Are Thermo Fans Better Options Than Running Standa

[GeeTR]

I’m surprised no one has brought up the mass the fan adds to the rotational mass of the engine!

From this thread and a few freinds lecky fan attempts I’m understanding that a shrouded, setup, either moded stock one, or custom, f.glass, sheet alloy'd 16" thermo would do.... but i cant STAND that weighted free revving feeling and EH Falcon engine fan noise of a skyline! Lighter flywheel would fix some of it I guess.

Be interesting to check the physical tourqe loadings that a alternator puts on the engine from normal electronics + 10AMP thermo.. and how that compares to the stock locked up engine clutch fan; truley see witch one costs more power, over the cruising, WOT etc that makes up fast street / track running.

In all honesty I would try v.hard to make a thermo work properly due to engine response and noise soley, flame away !!

I believe there’s a array of simple jaycar kits, mechanically switched, or electronic that you could use. Could get fancy and use a PICAXE to control both thermo and electronic water pump, tricky closed loop, solenoid on the thermostat to run a cooler water temp, read: head temp when in high boost mode, and then a higher more emission friendly temp when cruising. Just my way of adding complexity & possibility to a simple thread - sorry

- M

[Cubes]

GeeTR,

When I had the thermo's on it was wonderfully quiet. You don't realise how much noise the std fan makes until its gone.

I swear the car did feel a little more responsive ESPECIALLY in hot weather.

I have plans to throw thermo's back on but it will be some form of el factory thermo's.

[N I B]

Been fitting N15 Pulsar dual fans without trouble.

[Cubes]

Nice another option.. I will be sure to check those out.

Hows the fit NIB, factory like or do they require cutting and fab?

[GeeTR]

Yay, acceptance! Amen cubes

Dammit, have 6:30am start, but I have this notion of controlling water temp accurately and quickly to use as another factor you could control, stuck in my head- argh.

I know Bemma and others have been doing it for a while on the specy'r models. Surely just a stepper motor on the stock thermostate or a custom stepper’d valve wouldn’t be hard. Do that multi head coolant bleed setup thingo which is popular of late... you could spend many a weekend tweaking.. if only the time and money *sigh*

- M

[Bass Junky]

I have to admit I reckon thermos are the shiznet even though everyone says that they aren't worth it.

I hate the blowing noise the stocker makers, especially in the morning!

I haven't had a fan shroud for 3 months now and with the new radiator I've never seen it go above 82 degrees (still with fan though) even when driving for an hour with the Air con on. I also used to see the oil temp go up a little with the Air con on, but not now. Yay for biggins radiators.

So, I reckon it's only a matter of time before my stock fan totally accidentally and mysteriously breaks and I have to put a big thermo on.

[rev210]

I’m surprised no one has brought up the mass the fan adds to the rotational mass of the engine!

I have plenty of times....

[Abo Bob]

I have plenty of times....

Yeah but no one listens to you.

[Bass Junky]

REV210

As you are MR "Lower your rotational mass" on SAU, have you done this mod?

How did you go with engine cooling?

Did the fan come on and off and sap engine power at all?

Tell me your results!

BASS OUT

[AndrewD]

I cant believe you think your going to get an increase in power from the lower rotational inertia just by removing the mechanical fan.

The rotational inertia would equate to maybe a couple hundred Watts, not kW.

electric fans are better than mechanical purely from a control perspective. They flow less, but transfer the energy required from the crank to the alternator.

Its not a power gaining mod. More an engine saving one!

Think of it this way, at start stop traffic engine speed is slow. Fan speed is proportional to engine speed (hence so is flow, so long as cavitation isnt present). Electric fans arent related to engine speed, rather engine temp.

Edited October 22, 2006 by AndrewD

[GeeTR]

Well I still reckon some bored young aspiring mech / elec uni eng, needs to rig an electrical water pump, thermo and some form of PIC. Have some fun playing around with cooling, assuming both units down mind less the 12v

[Bass Junky]

Davies Craig have just released a variable speed controller which allows the operator to select the heat that he wants to water to be at. From 75 degrees up to 105 degrees.

[rev210]

REV210

As you are MR "Lower your rotational mass" on SAU, have you done this mod?

How did you go with engine cooling?

Did the fan come on and off and sap engine power at all?

Tell me your results!

BASS OUT

No actually I am MADAM " Lower your rotational mass" as I am into drag.

Yep did the mod a few times to different cars.

The engine goes well with cooling as I retain the fan shroud and use an appropriate size/ cfm fan.

The fan is normally 'on' in the low speed and stand still situations and off as the car is moving at speed.

The 'at speed' part is what the performance angle is aimed at, particularly as the belt pulley drive horsepower losses grow as engine speed and load does. It's when the hammer is down that you like to have the benifit of a redundant fan being driven.

Never really 'measured' the results as I thought them obvious but, I'm sure the might be a test somewhere if googled for.

Most factory skylines fan shrouds will accept the very large 16 inch davies craig fan with a little cutting to size.

Air guides for both the intercooler and radiator are worth chucking in too if you have the inclination for extra efficiency. Some foam can be used if your not a welding type.

AndrewD,

Rotational intertia doesn't equal horsepower to clear that up.

The weight of the factory fan gone helps improve the engine accelleration a small amount, combined with other pulleys made of lighter material it all adds up to help more.

The weight of the fan on the end of the water pump pulley increases the load on the belt, which increases the fictional power losses.

The benifits you mention seem quite valid by the way.

The reliable nature of the pulley fan has it over the electric fans however. If any part of the electric circuit goes down you have no fan, for the pulley fan to fail the water pump pulley has to fall off. For this reason an electric fan has to be done right with the fail safe fuses and relays and spares of these in the car at all times perhaps with a warning light for good measure.

[Bass Junky]

Rev.

Can you feel the alternator drain?

have you run with the fan off? how does it go just driving around normally? what temps do you see at cruise?

[Crimpage]

The altenator doesn't kick in tho to keep up with the current draw tho does it? I though that it just span at the same speed always spitting out the same power...

But what is an extra $90 for a ground stabalizer to help the electic system keep up...

[Bass Junky]

no it doesn't but when you load up the alternator, the engine comp often loads up the engine a bit as the alternator needs to spin a little faster to compensate.

You can feel it sometimes and if you turn on the high beams you can often watch the revs rise.

[Crimpage]

Thats true.

[GeeTR]

I think most of the "load" the engine sees, in these high draining conditions is between the windings and magnets themselves; not the the increased idle RPM from the idle control stepper.

[Bass Junky]

That's a better explaination.

That what I meant, but don't know enough about the inner workings of alternators.

[GeeTR]

Ha me neither, but it’s that interaction that drives a (most) electrical motors... so must be same principle reversed!