godjimm

Hey all, i have a question about my build. I have a 82 turbo motor with a p90a head currently on it. now the question is would i gain any performance with switching to my p79 head?? i have tried to look on this site but have gotten nowhere! any links or help would be awesome!

FricFrac

The P90 is designed as a turbo head and is pretty much the peak in L series head technology. If you are using it in a turbo car and you already have a P90 head keep it. Port matching and unshrouding the valves helps with performance. The "A" grind cam from the P79 is a good turbo upgrade as well.

NismoPick

I have posted this link probably 100 times on ZDriver....

Engine Design Utility

godjimm

Yeah i know the p90 is awesome but i have a p90a. and im on a tight budget and i have a p79 laying around. my p79 has the A grind cam in it aswell... so in other words would the swap i want to do be a wise choice?? What i am thinking is save money on head = better quality turbo and intercooler!

And yes nismo i have used the link you sent me but again i dont really understand what its telling me... all i get from that is numbers that dont help me very much. Is there anyone that has done the swap with a turbo and have they gotten respectable power??

NismoPick

I'll make this super simple for you...

NO

The P90, P90a, & P79 all have the same CC. The ONLY difference is the P90 has a 1mm bigger exhaust valve, and they all have different cam grinds. The P90a MAY have hydraulic lifters (83 only). The P79 also has round exhaust ports, so you'd need to fab up a custom manifold for the turbocharger, or source a SUPER RARE Nissan adapter mount.

If you got past the 6th grade, you should easily be able to understand what the numbers mean. I'm not trying to be rude, but that website tells you EXACTLY what each number means.

I guess if you want to waste time and money, for absolutely no difference, then it's worth while.

godjimm

all righty then! simple enough thats all i was looking for in the first post! now are all the cams interchangeable? say my A grind cam from my p79 in my p90a? there is a clear difference in cams and its way cheaper then a new one... BTW i understand what the numbers mean it just does NOT help with the question i had asked.

zenzee

I have a P-79 cylinder head checked in great condition no cracks or warpage, and has square PORTS at the EXHAUST. If interested let me know and i can also text pics to a cell phone. Thanks.

NismoPick

Interchangeable yes, compatible, no.

Click: http://atlanticz.ca/zclub/techtips/cam/index.htm

I imagine you will then say "I don't understand those numbers!!!!@#$!asd!".. so then click:

Cam Specs & Effects, duration centerline separation and lift, more on pereformance engine parts

Understanding How Camshafts Work - Engine Masters Magazine


^^^ Apparently didn't read past post #1.

FricFrac

Nothing wrong with a P90A head either and as NismoPick stated a P90A doesn't mean it has hydrolic lifters. You can convert a hydrolic to non-hydrolic but there is really no need.

Going to a P79 isn't where you want to go...

There are lots of ways to make HP with your setup if that's what you're after....

godjimm

nismo this is not at all my first engine build... its my first nissan engine and i have very good knowledge on engines and how they work... again with the link to the engine design utility AGAIN it did not apply to my question! and yes i just looked at the head... not hydrolic SWEET!!!! Thankyou fricfrac for answering my question, thats all i wanted to know. and thankyou nismo for the link to the cam interchange page also a very helpful link. and i am going MS3 and a T3/T40E turbo, NOS to spool that baby up and water meth injection. also intercooler and all those goodies. I have researched everything in depth and still had a head question... hence my post. Again thanks for the help!

Lesnocker

Do have to say its a little advanced! Im a 12 year veteran of the tool n die industry. I use trig to program haas and okuma lathes on a daily basis and that page just was alien to me! Be nice to to get chewed into for something we have no idea about. But thats fine Im going to be starting a write up on my head swap. Hopefully I can dyno everything to put up actual numbers. If cost is an issue as ive said before restore what got. Did find nice heads on the zstore website rebuilt with warranty for around 700.00 and if you cant afford 700. you shouldnt start lol.

Lesnocker

Also google the turbo bulids I found several blue prints and dyno results for what your looking for. this subject is worse than politics!!!! The left scream E88 square port or death!!! The right screams P90 and shims. Just like some Despise the ZX and some refuse to consider owning anything from before 84 lol. Cant we all just get along lol

FricFrac

Not sure I'd bother with NOS myself but methanol is a great idea for the L series. Not often used but they respond amazingly well to this mod. If you're concerned about spooling consider a modern BB turbo like a GT30 or GT35R with a small A/R.

I'm running MS3 and that's the FIRST mod I'd do to a turbo car. In fact I'm running an almost stock setup with my turbo car and MS3 and I'm very impressed so far even running at stock boost. Don't forget the exhaust - that's one of the most important mods for a turbo car....

FricFrac

Shimming the P90 is for running it as a NA head.... (eg shave it, raise the CR and shim the cam towers).

There are some pretty common threads though on turbo builds. Personally I like the best bang for the buck. Methanol is one of the big one's that get's overlooked for an L28 especially if you are going to tune it properly you can get a lot more timing back into the tune.

godjimm

Yeah the meth and MS3 are very important! i wana do it right the first time! The NOS is a very good way to spool any turbo its a small 25-35 hp shot and builds boost instantly. And i have the setup just sitting there... gotta love spare parts! And i totally agree the ozdat is super hard to understand aspecially if it means nothing to what i was looking for!

NismoPick

^^^ Maybe we're not looking at the same web page?

From OZDAT:

HEAD: L6:P79

Combustion Chamber CC 53.6

Number of Valves 2

Intake Valve(s) Diametre 44

Exhaust Valve(s) Diametre 35



HEAD: L6:L28ET:P90

Combustion Chamber CC 53.6

Number of Valves 2

Intake Valve(s) Diametre 44

Exhaust Valve(s) Diametre 36


Those are the important values that answer your question.


All you do is select the motor and components, and it fills in everything for you. I just hate to see such a useful engine design tool go to waste. I actually downloaded and saved that entire webpage in case it ever goes down one day.

godjimm

now with what you just told me as i have read and understood the only thing was a 1mm different size ex. valve. NOT flow data. NOT quench design. NOT cam options... bickering about this is getting old and i give up..! But honestly in my opinion the page did NOT help with the orignal question. That page was extremely helpful in my selection of other parts though, and i find it pretty cool. Either way the question was answered and im sticking with the P90a head i have...

NismoPick

If you had said that's what you were looking for in your first, second, or third post, I woundn't have pestered you. The word "performance" is pretty generic.

For future reference... good reads on Datsun cyl heads:
The L Series Engine Heads

The Datsun Workshop Cylinder Head page

The Dime Quarterly: Tech How-To: L-Series Cylinder Head Guide

Nissan L-series engine mod tips

godjimm

Awesome links! reading them all. and yeah deff could have been more direct... still not very good with the fourms if you cant tell. im not very computer savvy! Thanks again nismo!

PooFlinginMonke

The greatest variation between P79 and p90 heads lies with the camshafts.

Here's a link to camshaft information.

I've been running both P90 and P79 heads on the same engine (f54 with flat tops) for many thousands of miles and I can't really tell the difference.

NismoPick

Turbocharged?

godjimm

Theres no link.?.?

PooFlinginMonke

sorry man.....forgot the link to the camshaft information.

http://atlanticz.ca/zclub/techtips/cam/index.htm


Yes......about 40,000 miles worth in the lead sled pictured below and about 80,000 miles in various other cars.

Intercooled, non-intercooled........stock ecu/z31 ecu/M30 ecu......etc.

It's now running an untuned M30 ecu with dropping resistors and L28et injectors.

I ran it up right up to the limiter in top gear at kennedy space center two weeks ago.



Went to midnight madness a few weeks ago at 7psi with 3.54 differential instead of the factory 3.9.

Video taken from the 12 second mustang I lined up with on this run.