Hooking radiator hose on a 1UZ and using pusher fans

[rwdfreak]

1- Well I'm doing a swap and when I started to look at how I would hook up the rad and the water inlet outlet I became to wonder. Does it matter if the inlet pick-up water from the top rad port and the outlet (return) goes in the lower rad port.

I know many engine are seted that way and work well, but I'm wondering if the UZ has a diferent cooling configuration. Technicaly the pump push water in the outlet (return) hose in the rad and than if the T-Stat is open it goes in the engine. I can't see anything wrong as long as the t-stat is lower than the upper part of the rad (so the gravity push the water in the hose and the air can come out when first starting the engine after being drained).

2- I was also hoping to reuse the stock twin pusher fans from a 91 LS400. I checked them with a ampmeter and they draw 6.5amp at constant speed (12 volt on a batery). Since I don't have much room I cannot use the clutch fan and I don't think there's any possible way of putting an electric puller fan with a reasonably size radiator (planning to upgrade later for aluminum double/triple core rad). Don't be fooled by the picture, there's only 3.5inch between the pulleys and the rad support. Moving the rad forward would be doable, but I don't really want to get into that.

Anyone know if the volume displaced by those fan is enough to cool the engine? If not, would you have any fan brand or car model that use pusher fan(s) that would do the trick. The car has sufficient rad area and opening for air (even better than a stock turboed MKIII), there's no intercooler, A/C condensator or anything else obstructing the flow before or behind it (exept the engine itself). The engine is mostly stock for now, but I'd like to get around 250whp in the next years.

Anyway I'd just like to have your thoughts about I yshould rig those things.

Picture of what I intend to hook the the rad.

 

[rwdfreak]

I wonder why I post here. Every time I ask something I get no reply. I guess I will continue to use the search feature and don't bother asking my own questions.

 

[gloverman]

Hello

An answer to your question. The thermostat on a 1uz is in the lower radiator hose. The water comes out the straight alloy fitting on the LH side of the motor (LH is the side with the PCV valve on it) the water cools and cold falls. The water then flows into the motor throught the plastic cover and through the thermostat.
I have seen so many of these motors connected incorectly.

Good luck with that

Cheers

 

[rwdfreak]

Thanks for your answer.

However since it's pressurised by the water pump and that the water is forced to go in the rad. The cold water should not be able to go down as the hot water is pushed upward (they should be forced to mix at one point). I'm not saying that you are wrong, but by looking at other engines some have the T-Sat in the higher port of the rad and the return in the lower port.

But what you are saying makes sense in term of gravity. Since both, inlet and outlet, on the engine are at the same level. The pressure at the lower port of the rad due to water level and volume combined with gravity should be greater than at the higher port thus helping the water pump (but how big is the difference between the volume of water in the rad and the volume in the hose). At the same time pressure at the T-Stat and at the outlet of the engine should be equal as they are both at the same level.

This gives me more material for thinking. I could always swap the rad, but I'd prefer not to. I could make custom hose but the water inlet isn't clocked right for the apllication.

 

[cribbj]

Here are the official Lexus schematics (these are for the 3UZ engine, but are nearly identical to the 1UZ, except for one small line from the reservoir tank that goes to the thermostat housing on the 1UZ)

These 3UZ schematics are much clearer than the older 1UZ schematics:

 

[rwdfreak]

Thanks cribbj. I was wondering which port was the inlet and which one was the outlet for the heater core. Form the answers I've got on other forums that gives me enough theory and thought to make my own testing and conclusions.

I'll let you guys know how it turns out.

 

[edz]

2- I was also hoping to reuse the stock twin pusher fans from a 91 LS400. I checked them with a ampmeter and they draw 6.5amp at constant speed (12 volt on a batery). Since I don't have much room I cannot use the clutch fan and I don't think there's any possible way of putting an electric puller fan with a reasonably size radiator (planning to upgrade later for aluminum double/triple core rad). Don't be fooled by the picture, there's only 3.5inch between the pulleys and the rad support. Moving the rad forward would be doable, but I don't really want to get into that.

Anyone know if the volume displaced by those fan is enough to cool the engine? If not, would you have any fan brand or car model that use pusher fan(s) that would do the trick. The car has sufficient rad area and opening for air (even better than a stock turboed MKIII), there's no intercooler, A/C condensator or anything else obstructing the flow before or behind it (exept the engine itself). The engine is mostly stock for now, but I'd like to get around 250whp in the next years.

Anyway I'd just like to have your thoughts about I yshould rig those things.

Picture of what I intend to hook the the rad.

The fans don't seem really strong unless that's 6.5 amps each, then they should be ok. The main thing is that they seal against the radiator well to suck the air properly and spin the right way (don't laugh, just reversed a mates that was wired back to front and pushing the air back through the radiator to the front). The radiator needs to be in good condition too, the fans only really effective to about 40kmh (25mph), after that it can be off. Cheers Ed

 

[redrocco]

I am currently running twin electric pusher fans and am have no problems. I do however have a large aluminum radiator. I got my radiator, fan and fan controller setup from FF dynamics for around $420 USD shipped and am very happy with there products and service so far.

 

[rwdfreak]

Thanks for the answer guys, but I solved evrything and so far it seems to work OK. Due to hose fitment and core size I had no choice to upgrade and got a deal on a almost new Koyo 3row rad from a SR20 Silvia for 280$ with a 14 inch derale fan.

I havent raced the car yet and put the cooling system to a real test so I can't tell if everything is really OK. The engine bay is really crowded I could not reuse the factory undercover, but the kaminary front air dam I have has a duct that forces air into the rad.

My pusher fans are not really drawing more than 10amps and are at least 1inch away from the rad. I might instal the 14inch derale fan I have instead: http://www.jegs.com/i/Derale/259/16514/10002/-1

Temperature range from 180 and 200 deg F when the oil get to it's "normal operating" temp. I generaly have to put the fans on (or let my flexalite fan controler) open at around 200 when I cruise at 75mph and the temperature will keep going down if I let the fans on (and goes up again as soon as the fan stop). The temperature also does not raise if I go fast (100mph and higher). Although I did not keep those speed for long periods of time (one or two minutes at most as I want to keep my license and avoid costy speeding tickets) This bugs me a bit because I would have expected the temperature to stay within 190 deg without the fans when cruising. My guess is that the fans are deflecting the wind on the sides when not operating or at lower speed. To cure that I could probably completely duct the radiator to force the air into it.

This is how my cooling setup looks like (gotta admit it is tight)