FN035 in an a F150 with an AOD.

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alollich
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FN035 in an a F150 with an AOD.

Post by alollich » Thu May 02, 2019 6:23 pm

Hello,

I have a 1988 F150 that has been converted to mass air and runs on a A9P computer. The engine is a 302 with Trick Flow heads, stock 5.0 HO cam, ported truck upper and lower manifold, 24lb ford injectors and a prom 24 maf. The aod is a built aod, lentech valve body, and a 2800 stall converter. only locks up in 4th. The truck is lifted and has 35" tires on it. So its heavy and is like moving a brick thru the air.

I am confused with the numbers that I should be putting in FN035 and here is why. When I do a WOT pull and datalog the load (not loadX) i get numbers that are in line with other head/cam/intake cars that I have seen posted here. My load numbers seem to be slightly less than the 5sp cars as the converter does not lock up in 1,2, or 3 gear? Here is where my confusion starts...if on the highway when the truck is in 4th gear (converter is locked up) and I accelerate as hard as I can without a downshift the load numbers I record are higher than what I record on the WOT pulls. Lower the rpm the higher the load is. Do I need to take into consideration that the converter will be locked up at some points and the loads will be higher for a given rpm all be it when it happens it wont be at WOT (unlikely will ever be at WOT in 4th)?

Simplifying my question do I just enter what I get on the WOT pulls and be done even though I see loads higher in driving conditions other than WOT?

Thank you

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cgrey8
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Re: FN035 in an a F150 with an AOD.

Post by cgrey8 » Fri May 03, 2019 6:29 am

I could be completely off in left-field here, but I think your problem is simpler than it might seem.

First off, the stock HO cam is a torque cam that was designed to work with the stock HO intake/heads in non-ported form. So it's not surprising that lower RPMs are showing higher load values. As for why you would see higher load values in 4th than in lower gears, my guess is it's speed. As you say, the truck is a brick flying through the air, so there's a pretty high amount of pressure on the front of the truck. That pressure could translate to a "slight" boost into the intake over what you would see at lower speeds where that front-end pressure isn't nearly as significant. And because this is only a "slight" boost, it's affects would diminish as the RPMs (i.e. engine demands) got higher unlike with a mechanical booster where it gets spun faster as the engine spins faster. If your exhaust pipes are going out the back of the truck, you could have a similar phenomenon happening back there as well where the back of the truck is producing a vacuum as the truck moves through the air thus helping to pull the exhaust out of the tailpipe(s). But with only a small amount of vacuum, it's affects would diminish as the exhaust volume increases.

So getting back to your final question, enter what you get on WOT pulls and be done with it. Although I tend not to use the WOT fueling functions. I disable them and run all non-closed-throttle conditions out of the tables. That tends to work pretty good for the average street car.

If I had to guess why Ford put the WOT functions in there it was due to processor efficiency. It's easier/faster for the processor to iterate through a function than a table...it's just less data to have to sift through. And high RPMs is where the processor is being particularly challenged, so having a WOT function to calculate what otherwise would use a table was a decent compromise to help those using stock computers to competition race with.

But with computer technology getting cheaper, modern engines getting more complicated, and mfgs posting HP values from their engines right off the assembly line that'd split a stock Windsor 302 block down the center, nobody should be using a GUFx-era EEC and 302 to competition race with anymore. There's better engines and software available now that the high-dollar racers are using. Don't get me wrong, I'm not saying there aren't people out there running stock Windsor blocks in some classes. But whatever those race rules are, they aren't allowing 7500+ RPM engines that output 1000+HP. You'd need something a bit more modern to accomplish that with stock equipment.
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