Guest Anonymous Posted January 31, 2003 Share Posted January 31, 2003 The reason i ask is becuase i have both. I know this can get quite lenghty in replies. I am wanting to know first are all P90A hydraulic ? if so then you just answered my question. If not is it cheaper to rebuild/mod N42 ? thanx ! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted January 31, 2003 Share Posted January 31, 2003 also if p90a ever came without hyro. can i tell from castings ? Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted January 31, 2003 Share Posted January 31, 2003 You can tell when you pull the valve cover off as to whether they are mechanical or hydraulic. There will be no adjustment if they are hydraulic. It will be obvious. Quote Link to comment Share on other sites More sharing options...
280Zone Posted January 31, 2003 Share Posted January 31, 2003 Here is the difference hydraulic on the right. Some P90A came with hydraulic lifter some didn't. Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted January 31, 2003 Share Posted January 31, 2003 Ive been told some P90A heads are solid and some hydro. best way is to look to find out. Im no expert, but I would side with the N42 heads. Reason being that with a HYDROLIC P90A head the valves have been known to float at high RPM. Quote Link to comment Share on other sites More sharing options...
Mudge Posted January 31, 2003 Share Posted January 31, 2003 Yep, I dont like hydraulic if I can avoid it. Since these cars come without them for the most part, stick to it IMO. Quote Link to comment Share on other sites More sharing options...
Guest empracing Posted January 31, 2003 Share Posted January 31, 2003 my p90a has the left hand type lifter and ate my n42 heads for brekfast and thats a fact so for a direct comparison theres your answer just watch that comp ratio Quote Link to comment Share on other sites More sharing options...
Guest zline Posted February 1, 2003 Share Posted February 1, 2003 what application do you want? NA the N42 head will net you a higher CR which equals to more power if you want turbo P90 will give you a good C/R...you cant just ask for the best and expect us to know what you want to do w.o telling us... E88 head w. N42 valves milled to 40cc combustion chamber would be nice for N/A too =) Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 1, 2003 Share Posted February 1, 2003 Haha NA, never ! Turbo only. I hope my p90a are mechanical. Quote Link to comment Share on other sites More sharing options...
Guest empracing Posted February 1, 2003 Share Posted February 1, 2003 na or turbo the 90a will still flow better and sqwish better too. change the cr with pistons not chambers .run the god dam 90 . p.s i really wish i had the time to get these bloody things flow tested to end this silly debate. Quote Link to comment Share on other sites More sharing options...
Guest 240hybrid Posted February 2, 2003 Share Posted February 2, 2003 The only thing Im gonna say is if their hydrolics and your running them at high revs, there is a chance that one of your valves will float...not a good thing. Quote Link to comment Share on other sites More sharing options...
Dan Baldwin Posted February 3, 2003 Share Posted February 3, 2003 Originally posted by empracing:na or turbo the 90a will still flow better and sqwish better too. change the cr with pistons not chambers .run the god dam 90 . p.s i really wish i had the time to get these bloody things flow tested to end this silly debate. Flow testing can show basic steady-state flow characteristics, which can be an indication of performance potential. Results are certainly not definitive, though, just a part of the picture. Just curious, what's your quickest/fastest NA ET with the P90 vs. N42? Dyno comparisons? The benchmarks I know of for N42-headed cars are 12.88 @ 104 (correct me if I'm wrong, Norm) in a 2.9 liter ~11:1 CR motor, 235 rwhp in my 3.1 liter 10.8:1 CR motor, and 315 flywheel hp (correct me if I'm wrong, John) in a 3.0 liter 13.5:1 race motor. I'd agree that the debate is somewhat silly, because from what I've seen/read/heard there's not enough between the two heads to inspire impassioned debate. If I were building a new all-out motor and I had either head (P90 non-hydraulic or N42) lying around, I'd probably just use it. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 3, 2003 Share Posted February 3, 2003 > 315 flywheel hp (correct me if I'm wrong, John) > in a 3.0 liter 13.5:1 race motor. 305 @ 6,600 rpm. And again, the only valid comparison between the P90, P90A, and N42 is with stock, unmodified heads. Once someone starts cutting metal, the power producing abilities of the head has more to do with the skill of the cutter then the head itself. Also, flow bench numbers are meaningless without information about compression ratio and cam profile. Quote Link to comment Share on other sites More sharing options...
Guest zline Posted February 17, 2003 Share Posted February 17, 2003 *sigh* neverending battle p90 is a good head dont get me wrong - i just dont like it due to valve float issues im a n42 man its good for turbo and NA how many other nissan heads can you say that about? Quote Link to comment Share on other sites More sharing options...
Guest empracing Posted February 21, 2003 Share Posted February 21, 2003 Dan Baldwin ok dont get me wrong the n42 can go not denying i really belive the 90 has a better design in the chamber and the raised runners are going to be better all over.they really got it right in the later heads and i have solids in it so im not worryed hehehe just my $20.02 and if i ever sort out this crappy dizzy im going to get that et for you maybe if i get ritch il build 2 to compare Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted February 22, 2003 Share Posted February 22, 2003 </font><blockquote><font size="1" face="Just curious' date=' what's your quickest/fastest NA ET with the P90 vs. N42? Dyno comparisons? The benchmarks I know of for N42-headed cars are 12.88 @ 104 (correct me if I'm wrong, Norm) in a 2.9 liter ~11:1 CR motor, 235 rwhp in my 3.1 liter 10.8:1 CR motor, and 315 flywheel hp (correct me if I'm wrong, John) in a 3.0 liter 13.5:1 race motor. I'd agree that the debate is somewhat silly, because from what I've seen/read/heard there's not enough between the two heads to inspire impassioned debate. If I were building a new all-out motor and I had either head (P90 non-hydraulic or N42) lying around, I'd probably just use it.[/quote'] Hey Dan,that would be 12.88 @ 105.8 mph on slicks with a 10.6:1 CR motor. On street tires the best mph so far has been a 106.6 mph. later Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 22, 2003 Share Posted February 22, 2003 I'd agree that the debate is somewhat silly, because from what I've seen/read/heard there's not enough between the two heads to inspire impassioned debate. If I were building a new all-out motor and I had either head (P90 non-hydraulic or N42) lying around, I'd probably just use it. Couldn't have said that better. Just to jump-start the dead horse , what was this about raised runners in the P90 helping the flow? As far as I can tell, only the end at the valve was raised. The port comes out of the head in the same place as on the N42 (i.e., the port has to make a sharper turn - no way around that). How exactly is that going to help the port to flow? Quote Link to comment Share on other sites More sharing options...
Guest zline Posted February 22, 2003 Share Posted February 22, 2003 I'd agree that the debate is somewhat silly' date=' because from what I've seen/read/heard there's not enough between the two heads to inspire impassioned debate. If I were building a new all-out motor and I had either head (P90 non-hydraulic or N42) lying around, I'd probably just use it.[/quote'] Couldn't have said that better. Just to jump-start the dead horse , what was this about raised runners in the P90 helping the flow? As far as I can tell, only the end at the valve was raised. The port comes out of the head in the same place as on the N42 (i.e., the port has to make a sharper turn - no way around that). How exactly is that going to help the port to flow? well if you think about it because its got hydraulic valves on the p90a its gotta have a bit more airflow on the valve side but most datsun port design besides square or round is about 80-90% the same deal the p90 is no acception. The raised runner valve side is only to provide more air to the valves. Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 22, 2003 Share Posted February 22, 2003 well if you think about it because its got hydraulic valves on the p90a its gotta have a bit more airflow on the valve side What is the logic behind this? Maybe I just need to take a look at a P90a - does it not use valve guides or something? Not trying to be a smartass - I just don't understand the reasoning here. My point was that I don't see anything inherently superior in the P90's port design. It appears to be the opposite to me. Quote Link to comment Share on other sites More sharing options...
Guest zline Posted February 22, 2003 Share Posted February 22, 2003 well if you think about it because its got hydraulic valves on the p90a its gotta have a bit more airflow on the valve side What is the logic behind this? Maybe I just need to take a look at a P90a - does it not use valve guides or something? Not trying to be a smartass - I just don't understand the reasoning here. My point was that I don't see anything inherently superior in the P90's port design. It appears to be the opposite to me. there isnt thats just the thing... raised runner on the valve side just promotes airflow to it so the valves can operate normally at low rpm because it does not open and close uniformly at low rpm...this is why i dont like the p90a head...mechanical p90s are okay....i still vote n42 for any app...i like it because its so versatile Quote Link to comment Share on other sites More sharing options...
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