PI vs NPI Head/Intake Identification

[edbo]

I talked to the former owner of my '98 Stang 'Vert last night as we are pretty good friends. He mentioned to me that he had a problem about a year after he purchased the 'Stang (new) and had taken it back to the dealership where he stated the heads and manifold were replaced on the car.

He isn't as informed as we are as to what NPI and PI heads are so he wouldn't know if there is some chance that any PI heads could have been installed. He always insists that this was a very late '98 model and that there had been a subtle change on it vs. early '98s, but I have still yet to hear of anything to validate that particular claim.

What I do know is this: My motor pings something fierce on regular octane fuel (which I only ran once). It's much better on mid-premium grade fuel and I always rotate the Mid and Premium octane fuel at half full tank. This brings me now to my question: Is there a way to identify PI vs NPI heads externally without having to remove them?

 

[GDawg]

I talked to the former owner of my '98 Stang 'Vert last night as we are pretty good friends. He mentioned to me that he had a problem about a year after he purchased the 'Stang (new) and had taken it back to the dealership where he stated the heads and manifold were replaced on the car.

He isn't as informed as we are as to what NPI and PI heads are so he wouldn't know if there is some chance that any PI heads could have been installed. He always insists that this was a very late '98 model and that there had been a subtle change on it vs. early '98s, but I have still yet to hear of anything to validate that particular claim.

What I do know is this: My motor pings something fierce on regular octane fuel (which I only ran once). It's much better on mid-premium grade fuel and I always rotate the Mid and Premium octane fuel at half full tank. This brings me now to my question: Is there a way to identify PI vs NPI heads externally without having to remove them?

Well, if you have PI heads with a PI intake, you are going to only have one coolant sensor on the intake. The oil fill tube and oil dipstick on NPI are located on the driver's side. Some PIs have them (one or the other or both, not sure exactly) on the passenger side. If yours are on the passenger side then you definitely don't have NPI heads. The PI heads are marked "PI" but not sure of the exact location of the marking.

 

[markwsoil]

Stomp on it hard. If it feels like you're driving your Mom's 1979 Galaxy 500, it has NPI heads. If it runs like a scalded dog and half scares you to death, it's got the PI heads. I've driven both, and that's how it feels (was forced to buy the NPI car because of cost).

 

[mrvax]

This is true. There were no 1998 GT's with PI heads from the factory. My car was a late build also. PI heads will throw you back pretty hard, non-PI's won't. The biggest difference is between 4000-5500 rpm.