if i'm correct thye started putting the 4.6 in mustangs in 96. is the 96 motor any different than mine ? or they kinda the same cuz i never saw under the hood of any mustang older then mine

 

They are the same motor. The 96-98 variants didnt flow as much air through the heads/intake/cams, therefore having alot lower power curve and they seemed to fall on their face at 5000rpm or so. in 1999, ford introduced the PI heads (Performance Improved). This was a better flowing head design, better cams and better intake. This brought the power up quite a bit and made them a much stronger car.

Alot of folks have done the headswap to PI parts on their 96-98 GT and acctually make more power than a 1999+ car. The reason is because the 96-98 cars had flattop pistons, which with the PI heads, had a higher compression ratio than the 99+ cars with the same heads.

 

MMMMMMMM Juicey information

Thanks Scott

 

:scratch: I am confused? What years do u swap heads with? :scratch:

 

Swap 99+ heads onto 96-98 GTs.

 

Thanks, So that adds power? Then your older motor has more power than the newer one?

 

yup, thats what they're getting at.

 

Thanks, So that adds power? Then your older motor has more power than the newer one? [/b][/quote]
yes. The reason being is that 96-98 motors have flat top pistons. BUt they have really bad flowing heads and intake.

99+ cars have dished pistons and much better flowing heads and intake. But the deck clearence on the 99+ heads is shorter than on the 96-98. Therefore when you put the 99+ heads with a smaller deck clearence, on 96-98 motors with flat top pistons, you get a higher compression ratio than a 99+ car, which produces more HP

 

Ok, Now I understand

 

the intake was the biggest culprit as the PI heads have better bottom end and mid-range flow IIRC while the old 4.6 heads actually outflow the PI heads on the top (for all the good that'll do ya).

 

You are partially right Bob, but the PI heads cams and intake together will make more HP across the board than a non-pi head car with a PI intake and/or cams.