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Old 06-19-2013, 08:15 AM
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97 4.6 converted to PI intake and maybe heads question and suggestions

I posted this in the engine forum but didn't get much traction so I am posting here. I hope you all understand.

Ok I have a 97 Econoline with a 4.6l. I am very interested in a PI head and intake swap. Just worried about the compression and trying to use 87 octain fuel. My main reason for this swap if for economy and power. I am not going to race the van but I know their is a place to improve its MPG's. I plan on upgrading the ignition and cold air intake that's easy.


The questions I have are -

Can I have the stock pistons machined with valve reliefs to reduce the compression ratio enough to run regular unleaded fuel?

Can I use aftermarket headers for F series trucks on a van?

Has anyone done this in a truck and what were the improvements?

Who do y'all suggest to retune my ECM or if it is needed?

Truck PI intake and PI cams vs car PI cams with truck PI intake?

Or should I just do the intake and cam swap and machine the surface of the NPI heads and do the article below?


(This article was posted on SN95Forums by member blackfang.

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.)


Thanks Trevor
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  #2  
Old 06-20-2013, 08:58 PM
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yawn, love the re-post...
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Old 06-22-2013, 01:15 PM
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Quote:
Originally Posted by chloichina View Post
I posted this in the engine forum but didn't get much traction so I am posting here. I hope you all understand.

Ok I have a 97 Econoline with a 4.6l. I am very interested in a PI head and intake swap. Just worried about the compression and trying to use 87 octain fuel. My main reason for this swap if for economy and power. I am not going to race the van but I know their is a place to improve its MPG's. I plan on upgrading the ignition and cold air intake that's easy.


[SIZE="5"][COLOR="DarkRed"]Can I have the stock pistons machined with valve reliefs to reduce the compression ratio enough to run regular unleaded fuel?
Valve reliefs may add a around a cc to your dish volume.

The PI head swap puts you just under 10.5:1 (~10.46:1 assuming 10.5cc NPI piston dish volume and 42.5cc PI chamber volume).

Add a cc of dish volume and that will drop you to about 10.3:1.

You can run 87 octane with a custom tune, but at that compression timing will be low enough that you will be giving up a good amount of power. I would also swap to a NGK (TR/BR) 6 or 7 heat range spark plug.

Quote:
Has anyone done this in a truck and what were the improvements?
The trucks don't benefit as much as the Mustangs because of the small cross-section, long intake runners of the Triton truck intake and restrictive truck exhaust. With exhaust and a Mustang manifold, PI swap gains will be identical to the Mustang.

Quote:
Who do y'all suggest to retune my ECM or if it is needed?
SCT

Quote:
Truck PI intake and PI cams vs car PI cams with truck PI intake?
No difference in truck/car PI cams. Every PI cam is identical, whether it came in a F150, Mustang, 4.6 or 5.4.

The truck PI intake will provide more power/torque up to ~4000 rpm, but it will be out of breath before 5000 rpm. The PI Mustang manifold makes far more power in the 4000-6000 rpm range. Depends of what you want.
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Old 06-26-2013, 06:43 AM
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Quote:
Originally Posted by Big Bad View Post
Valve reliefs may add a around a cc to your dish volume.

The PI head swap puts you just under 10.5:1 (~10.46:1 assuming 10.5cc NPI piston dish volume and 42.5cc PI chamber volume).

Add a cc of dish volume and that will drop you to about 10.3:1.

You can run 87 octane with a custom tune, but at that compression timing will be low enough that you will be giving up a good amount of power. I would also swap to a NGK (TR/BR) 6 or 7 heat range spark plug.



The trucks don't benefit as much as the Mustangs because of the small cross-section, long intake runners of the Triton truck intake and restrictive truck exhaust. With exhaust and a Mustang manifold, PI swap gains will be identical to the Mustang.



SCT



No difference in truck/car PI cams. Every PI cam is identical, whether it came in a F150, Mustang, 4.6 or 5.4.

The truck PI intake will provide more power/torque up to ~4000 rpm, but it will be out of breath before 5000 rpm. The PI Mustang manifold makes far more power in the 4000-6000 rpm range. Depends of what you want.

Thank you so much for your knowledge. I really appreciate it.
Thanks
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Old 06-26-2013, 06:54 AM
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chloichina chloichina is offline
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Quote:
Originally Posted by Big Bad View Post
No difference in truck/car PI cams. Every PI cam is identical, whether it came in a F150, Mustang, 4.6 or 5.4.

The truck PI intake will provide more power/torque up to ~4000 rpm, but it will be out of breath before 5000 rpm. The PI Mustang manifold makes far more power in the 4000-6000 rpm range. Depends of what you want.
So maybe resurfacing the stock nPI heads and PI cams might do the job and play with the intakes to find the best results?

Had to digest the information you supplied!
Thanks again
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Old 06-26-2013, 03:28 PM
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Originally Posted by chloichina View Post
So maybe resurfacing the stock nPI heads and PI cams might do the job and play with the intakes to find the best results?

Had to digest the information you supplied!
Thanks again
The PI headswap is worthwhile. Far superior INT port flow below .500" lift, larger EXH valve and stronger EXH port, more compression, more efficient combustion chamber.

I'm not quite sure of your usage profile, but unless your van is lugging trailers around most of the time I would consider a complete PI Mustang top end and bump your minimum octane requirement up to 89 or 91 octane. The extra compression will improve fuel economy a bit and performance by a lot.

Keep in mind if you go with a PI Mustang top end, you will need to bump wide open shift points up to 5500-5700 range and run a NGK 6 heat range (TR6/BR6EF) or Motorcraft 22 heat range (AGSF-22C/AGSF-22FM) plugs for optimum performance. This will require a custom tune.

Real "custom grind" cams would be very beneficial to you, even in a heavy application like your Econoline.

I would consider a set of cams that allow you to retain stock valve-springs, meaning .540" lift or less.

A good "torquer" truck cam for PI 2V heads (and only PI heads as NPI heads would benefit from a different exhaust lobe) would be something like this:
INT: 218-220 degrees @ .050"/ .525"-.540" lift
EXH: 216-218 degrees @ .050"/ .500-.540" lift
108-110 Intake Centerline
113-115 Exhaust Centerline

Figure roughly 25 RWHP over factory PI cams with a setup like that that matches/exceeds the PI cams even below 2500 then dominates them from then on. Will pass emissions without audible "chop".
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Old 06-26-2013, 03:28 PM
 
 
 
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