I'm rebuilding a 4.0 block soon to put in my 01 D2, I have a good 4.0 rotating assembly but I am intrigued by the 4.6 swap. I couldn't find too much on here searching, so I wanted to know what people who have done it think. I've seen people say 4.6 crank, rods and pistons, and also seen 4.6 crank and rods, with 4.0 pistons. Whats the difference and which one is better? And does anything need to be done with the ECU? Or is it a small enough change that it doesn't matter?

 

Bosch 4.0 and 4.6 block should be the same. Are you getting top hat liners? I did the 4.6 crank and rods with 4.0 pistons for a bump in compression. I also went with an upgraded cam. Stock ECU.

 

That's the route I was most heavily considering. And yes, plan to get the block top hatted. What cam did you go with?

 

Can't speak to the combo as I have not done it, but after 25 trucks I can tell you the 4.0 gets about 1-2 mpg better highway mileage and I cannot feel the power difference and I have towed with both.

 

To me the 4.6 had more pep than the 4.0 even with nearly double the miles on the clock. Might just be me though.

 

Used Genuine LR lifters. I also went with new rocker assemblies Rocker Arms Unlimited out of Redding, CA.

That was 2 builds ago.

Went BIG with the last build from TWS. You may want to check out their cam/lifter packages, push rods, and deeper head studs. Just be careful, it’s a slippery slope…

Who is going to do the liners?

 

I noticed a huge difference with the 4.6 compared to the 4.0. The truck with the 4.6 was heavier too with heavier rims + tires. But the 4.6 only had like 8k miles compared to 140k so not apples to apples.

 

both the 4.6s i drove had more get up and go than the 4.0. one 4.6 was in a stock 04 and the other was in modded 04 with steel bumpers, larger tires, life, etc. they still seemed quicker off the line to me than the 4.0.

 

We daily drove the 2002 4.0 and a 2004 4.6 for a couple years, and though there certainly is a difference in power between them, if you zoom out and put the power difference on a spectrum that includes more than just the two Discos, it's not anything meaningful. IMO. You might want to find a 4.6 being sold locally and give it a test drive to see for yourself?

 

No idea yet, I don't know any machine shops in the area so I'm looking around at the moment.