P90A Head

[Zeus]

I recently purchased the engine below on eBay.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4539470286&sspagename=STRK%3AMEWA%3AIT

It comes with the P90A head which I have never looked into because of the work involved to use it on high compression n/a applications. My understanding is that these used 'hydraulic lifters'. After looking at a few pictures of them, I don't see any noticable differences in the valvetrain.

Could someone post some pictures of the P90A in detail? I just dont understand where the lifters come into play.

Thanks

[Brett240]

Not all p90A heads had hydraulic lifters. mine doesnt. you will know when you have a good look at it

[beandip]

I recently purchased the engine below on eBay.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=4539470286&sspagename=STRK%3AMEWA%3AIT

It comes with the P90A head which I have never looked into because of the work involved to use it on high compression n/a applications. My understanding is that these used 'hydraulic lifters'. After looking at a few pictures of them, I don't see any noticable differences in the valvetrain.

Could someone post some pictures of the P90A in detail? I just dont understand where the lifters come into play.

Thanks

I hope you realize that the P-90a came on a F-54 block with dished pistons and was set up for a turbo. The F-54 block with flat topped pistons came with a P-79 head . They both have the same shaped combustion chamber but the 90a and 90 are lower compression. For a NA application you will need to take about .080 off the surface to raise the comp to get performance , along with some flat topped pistons. As to the issue of the lifters , I cannot help with this , I stayed away from that combo because I wanted to run SUs and dident want to be replacing pistons . From what I have read the P-79 flows only slightly less than the 90 but since I am not in compitition this was not a factor for me. I have .030 off my head for 9.8 compressino . D o you have the web page address for Brians Garage ? there is good info there on this application. All the best . Gary

[Zeus]

Yes I am aware that the P90A is a turbo head and that modifications are needed to get it to work. I was only asking for pictures of the hydraulic setup.

[Zeus]

Well I spent the weekend in the Los Angeles area picking up this engine and other stuff. Upon taking off the cam cover, I do not notice any differences between this P90A, my N42 or my E31 as far as valve operation goes. This leads me to believe that this is a non-hydraulic P90A...

Does anyone know if there are any differences between a P90 and this mechanical P90A? Also, I am going to be running SU's and headers, would I see any gain using this P90A over my N42?

Any thoughts or suggestions are welcome. Thanks

[beandip]

The information that I have says the p-90a-p-90 & p-79 all have the same shaped combustion chambers the 79 has damond shaped exhost ports with a sleve that is ment to heat the gases in the manifold for emissions . Now the same info says the three head are the latest evolutoion of this inline engine and flow and work better than the N-42 . I have a P-79 milled .030 for a 9.5 to one. I dont have a flow bench to varify the above info , however the ''they'' say the 90s both flow the most and are superior. The 79 is a vary close 2nd . I went with what I have and am not building a race car, so it was not important to me. I hope this helps , send me a PM if you want more info from me on this . Gary

[hls30.com]

What both of you probably have is a P90A that was rebuilt with P90 parts(the hyd. parts have been NLA forever) According to Nissan, all P90As left the factory Hydraulic. My master Nissan Mechanic said that even the dealers used the non Hyd. parts to rebuild the Hyd. head when the parts supply dried up. The differeces in the actual head casting between the P90 and the P90A allow the Non hyd. parts to fit and work on the hyd. head, but not the other way!

Will

[Gav240z]

That's exactly what i would have though Will. If your in Australia you can't exactly get a P90A anyway well I've only ever seen one. I'd assume that anyone running it would have changed back from Hydraulic lifters.

It should be stated that you do not HAVE to shave the P90 to achieve high compression it will all depend on your rod and crank combo for the stroker motor you can sometimes get + deck clearance.

It all depends on the motor you are building an N42 can be ported and perform very well it all depends on what your are going for in your build.