Hello, well like the title says, can you upgrade a 4.6 with NPI heads by simply replacing them with the PI cylinder heads ? That's what I understand, but I want to know if the intake and exhaust manifolds, throttle body etc. are interchangeable. Basically I need to know every part that's different so I can determine if doing it is affordable for me or not.

I recently purchased a 1998 E-150 Van with only 15,000 miles on it and it will need some more power as it's converted for a wheelchair user (me) with a heavy lift and a raised roof to slow it even more. I will be towing a trailer very often that's about 2000 lbs. as well and I'll be mostly west of the Rocky Mountains so I'll need the extra power.

I tried searching but could not find what I'm looking for so thought I would ask. Any friendly advice greatly appreciated.

 

You can do it. You're going to need the intake manifold and cylinder heads. All of the other items are interchangeable. The problem is the compression that you'll end up with when you do the swap. The NPI uses a smaller dish in the piston,so you'll end up at 10.2-10.5:1 compression. You'll have to do one of two things. Have it retuned removing some of the spark advance in the spark tables,or run premium fuel to keep it from spark knocking. If you're wanting to do a simpler swap that won't need any changes like that-get ahold of a set of OEM PI camshafts and swap those into your '98 model. You'll get approx 10 hp and 20 ft-lbs gain from that swap,and it's far less expensive to do,and doesn't have the compression issues of swapping the heads.
JL

 

so seeing as i have no idea with these mod motors what does npi and pi stand for ??? i'm gonna assume non police interceptor , and police interceptor ? or ........ after my 53 is done thinkin' bout beating the tar out of the 95 4.6 bird i just got at the drag strip so cheap horsepower appeals to me ............

 

PI = Performance Improved
NPI = Non-Performance Improved

 

PI = Performance Improved
NPI = Non-Performance Improved

 

Thanks for the information Johnny, are the car & truck componets interchangeable?

Example, Will the PI (performance improved) cylinder heads & intake from a 4.6L Mustang lets say.. a 2001 model bolt right on my 1998 E-150 4.6L engine with no mods at all? Or do I need to source the parts from a truck or van with PI?
How much of a power increase would this give? The little information I have found so far claims doing this upgrade produces around 60 horses at the wheel which is great for using all stock parts, I just dont know how realistic those numbers are.

Does anyone know with 100% certainty what the stock horsepower & torque ratings are for my 1998 4.6? I believe the truck & van ratings are the same, actually I would like to know the ratings from 1997 through mid 2000's so I'll know what years to look for to source parts from.

I'm certain someone has done this before, or at least researched it.

Thanks again,
PW

 

The heads,etc from a car are interchangeable with a truck/van,but using the car intake will make the truck/van a gutless pig. Dimensionally, all Modulars are the same. There are small quirky differences between Windsor and Romeo versions of the engines that'll drive you nuts trying to finish up a swap like your speaking of. Bolt sizes,timing cover differences,etc,etc.
The 60rwhp number is bogus. By swapping the heads,cams,etc all out from that of a E150 or F150 with PI heads will get you 20-25rwhp. You've gotta remember,many of the people discussing the PI swap are talking about doing it on Mustangs that have a MUCH better flowing intake manifold,and they're usually swapping on a set of ported heads with aftermarket camshafts. '98 NPI truck engines were rated 220hp,and the '01-up PI head truck engines are rated 240hp. The cylinder heads themselves are honestly equals when it comes to capability of airflow-the camshafts, intake manifold, and the PCM tune are where all of the power gains come from. There a minimal amount of power to be gained in a truck PI intake-it's still got the same restrictive design for low-end torque production as it's NPI counterpart-just ever so slightly less, and it's port shape is for the more squarish PI intake ports so it'll seal to the cylinder head properly.
As for parts sourcing based on years:
'97-'99 are the same
'00-present are all the same
This is based on the cylinder head type and camshaft specs. There are little differences through the years,but as far as power potential-the above is true.
I've driven both PI head and NPI head trucks- the '01 F150 work truck with PI heads (supercab 4.6L/4R70W 2WD) compared to my old '98 F150 with NPI heads and PI cams (supercab 4.6L/4R70W 2WD),and it was almost impossible to tell the difference between the two.
I would'nt touch the heads-I'd swap the cams and be done. There's not enough power gain benefit to offset the absurd amount of work to pull the heads,etc and the costs involved with head gaskets and head bolts,etc. All you absolutely have to have for the cam swap are the cams themselves and a tube of RTV-all of the gaskets are re-useable rubber seals,and there's not even any reason to change the oil or drain the coolant to do it.
JL

 

I really apreciate you taking the time to type all that out and explain it as well as you did to me. I agree 20 hp would not be worth the effort let alone cost, I would think you could get that easily much cheaper.
The air filter & intake looks very restrictive, is there a better alternative? Do headers help or are there better flowing factory exhaust manifolds? Sorry for so many questions but it seems like your giving me the straight answers I need. So I'll ask some more.
What would you do if you were in a similar situation? Leave it alone? Modify it? if so, how? Trade it in for a 5.4 or 6.8?
One more thing, this van does not have any type of towing prep package but can you tell me if these have a transmission or engine oil cooler? Both? I'm confined to a wheelchair and cant get a good look at anything dammit!

My background is in the motorcycle industry and I'm no expert on trucks, vans or cars so that's why I'm rather ignorant of the subject. I just bought this van and fear I'll burn up the engine or transmission towing 2,000 - 2,500 lbs. through the mountains. But after searching over 6 months this was by far the best for my needs that I could afford even with the smallish engine.
Full size van with a raised roof, a good 2,000 lbs. of handicap modifications and towing another 2,500 lbs. seems like a mighty load for the 220hp 4.6 or am I worrying about nothing?
When you dont have the option of getting out and walking if things go bad, it makes you think before you act.

Thanks,
PW

 

PW, the 4.6L will do what you need just fine in stock form. My old '98 pulled a 31' travel trailer all over the place and did it without a bit of a problem. The entire key is to have a good trans cooler and keeping the basic maintenance up. A gear change would be a good place to start-with that much weight,I'd say a 4.10 gear would be best. We've got 4 different E-series vans at work with a 4.6L and a 4R70W with the 4.10 axle and they get 13-15 mpg running around with a full load of ladders, tools and materials.
Headers aren't gonna gain you much more than the stock pieces-especially when you consider the hp-->$$ cost.
The OEM air inlet tube will be more than sufficient-it's a bit restrictive,but the OEM intake manifold is much worse.
I'd make sure it's got a good trans cooler,make sure it had a set of 4.10 gears,and drive it.
JL

 

thaks for the info from me too.............