does anyone know why ford uses a dohc in the navi ? ? ? hp is the same but torque on the 04's for the navi is 355 @ 2750 and the f150 365 @ 3750 ? ? ? is there any benifit to the doch motor ? ? is it just too expensive to put in the f-150 ? ? any one have any knowledge of any of that id appreciate it!

thanks ahead of time

 

Cost mainly...DOHC heads are expensive to cast and assemble compared to a SOHC design. Packaging restraints, the 5.4 4V is a BIG engine. And I guess part of it is a snooty attitude, more cams, more valves, big wow factor in a Navigator when you pop the hood and see those nice "Lincoln V8" and "Intech" emblems. Probably helps to differentiate the Gator from the Expy and pickups as well.

 

My guess....

I think the 4V is in the Navi because it will provide smoother exceleration. It may have less torque but it has enough, and has it in the right places to get that (attractive) tank moving. I would guess that Ford figures that the average Navi buyer doesn't want the torquey feel of the pick ups, they want a smooth yet powerful SUV.

The two and three valve F150 engines are set up to deliver torque, in the places it's needed to haul varying loads. It's a truck, not some kooshy SUV so they sacrifice some of the smoothness.

They use four valve heads in sports cars and they perform very well. The 5.4 in the Navi has bigger parts than most of the sports cars. It's harder to move all thoes big parts fast, safely. I believe the Navi does all right for an SUV but if they could tighten up that engine (at a huge cost they would have to pass on to the consumer) they could spin that thing up faster and make more power.

Sorry I don't have facts for you. Just thought I'd pass on my opinion.

 

The 4V motor blows the 2V out of the water. Look at the RPM numbers - you have to rev the 2V higher to get the same torque - that equates to the navigator being 100 yards farther down the road after the stoplight than you are before your torque kicks in.