What we need is an archive of posted Dyno run graphs, together with the engine specs. This would at least help people decide what to do. Matching claim V's claim is always a problem because even when they have tested the items what about the rest of the engine?

John - what do you think??

Tony, VERY good idea, I can work on this.

Just my .02,

But if you go through all the threads on Modular Depot (a lot more 96-98 Mustang owners have done the PI intake/cam/head swap than Cvic owners)...you'll note the following:

1. The NPI intake is more restrictive on NPI power than the NPI cams. Accordingly, you will get more power out of swapping the PI intake (PI intake gaskets and black RTV) on the NPI motor than swapping the PI cams on the NPI motor. When I dyno'd my NPI motor (with 80mm MM MAF, CAI, '04 ziptube and SCT 93 octane "flash")....I was amazed to see than my hp remained flat from 4,200 to 5,000 rpm and then did a nice gradual fall down from 5,000 to 5,500. When I posted my dyno results, all the NPI veterans on TCCOA and Modular Depot laughed and said "welcome to the NPI intake".

2. If you review the cam specs of NPI vs. PI, you'll see that while the PI cams have more lift...the NPI cams have more duration. The PI cams generally make better power and the increased lift/less duration works well with the PI manifold (PI manifold by itself may lose a little low-end torque to the NPI manifold).

3. PI heads have a nominal combustion chamber volume of 42cc, NPI heads have a nominal combustion chamber volume of 51cc. PI pistons have a 17cc dish and NPI pistons have a 11 cc dish. Headswapping PI heads on a '98-00 CVic gives you a nominal 10.52 to 1 compression ratio vs. the stock PI nominal compression ratio of 9.66.

4. Despite all the ballyho about PI heads, the best 2V head on the market is still the SVO (NPI based head). The next best heads are ported NPI late model heads with oversize valves. Look at both Sean Hyland and Renegade Racing...both conclude that fully ported NPI heads outflow fully ported PI heads.

Conclusions:
Speed cost money, how fast do you want to go?

A. If you want to go fast for less, buy the cheapest, mechancially sound 1998 P71 (w/3.55s & TractionLok) that you can find (3,000-6,000) and add the following:
Used PI heads ($350)
Used PI intake ($150)
New '04 zip tube ($40)
New MM 80mm MAF ($150)
CAI ($200)
SCT tune ($175)

B. If you want a late model PI engined car you still have to do the following after you pay the much higher "intro price":

PI cars:
'01-02:
Install '04 Zip tube, MM MAF and CAI and SCT tune and still be down at least 10hp from a head swapped NPI car.

'03
Install '04 Zip tube, MM MAF, CAI and SCT tune and still be down at least 10hp from a head swapped NPI car plus being heavier (100lbs??) with less brake capacity.

'04-'05
SCT tune and still down at least 10hp from a head swapped NPI car plus being heavier (100lbs??) with less brake capacity.

Easy to see the superiority of the PI motor? Makes less power and costs more money! That notwithstanding, we should look at weight comparisons for non P71 cars too:

No worth boring everyone with silly comparisons....but leather benches and goodies all add up in weight. My 2000 CVic P71 weighs in at 4,198 on the scales with a 1/2 tank of gas, full size spare and jack in the trunk, me (190 + 10lb for leather jacket, clothes, shoes), 16" steel wheels with trim rings and center hubcaps). Per the tech official at US 41, my Cvic at 4,198 with me in it is LITE...most Marauders and loaded CVics hit the scales (w/driver) at 4,400-4,500lbs.

FWIW, there are numerous '96-'98 Mustangs running 12s with stock PI heads bolted to stock NPI shortblocks ("bolt-on" cams, PI intakes, LT headers, MAF, TB, Upper Plenum)

PI Motored cars...yeah they're clearly better....still waitintg for a PI motored Tbird to beat Johnny Langton's 12.5 in Houston!!!!

Mitch

I am confused. Do the newer 01-05 civillian Crown Victorias come with the PI heads and PI intake stock or are you talking only about the police interceptor version? If so, why is it that it only makes 240 hp vrs. the Mustang Gt's 260 hp which uses the same motor on the same 9.4:1 compression? Are the stock exhaust really that restrictive?

01-up 4.6L 2V V8s all have PI heads and PI intakes and PI cams.

The Panthers have more restrictive intakes and exhaust setups vs Mustangs, and there's also a tuning difference.

With a dynotune, some exhaust and intake work, a full PI headswap will put a pre-01 Panther into the 260 crank hp range.

Quote:

---

2. If you review the cam specs of NPI vs. PI, you'll see that while the PI cams have more lift...the NPI cams have more duration. The PI cams generally make better power and the increased lift/less duration works well with the PI manifold (PI manifold by itself may lose a little low-end torque to the NPI manifold).

---

NPI and PI cams have the same duration. Any difference is minimal and negligible. The PI cams have more valve lift. IIRC starting in 98-up the PI valvesprings are the same as the NPI valvesprings.

Charlie,

NPI cams: .480I/.480E lift, 204/208 duration @ .050
PI cams: .535I/.505E, 192/184 duration @ .050

Source: Sean Hyland

What's your source of information behind your assertion that PI and NPI cams have the same lift??

BTW, installed spring heights and spring pressures are different between the NPI and PI heads.

Mitch

Charlie said that they have the same duration, not lift. He was correct about the lift.

(Of course he was wrong about the duration unless you consider the difference "minimal and negligible".)

All right guys, make it clean and no low blows...

Any thoughts as to how adding PI heads to a NPI engine would affect the longevity of the engine? I would be working on an engine with 80,000 to 100,000 highway miles, either a State admin car, or a well-treated Highway Patrol edition, hopefully with relatively low idle hours. I would think that with the added compression, piston ring life could be affected.

VMM, no problems.

I would not trust ANYTHING SHM puts out in print etc as the "gospel", and most of it I regard as inaccurate at best or even down-right misleading in some cases.

Then again, I would not TAKE (as in for free) one of theri engines for use in anything I own either.

Thanks, John.

Hi I just bought a 2010 crown vic pi and I had the exhaust done with muffler deletes and pipes coming out before the rear wheels but what I want to know is how much power I can expect to gain if I do a cam swap and if there is anything I should do before I do it like change throttle body and so on thanks for the help in advance I had alot of cars and bikes but never a crown vic pi

why do you want to do a cam swap ?

Because he wants more power, duh...

Seriously, though, I think that's a bot. It's his first post, and he's replying to a thread that's old enough to get a driver's license.

Or he's a clueless rube who has a tenuous grasp of how internet searches work.

One or the other.

PROVE ME WRONG.