Hi Guys,

I have a howie rad which has a pretty big core (1/4" thicker than the koyo to give an idea).

 

Anyone here running an aftermarket rad without the viscious fan (i.e. aftermarket electric fan).

 

Easy to fit ?.

Can you notice quicker turbo spool up without the viscious ?

I blew my rad, and the water pump free-wheeling in air certainly seemed to give me some extra HP and free up the rev range. Until the steam blocked my view that is...

I dont know stu but i like the sound of that set up.

Gotta be betta without the viscious,

mike duffy u can do this too :-)

is it the Z1 rad stuey?

personally I wouldnt even consider an electric fan. From experience the airflow from a viscous fan is better at idle speed than any electric ive seen at full speed. Also at full lockup it pushes so much air through you can feel a gust coming through with the bonnet closed. Also id have to say the viscous fan is probably more efficient than an electric anyway. Because the viscous is runnign directly off a belt drive, where an electric is sourcing power from the alternator (more load on this and alternators are not 100% efficient) and then back through a motor which is equally as inneficient as the alternator. You might gain a couple of bhp which is negligable, but you end up with a cooling system which is not as good (look on TTnet, there are reports of zeds with electric fans overheating and just generally not working). I know which i'd rather have.

But then how close to the fan would it be. Ive seen mac's koyo and its pretty damn close to the fan.

Like Clarkey said. Look on TT.net. There is quite a lot of information on there about it. The general idea I got, is electrical fans are OK and do free some power, but they cooling is no where near as good. Up to 80ºC they are the same, but on a hot day they just cant push enough air. When the temperature reashes 80ºC the normal fan will probably keep it there, but the electric ones are fighting a losing battle and the temperature just keeps going up and up. Lets also consider that the viscus fan does not come of full strength until it has reached 105ºC or is it 110ºC? Either way when the temp reaches 80ºC the electric fan will be at full power and stuggling while the viscous fan will be no where near full speed.

 

I suggest you search TwinTurbo.net.

 

Stuart

gotta disagree with that clarkey / stu.

electric fan much more efficient in slow moving traffic or at idle, as opposed to the

viscous which is going at it slowest rotation when u need it most, low revs = slow rotation, and its fastest rotation when it may not be needed at all ie. 80mph on the mway .

Me thinks this could be one of those conflicting ones that will just go on and on. Going back to the days when i used to go to SE with a silvia turbo, removing the shrouds was something peter very often done on cars along with fitting a new electric fan against the rad and removing the viscous one.

This i had done on mine and i noticed a difference in engine noise, not much in way of power, but the fan that was set to come at certain temps, hardly ever did and bare in mind i live on island with loads of town driving, infact the fan came on about 5 or 6 times ayear, when it did the temp needle would drop DRAMATICALLY,to me proving it cooled things down really quick, i know am gonna get shot down on this, but i'd be surprised if the fan stu's fitting is hardly gonna come on at all with his rad, we'll have to wait and see.

Topless yes it's from Z1 mate along with me own.

cheers

smithy

I bought a leccy fan the biggest one i could get from demon tweeks and used it for a couple of years with no problems, but i did change back after reading some of the concerns on TT net. If you have a good aftermarket temp gauge you can always monitor things and see how it goes.

Paul

Mark, Yep it's a Z1 jobbie :D.

 

I have a feeling that most people who had the problems on TT.net were using the fan with a stock rad. Well I've got A Howie 2.25" Rad, Aftermarket Oil Cooler, Greedy I/C's & Doolz twin pop, so There should be enough cooling there to do the job even at big BHP.

 

And if there's not I'll just fit a CO2 kit for the rad and the I/C's :D.

 

Some of you on here may know of Colin Ashford,ZClub Drag Challenge Winner(again!)has been running a SE Nissan twin electric fan set up for about 5 years(more or less)seen him do 8 runs in one day in 32c heat and countless other hot hot days,he has never had a cooling problem :eek: ,were as i seriously thought no,i am not running it in that heat :D so the conclusion is it must be ok with the right setup.

Tony

gotta disagree with that clarkey / stu.

electric fan much more efficient in slow moving traffic or at idle, as opposed to the

viscous which is going at it slowest rotation when u need it most, low revs = slow rotation, and its fastest rotation when it may not be needed at all ie. 80mph on the mway .

 

 

You can disagree with me and Clarkey. But go on to TT.net and search for yourself. You can then disagree with people who have them on and say that its not as good as good and disagree with the people who put the viscous ones back on.

I have given a lot of thought to this lately, my other hobby of sitting alone in the dark has worn thin!

 

The stock fan chucks out 6000cfm, now I presume that is at full revs, so averaging out the engine speed the fan flows about 3-4000cfm as a mean figure.

 

At speeds at I believe above 40 mph the stock fan actually acts as a hindrance to air flow, so when is the fan actually of any use? It seems that from those statistics if they are correct, it would be only be of use at high engine revs when combined with low car speeds, which on a zed lasts about 3 seconds!

 

The best electric engine fan throws out 2900cfm, which is the average speed of the zed fan! The advantage with this is that it will cool the engine when sitting in traffic at a better flow than the zed fan, which for me living in London could be an advantage!

The mere fact that many performance and road stock cars, no longer use Viscous fans anymore, it was always something from early days and carried onto some makes/models only until the late 80's early nineties, now do yer ever see a Viscous fan ?

cheers, smithy

It would be interesting to see , if anyone with an accurate temp gauge can make improvements to the running temp with an electric fan and aftermarket rad!

Hi Guys,

I have a howie rad which has a pretty big core (1/4" thicker than the koyo to give an idea).

 

does not answer your fan question but look.

 

Ok Stu this is what my rad man said....................

 

I had an air lock in my Koyo rad when it was fitted,I took it to a guy that I have known for a few years now,and he has over 20 years experiance in cooling systems.

He said this rad is the wrong design WTF :confused:

He told me that the end tanks were too thick and all large end tanks do is store boiling water that will flow back into the core.He told me that the core was quality and if he was to make one he would do the end tanks half the size.

does not answer your fan question but look.

 

Ok Stu this is what my rad man said....................

 

I had an air lock in my Koyo rad when it was fitted,I took it to a guy that I have known for a few years now,and he has over 20 years experiance in cooling systems.

He said this rad is the wrong design WTF :confused:

He told me that the end tanks were too thick and all large end tanks do is store boiling water that will flow back into the core.He told me that the core was quality and if he was to make one he would do the end tanks half the size.

 

So is he saying that an aftermarket Rad is no better than stock ?. or that it could simply be improved more by smaller end tanks ?

Just thinking how this can happen :confused: the water pump pumps the water around the engine, it enters the rad at the bottom and flows up (or is it the other way round ? ). If this is the case the water pump would prevent flow of hot water back into the engine surely ? ).

 

Also speaking of air locks, could this have been what caused your piston damage ? Heatsink maybe ?. How did you know you hads an airlock and how did you get round it. Would be good to know for when I fit mine, Thanks.

So is he saying that an aftermarket Rad is no better than stock ?. or that it could simply be improved more by smaller end tanks ?

He said it would be improved by smaller end tanks

Just thinking how this can happen the water pump pumps the water around the engine, it enters the rad at the bottom and flows up (or is it the other way round ? ). If this is the case the water pump would prevent flow of hot water back into the engine surely ? ).

No the hot water enters the tank via the top rad hose;) the tank is so big it just holds the boiling water until the water pump can flow it back around the engine,a larger capacity water pump would help solve this

 

Also speaking of air locks, could this have been what caused your piston damage ? Heatsink maybe ?.

No the piston cracked due to age,a ten year old piston wont last forever running a bar

How did you know you hads an airlock and how did you get round it. Would be good to know for when I fit mine, Thanks.

I knew because the after market temp gauge was rising,I simply got rid of the air lock via the bleed screw on the top of the rad,had to repeat this a few times

__________________

If you are using the term boiling meaning hot no problem, but I believe the water in the system does not boil until over 100+ degrees because it is pressurised!

 

So is your rad man saying that the end tanks help distribute the water evenly throughout the core and that having a bigger end tank stops that?

 

BTW you cannot have a larger or faster water pump fitted because of the problems with something called cavitation, this occurs when you overrun the supply. Causing vapour bubbles to be created in the coolant and the flow would be less than usual.

 

By the way an easy way of filling the engine with coolant without it taking eons, is to take off the top rad hose at the rad tip it up and just pour the coolant in there, this is where you get air locks and also if it is attached depress it lightly with your hand and this allows the air to flow out!

I'm guessing that he means that the water is best cooled through the heart of the rad using the fins that the air passes over - the bigger the end tanks the more water thats held not really being cooled down and so is inefficient at its job - thinner end tanks means less standing hot water not being cooled down. A good theory if I'm reading it right.

Yes that what I was thinking that the area used by end tanks should be used by more surface area for cooling!

 

But water has a large thermal capacity so there must be an equilibrium where the ratio of water capacity to surface area is optimised. I think we are talking too much about cooling, I have to work tonight and I should not bring my work home :slap:

Nice tip there Mark about filling the engine with water. Will be using that one.

 

The end tanks one is still confusing me a little. Surely any water in the rad will start to cool a little as apposed to it being in the engine, even if we are talking minute amount, I can see Macca's man's point but I can't see it being a big problem.

LOL!! missed this discussion!!

 

cooling fans are mostly required at low speed, where airflow is too slow over the rad to cool (when an electric fan would be better), & at high engine speeds, where the airflow over the radiator may not be sufficient.

 

the water flow through the rad is top to bottom, not because of the pump, but because the hot water entering the rad is cooled down. colder = denser so down it travels. the pump is there to assist the water flow around the engine.

Good theory. But surely the end tanks would have to be massively over sized to cause even a slight overheating problem? The coolant is always moving thru the rad (when the thermostat's open) , at the same speed whether the end tanks are small or big? but if too small would restrict flow.

But even if u think smaller end tanks are more efficient, the top hose is pretty big and holds alot of coolant, should that be smaller too? :-)

Good theory. But surely the end tanks would have to be massively over sized to cause even a slight overheating problem? The coolant is always moving thru the rad (when the thermostat's open) , at the same speed whether the end tanks are small or big? but if too small would restrict flow.

But even if u think smaller end tanks are more efficient, the top hose is pretty big and holds alot of coolant, should that be smaller too? :-)

 

LOL Trevz,Its his theory and the guy does know whet he is talking about trust me;)It's almost as mad as telling an IT bod with 20 years experiance how to defrag his PC.

I'm guessing that he means that the water is best cooled through the heart of the rad using the fins that the air passes over - the bigger the end tanks the more water thats held not really being cooled down and so is inefficient at its job - thinner end tanks means less standing hot water not being cooled down. A good theory if I'm reading it right.

 

Spot on Bilky,at least someone understands:D:D;)