620 motors and z motors have the same water pump?

[Llittle_Llama]

I found this while searching for a pulley today: http://www.thezstore.com/page/TZS/PROD/PCLC06/16-7025

 

 

Would that work on my truck? It's kinda high in price, but would not be a bad idea to consider. I looked up the gaskets for both vehicles and they have the same part number so I can't see it not working. Any reason I shouldn't run this?

[izzo]

Did you try the search button dood?

 

There was a thread a few days ago about someones water pump pulley not lining up, and i am pretty sure the differences were covered in that...

 

Goto rockauto.com and lookup the part numbers between L20 and 240/260/280z and see if any of them are the same pump. Research, do it before posting

[erichwaslike]

there wood be no alignment issue as that thing has no pulley. just need to make sure the flange surface is the same shape and all that

[Skib]

yes that will fit, its for an L series.

 

 

:rolleyes: even the L16/L18/L24/L26/L28 front covers are all interchangeable. and the L20 cover is the same except for being a bit taller.

[izzo]

I was referring to what the thread was about that this stuff was covered :D

 

I also mentioned going to rockauto, and looking up part numbers and seeing if they are the same. That way he could learn to research before post.

 

 

Either way, cool product dwnshifter

[datzenmike]

I'll also fit the Z20, Z22 and Z24 motors. But no advantage. No pulley, so another shorter belt needed. Does not increase circulation with engine speed like the belt driven one. Draws extra much needed current from other accessories. Not cheap!!!! and not cheap or easy to replace if it fucks up later.

[datsunaholic]

There's no advantage for running that on a street vehicle, except that you can run it when the engine is off.

 

For a race car or a drag car, it does make some sense. But to "save power" it doesn't do that. What it does do is keep water circulation at the same speed all the time, unless it has sensors or such to vary speed and I don't think it does. There are times when a belt-driven water pump is being spun too fast, but that's rarely the case with a street engine (and even then, not for sustained intervals) and racers generally up-or-down size their pulleys so that the pump is spun at its most efficient rate at the most often run RPMs.

 

So on to whether or not it saves "power".

 

It takes a certain amount of power to turn a water pump, which is a parasitic load on the engine. It's not much, but it's there. By removing the water pump belt, you save a little engine power. Problem is, the electrical energy for spinning the electric water pump has to come from somewhere. Generally, that's the alternator. And due to the law of conservation of energy, the energy needed to spin an electric water pump that flows the same amount as a belt-driven water pump would be the same IF you had a perfect, lossless system. But that's never the case- you lose energy turning rotational, magnetic energy into electricity and then converting it back to rotational energy (alternator to pump). So, the additional load on the alternator is more running the pump than the load of just running the pump via a belt. In addition, the load on the belt is variable with engine speed- goes up as speed increases. The electric one is probably fairly constant, but to make it work at high engine loads it'd have to run at full speed, and it's do that even when the engine is at low speed unless it has some sort of variable switching.

 

Now, you CAN make the engine completely free of waterpump load. You'd run it off the battery, but you also cannot be charging that battery off the engine alternator because the alternator would take the load up to its output limit. This is somewhat common on drag cars, which run no engine accessories at all- including no alternator. They just hook a battery charger up between runs and run everything electrical off the battery. Since its a short run, you don't need to worry about the battery discharging. You can't reasonably do that with a street car. You'd have to have separate batteries or cutout systems to disengage the alternator whenever you wanted "more power", but even then you're losing power spinning a non-op alternator.

 

For note, it takes about 1HP to produce ~50A if the alternator is running at 14V in a perfect, lossless world. (1 HP = 745.7 Watts. 745.7Watts / 14V = 53.3 Amps ) In the real world, car alternators are only about 50% efficient, so you are consuming 2HP engine power to run 50A output at the alternator, or around 4HP to run 100A. Not a heck of a lot on the street, but to a drag racer that's something because differences are measured in hundredths of seconds.

[Llittle_Llama]

It sounds like the electric pump will be more trouble than it's worth. I'll definitely be sticking with the earlier model unit then. I just need to find a pulley now!! Now I would search for this, but I already searched pulley all over Google and got nothing hence me making a post. I did look up the parts and part numbers for the stock gaskets, but I didn't know if anyone else was using this or if it was a waste of money (which for my purposes it is). Now on to my second question, what are my options as far as pulleys? Will any L series pulley work, or does it need to be off of a truck/car? Will I have any issues lining up the belt?

[datsunaholic]

I run a pulley and water pump that was spec'ed for a '74 620 on my '78, which has a 1980 engine, and on my '74, which has a '78 engine. The '78 has an aftermarket flex-fan, and the '74 uses the stock 74 4-blade. Seem to work OK. My '76, I still have bone stock, with clutched fan. All 3 have gotten water pumps in the last 5 years, never had a problem once I ensured I had the right pumps on hand. I've never had alignment issues. Only ones I think would be problematic would be using stuff for a Z-car, which used a totally different setup (even though the pumps look identical). One thing to watch out for is I've seen Datsun water pumps that have no flange or anything- you have to press off your old flange and reuse. Getting that aligned isn't easy.

 

My 4X4 setup...

 

 

 

 

That's the one with the flex-fan on it. Strange thing is I can't remember where I got the flex fan from. I broke the previous flex fan, and I know I didn't buy another because I couldn't find one. I must have had it laying around, but dunno where I got it from.