NPI and PI engine questions??

[cobra clone 98]

yea i got them in on the deal.. i dont need them. thought i would just sell them

 

[Mikel]

Here is a article you might find helpful....

stock npi engine= 215hp
stock pi engine pi heads= 260hp

Alot of people have gotten on the bandwagon by thinking you need PI heads with the PI cams and PI intake. You don't and there are some running 12.3's on NA NPI headed motors.

For the owners of the 1996 – 1998 Ford 4.6L 2V Mustang GT, the PI (Power Improvement) swap can provide an excellent power boost for these underpowered motors. The PI swap may consist of a complete head and intake swap for full power benefits or just a PI cam and intake swap for decent power gains and other considerations. The pros and cons of both are discussed below.

Note: 1996 – 1998 Mustang GT’s are non power improved (nPI) equipped cars. 1999 – 2004 Mustang GT’s are power improvement (PI) equipped cars.


The PI cam and intake swap also provides decent power gains absent the draw backs associated with the PI head and intake swap. Swapping PI cams and a PI intake on nPI Stangs results in a 30 – 35 RWHP gain. The cams alone result in a 13 – 16 RWHP gain and the intake results in a 15 -18 RWHP gain. The extra 10-15 on the PI head is the bump in compression with an added cost for the heads.

The benefits of this swap are lower costs, less labor, and the fact that you maintain stock compression ratios. PI cams can be purchased used from many parts forums (such as those found on Corral, Modular Depot, or Mustang World) for about $100. PI intakes can be purchased for $100 - $200 depending on condition and whether or not they have the aluminum cross-over (recommended). The install kit with all the gaskets, heater tube etc, is about another $50 - $60. Therefore, for about $300 or less you can obtain up to an extra 35 RWHP making this mod an excellent dollar for horsepower gain! In addition you can use the saved money to port the NPI heads that will have more hp than if you went the PI head route. Some of the common rebuttles is "well i will prot the PI heads then". However, the drawback is that you have introduced much more airflow that the Pi cams, which are oem btw, can't be used to their full potential resulting in no real gain, but possibly a loss of hp. Too much airflow for the cam setup isn't going to yield hp.

When swapping PI cams, I recommend that you purchase 2001 + cams. These cams are Romeo cams (manufactured in the Romeo plant) and they have bolt on sprockets. Since the sprockets can be unbolted, you can use the Anderson tool to swap the cams. This makes the job a snap since all you have to do is take off the valve covers, cam covers, use the tool to hold the timing chain in place and then swap cams. Conversely, to do the entire PI head swap, you will have to either pull the entire motor, or tear it down in place to remove the heads.


The PI intake is a considerable improvement over the nPI intake. With its increased port volume and improved runner design, this intake has been shown to give up to 18 RWHP increases to the nPI equipped Stang.

When swapping the PI intake on nPI heads, make sure you purchase nPI gaskets since these gaskets seal the water ports. Failure to seal the water ports can result in coolant leaking into the combustion chamber and subsequent engine failure, so be sure to use nPI gaskets. Although these gaskets effectively seal the water ports (a must), they do not completely seal the intake ports. You must use high temp silicone sealant (permatex) to seal these ports. AGAIN… only apply the permatex to the intake. Applying excessive amounts of sealant can cause it to ooze into the intake port and obstruct it resulting in hesitation and reduced power.

I hope this helps any future 96-98 GT owners that you do not need a PI head to make power with these cars. Johnny Langton pioneered the first PI cam and intake swap and his 4.6 2v NPI motor runs 12.3 so he is proof this can be done and on a budget.

So

 

[Mikel]

So, I have a 1998 gt 145k with exhaust in the coolant! Do you think I could swap the whole motor out with a 99-04 4.6 2v?

 

[NEURON]

So, I have a 1998 gt 145k with exhaust in the coolant! Do you think I could swap the whole motor out with a 99-04 4.6 2v?

Sure its done all the time, also Crown Vic. engine are used too. I would Google it for lots of information on the swaps.

 

[96blak54]

^ excellent advice!

 

[Mikel]

Sure its done all the time, also Crown Vic. engine are used too. I would Google it for lots of information on the swaps.

Thanks!! I’m looking at a 99 grand Marquis with 87k, should be the same as a crown Vic I’m thinking!

 

[07GtS197]

Just be aware that no crown vic/grand marquis/town car got pi motors until 01. Otherwise youre good to go, just swap over the intake, fuel rails and all that over to the new motor from the old one.

 

[Mikel]

Ok thanks!! Maybe I’ll keep looking then!

 

[Mikel]

Just be aware that no crown vic/grand marquis/town car got pi motors until 01. Otherwise youre good to go, just swap over the intake, fuel rails and all that over to the new motor from the old one.

There is also a 4.6 out of a 2005 Crown Vic that sound like a much better choice! Just that the swap may be a bit more complicated! But doable!

 

[96blak54]

Any 04-up 2valve will be the better choice. Somewhere in the mix of 02 and 03 the 2v heads finally got revised with 9thread sparkplug holes. 04-up vics, lincoln, mercs, and E-series vans all came 2valve

 

[AStangThang]

Definitely 2004 and up. Just for some clarifications, I've had a 2006 crown Vic and 2005 E-series van, and the van had the 4.6L. Both had Romeo six bolt crank 4.6L V-8's, and same part #'s for cylinder head castings, and camshaft #'s.
96Black54 has done tons of research on stock 4.6L's camshafts, all Camshafts have had different part #'s, but the same engine. Seems like in 2004-'05 they made the change and kept all Camshafts the same across the board. I repeat myself, it "SEEMS" they kept the Camshafts the same from '04 and on. IF ANYONE HAS ANY 01-04 ROMEO MUSTANG GT CAMSHAFTS YOU SHOULD HAVE THEM TESTED BY 96BLACK54 IF HE WOULD HAVE YOU LOL. IM NOT YELLING GUYS, ONLY GETTING ATTENTION. I've got a set of '06 PI ROMEO camshafts from a Vic, and from my measurements the exhaust lobe is between .530-.540, intake lobe is between .500-.510. These measurements look like mustang Camshafts, but who knows lol. I would love to send them to him to test them, and to have more part #'s for us to list, so for the new guy who doesnt know any better, he won't get hiss ads took on a set of non-mustang pi cams.

 

[d.garza18]

So can I slap 01+ pi cams in my npi 2v heads and not have to tune it?

 

[96blak54]

^ yes will be just fine. Go ahead and swap!

 

[d.garza18]

^ yes will be just fine. Go ahead and swap!

Awesome! Definitely considering this. I’d like to doit without taking off the timing cover. Just use cam tool and pull valve covers. Would I have to change valve springs or is it just as simple as pulling the npi cams and slapping in the pi ones?

 

[96blak54]

Honestly the front cover isnt as bad as you think. Normally the cover gaskets dont need to be switched long as you take care not to rip them. Taking a razor blade to the rtv'd areas. Sometimes valve cover gaskets can be reused, but you wont know till their pulled.

Pull the dampener off, pull the valve covers, pull the front cover, mark chain to the sprockets, pull tentioners, pull cam caps.....heck, youve gone this far about reading how to, just do it! Youll get it back together. Just be sure to lay out how it all came apart and youll have no problems getting it back together.

 

[delling3]

I am preparing to do this swap, along with installing a PI intake I was contemplating not pulling the timing cover also, but after watching some videos on YouTube, it really doesn’t look like a bad job. The timing chain guides are plastic, and are prone to wear, so it’s a good time to replace them.

 

[96blak54]

^ exactly

May as well figure these engines out and boost your rebuild confidence in the process.

 

[d.garza18]

^ exactly

May as well figure these engines out and boost your rebuild confidence in the process.

I agree. I’ve been going back and forth on how I want to doit. The timing is just intimidating. So I guess I will just pull the front cover and tackle it head on. Worst comes to worst I make a mistake and y’all guys are here to help me correct it. Just so many questions I have.

 

[96blak54]

How about we guide you through it? No mistakes are needed!

Do you have an assortment of metric sockets?

Also grab a cheap harmonic dampener puller.

 

[d.garza18]

How about we guide you through it? No mistakes are needed!

Do you have an assortment of metric sockets?

Also grab a cheap harmonic dampener puller.

Yes I do! And my buddy may have a harmonic balancer puller I have to check again, if he doesn’t where can I find one? What else