Guest DaneL24 Posted August 12, 2003 Share Posted August 12, 2003 I'm in the middle of building an L28, and I have a P90A hydraulic lifter head from a turbo motor sitting around thats in great shape. I also have an E31 head already in my 240Z, that I was planning on dropping onto the flat-top L28 with a Schneider .460" Lift 260/270 Cam...but I would like the larger 280 valves. The problem with the P90A head is that the cam is internally lubed (has oil holes on lobes) and the cam I bought has no oil holes...as it is meant to be used with an oil-spray bar from an E31 head. If I could swap the cam towers from the E31 onto the P90A, assuming the oil passages between the head and cam towers matched up...I would have all the lubrication necessary for the solid cam. Now about the hydraulic lifters...I have read that you shouldn't use a cam with increased lift on a hydraulic lifter head, but I can't see any reason why not. The cam lobe still opens the valve, the hydraulic lifter just replaces the adjustable rocker posts...and moves up or down slightly by oil pressure to maintain the proper valve clearance. Valve clearance is more of an issue with distance from the camshaft center axis to the low end of the lobe than valve lift. For example, if you had a reground cam that was grinded all the way around...you would either need larger lashpads to compensate or the hydraulic lifter would lift to make up the clearance (at the expense of valvetrain geometry). So what is the reason people say not to use a higher lift cam with a P90A head? Is it because of the lubrication issue or because of the actual function of the hydraulic lifters? Like I said...the hydraulic lifters have nothing to do with valve lift, just valve clearance, so I don't see how that could be an issue...just the thing about the lubrication. Thanks in advance. Dane Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 12, 2003 Share Posted August 12, 2003 You can swap the cam towers, I have done that without incident. I have however never seen someone run a hotter cam in a hydraulic head without issue's. Doesn't mean you can't. Are you planning on cutting the head? If not I would suggest the E31 would give you more compression, and more HP with the cam, maybe the compression would be a little high, so run super unleaded. Quote Link to comment Share on other sites More sharing options...
Bob_H Posted August 13, 2003 Share Posted August 13, 2003 I ran that exact cam,(actually it was 270/280 duration, the Motorsport Auto 2003 cam) for four years on a P-90A with no problems. I did exactly what you are asking, the earlier externally oiled cam towers with the spray bar and an internally oiled cam. Check out my page: http://www.geocities.com/row4navy/p-90.html It addresses all your questions toward the bottom, including why people have issues. BTW that page was written in 1998. -Bob Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted August 13, 2003 Share Posted August 13, 2003 Bob_H Thanks...I read the page and it made perfect sense. The valve spring applies downward pressure against the hydraulic lifter via the rocker arm as a lever and the cam lobe as a fulcrum. With a bigger cam...you generally need stronger springs...which will put more downward force against the lifter. My cam only has an extra .050" of lift, and I will be using stock springs. Closed seat pressure will be the same as stock...and max lift seat pressure will only be a little more than stock, but not enough to overcome the lifters. Its good to know the cam towers swap and I can use the oil spray bar towers from my E31 to lube my solid cam. Lockjaw: As far as compression with this cam, I compared the specs between my Schneider cam the stock cam and the intake valve closes only 3 degrees later ABDC with the aftermarket one...most of the extra duration is made by opening the intake valve sooner to increase overlap. Schneider probably did that on purpose so this cam could be used with relatively low 8:1-9:1 compression. Cylinder pressure will be only slightly lower than a stock L28 with the P90A/Flat-top piston L28/Schneider cam combo...plus I will gain a lot on the high end. Since the timing of the intake valve closure is so much like a stock cam, I might even run into detonation and have to retard the spark timing with the E31 head. With slightly lower than stock cylinder pressure...that could give me room to run a little more spark advance, easily run on pump gas...or even get a little nitrous down the road! I'm sold on the idea...P90A it is! Quote Link to comment Share on other sites More sharing options...
Guest DaneL24 Posted August 13, 2003 Share Posted August 13, 2003 Oh yeah...and I do have the ZXT oil pump for the extra oil pressure. This should work no problem. Quote Link to comment Share on other sites More sharing options...
David K Posted August 13, 2003 Share Posted August 13, 2003 zxt oil pump does not increase oil pressure, its just able to pump more oil. Quote Link to comment Share on other sites More sharing options...
JustAFantaZ Posted September 8, 2003 Share Posted September 8, 2003 http://www.geocities.com/row4navy/p-90.htmlThanks for that link! It led to hours of enjoyable reading with other good crosslinks like http://www.geocities.com/zgarage2001/z.html Quote Link to comment Share on other sites More sharing options...
JustAFantaZ Posted September 8, 2003 Share Posted September 8, 2003 zxt oil pump does not increase oil pressure, its just able to pump more oil.According to Bob H.'s Web site, it increases volume and pressure. http://www.geocities.com/row4navy/p-90.html The turbo gives you a higher volume and a slightly higher pressure. Which is true? Quote Link to comment Share on other sites More sharing options...
Guest mikey_clark Posted September 9, 2003 Share Posted September 9, 2003 Hey Bob H, How's the idle on your z with that cam. And how is low end performance? I want to increase power on my z but want to keep it very streetable. Quote Link to comment Share on other sites More sharing options...
Bob_H Posted September 10, 2003 Share Posted September 10, 2003 zxt oil pump does not increase oil pressure' date=' its just able to pump more oil.[/quote']According to Bob H.'s Web site, it increases volume and pressure. http://www.geocities.com/row4navy/p-90.html The turbo gives you a higher volume and a slightly higher pressure. Which is true? There is an important distinction that is not made. Both statements are correct The turbo pump by itself will only put out more volume at the same pressure. However, you are pumping that oil through a given "orifice" if you will, of the engine. Neither pump will put out more "max" pressure as it has a spring relief set for a certain pressure. What will happen is say at idle, the regular oil pump is putting out 5 gpm at 30 psi,(all numbers made up - these do not correlate to the actual pumps). The turbo pump will put out 7 gpm at 30 psi, but the engine resists that extra volume and the effective pressure might be 32 or 35. It is an academic discussion. Once the pumps reach a pressure that the spring relief is set to, both will only produce that much pressure. Bottom line, as I say on my page, if you are having pressure problems the solution is not a turbo oil pump. The turbo pump is a good solution if you are adding volume to the overall system by something such as a remote filter setup or an oil cooler, and that should be the primary reason for switching to a turbo pump. And Mikey, the cam is a very streetable setup. It had good idle and good power down low. Do remember that my motor was a 3.1L and my results will be slightly different than someone with a basicly stock 2.8L. -Bob Quote Link to comment Share on other sites More sharing options...
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