RedBanner Posted June 16, 2013 Report Share Posted June 16, 2013 So my o.p.s.u. went out today. Got a mechanical (I guess technically hydrolic?) And went cold it runs 40/45 same as my other l20b's with stock oil pumps. But as I pull into the drive way after a long drive drive my pressure sits at about 15 psi at an idle of around 800 rpm. It pops right up with the throttle, but since my 2 door will never idle that low I cant compare it to that. Im concerned. To the point im about to just swap my oil pump. Unrational fear? Idk. But id like to know what your guys oil pressure is at a low idle when at running temp. Quote Link to comment
DanielC Posted June 16, 2013 Report Share Posted June 16, 2013 10 PSI per 1k rpm. Ex. 30 PSI at 3000, 70 psi at 7000. 1 Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 Thanks. Quote Link to comment
plumb420 Posted June 16, 2013 Report Share Posted June 16, 2013 At 1k rpm I'm at 20psi stock oil pump. 1 Quote Link to comment
izzo Posted June 16, 2013 Report Share Posted June 16, 2013 snag a KA oil pump if yer worried. they run a little more flow I hear... 1 Quote Link to comment
I'm BLUE Posted June 16, 2013 Report Share Posted June 16, 2013 I'd say I'm closer to your stats my boy ! maybe a little above or below depeding if my eye trolls me... :sneaky: I honestly wouldn't worry about that one bit :) My idle vary's from 750-850-1000 max between driving 2 different z's though lol. I can testify the zx auto turbo pump sure pumps though lol (you check your gauge for "too high" lolol) 1 Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 Thats another question I had, how much is too much? As in when do I ad a decompression chamber and spray bar lol 1 Quote Link to comment
I'm BLUE Posted June 16, 2013 Report Share Posted June 16, 2013 Thats another question I had, how much is too much? As in when do I ad a decompression chamber and spray bar lol :lol: EDIT: errps shouldn't have posted and instead of just +1 ... doh !!! ... :ninja: 1 Quote Link to comment
MicroMachinery Posted June 16, 2013 Report Share Posted June 16, 2013 What weight of oil are you running? Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 Um... 10 30 most likely. Run 50 in the 2 door. Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 Nope sea 30. Not 10w30 Quote Link to comment
MicroMachinery Posted June 16, 2013 Report Share Posted June 16, 2013 I don't run that thin of oil. Delo 15w-40 is really nice, because of the ZDDP content(great for flat tappet cams), and on top of that, it's thicker. The factory recommendation for our L series engines was 20w-50, but that's pretty friggin' thick. Today's oils, while better in alot of ways, aren't really that good for older engines, which is why the higher ZDDP is nice, because it's more similar to the oils that were around when our cars were new. Thinner oil will make your pressure lower. 1 Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 My fsm said 30 weight ... honestly it.does. added my own zddps (wich is expensive additive) Quote Link to comment
Z-train Posted June 16, 2013 Report Share Posted June 16, 2013 The FSM says different weights for different climates.20/50 is for the toastier places. Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 I went with a 0 to 90 degree range. Seemed appropriate. Quote Link to comment
datzenmike Posted June 16, 2013 Report Share Posted June 16, 2013 So my o.p.s.u. went out today. Got a mechanical (I guess technically hydrolic?) And went cold it runs 40/45 same as my other l20b's with stock oil pumps. But as I pull into the drive way after a long drive drive my pressure sits at about 15 psi at an idle of around 800 rpm. It pops right up with the throttle, but since my 2 door will never idle that low I cant compare it to that. Im concerned. To the point im about to just swap my oil pump. Unrational fear? Idk. But id like to know what your guys oil pressure is at a low idle when at running temp. . The stock gauge is slow reading and does not show sudden short blips. If the gas sender showed every slosh the tank made it would be impossible to know how much gas you have while driving. Same with oil. Sudden stops can even uncover the pickup and oil pressure drops to near zero. To the average Joe public driver this can be very upsetting just as having hard numbers on a gauge is. Better that they don't know. As a motor ages, the main and rod bearing clearances open up and oil pressure bleeds out faster and the stock pump can't supply it fast enough at low speeds. In order to make pressure the pump has to supply more than needed so that the extra backs up and the pressure rises. If it gets high enough there is a relief valve and spring to recirculate to the inlet of the pump. The cure is not shimming the relief valve. The cure is a pump that supplies more volume of oil so that it has more at lower RPMs and the pressure backs up and rises. I've said this a dozen times, but, my 180k L20b had a hot idle oil pressure of 17 PSI. With no other change but a KA oil pump, a used one at that, the pressure rose to 29PSI. !!! The internal rotors of the KA pumps are 13% longer. I measured them. I run a KA24E S13 oil pump in my '74 710 and either a KA24E D-21 or a Z24i D21 pump in my 620 and my '76 710 goon. It's one of the first things I would add to any L series motor. If running a spray bar this is imperative. Most available at wrecking yards.... '89-'90 KA24E S13 (240sx) not the dual cam they were internal pumps. '89 and on KA24E or KA24DE D-21 Hardbody truck engine. Both engines had external oil pumps. '86.5-'89 Z24i in the D-21 Hardbody. Not the earlier 720 Z24i, they didn't have this pump. 280ZX turbo automatics (maybe standards) had them but these are getting old. LD28 Maxima Diesels Z18ETs are reported to have them also. NO YOU CANNOT TELL FROM THE OUTSIDE WHICH ARE HIGH VOLUME PUMPS. Quote Link to comment
MicroMachinery Posted June 16, 2013 Report Share Posted June 16, 2013 I went with a 0 to 90 degree range. Seemed appropriate. Geez.. I put 5w-30 in mine and my oil pressure light wouldn't stop flickering. Put a stop to that REAL FAST. Quote Link to comment
datzenmike Posted June 16, 2013 Report Share Posted June 16, 2013 Never use anything 5W ever. Quote Link to comment
RedBanner Posted June 16, 2013 Author Report Share Posted June 16, 2013 But. Doesnt it improve fuel mileage? Lolol Quote Link to comment
datzenmike Posted June 16, 2013 Report Share Posted June 16, 2013 Yeah.... to the wrecking yard. 2 Quote Link to comment
Guest_kamakazi620 Posted June 16, 2013 Report Share Posted June 16, 2013 I've never ran anything thinner than 10-40w I did 20-50w once....... Quote Link to comment
GreaseMonky Posted June 16, 2013 Report Share Posted June 16, 2013 I don't run that thin of oil. Delo 15w-40 is really nice, because of the ZDDP content(great for flat tappet cams), and on top of that, it's thicker. The factory recommendation for our L series engines was 20w-50, but that's pretty friggin' thick. Today's oils, while better in alot of ways, aren't really that good for older engines, which is why the higher ZDDP is nice, because it's more similar to the oils that were around when our cars were new. Thinner oil will make your pressure lower. Delo, Rotello, and a lot of the other diesel oils, are no longer coming with the levels of ZDDP anymore, Quote Link to comment
DanielC Posted June 16, 2013 Report Share Posted June 16, 2013 I use Valvoline VR-1 30 weight "racing oil" in my Datsun engine. ever since a case of oil looked like this. 1 Quote Link to comment
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