V8 TECH: 96-98 vs. 99^ PI heads on a 4.6 V8...

[RGR]

A few notes: I think the PI heads (2V) are BIG for a 4.6 and
the flow is not that high for the "apparent" port size. IMO (and
verified by a big-time shop I talk with) the older 96-98 2V heads
are better suited (fully ported) for a 4.6 than the new bigger PI's.

When a Blower is added, the new PI's are really sweeeet

More:
For 4.6 using PI heads I'd be rather conservative
on the porting, they have huge ports (lower velocity) and are really a
5.4 head, it's a universal application head for both engines.

You want porting that has the smaller ports, unless you are going
with a high-boost SC application, positive-displacement blowers
can use the bigger stuff while centrifugals work best with heads
that are ported more closely to NA specs.

A friend of mine is an R&D manager in a big shop and they were
getting better results with 96-98 2v heads (ported) over the
PI stuff, way better matched as far as port volumes go, I think
it was RWHP they were testing and it exceeded 400 BHP with
relatively mild camming (~224*) and older 96-98 heads. But
their porting guy is first rate, and their shop is rather advanced.



In short, if you have a 96-98 GT and want more NA power, don't get the
new PI heads, get yours ported! It will be cheaper and easier, and another
hot ticket is use the PI cams, they are cheap and make great torque.

[silverstangboy]

very awsome, I've heard that before, but never really knew how true it was, still I must say im really surprised.. there was alot of tech in there, especially for an engine that people are well, normally kinda lost with.
question though, with the teardrop heads (96-98) are they using the expensive ass SVO aluminum intake to port with? thats alot of reason alone why people don't use the older heads as much, though I hear there is a port match (sortof) block you can get between the teardrop heads and the PI intakes (which apparently also flow alot better untouched)

is there another direct fit portable intake for the teardrop heads?

im impressed though, 400 at the wheels! n/a on a two valve

[RGR]

It was 400 BHP, I clarified that in the first post, sorry
Still impressive though! I think they used a stock intake
or made a PI work.

I was dreamwheeling a passenger car intake conversion, it is
aluminum and dirt cheap, it would need plates to make the EGR
passages not leak on the 96-98 Mustang heads, but it can be made
to work, and them you have an intake that can be ported or whatever!

[98GTSTANG]

Quote: Originally Posted by silverstangboy very awsome, I've heard that before, but never really knew how true it was, still I must say im really surprised.. there was alot of tech in there, especially for an engine that people are well, normally kinda lost with. question though, with the teardrop heads (96-98) are they using the expensive ass SVO aluminum intake to port with? thats alot of reason alone why people don't use the older heads as much, though I hear there is a port match (sortof) block you can get between the teardrop heads and the PI intakes (which apparently also flow alot better untouched) is there another direct fit portable intake for the teardrop heads? im impressed though, 400 at the wheels! n/a on a two valve

I was thinking of doing a PI swap, but you say this is cheaper. What is the horsepower gain from this without any power adders? How much does it cost to get the heads ported? I need to beef up my 98.

[justin00stang]

I saw at least one car that had ported non-PI heads make no power, I suspected the porter.

[RGR]

Quote: Originally Posted by 98GTSTANG I was thinking of doing a PI swap, but you say this is cheaper. What is the horsepower gain from this without any power adders? How much does it cost to get the heads ported? I need to beef up my 98.

You could probably get good porting for ~$400 with stock valves
but PI valves are a good upgrade for cheap... or port it yourself!

PI cams are still a bit small (201 Int./ 210 Exh. if I remember right) for an
essentially RPM motor (OHC), Livernois used a 224 cam (.050 duration)
to get that 400 BHP. I'd use a Comp 224 grind and matching
springs. Using the PI 224 grind allows .550" lift where the non-PI
cams just go .500" but you need to match cam/spring/retainer/seats
and maybe even valves to use the PI-spec (.550") cams. But worth it
IMO!