This is a LONG detailed account of the 302EFI Speed Density to 406EFI Mass
Air conversion of my 1987 Bronco.
==============
July 9th.
Well, Well, what a lovely 4th of July I had!
There I was, climbing the road to the top of Glacier National Park in
Montana.
And all of a sudden there are billowing clouds of steam pouring out of the
bronco's hood.
For reasons unknown the electronic thermostat on the dual fans I had
installed last fall over heated to the point of melting the connections on the
printed circuit board and allowing the wires to come loose. This caused the fans
to shut down and the engine to MASSIVELY overheat. Of course a HOT engine with a
heavy load is a bad thing. This resulted in a spark plug MELTING, a valve
getting toasted and a cylinder, well, how shall I say this, a cylinder piston
that is no longer part of the happy family I used to call my engine.
Being the Idiotic Insane Bronco lover that I am, and never forgetting my
personal Bronco Motto,
"The correct application of copious quantities of money can solve ANY
BRONCO problem"
I arrive at that moment where I must decide to spend several grand to rebuild
the 302 or
JUST BUY A NEW CUSTOM ENGINE..
Gee, I wonder which I should do? <VBG>
I am leaning strongly towards a 351W custom built for ease of installation.
---
At the time I was told it would take 1 week to get the
new engine built and installed, and thus my BRONCO SAGA began...
---
Week of July 12-16th
They searched for the elusive 351W block for the buildup.
Days went by without being able to find an appropriate block.
Finally a suitable block is found and shipped in.
The engine shop suggests that I consider building a stroker Motor to get the
low end torque I am after.
Parts for the Stroker are ordered.
My Teenage Dream engine is starting to take shape.
Just got off the phone with the engine builder and the final parts have
been selected and are on their way.
Specs are now looking like...
351W with a stroker conversion and a 0.030 bore for a ....408 Cu In
engine.
9.7 to 1 compression using Forged pistons with a forged crank and forged
connecting rods.
The engine is being built to run on 85 octane pump gas.!
If I decide to run on 91 Octane, the following torque numbers will
increase significantly.
1,500 rpm = 352 ft/lbs
2,000 = 376
2,500 = 396
3,000 = 421
3,500 = 423
Note, these numbers are for 5,000ft elevation!
He said I should install a variable timing control on the dash.
Then as the altitude or the octane changes I can dial it in and take full
advantage of the extra power.
Planned life on the engine is 200K + miles before rebuild with proper
maintenance!
---
Week of July 19-23
The new block arrives and is sent to be bored and prepped for the rebuild.
The new block fails a cylinder alignment test and has to be replaced.
2nd Block arrives and is bored and prepped.
Rotating assembly is sent out to be balanced.
---
Week of July 26-30th
Engine builder decides to go on vacation for a week.
Engine heat production becomes a real concern at this point.
So we order in a new Hi capacity Tranny pan, new thermostat, wire the
electronic fans for manual override and find some new "Super Cooling"
radiator additives.
---
Week of August 2nd-6th
The engine finally gets assembled at the engine shop and shipped down for
insertion in the Bronco.
---
Week of August 9-13th
Last night my old 302 came out of the Bronco, and WHAT a mess it was!
That poor engine was trashed.
The timing belt was so sloppy that it would amaze you.
All but 1 of the 8 intake runners in the manifold were coated in a think
black sludge!
The injectors all looked burned and old and in general the engine just didn't
look very happy.
The new 408 arrived at the shop and i got to see it for the first time.
The new 408 is looking better and better.
When I was at the shop they were bolting in the Oil pickup and were getting
ready to install the new distributor.
The Aluminum Edlebrock Water pump was a bust.
Damn Shame. Just didn't work correctly with this engine.
This morning they should be attaching all of the sending units for the
dashboard and finally installing the long awaited valve covers. Then its time to
begin fabrication on the fuel rail for the injectors.
So far they are still holding to me having the truck Friday Night!!!
<< This is the week I joined the BIG BRONCOS List
and OX saved my truck! >>
---
August 13th.
>Assuming 350 HP, a BSFC (brake specific fuel consumption) of .5 and 80%
>duty cycle (of injectors), you will need 27.4 lb/hr injectors. Can only
>get 24 and 30's. I would go with mass air with stock calibration (19
>lb/hr), 30 lb injectors and custom chip from Johnson motorpsorts. Use 95
>ca. processor if you have E4OD.
OX
Listen up everybody.
Ox may have just saved my brand new engine from a Very Hot death.!!
OX, you were RIGHT ON THE MONEY with the fuel flow and the potential
"Extreme Lean" Condition.
I did the math as you suggested.
I called the engine shop that built the engine and FORCED him to go through his
entire Fuel Consumption, Altitude conversion, Horsepower production yada yada
yada routine.
And he now agrees.
HE WAS WRONG.!
You were absolutely correct!
The Current EEC with 19lb Injectors WILL NOT WORK.
Somewhere along the line he must have punched in a wrong value in the computer
model they used to produce the layout for this engine.
He is now calling the installation shop to tell them NOT to fire up the engine
until they decide what to do!!
WELL DONE MY FRIEND!
Here is what we came up with upon doing a recalc of his initial values.
Peak Horsepower at sea level should be 450.
( 450HP / 0.5 )
naturally aspirated engine will have a brake specific fuel consumption of
0.50
This means that the engine will use .50 lbs. of fuel per hour for each
horsepower it produces.
( 225 / (0.8 x 8) ) = 35.15lb per hour flow rate !!
80% duty cycle for each injector x 8 injectors
Same thing at my elevation of 5,000 ft
Peak Horsepower at altitude should be 356.
(356HP / 0.5) = 178
(178 / (0.8 x 8)) = 27.81lb per hour flow rate !!
In either case there is CLEARLY no way the 19lbs injectors could supply this
engine.!
Well as of right now they just Fed-Exed the EEC Module back east to SuperChip
to burn a new chip.
They sent back the 19lb injectors and ordered the 30lb flavor to replace
them.
They still don't want to give up on the Speed Density control system though.
So we are still going to get a chance to see just what happens when you try
to run a HIGHLY modified 406 on a Speed Density system designed for a 302.
Either way it doesn't make much difference to me.
If it doesn't work, they are putting on the Mass Air on their nickel.
---
August 16th.
Just got off the phone with Super Chips in Florida.
This is the shop that my EEC was shipped out to for reprogramming.
His comments were.
#1.
The EEC in the 1987 EFI system is OLD, very old.
As a result it has very limited options for custom programing.
#2.
To get it "RIGHT" will take at least 2 chips and probably 3.
They will burn an initial chip based on the engine setup and expected
performance.
We install the chip and run it on a dyno.
Supply them with the results and they burn Chip #2.
We install chip #2 and run it on a dyno as well.
Send them the corrected test results and they then burn the final chip.
#3.
This older EEC can be made to run the 406 pretty well.
And in fact they have done a few for Mustang owners that have worked out OK
BUT..
By going to Mass Air and the newer A9L computer I should see a {+15% or
better} across the board improvement in
A. Total Available Power
B. Fuel Economy
C. Engine performance Tune ability
#4.
The EEC that came out of my 1987 Bronco is labeled (IN BOLD PRINT)
For 3.0L SABLE and TAURUS ONLY!
He says that I got a re-programmed computer right from the factory as when
the new EFI Broncos started rolling out they didn't have their own computers.
--
Super Chips just called back.
having reviewed all the details for my engine/truck combination they said
DON'T DO THE SPEED DENSITY.!!!
My current 1987 EEC has . .
No Max Speed Limiter
No Max Rev Limiter
No Wide Open Throttle control
No Idle control
They are suggesting that I get a
"X3Z" Computer from a 1993 Mustang GT 5.8 liter.
---
Week of August 16-20th
At this point everyone agreed that the Speed Density unit in the truck was
NOT going to be able to power this engine.
So a new Mass Air system was ordered from Ford SVO.
The kit arrives in bits and pieces.
MASSIVE modifications have to be made to the wiring harness to make it fit in
the Bronco!
It takes the better part of 3 days just to Cut/Splice/Install the new
harness.
More modifications have to be made to the engine to set it up for mass Air.
The EGR doesn't fit on the new intake manifold.
Multiple new O2 Sensors have to be installed.
New high pressure fuel pump and Fuel Rail widening kit are needed.
Y-Pipe on the exhaust has to be cut and widened.
The Air conditioning pump doesn't fit, so a custom bracket is fabricated.
The ignition module doesn't fit and has to be relocated to the driver side of
the engine bay.
The MAIN POINT HERE is that converting from a 1987 302 Speed Density to a
351W Mass Air was NOT a simple task!!!
Time and time again the parts we ordered didn't fit or wouldn't work as we
expected.
----
August 26th
IT LIVES!
After all but 50 days we fired the engine for the first time about 3 hours
ago.
DAMN, BUT IT SOUNDS GREAT!!
And talk about INSTANT throttle response!
----
August 27th
Oh Well.
Looks like I was far too optimistic yesterday after they started the new
engine.
She sounded great in the engine bay.
Looked like she was running strong as could be.
Then it left the shop for the first test drive.
During the test drive it became painfully obvious that the engine was not
delivering anything close to its anticipated power.
The engine felt like it was bogging down badly AND it was Leaking Oil!
For reasons as yet unknown the fuel/Air ratio is off.
after getting back to the shop they plugged in the computer to look for codes
and there were none.
The new computer thinks everything is just fine.
The only thing they could find was that the fuel rail pressure was off by
2lbs from what SVO said was ideal.
The guys at SVO said that for the specific computer we installed, that 2lb
variance could be significant.
So they are replacing the fuel pressure regulator with a manual one in hopes
that it actually has some impact.
Somehow I doubt that is the problem though.
So much for my dreams of wheeling this weekend.
-----
August 30th
They just installed the new Manual Fuel Pressure Regulator and called to tell
me that it made a HUGE difference in available power.
While they were at it, for reasons unknown, they tested all of the Jacobs
Plug wires and found two of them that were only marginal at best, with one of
them passing nearly no power to the spark.
My guess is that that one was the one going to the toasted cylinder on the
302.
So they replaced all of the plug wires with 10mm and put "header
boots" on all of them as well for added thermal protection.
For the moment the engine appears to be running quite good now for the first
time.
They took the Bronco out for its 2nd test drive and everything was going
great till it died.
After towing the truck back to the shop they found that the distributor gear
had worn off.
Seems they forgot to put the right type of gear on to match the Roller Rocker
Camshaft.
So the gear just ground itself into oblivion.
---
August 31st
Found the Oil Leak after they dropped the tranny out this morning.
Looks like the rear main seal blew out when they first started the engine.
The Oil Pressure reading was in Excess of 100 PSI when they first started it.
Its now idling at 50PSI and about 75PSI at high RPM.
They are expecting this pressure to continue dropping over the next 1000
miles of break in.
---
September 2nd
After another failure in the ignition system I FINALLY got the truck out of
the shop today, and was able to drive it home for the first time.
the power is about twice that of what the 302 had.
I was expecting about 3 times what the 302 had, but..
The AOD Tranny is NOT up to the huge increase in torque.
There is a lot of slippage and the shop tells me that I should see an
additional 25-30% increase in total power over the next 1,000 miles of driving
as the engine begins to break in and the rings seat themselfs.
