The Saga of my First Stroker -- and some restoration...

[Dragonfly]

I was out autoxing all day today so I did not get your PM untill a few minutes ago... looks like you did ok. As far as the oil pressure at idle, the stock Z sending unit is notorious for being less than accurate especialy at idle, if you really need to settle your mind get a mechanical gage and use it instead of your sending unit and oil pressure meter. Be aware though that the mechanical gages have an accuracy of 3% full scale so if you get a gage that is 0 to 200 psi it could be off by as much as 6 psi and you only need about 6 psi at idle and no more than 40 to 60 psi at speed (for a non turbo motor) any more than that on your n/a motor and you are just adding parasitic drag and stress on the pump and shaft. Remember what is important is volume, as long as you have enough volume (which you should with a stock pump and you definately would with a turbo pump) 40 to 60 psi at speed is quite capable of protecting your engine.

 

Dragonfly

[josh817]

Well **** thats REALLY good news. 0-90psi gauge and it sits just above 0psi so that should be about 6psi. You can see the gauge in the video so judge from there. Uploading to Youtube right now.

 

Dad already taught me that lesson on gauges and accuracy... Hounded me because I was saying just get this fuel gauge, its cheap. Gauges aren't accurate on the ends, more accurate/most accurate in the center. 0-200psi is too big of a range. 0-100 is more like it I would think. Maybe 125 because if you go over 100psi... God save you and your passenger from oil leak inside. x_x

 

 

Video:

http://www.youtube.com/watch?v=bHAyvZ5CR5k

[woldson]

Start up rebuild and normal that I've seen on a cold engine is 60/70lbs.

This read is from my 280zx's stock gauges.

 

Work on oil before you chase down other issues. Bitting off all at once may lead to failure and fustration.

 

Also trust the gauge and sensor untill it is proven otherwise. Don't rush past this untill you are sure.

[josh817]

Took the car for a spin and the gauge read well. Sits where it should and slightly above 0 at idle so thats good. Its a rocket and I haven't even hounded on it yet. Only went about 3 miles, brought it up to 5k and let the engine brake. Only problem is that the motor ran stupid hot. If I have to get an aluminum radiator I'm going to strangle Dad since he kept saying just recore this old radiator. >_< I spent $190 to do that... >_< No one will buy a radiator that price. So hopefully its just a new motor, too much advance, and lean. Get everything figured out and maybe it will drop back down... Thats TOO hot for me, especially for 3 miles and nice driving... I noticed when we came to a stop sign my idle was at 1500RPM but when we turned the motor off and turned it back on, it was at 1000-1100RPM as usual. We won't tune the carbs until I get back pressure on the exhaust. Right now it dies down and comes up if you blip the throttle so we'll see.

 

Vid 1, not even half throttle :]:

http://www.youtube.com/watch?v=_BXs1svOc5s

[madkaw]

I have surfed thru your threads so i might be missing something but I'd say your taking a big risk right now. That is not enough oil pressure at idle, especially at 1500rpm. Like Woldson said, it should be more like 60psi, especially on a cold engine. This could account for the hotter temperatures-especially with these motors. Buy a new oil pump and prime it correctly. Check this out

 

http://www.classiczcars.com/forums/showthread.php?t=23392&highlight=cam+oil

[josh817]

The gauge reads down low at idle but when you drive around at 3k rpm its doing between the middle and the right side of the gauge, and its a o-90 gauge so thats what? 60psi-ish. Doesn't make sense to have 60psi at idle in my mind.

 

http://www.youtube.com/watch?v=fzRLApUSrXU

 

^ View of gauges in 3rd going 30mph. It was hot. :[ I'll check the cam lobes and such. I think most after market cams do internally oiled.

[Dragonfly]

Here is some information about oil pumps and pressure/volume that should help you.

 

Pumpology

An oil pump, by the way, does not create oil pressure. It pushes oil from one place to another. It is a positive displacement pump that moves oil as it turns. Oil is incompressible so once it leaves the pump it continues to flow until it encounters resistance in the filter, oil galleries and bearings. It's the resistance to flow that builds pressure in the oil system. Trying to force oil through a small opening creates more resistance and pressure than allowing it to pass freely through a large opening.

A worn pump can't deliver the same volume of oil as a new pump, so with less flow there's a drop in oil pressure.

As pressure builds in the oil system, it exerts pressure. A spring-loaded "pressure relief valve" built into the oil pump (or near the pump) opens when pressure exceeds a certain limit (typically 50 to 60 psi) and either reroutes oil back into the pump's inlet or the oil pan. This prevents a dangerous buildup of pressure that could rupture the oil filter or blow out press-fit oil plugs.

At idle, most oil pumps do not produce enough flow to force open the relief valve. Oil pumps that are camshaft driven turn only at half engine speed so output isn't great at idle and low rpm. Even pumps that are crankshaft driven and turn at engine speed (or double engine speed in a few instances) don't pump enough oil to overcome the relief valve spring. The relief valve generally only comes into play at higher rpm when the pump's output pushes more oil into the system than it can handle. Then the relief valve opens to vent oil and limit maximum oil pressure until the engine returns to idle or a lower rpm.

How Much Oil Pressure?

Vehicle manufacturers have traditionally recommend a minimum of 10 psi of oil pressure for every 1,000 rpm of engine speed. Using these numbers, most stock engines don't need any more than 50 to 60 psi of oil pressure. With tighter bearing clearances, pressure goes up requiring less flow from the pump and less parasitic horsepower loss to drive the oil pump. In racing applications, the old school of thought was more oil pressure was needed to keep the engine lubed. That's true if bearing clearances are loosened up. But most engine builders today tighten clearances so less oil flow is needed to maintain adequate oil pressure. This approach increases the horsepower output because less power is needed to drive the pump at high rpm.

A stock oil pump is usually more than adequate for most street performance engines, and even many racing engines. NASCAR engines typically get by just fine with no more than 50 psi of oil pressure at 9,000 rpm! Some top fuel dragster and funny car engines are set up so the oil pump will dump excessive oil pressure at high rpm so more power will be routed to the rear wheels.

Some racing engines use a "dry sump" oiling system. With this type of lubrication system, an external oil pump is used to suck all the oil out of the crankcase to reduce "windage" (oil drag) on the crankshaft. The oil is routed to an external tank and an oil cooler before it is recirculated back into the engine.

High-Volume & High-Pressure Oil Pumps

In applications where more oil flow is desired either to increase oil flow or pressure for better bearing lubrication and cooling, an oil pump with longer or larger gears may be installed. The physically larger surface area of the gears pushes more oil through the pump at the same rpm than a stock pump. A high-volume oil pump typically flows 20 to 25% more oil than a stock pump. The increase in oil flow produces an increase in oil pressure at idle, which helps compensate for increased bearing clearances. Consequently, some people may install a high-volume pump in a high-mileage engine in an attempt to restore normal oil pressure. But oil isn't metal, and the only real cure for low oil pressure is to replace worn bearings and restore normal clearances.

High-pressure oil pumps are another option. A high-pressure pump contains a stiffer relief valve spring that does not open until a higher pressure is reached (75 psi or higher). The actual flow rate of a high-pressure pump may be no different than a stock pump, or it may be higher if longer gears are used. Either way, the pump will increase the system oil pressure reading at high rpm when the pump is working hard, but it won't have any affect on idle pressure when the pump is turning slowly.

A high-volume or high-pressure oil pump may be recommended in engines where bearing clearances are looser than normal, in engines where an auxiliary external oil cooler has been added to improve oil cooling and in racing engines where a oil accumulator has been installed.

 

This information and much more can be found here: http://www.aa1car.com/library/2005/us020516.htm

 

It is explained in a better way than I could explain it, but if anyone wants to do even more reading than that by requesting that I write a detailed essay of how viscosity/volume/clearances effect pressure I will BUT understand that if I do take the time and effort to write it all up I will be very short with those who do not read it and then ask stupid questions.

 

Dragonfly

[josh817]

Yah I understand it all except clearances so thats what I will look into. I honestly think though my oil problem wasn't really a problem. Had oil pressure when driving, had higher pressure at idle today than yesterday.

[woldson]

Good to know it is up there when driving. Mine will be down around 10 when the engine is at running temp, at idel.

[Quin]

I'm not really familiar with Ls, but 7Ms only make about 5PSI of oil pressure at idle. Low pressure, high volume system. Again, I'm not sure if Ls are even remotely similar but just some food for thought. Can't even get 40+PSI, there's a pressure relief that pops open at 40.

[josh817]

Maybe you can change out the springs like on Nissan pumps. I look into the how to Mod the L-engine book and its talked about it.

 

I think I'm running very rich and maybe too much advance which leads us to timing. I'm running really hot, when I tell Dad that a lot of people are dyno'ing their motors at a safe peak HP with 30º+ of advance he says he can't believe it because a Triumph motor would burn a piston with that much. Tomorrow I'll have time to retard the timing a little and test out my Water Wetter but I'm still running pretty hot (about 220º-230º). I'm going to flip **** if that radiator isn't sufficient enough because Dad kept saying no to Aluminum and then sends my radiator off to a shop without telling me and hands me a bill for $190... No one is going to buy this thing for $190... XD

 

Anyways, what do you think I should aim for, advance wise. Can't tune carbs yet but the exhaust shop is a good 5-10 minutes away and I want to at least make it there. Get back pressure, and then tune. I have a good feeling we're running lean because these are 40mm carbs that ran only slightly rich on a 2.4L. However, I don't know what to expect temperature difference wise because I have never played with carbs before. I would think that if it was running STUPID lean, it would be detonating and crap like that, just sound really nasty and horrible. But its not. I'd really hate to NOT be able to run decent advance because I'll over heat. I'm not sure what he set it at and I don't have a timing light so I'll just retard it, adjust idle, retard a little more.

 

Tell me what you guys think!

[Quin]

Without knowing what is going on, retarding it a little is safe, but if it's not detonating I'd say you're okay :dunno: keep it out of the high RPMs until you get it figured out for sure. Do you have a wideband available? I know this car used to be turbo, most modified turbo cars typically have one. Yes, you can change the springs out on 7Ms (most people do, or at the very least shim it).

 

Running lean could be the reason you're running so dang hot, that radiator might be fine when your motor is running properly. Don't stress about that just yet.

[josh817]

I didn't see any bung on the exhaust with the turbo motor. I don't think it was running any O2 sensor at all. My plans are indeed to buy a narrowband as a filler gauge and to help tune. Yes it will be a light show, however they do work WOT and thats what I car about. If we can make smooth transitions, clean running, good response, and then adjust WOT I think we'll be fine. However I have a feeling that the venturis in these aren't sufficient. We have discussed this in the Weber thread. I'm not really up for buying proper ones right now... Just get it running nicely and not worry about power until later.

 

 

 

 

EDIT:

Wow... One of those DOAH! moments... Out of curiosity I took a piece of paper and stuck it up to my PULLER TYPE fan and hey guess what! >_< It sucked the piece of paper in from the motor side, its a pusher! >:[ So since its a curved blade I took it off, flipped it around, changed the polarity and now its the right way. :] NOW LETS TRY! >_<

 

One thing I'm learning from all this stuff is pay attention to detail and don't assume anything. It takes twice as long to figure it all out completely, but at least you do it right and don't mis-diagnose.

[Daeron]

You don't need a new radiator. If yours has been re-cored, then it is sufficient.

 

I was going to say, before reading the "doh" above, that you DO need to make sure you are flowing adequate air through that radiator, though. Not just regarding the fan, but also the air flowing into the opening of the grill. How much have you read about the front aerodynamic issues with the S30? It *can* become an issue to ensure you flow enough air THROUGH the radiator and not around it. If your fan fix does not fully solve your problem, you need to do some more research into this subject before chucking your radiator for an aluminum one. The subject is very subtle and I cannot recall enough of the finer details to review it for you off the top of my head, but I can point you towards the threads where it is discussed if you want.

[josh817]

Well for more directed flow I can attempt some sheet metal work but aerodynamics as in like car getting light when at speed, I don't care for really to do any extensive work.

[Daeron]

Well for more directed flow I can attempt some sheet metal work but aerodynamics as in like car getting light when at speed, I don't care for really to do any extensive work.

 

I pretty much meant that there are aerodynamic issues going on that can prevent air from even wanting to go INTO the grill opening. You may not be experiencing any of them with your vehicle, the way the front end is set up; then again, you may. I wanted to alert you to the deep deep complexities that are involved in this subject. Keeping a hi-powered Z cool has frequently been an issue for people over the last 35+ years, and things were brought to light in the aerodynamic testing sessions sponsored by various board members last summer that indicate that quite often, and for a couple of different reasons, air simply does not flow through the radiator well. IF you should continue to have higher than desired running temperatures (after fixing the fan, and after tuning the spark and fuel to a point where you are somewhat happy with it) then some patient reading is in order.

 

Like I said, I don't know what valance/front spoiler you have, tire size, etc.. if your car is essentially stock ride height, wheel size, etc, then the issue is largely negated (i THINK) so don't panic over it.. but if time goes by and the heat persists, research this issue before scrapping your recored radiator.

[jc052685]

I didn't see any bung on the exhaust with the turbo motor. I don't think it was running any O2 sensor at all. My plans are indeed to buy a narrowband as a filler gauge and to help tune. Yes it will be a light show, however they do work WOT and thats what I car about. If we can make smooth transitions, clean running, good response, and then adjust WOT I think we'll be fine. However I have a feeling that the venturis in these aren't sufficient. We have discussed this in the Weber thread. I'm not really up for buying proper ones right now... Just get it running nicely and not worry about power until later.

 

A narrowband o2 is trash!!!!!!!! you can not tune with one. Buy a descent wideband!!!!!! You can get them for like $200 shipped.....hum, sounds like some cheap insurance for such a build.

[josh817]

They're only carburetors. You will never have them perfect as each day is a new running condition. Most people just tune by how it feels and plug checks, I'll just use a narrowband and my butt. :] Most of the dudes in the race club are running narrowbands too, like I said, usable at WOT.

 

Ducking, didn't know about that. The car is lowered slightly I think and its an MSA Type III kit.

[Quin]

You can do that on a domestic motor, imports go boom. My buddy and I adjusted timing on his Mustang by advancing it into detonation and then backing it down hair by hair until it wasn't doing it anymore. If I detonated ONE time in my Supra I'd blow the head gasket in a heart beat. See if someone you know has one you can use for an hour or two. Surely carbs cannot vary THAT much from one day to the next, just make sure you aren't running stupid lean during normal driving. I've seen AEM WBs with gauges sell for under $200 shipped on Supramania, maybe you could find one eBay or something?

[Noddle]

I'm using this

 

http://14point7.com/Widebands/Widebands.htm

 

Cheap wideband for $50ish + sensor

 

some basic electronics understanding is a bonus (I.E. how to solder)

 

Nigel