PI Intake swap postmortem

I should hope so - that's the point of ported heads, isn't it!

Now, when I say "pulls to 6K" on my car, I don't mean it's making peak HP all the way out there and I'd have to get dynoed to accurately determine shift points and all that, but, it does pull strongly all the way up there now unlike before where it felt like it might not even make it to 6K with a load on it and you could really feel torque dropping off rapidly beyond the edge of the usable power curve.

Since we're here... I was able to get the broken upper plenum bolt out last night, no problem - there was plenty sticking up out of the intake to grab with some vise-grips. That mostly cleared up a minor and very subtle driveablitily issue I had started noticing below 1500 RPM in 3 gear or higher with the throttle just barely cracked. Throttle response felt a little crisper overall below 2K this morning - it had started feeling a little soft after the initial crispness right after the intake swap.

I found another small possible vacuum leak in the hose from the evap purge valve to the intake - the hose seems to have stretched and is just a hair too big so it isn't sealing well on the nipples on the valve or the intake and if you wiggle them around you can hear a leak get better and worse. I replaced the hoses last year or the year before and it seemed like it fit right at the time so I'm not exactly sure what's happened. Also explains the occasional faint whiff of gas vapors I catch.

mgoesse said:

I just wanted to thank everyone here for the excellent information! Nice write up Patman0911, lots of information I have been hunting everywhere for! I was driving my '96 GT to school after having just gotten it out of storage for the winter. When I got there, I blew my head gasket in the parking lot. I thought this was the perfect opportunity to do the pi head swap, so I got myself a set of pi heads and intake off a 2001, as well as the coolant nipple and pi coolant tube, and (thanks to your post clearing this up), an alternator bracket. I love my Mustang and can't wait to drive it after this swap. Thanks again for a good write up!

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Good luck! Should be a really nice increase in power with the full PI swap. Glad you found the info helpful.

I don't know if I added anything new - most of it's out there somewhere and been around for a while, but I tried to collect as much as I could into one place because you have to do a lot of cross-referencing of all the various writeups because they all gloss over one aspect or another or take for granted that you already know all the ins and outs of the various year differences in these motors.

D-BOI said:

you dont have to tap the pi intake if you get the romeo one for the 96-98 do you?? thats only for the windsor right

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I don't think there's such a thing as a Windsor or Romeo PI intake (when talking about passenger car intakes), there's just the early all-plastic PI intakes and the later aluminum crossover PI intakes - they updated the intakes after passenger car engine production resumed at the Romeo plant so some Romeos have the all-plastic intake.

All PI intakes have only one coolant sensor hole tapped and all NPI require two coolant sensors so you have to deal with it one way or another with either style PI intake or give up the your temp gauge.

The all-plastic intakes only have provisions for one coolant sensor so you either have to find a location to tap on the head or block, tap the t-stat housing (gauge may not read accurately when the t-stat is closed - also not much metal to work with so it probably needs reinforcement) or run a tee for both sensors in the crossover (not a very good solution as it's almost impossible to get good readings like that - see the thread about coolant boiling over in tech currently - and both your gauge and the PCM will get bad readings possibly affecting driveabilty and MPG)

The aluminum crossover intakes already have a spot for a second sensor in the correct location but it needs to be drilled out and tapped, or, you can swap the crossover tube from an updated aluminum crossover NPI intake which already has that hole tapped.

The two coolant sensors operate in different electrical ranges so you can't just splice the wires together and make it work. There is a GM dual coolant sensor that could possibly be made to work if the ranges could be corrected to fit what the PCM and dash gauge expects to see, maybe just some simple resistor circuits would work - I started to look at that once but then the aluminum crossover PI intakes started to become widely available and reasonably priced and there didn't seem to be any more need for a complicated solution to a simple problem.

If you're doing this swap and have the all-plastic PI intake, I recommend selling or giving it to to someone with a PI car that needs an intake and getting the aluminum crossover PI intake instead - it's really just much simpler and you won't have any issues to worry about with the cooling system monitoring since everything is in the correct factory location and functioning as intended - you'll have enough to worry about with wondering if you put everything back together right and leak free without also having to worry if the temperature readings are right or are you actually overheating but the gauge is reading low...

The first one is correct, although I've heard people say the Ford intakes are better than the Dorman intakes. FRPP PI intakes should be about the same price.

That second intake isn't off a Mustang, although it appears to be a PI intake and should work just fine. It looks like that location is already tapped and it's being used as to warm the air passing through the IAC.

You don't really need all the extra stuff that comes with that intake - you'll need to reuse your old return-style fuel rails and you'd probably want to reuse your TB and plenum as even if that was a Mustang TB/Plenum some of the hose fittings (IAC, PCV and EVAP) may be different sizes between different years - that plenum doesn't look like it would work for a Mustang anyway though, not without some modification, at least.

I'd keep looking, I've seen used PI intakes go for a lot less than $150 - I've seen as low as $75 for aluminum crossover intakes and even less for all-plastic intakes but $100 is probably a fair price for a PI intake in good shape unless you've got the patience to scrounge for a slightly better deal. Keep an eye on the classifieds on the various Mustang boards and keep looking out for them on eBay - I found mine on one of the boards and it was a much better deal with more parts that I actually needed for the swap and more useful extra parts I didn't need that I could sell off to defray the costs than that piece does. Check the junkyards too - you can score PI intakes off other passenger cars and some trucks but pay attention to what you're looking at because other vehicles got PI motors in later years than the Mustang and it's a bit hazy as to who got what when, and some trucks get truck-specific intakes and some get regular PI intakes.

This is what a PI intake should look like:



Notice that the first runner from the front of the intake feeds cylinder #5 on the drivers side. On a NPI intake, the first runner feeds the cylinder #1 on the passenger side of the motor.

If you can see the bottom of the intake, you can see the rectangular PI intake ports - NPI ports are circular.



PI on the left, NPI on the right. Notice how much deeper the runners on the PI intake are (the reason you need a new coolant tube for the block valley), whereas the NPI intake runners are much squatter.