what is PI and non-PI? I hear these terms and have no clue what they are. Is my car PI or non-PI?
stupid girly question but...
- Thread starter Seraphitia102
- Start date
Dope 97GT
New Member
PI and non PI refer to the cylinder heads on the 96-04 mustang gts or the 4.6 sohc engines. From 96-98 they had the NPI heads which made around 40 or so hp less than the 99-04 cars which had the power improvement cylinder heads.
Your car is a PI car because of the year 99-04.
Your car is a PI car because of the year 99-04.
four six
Member
PI heads are the Power Improved heads that came on 1999-2004 GTs
Non-PI heads are non-power improved heads that came on 1996-1998 GTs.
The heads have a lot better flow over non-pi. Yes you car has PI heads
Non-PI heads are non-power improved heads that came on 1996-1998 GTs.
The heads have a lot better flow over non-pi. Yes you car has PI heads
four six
Member
BooWFO
New Member
You all forgot the fact that the PI cars have slightly better, intakes and cams. Combined the heads, intake, cams make them PI. 
Dope 97GT
New Member
BooWFO said:You all forgot the fact that the PI cars have slightly better, intakes and cams. Combined the heads, intake, cams make them PI.
yeah nice addition
BlackenedSVT
Active Member
Seraphitia102 said:
I'm actually surprised you dont know that. You've been around these forums for a while now. Just surprised you haven't asked any of us earlier
But now ya know
Twista
Active Member
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Twista
Active Member
One of your questions has still not been answered. An S281 is a supercharged engine, so whether or not the base engine is PI or not you are WAaay up on power compared to a normally aspirated (non super charged) engine of either type.
As explained, this involve different and MATCHING cams, heads and intake manifold.
The Cams are entirely different in that the earlier cams are designed with a longer duration (leave the valves open longer), shorter lift philosophy while the PI cams use a shorter duration, higher lift philosophy.
The cam design philosophy change is to take full advantage of the high flow characteristics and flow pattern of the PI heads. For this reason if one were to change heads on an early engine to PI, they will be missing some of the power addition available if they do not also use PI intake and cams.
As explained, this involve different and MATCHING cams, heads and intake manifold.
The Cams are entirely different in that the earlier cams are designed with a longer duration (leave the valves open longer), shorter lift philosophy while the PI cams use a shorter duration, higher lift philosophy.
The cam design philosophy change is to take full advantage of the high flow characteristics and flow pattern of the PI heads. For this reason if one were to change heads on an early engine to PI, they will be missing some of the power addition available if they do not also use PI intake and cams.
Dope 97GT
New Member
MBDiagMan said:
not all saleens are supercharged i believe the speedsters are and the s281extremes are hers is not.
jstreet0204
Active Member
MBDiagMan said:
s281's are not supercharged. s281sc's and s281E's and a few others got a superharger. s281 is the base model.
