ok another noob question

2003whitegt · Mar 9, 2010

Ok, so another noob question. I've been reading thru the threads and have seen where it was written the in the vin code for the 03 gt's that the X in the 8th position means PI. My question is what is the difference between the PI and nonPI engine codes mean? Thanks for the help, and please dont beat up on me too much...lol

wmburns · Mar 9, 2010

PI non-PI differences

Are you asking what is the VIN code for a non-PI 4.6? ("W"). OBTW, Mustang GT's all got a PI motor starting in 1999.

Are you asking what is the difference between a PI and non-PI engine?

The engines have the same basic external measurments. The heads are different to improve air flow (hence PI). Because the heads have different shaped intake ports, the intake manifold is different.

The PI heads have a smaller combustion chamber. The non-PI has flat top pistons. To keep the CR nearly the same, the PI motor has recessed pistons.

When PI heads are installed on an non-PI motor, you get the air flow improvement and a 1 point increase in CR.

Rickyll7 · Mar 9, 2010

wmburns said:
Are you asking what is the VIN code for a non-PI 4.6? ("W"). OBTW, Mustang GT's all got a PI motor starting in 1999.

Are you asking what is the difference between a PI and non-PI engine?

The engines have the same basic external measurments. The heads are different to inprove air flow (hence PI). Because the heads have different shaped intake ports, the intake manifold is different.

The PI heads have a smaller combustion chamber. The non-PI has flat top pistons. To keep the CR nearly the same, the PI motor has recessed pistons.

When PI heads are installed on an non-PI motor, you get the air flow improvement and a 1 point increase in CR.

Not flat tops, but close. Some 4v engines have flat tops.

2003whitegt · Mar 9, 2010

thanks

Thanks for the info. I was wondering what the difference was. I didn't want to start modding the engine without knowing the difference.

JerseyTrueBlue · Mar 10, 2010

To elaborate a bit more, you have one of the latest model new edge mustangs. Being an 03, you have the best of the best so be glad lol. Well as far as motors go that is..I don't like the T-3650

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