A carb will be cheaper and make more power, you just need to get it tuned right. There, now that’s out of the way.
I’ve looked into the 5.0 retrofit a lot too, and it does offer the opportunity to be cheaper for an ECU than the nearest competitor (which is Megasquirt). Yes, it’s been done, and yes, the distributor is the hard part. I believe I’ve found a simpler solution but haven’t had time to confirm it yet.
distributor The main difference between the 5.0 dizzy and
most Mopar dizzys: Mopar has a VR sensor and 5.0 dizzy uses Hall Effect. The guts of the 5.0 are too different to swap into a Mopar housing unless you have a lathe or mill to make some accurate adaptation pieces. For a drillpress guy like me, that route’s a no-go.
I’ve heard of guys cutting/welding the Ford top to the Mopar bottom, splicing shafts together, grinding a flat tang onto a Ford shaft, etc, but concerns for shaft runout, hardness compatibility to the oil pump drive shaft, and long-term durability concern me with those methods. It would be a real downer to have a hardness mismatch or a wobble make metal shavings in the engine.
Along the way I discovered a Hall sensor and shutter wheel for the Mopar dizzy housing, now I need to figure out how it fits the BB shaft. Need to figure out which shaft is better to use - from either points or electronic dizzy.
Next:
The Ford ECM reportedly looks at the distance/time between rising/falling edges on the shutter wheel and it may not like the Mopar Hall sensor signal due to difference in diameter of wheel. I have compared Ford and Mopar wheels in Autocad and believe the wheel can be modified to emulate the Ford wheel a little better. I also have an idea on how to compare them electrically -- I simply need some spare time to wire up a TFI system to generate the signal, then I would use my Megasquirt to datalog and compare them. Here’s the biggie, though - since I have a Megasquirt system I’m working on, fiddling with a 5.0 system got put on the backburner.
speed-density or mass-air? You’ll have to decide whether to use SD or MA for this conversion. MA usually gets the quickest nod, partially from internet lore from Mustang circles regarding its flexibility, and also the allure of ‘sequential’.
However, I’ll propose SD instead – it’s a little older and ‘cruder’ and therefore I think it would be less sensitive to the VE difference between a 5.0 and a bigblock Mopar. The newer the ECU, the more sophisticated it is, the more emissions strategies it has, and the less likely you can ‘trick’ it with fuel pressure adjustments or resistors on the sensors. (Plus a MA sensor is nearly impossible to do a stealth installation with, and you’ll need an 80mm-ish size, which is an aftermarket piece. ($))
Here’s my theory:
Sequential EEC can
conceivably look at the time between a cylinder firing and the result from the O2 sensor (at any particular RPM). It knows which cylinder is firing and possibly its distance to the sensor, and it makes adjustments based on that. Sequential is also more sensitive to cam and ignition timing (firing order) – reportedly it’s not a big deal on Fords if the order doesn’t match, but why go to the extra effort of MA if sequential’s benefit is lost?
,
If you use SD, though, it injects and makes adjustments bank-bank, so I think it will place less importance on instantaneous O2 sensor readings and O2 sensor location. Also, running bank-bank SD removes the low-RPM importance of Mopar vs Ford valve timing, i.e. timing the injection on the closed intake valve. (and we all know that sequential’s closed-valve benefit disappears as RPMS increase, right?)
I read somewhere that EEC can only adjust fueling +/- 12.5%. In our retrofit scheme, injector size and fuel pressure adjustments will make up for crude across-the-board fueling differences for the increased displacement and MAP, and EEC can then adjust as much as possible for the subtle differences in the VE curves between engines.
EDIS was mentioned.
Although EDIS circumvents the dizzy retrofit, it introduces a trigger wheel retrofit, which might be just as difficult from a fabrication standpoint. Also, it requires newer EECs, which are more likely to be OBD2 and have a bunch of extra stuff in them like electronic trans control, ABS, etc. Yes, that stuff can be turned off via a re-flash or a Tweecer, but that’s $$. The more you spend on this Ford system the closer you are to the cost of a fully-programmable Megasquirt IMHO.
Here are my favorite 5.0 links:
http://www.cuda-challenger.com/cc/index.php?topic=28401.0http://www.therangerstation.com/tech_library/TFI_Diagnostic.htmlhttp://www.veryuseful.com/mustang/tech/engine/EECIVInnerWorkings/http://www.my5oh.com/forum/viewtopic.php?p=225#225http://www.cuda-challenger.com/cc/index.php?topic=7247.0http://www.detomaso.nu/~thomast/efi/I’ve you’ve read this far, you’ve earned a cookie! I have lots more info compiled, if there’s interest I’ll throw more info out. But right now… my hands hurt…
