Hello all. I am retro fitting a 5.4 triton from an 01 expedition into a 79 f350. I'm going to be converting the MPI to a carb using MSD ignition controller. This truck will be a show truck so keep in mind that everything I'm doing is for show not functionality. I will be doing a twin turbo set up (not sure what turbos yet) and my question is, has anyone fabricated a set up similar to this before? What will be my challenges? What's the easiest way to lower my compression ratio to accept ~18ish lbs of boost?

 

Maybe I'm missing something here!
If not for functionality, why is building 18 pounds of boost a concern?
If your going to 'blow' through a carb, the carb has to be a special and placed inside a sealed box.
If 'drawing' through a Carb, not so special. Just an outside mount and setup to meter enough fuel
Sizing for two Turbos requires you to know there capacity to feed the engine displacement and the carb ability to meter fuel in the correct amounts throughout the RPM band.
Know that boost pressure is a measure of 'flow resistance' through the intake tract to the cylinders.
That is the boost pressure you will measure on a gauge in the intake tract and not what the cylinder gets after the flow loses are subtracted.
Said another way, if the intake tract were made to flow more air without changing the Turbo drive speed per RPM , the boost would be less at all Rpm points.

You have lots of home research and engineering to do before any work even starts and Turbos are even selected.
You need an ignition with an adjustable ignition advance curve ability.
This is why companies employ people with engineering degrees.
Then do a lot of testing until all the issues are worked out.
Good luck.

 

twin turbo manifolds for the 5.4 can be had from treadstone performance

as for swapping from efi to a carb , not a great choise
also if you're thinking you're going to use the eddelbrock 4.6 carb intake manifold , think again as you will need also the adapter plates to install a 4.6 intake (any 4.6 int) onto the 5.4 and you may or may not still be able to get the adapters

and the 5.4 factory intake is far superior to the old carb style eddelbrock - even IF the eddelbrock intake just "looks cool", it will cost you 5-10 hp

carbs and turbos .. not a good idea as carbs , airborne gassoline and heat don't play well together
efi keeps the gas out of the intake stream until it's just about to enter the combustion chambers

I would look for an aftermarket system to run the factory injectors if you don't want to pull apart the factory 5.4 wireing
AND your fuel regulator is going to need to be a boost referenced unit that adds one pound of fuel pressure for every extra pound of boost

to add , in my opinion , as I have researched every possiable engine build combination for the 5.4 ford .. don't waste your time .. go get a 460

to do anything with the 5.4 is cost stupidity , in any possiable variant of build from a straight 2 valve build up to a twin cam 4 valve .. using WHATEVER head , it's just going to be stupid expensive for what you get back out of it .. which ain't gonna be much when measured against the money you're gonna have to spend

every way I researched building the 5.4 I came up with a cost around 12K .. for about 400HP

buy a set of trick flow heads for the 460 ,$3600 , a ford racing 429/460 CJ block , $2100 and a scat crank kit for about 35hun and you'll actually have something .. that won't even need turbos

and to add , a blow through system with the carb or throttle body mounted directly to the intake manifold will be safer than a suck through system
firstly you won't have gas in the system until you reach the intake manifold

secondly , any suck through system that puts hoses and tubes for the intake charge AFTER the carb or throttle body can become very dangerous as a result of any intake track leak opening up as this then becomes an open throttle position from the engine's viewpoint - thus causing anything from a high idle (vacume leak) to a run away engine

https://www.google.ca/search?q=5.4+f...ckpdaPBNm8qtgD