Starting a new project. 1990 F250, 351W, E4OD, 4X4, 35" tires and 3:50 gears. Obviously with those gears and tires "underpowered" is not even close. Being as the motor is finally showing its age, I am looking at trying to draw some more power out of it. Specifically these are the mods I am looking at:

4.170 Stroker Crank (427Cid)
10:1 Compression
Mild port job on heads
bigger throttle body
headers w/true duals
Comp Cams 4X4 Cam
(Specs
*Duration at .050 in.: 210 intake/218 exhaust
* Gross valve lift: .477 in. intake/.493 in. exhaust
* Lobe separation: 111 degrees)

has anyone done a stroker with the Speed Density setup, and if so what issues will I be needing to address? I have looked at the Mass Air conversions, and they dont support the E4OD, only the regualr AOD for this application. The truck will be a driver, so I want to retain the dependability of the EFI, as well as the Cruise, OD, etc. Otherwise I would pull the 351 and E4OD and just put in a 460 w/C6 and be done with it. Any suggestions welcome.

 

I did nothing more than a cam swap on an 86 Mustang with speed density. It was a mild cam but driveability went right out the window. It had idle surge, ran so rich it made your eyes sting, and was an overall disappointment. I had to switch to mass air to make it work.

Make sure you do some serious homework before trying this!!

 

For that engine, I would go carbed with either a barry grant DEMON carb or and Edelbrock 650 - 750 CFM mechanical secondary. EFI will be a real pain to setup, many runs at a dyno and many chips burnt to make it run right. This is for mass air! Can't do it with Speed density. A carb will be cheaper to tune and then you can go to a dyno and make a few pulls and make adjustments then, not stop for two weeks to get a new chip burnt.

Just a side note: A 351w stroked to 427 CID will have some wicked rod/piston goemetry. It may not last as long as you would like it to. a 396 ( i think that the next size down) would be better and you would not give up much HP and gain some engine life. The 427 kit puts a lot of side to side pressure on the bearings rods and piston pins because of the extreme angles the rods will be at @ 90 and 270 degrees. You know that you have to have machine work done to the block for clearing the larger stroke, right?

Just my .02 cents.

 

You can check with Byron at Race Systems .com. He set up a 351 stroked to a 408 for me before. We used a 93 VEX-1 ECM out of a mustang to work in conjuction with mass air and a E4OD. This was done originally for a previous 95 Bronco I had. Now the 408 is going in a 94 truck. Not sure yet if he will have to use my VEX-1 or if the existing truck computer will be compatible with the programming needed for the 408/E4OD combo.