateful for the help I'm receiving.

Eric
 
We get our knowledge based on our own experiences and others experiences thus the public forum. not too many people here will be able to explain the ins and outs of a SD system and why it will work for your specific combo. Either trust what we say or leave it stock.... you are basically planning a stock 302 build with a cam that works with SD as people have ran that cam... the cam in my truck is more aggressive than that. Nothing about your planned build is over the top.
 
There is no engineering explanation unless you want to get a PhD in fluid mechanics and dynamic systems. Below that level there will always be a significant amount of the LBR method involved. To that end, here is why it will work in gear head terms.

The biggest issue with running big cams is the loss of idle vacuum that goes with them. The Ford speed density system is not very forgiving when the idle vacuum drops, but the L is better about it than the previous generation of systems. So how do you generate idle vacuum and what makes you lose it? Pretty simple stuff. When the intake valve is open and the piston moves down the cylinder, the TB creates a restriction to airflow and a vacuum forms behind it in the intake manifold. This vacuum is typically about 20"Hg at idle. This is the vacuum level the PCM expects to see at idle, plus or minus a little bit. When the vacuum isn't close to that level, it gets confused because it is not operating in the realm that it has been told represents and idle condition.

What does the cam have to do with that? It basically controls how and where air/fuel/exhaust flows through the engine. Two things are the most telling about idle vacuum: overlap and intake valve closing point. During overlap, both valves are open as the engine transitions from the exhaust to intake phase of the cycle. Since both valves are open at the same time, part of the vacuum that would be trapped in the intake leaks out the exhaust valve. It's been said that most Fords are pretty happy up to about 40 degrees of overlap, questionable up to about 50, and probably will not work over that. Calculate the overlap by adding the intake opening point and exhaust closing point. For your cam, you get 33 degrees which is well within the LBR "runs good" limit.

I mentioned the intake closing point because the later it gets (as the cam gets bigger or is installed more retarded) the more reversion will occur and reduce vacuum. You really don't need to worry about this. By the time this becomes a factor, the overlap is already causing you enough problems.
 
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