As I mingle amongst the small block community, I am constantly learning something new which also raises more questions. One question that pops into my head once in a while that I always forget to ask about in conversation is about the P5 heads.

I understand they succeeded the W8's for the PS trucks. After that did Mopar just kill that engine program altogether? Curious as to why. Looks like a pretty mean top end. I know if one car that has one on an 4 cyl. in NHRA, and I guess maybe some dirt/circle 4 cyl. motors still run them, but not exactly sure.

I see the P7's for sale quite frequently, but never the P5's on any drag cars, or for sale.

From what I understand Mopar stopped casting them for a while, and they were only run on a specific R4 which Mopar stopped running. There are racers out there using them in Comp and Super Stock, including Pro Stock here in Australia. As the supply of these heads has become an issue, I know that the Australian Pro Stock team has had to resort to having the heads cast here in Australia. The R4 blocks are still an issue, sadly producing an engine block is a time consuming and costly exercise, so in reality the demand is not there to produce enough R4 style blocks and recover your money.
AL....

more please!!!!!!

Who knows?

Probably because, NHRA axed the Pro Stock Truck class.

Tom Mettler still runs a PST in Comp Eliminator, he won at Seattle not too long ago. That looks like his car in the pic Vic?
AL....

It is. I swiped it from an old post.

P-5 heads are wicked.

A friend of mine from back home runs an R-4/P-5 Hemi in his
Super Stock pulling truck. His is a little over 390" in a 410"
limit class. Can't quite get 400" from an R-4.

I need to get some pictures next time I'm there.

Indeed they are wicked!

What's the limitation on the R4 with cubic inches, the bore, cam height location, or something else? It's ok with me though, I love the sound of a 358" motor hitting the high notes down the track. I guess the R4 the only block these heads will bolt to as LA360 mentioned. I am with you HEMIDARTS, I loved those PST's, it was different and fun. I saw somewhere that Aldermnan's old truck (or one of them) now has a Diesel motor.

R-4 blocks start out with an 8.600" deck height.
They use Ford 2.250" main journals. Bores of 4.220"

I have more pictures of the P5 in Mettler's Dakota on home computer, but I am working out of town.

the pic above was taken at Mopars at the strip...
they ran quick 16...

they have quite the maintenance routine between rounds...

I think from memory the guy running one down here runs it at 399 cubes. The stroke is in the 3.6" range with the bores maxed out at around 4.22"-4.25"

They are very trick, one day I'll own a pair, lol
AL....

Thats freakin sweet....

So what do they flow??? How big of an intake valve is in them???

Be nice if you could do one at 450+ ci so you wouldn't have to twist it to 10,500+ rpm.

Thank you JSL!!! If you have anymore please post them!