P-Head review

timk

Founding Member
Jan 8, 2002
156
0
16
st.louis, mo
this is long and boring, but for anyone considering a budget buildup, this may be for you.

i decided to install my GT40 P heads that originally came with the explorer engine i installed in my car last fall. i was a bit disappointed with the low end and valvetrain noise on my current setup. so, having just gotten the cobra, i figured i could have the 95 down for a while and take my time.

i took a few pieces off a day. no hurry. then, i put a few pieces on a day. i never had any help. the hardest part was lifting the drivers side head up and over the a/c line and into place. other than that, piece of cake.

i bought a ford head changing kit from summit. the supercharger kit, with better bolt and supposedly tougher gaskets, $99.

i bought MAC 94-95 P headers from central coast mustang. they were $210, and they came with copper gaskets. these headers are probably worth $7. they come with 11mm 3/8 bolts. you cannot access the bolt heads with a wrench once installed. so, i went to sears to buy stainless allen-head bolts. best $15 i ever spent! P heads recess the plugs very deeply, and sort of under the exhaust ports, and as such, you have to use a spark plug wrench that has flats on it for a wrench, because your rachet isn't going to fit onto it because of the closeness of the primaries. i finally figured this out, and it was all good.

started car up, easy. copper gaskets leaked immediately. not necessarily because copper gaskets aren't any good, but because my $210 (worth seven dollars) headers are not true. live and learn. next day, spend $16 on ford OEM explorer exhaust manifold gaskets and 2 1/2 hours later, no leaks.

i have to say, there is no better bang for the buck than P heads. you can find these things for less than $300. (i bought the whole '99 explorer 5.0 for less than $800 with only 6k on the clock.) the power from 2k to 5k has to be 10% better than my current setup, with NO OTHER CHANGES, other than the $210 (seven dollar) headers. if i had known that, i wouldn't have removed the P's from the block in the first place when building the engine originally. that said, perhaps my cam choice wasn't ideal for the ported stockers, and it's a better choice for the P's. the ported stockers made peak power at 5500rpm, but were weak up until 3000. these don't pull much past 5000rpm, but there is torque everywhere now. whatever the case, my car is an absolute BLAST to drive. there is little or no valvetrain noise now, perhaps because the upgraded valvesprings in the old heads put just enough extra strain on whatever valvetrain abnormalities i had. the P springs are stock, only good for sub .500 lift, but the Steeda cam has only .480 with 1.6 rockers, so i'm safe there.

if my tax return is as good as i think, i will have this setup dyno tuned, and compare the numbers to my last dyno graph. the previous setup yielded 250/280 on a dynojet dyno. but, whatever the numbers, i guess i don't care....more fun is more fun.
 
awesome... glad everything worked out.

I cant wait for my Ps... I need a job:(

if you change the cam and springs... the P heads like a split cam with duration that favors the exhaust like a comp xe270 or similar cam
 
P heads are awesome for budget buildups...there was a guy on Corral that made 299rwhp with P's and an AFM cam.

I have no idea how they compare to Thumper heads but I would think they are within a few HP of each other. I don't think I would go through the trouble of swapping from ported E7's to P's, but AFR's on the other hand... :D
 
this is good to hear, i really would like to get a set of these heads and give them a shot, even if i don't like the powerband i think i can get rid of them for what i bought them for.


anyhow, more details are in order what gears cam intake etc is in your setup and what was the old setup. I would really like to know.

jason
 
yes, i imagine if i had gone the custom cam route, or at least carefully chose a cam for either head, both would perform better. live and learn. i do not, however, see going through the work to change the cam. it's fun to drive. since this is a paid-for daily driver, another engine may be in order in the future.

imyourzero, it was really only a matter of labor for me. i already had the heads. all i needed to buy was the headers and the headchange kit, and i already had the other heads and headers sold, which more than took care of the bill. they may very well be within a few hp's of one another, but the area under the curve is NOT the same :D

and as an added bonus, i drove a 200 mile highway trip today...averaging 24mpg...if i got 20mpg with the old setup, i was lucky. i don't care about milage, but it's a nice extra.

setup....P's with stock springs and valves, stock stamped rockers, cobra intake, steeda #19 cam, pulleys, 75mm Pro-M, 65mm FMS t-body, 3.73's, MAC P-headers, BBK xpipe w/cats, Dynomax SuperTurbo catback.

old setup...ported E7's with upgraded .550 lift springs, BBK shorty headers...the rest was exactly the same.

it's just morbid curiousity, but i DO want to compare dyno graphs. given what ported E7's cost if you buy them (as opposed to doing it yourself), the P's are a bargain, especially if you had planned on getting aftermarket headers already.

oh, and by the way...you can bolt your smog tube to the back of the P heads. the tube wont do anything, but if you have to pass a visual, you can attach it all with no problem...just make sure you plug all the air lines or gut the smog pump.
 
Don't know for sure - I kept the stock cam which checked out very close to the Crower 15510 cam - just a little more intake duration. I also am going to use the 1.6 roller rockers. Not sure that is the optimum move, but the stock P heads show little flow improvement from .400" to .500" lift, so why change from the .444" stock 1.6 lift to the .476" lift the 1.7s would give? They are Factory Stock heads, so no tool has touched the ports but the valve seats, seat height, valve work, Manley valves (1.90, 1.54), Comp Cams springs and Isky studs are top shelf items. I have Scorpion rockers for them. I aksed Troy Carter - the F/S racer who ran them to within a .10 of the class record if he flow tested them but he did not. I am about to put them on the car and I still can't make a final decsision about working the exhaust a little as my cam has 219 intake and 212.5 exhaust duration. I'm guessing 260HP or so with my fingers crossed. This is my 8 months of the year daily driver and I just hope I don't loose the absolutely GREAT off-idle torque I had with the ported stocker intake. If I loose too much to keep me happy, I may work the stocker a little more and put it back on.
 
timk said:
imyourzero, it was really only a matter of labor for me. i already had the heads. all i needed to buy was the headers and the headchange kit, and i already had the other heads and headers sold, which more than took care of the bill. they may very well be within a few hp's of one another, but the area under the curve is NOT the same :D

That's great, but...if what you say is true, I wouldn't want the P heads at this point. When I went from stock heads/stock cam to Thumper heads + XE270HR, I actually gained low end. I have more torque now than I did before, plus 4.10's, so I really don't need any more low end...I'd spin all day long and never get traction. More torque is a good thing but it sounds like swapping to GT40P's would also translate into me buying a set of drag radials and lower control arms... :)

Glad you're happy with the new setup! :nice:
 
i bought MAC 94-95 P headers from central coast mustang. they were $210, and they came with copper gaskets. these headers are probably worth $7.

I actually laughed out loud when I read that. Haha, stupid MAC headers, I've never heard a good thing about them, but oh well.

Nice post. It makes me want to scour around my house and find something to pawn for some P's.
 
I'm putting the MAC P headers (also NMRA prepped) I got with the heads on mine, but I sent them to Jet-Hot to be cermaic coated on the inside and outside. Before I sent them, I mocked them up on the heads and used my bur set to widen the bolt mounting holes to avoid alignment problems later.
 
I put the p heads on mine i put new valves and springs on them used the stock rockers and had to change my hooker headers for ford p headers.Its like a new car i dont know if its the headers or the heads but the first thing was the sound really great and what i was looking for was more pull in the upper rpm. These heads pull all the way no matter what gear your in i can really feel it great upgrade if you want to change your heads.
 
any word on what the car dynoed after?

I just got my p heads thursday and i am working the exhaust ports as we speak. It will be nice to see what a difference the Ps will make over the unported e7s i have now.
 
My combo was recently redynoed after tuning. The P heads, MAC shorties, Explorer ported intake, degreed in stock cam (same as before with new chain) and 65mm TB has netted me 58HP and 40ft-lbs over my untouched 195,000 mile longblock with sloppy chain, ported stock lower and stock upper/TB. 277RWHP and 330RWTQ.
 
Scott Hasty
Factory Stock 6130 (F/S 10 for 2005)

306 w/ GT40P Heads, Cobra Intake, Stock Cam, 1 5/8 shorties, T5, and no porting allowed.

Best NMRA ET 12.204 @ 110.8, 1.71 60' at 3100lbs on Drag Radials.
Best ET 11.97 @ 112.77, 1.60 60' at 2900lbs on Hoosier QuickTime Pros.


Just remember any car can be made fast with the right suspension and driver. Even stock heads with a well "setup" car can hit 12s.
 
I dident get it dynoed im just speaking from the seat of my paints i like the them and would tell anyone who wanted to get p heads to do it. The only thing i would have done diff was not to mess around with any headers that were not mad for p heads. just to much time spent trying to get plugs in and i wound up breaking plugs and burning wires. Do yourself a favor and just get the right headers.
 
I LOVE the GT40P heads, I mean what is there not to like. If I knew I could run them with a turbo (I'm worried about the header clearance issues) I would put them on my '90GT turbo project.
 
tmoss said:
My combo was recently redynoed after tuning. The P heads, MAC shorties, Explorer ported intake, degreed in stock cam (same as before with new chain) and 65mm TB has netted me 58HP and 40ft-lbs over my untouched 195,000 mile longblock with sloppy chain, ported stock lower and stock upper/TB. 277RWHP and 330RWTQ.

Sweet...so you got it back on the dyno with some additional tuning since the 257 pull? Looks like a 20 HP and 20 TQ gain, well done!