"Heads" up!

[RangerSVT]

Just another " heads " question. The heads in question are the 4 valve heads on the 4.6l and 5.4l engines specific to the intech family in the mark viii's, continental's, and navigators. The 32 valve aluminum 4.6l engines (named teksid, for the manufacture) in the mark viii's and continentals are near identical, with the continental engines having a slightly detuned version for the front wheel drive. All 32 valve 4.6l engines were the same except for the 03-04 cobra motors having a 4 bolt iron block, all others were a 6 bolt aluminum block. The 32 valve 5.4l found in the 99 navigator, also using the intech name, is said to share the same design of the 4.6l iron intech block. Later year navigators dropped the intech name.

So now that the history lesson is over (and what I found out from researching), what I haven't found out is there any difference in the 4.6 and 5.4 heads? If so, what differences are there, and what years apply, if any.
As extra credit, what fuel system (return/returnless) does the 4.6 intech run, and when and what (vehicle) did the throttle body switch to DBW (drive by wire)? I found an 01 continental that has returnless fuel system and DBW. I know the continental was detuned for front wheel drive duties, but dont know if the rating (260hp vs 280hp of the mark viii) was just a tune or hard parts. Let the discussion begin...

SVT

 

[bigmark303]

As far as I am aware 5.4L DOHC heads do fit 4.6L DOHC engines. The 4.6L intakes dont have enough meat to port match the much larger ports of the 5.4L head though. Im not aware of anyone who has accomplished a 5.4L head swap on a 4.6L NA engine.

I have although heard of guys being able to fit the 5.4L heads succesfully to the Forced induction 2003-2004 Cobra engines because of the difference in intake allowing it. This was over 4 years ago when I used to build 5.0 OHVs. Never personally got into 4.6L or 5.4L engines myself.

I can address the Lincoln side of things as far as the power difference between Continental and Mark VIII 4.6L engines.

The power difference in the continental 260hp up to 1999 was split port heads and a different intake manifold. 1999-2002 Continentals made 275hp with the tumbler heads and revised intake The 275hp even after the updated cylinder heads and intake for the continental could have been higher dependent on the tune.

The Mark VIII only used the split port heads and earlier intake. In 1995 for the LSC version was simply re-tuned to make 290hp instead of 280hp from previous years. No parts were updated or revised.

 

[adsm08]

Checked the shop manual. 2000 is returnless, but has instructions for replacing the throttle cable, so I would assume 2001 was the first year for ETBS (Electronic Throttle Body System).

Going back as far as 98 the fuel system is listed as returnless. In 97 the shop manual stopped specifying return or returnless, but shows a return line on the diagram of the fuel pump connections, so I would assume 98 is the first year of returnless fuel system.

 

[RangerSVT]

Hmm, everything I'm finding tells me all mark viii's were return fuel.
The 5.4 heads will fit and bolt on the 4.6 blocks, the problem is, is there is no intake, stock or aftermarket, that will fit a 5.4 head on a 4.6 block.
The B heads were used on all mark viii's, but in 97 they got a different intake design. Thanks for the info guys!

SVT

 

[RangerSVT]

Hmm, everything I'm finding tells me all mark viii's were return fuel.
The 5.4 heads will fit and bolt on the 4.6 blocks, the problem is, is there is no intake, stock or aftermarket, that will fit a 5.4 head on a 4.6 block.
The B heads were used on all mark viii's, but in 97 they got a different intake design. Thanks for the info guys!

SVT