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#704643 - 05/15/05 11:53 PM Re: HP Gains: PI Cams on a NPI Engine?
Virginiamountainman Offline
Over the Hill

Registered: 04/04/02
Posts: 2093
Loc: North Carolina
Quote:

Virginamountainman - ask yourself this:

Why would a NPI head car make better power than a PI car when the only (major) differences apart from the heads are that the NPI car has a more recent air intake? This would suggest that the air intake is worth more than the PI heads which seems most unlikley to me!

How about if you added the intake to the PI car?

Something is wrong in the math here.

Incidentally, if there is any way you can afford it get an 03 - the suspension & brake changes transform the car.

One Q - by "air intake" I assume that you mean the "zip tube" - if that is so then you need a larger MAF since the zip tube is for an 80mm MAF (or some sort of adaptor).




I am completely familiar with the difference between an intake and a zip tube. I was referring to the intake manifold. And yes, it appears there is something wrong with the Math. That is the reason for the post. I don't mean to call anyone out, but I have heard from one person in this thread and another person while searching that a PI intake and PI cams on a NPI engine is worth about 30 HP on the ground. Again, my point: That would equate to about 245 to 250 HP at the crank with that logic. And you are right: the numbers don't add up, since an '01 is rated at 235 HP at the crank with PI heads and intake stock.
_________________________
2004 silver unmarked P71 Lieutenant's car from NCSHP, purchased 060208 with 90,247 easy miles. Geared 3.27. Accufab 70MM throttle body. Accufab plenum, ported and polished. NGK TR55IX plugs. Magnaflow direct fit high flow cat pipes. Magnaflow 12255 mufflers. Steeda underdrives. Goodyear Assurance TripleTred 225/60/16. Drilled/slotted rotors with ceramic pads. UHaul trans pan with a STINKING drain plug that should have come from the factory.


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#704644 - 05/16/05 08:47 PM Re: HP Gains: PI Cams on a NPI Engine?
Tony_the_Brit Offline

Over the Hill

Registered: 09/16/01
Posts: 2919
Loc: Indiana - South Bend area
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??
_________________________

11 Crown Vic LX Blue 151,000 m

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#704645 - 05/17/05 03:04 AM Re: HP Gains: PI Cams on a NPI Engine?
JohnG Offline
Tech Admin
Grand Poobah

Registered: 06/15/01
Posts: 13025
Loc: Socialist state of MN
Tony, VERY good idea, I can work on this.
_________________________
- 2004 Mercury Grand Marquis (GMQ) GS - aka "Data"
Save MILLIONS, vote to outsource our Executives!
What happeded to "government by the people, of the people and for the people"?
RIP Ronald W. Reagan "The Great #40"

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#704646 - 05/17/05 03:54 AM More Myths: WasHP Gains PI Cams on a NPI Engine
Mitch Offline
Rookie

Registered: 04/22/04
Posts: 54
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
_________________________
'00 CVPI
ADTR CAI w/80mm MM MAF
'03 MAF to TB zip tube
SCT tune

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#704647 - 05/17/05 10:39 AM Re: More Myths: WasHP Gains PI Cams on a NPI Engine
StevenJ Offline
Over the Hill

Registered: 05/16/05
Posts: 1260
Loc: Florida, USA
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?
_________________________
Love to argue but life is too short! Or was it that the argument was too confounding and the days take forever to pass? I forget.

Car-
2003 Mercury Marauder 300B Silver Birch

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#704648 - 05/17/05 10:42 AM Re: More Myths: WasHP Gains PI Cams on a NPI Engin
metroplex Offline
Metroplectic

Registered: 11/13/00
Posts: 49827
Loc: Motor City, USA
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.
_________________________
These aren't the droids you're looking for!

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#704649 - 05/18/05 02:14 AM PI vs NPI cams
Mitch Offline
Rookie

Registered: 04/22/04
Posts: 54
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
_________________________
'00 CVPI
ADTR CAI w/80mm MM MAF
'03 MAF to TB zip tube
SCT tune

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#704650 - 05/19/05 12:40 AM Re: PI vs NPI cams
Tony_the_Brit Offline

Over the Hill

Registered: 09/16/01
Posts: 2919
Loc: Indiana - South Bend area
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...

_________________________

11 Crown Vic LX Blue 151,000 m

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#704651 - 05/21/05 05:45 PM Re: PI vs NPI cams
Johnny-Langton Offline
Member

Registered: 12/24/04
Posts: 116
Quote:

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



Mitch,I've measured both cams,and not just one set...several.
Here's the average of those sets:
Non-PI:
Intake .462" lift/201 @.050"
Exhaust .462" lift/208 @.050"
114 intake C/L
113 exhaust C/L

PI:
Intake .507" lift/200 @.050"
Exhaust .534" lift/210 @.050"
114 intake C/L
115 exhaust C/L
The duration and centerlines are so close that I'll say the slight differences seen are production tolerances.
There are alot of items in that SHM book that are incorrect.
JL
_________________________
'97 Tbird LX 4.6L/4R70W-N/A
12.28 at 109.57
Ported Non-PI's
Comp Cams

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#704652 - 05/21/05 06:36 PM Re: PI vs NPI cams
Virginiamountainman Offline
Over the Hill

Registered: 04/04/02
Posts: 2093
Loc: North Carolina
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.
_________________________
2004 silver unmarked P71 Lieutenant's car from NCSHP, purchased 060208 with 90,247 easy miles. Geared 3.27. Accufab 70MM throttle body. Accufab plenum, ported and polished. NGK TR55IX plugs. Magnaflow direct fit high flow cat pipes. Magnaflow 12255 mufflers. Steeda underdrives. Goodyear Assurance TripleTred 225/60/16. Drilled/slotted rotors with ceramic pads. UHaul trans pan with a STINKING drain plug that should have come from the factory.


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#704653 - 05/21/05 06:43 PM Re: PI vs NPI cams
JohnG Offline
Tech Admin
Grand Poobah

Registered: 06/15/01
Posts: 13025
Loc: Socialist state of MN
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.
_________________________
- 2004 Mercury Grand Marquis (GMQ) GS - aka "Data"
Save MILLIONS, vote to outsource our Executives!
What happeded to "government by the people, of the people and for the people"?
RIP Ronald W. Reagan "The Great #40"

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#704654 - 05/21/05 07:09 PM Re: PI vs NPI cams
Virginiamountainman Offline
Over the Hill

Registered: 04/04/02
Posts: 2093
Loc: North Carolina
Thanks, John.
_________________________
2004 silver unmarked P71 Lieutenant's car from NCSHP, purchased 060208 with 90,247 easy miles. Geared 3.27. Accufab 70MM throttle body. Accufab plenum, ported and polished. NGK TR55IX plugs. Magnaflow direct fit high flow cat pipes. Magnaflow 12255 mufflers. Steeda underdrives. Goodyear Assurance TripleTred 225/60/16. Drilled/slotted rotors with ceramic pads. UHaul trans pan with a STINKING drain plug that should have come from the factory.


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#4094900 - 02/05/21 08:45 AM Re: HP Gains: PI Cams on a NPI Engine? [Re: Virginiamountainman]
FR3AK Offline
Stranger

Registered: 07/12/20
Posts: 2
Loc: United States
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
_________________________
DROW A WILSON

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#4094976 - 02/05/21 08:04 PM Re: HP Gains: PI Cams on a NPI Engine? [Re: Virginiamountainman]
2004_p71 Offline

no replacement for displacement
Posting Addict

Registered: 09/04/03
Posts: 15777
Loc: Quebec Canada
why do you want to do a cam swap ?
_________________________

Best time 13.079 @ 105 1.8 60'
comming back this fall

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#4094996 - 02/05/21 10:17 PM Re: HP Gains: PI Cams on a NPI Engine? [Re: 2004_p71]
dixiebandit69 Offline
5.4 Club
Member

Registered: 01/17/12
Posts: 327
Loc: Texas
Originally Posted By 2004_p71
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.
_________________________
2007 Grand Marquis LS: 5.4 swap, 9.9:1 compression ratio, Comp XE268s, NPI pistons, PI heads ported by me, Accufab upper plenum, 75mm DBW throttle body, Factory PI intake with Chinese spacers, CVPI dual exhaust, CVPI torque converter, CVPI air-box and zip tube, J-Mod, 3.55 gears, FMS Trac-Loc differential
17" Dorman CVPI steelies, BFG Comp T/A 255/45 R17s

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