1840cc 66 Roadster Build

[JT68]

Maybe this should move to another thread….please move if warranted Steve.

While some of the above posts are correct. There is much BS/myth attached to electric fans. What is certain is the following:

1. A mechanical fan is the much simpler system. No question about it. About the only common thing that will fail the system is a broken fan belt.

The electric system is dependent on a motor, wires, battery, multiple connectors, thermostat, relay, switches and the alternator. A failure of any of those will stop the car and/or shut down cooling. All those components can and do fail with some probability much higher than a fan belt. (Just the number of components makes failure much more likely).

2. The only way an electric system saves any energy or “frees up any power” IS WHEN IT IS OFF. So it only is a “performance upgrade” if it isn’t operating! Lol.

Otherwise, due to physics and conservation of energy, FOR THE SAME AMOUNT OF AIRFLOW, an electric system uses MORE energy!

It’s physics 101….there are multiple energy conversions all with mechanical and heat losses with the electric system and none of it is free!

The motor converts electric to mechanical with 50-75% efficiency ( all electric motors have frictional and heat losses)
There is minor electrical loss in all electrical systems.
The battery supplies the motor, but that isn’t free. It get recharged by the alternator also at roughly 50% efficiency. Heat,friction etc.
The alternator loads the engine of course! So you are back to loading the engine to drive the fan- AT GREATLY REDUCED EFFICIENCY FOR THE SAME CUBIC AIRFLOW.

If your car is running hot, it isn’t the mechanical fan. They are inherently MORE efficient. A higher capacity radiator is almost always a good investment for a roadster.

The most common error folks make with the mechanical fans is removing the shroud. In that case, air can be drawn from around the radiator rather than through it.

Again, the most compelling reason for an electric fan is so it can be turned off electrically. Otherwise, there is really little reason to bother with all the additional stuff (and of course they look completely wrong in a roadster).

[Bwk2000]

…
REASON: At least 3 local roadster owners have added pusher electric fans to prevent overheating when idling in slow traffic. These are U20 and R16's with good stock or aluminum radiators.

BENEFIT/EFFICIENCY: Might be miniscule, but everything I've read is that mechanical fans rob horsepower and/or fuel economy.

APPEARANCE: Yes, a mechanical fan blade and shroud look period correct. I also think it looks clean without them, which is what I was thinking of.
...

All valid points Pete.

There is a good reason why almost all automotive cooling applications have gone electric by the time we entered the 21st Century; three actually: efficiency, fuel economy and power savings (all related).

Now, I just did a quick test on my own elec. cooling system on the roadster. It draws 15A @ 13.5V when running and I have it set to kick in at around 185F. Even after allowing for just 50% alternator efficiency, that still only translates to about a 1/2 HP parasitic loss (0.544 to be exact) and that’s ONLY when it’s operating (idle, rush hour traffic, etc). The rest of the time when I’m driving it’s off, so the net power loss then is Zero - I’ve never had a problem with overheating at anytime.

For a stock u20 solex car, that 1/2 HP would result in a part time parasitic loss of only about 0.3% for running the cooling fan, for a stock R16 it would be about 0.5% … No mechanical belt/fan system can come close to matching that for efficiency - Better efficiency, better gas mileage, less power loss from parasitic drain. Call it a win - That is why everyone does it now.
Electric motors are ALWAYS much more efficient than mechanical.

So …
Is a belt system simpler? Yes.
Is it cheaper? Yes.
Is it less likely to go ‘wrong’? Probably.
If the factory cooling system is not broke should I ‘fix it’? No.
Will an electric fan provide much better cooling at idle and in slow moving traffic compared to a mechanical one? Yes.
Is an electric fan more efficient and economical? Yes.
Can just an electric fan work well on our cars? Yes.
Does an elec. fan not look right on our cars? Maybe - That one is in the eye of the beholder.

All that being said, I really don’t see an issue with having either option on our little roadsters. They will both do the job of cooling the engine just fine as long as everything else is working properly (even if you just wanted to add a pusher elec. fan as you mentioned).

Bottom line:
It’s your car, you mod it whatever way you want to.
Remember, nothing here is permanent, it can always be switched back if you’re not happy with it.

Good luck.
Let us know how it turns out.

[S Allen]

I don't have a running car as yet but I plan to use the plastic fan, radiator shroud, recored 2 lire radiator and the lower frame mounted air scoop for cooling. On the purple stoker all I had was an electric fan and it did quit working once. Electrical issue. Thank goodness it has a cast iron head which is less prone to warp. It got hot but not hot enough to do any damage.

The 67 2 liter will be all stock except the 3 row recored stock 2 liter radiator.

Steve

[JT68]

That's a good plan Steve. The key is a really good radiator and shroud. My advice is spend the money on the best radiator you can. If the system has sufficient capacity, the fans really don't do all that much in normal driving. Many of the 1600 radiators and the cheap AL radiators can't cut it. The 2L with a thick core is great.


The problem with saying "my electric fan only draws 15A" is that is a relatively small fan moving a moderate fixed volume of air. Clearly that's an apples-to-oranges comparison with the stock mechanical fans, since at 2 or 3 or 4k rpms, the 4 blade is moving 5 or 10x the air of a 15A accessory fan. (That is why I prefaced what I posted with "FOR THE SAME AMOUNT OF AIRFLOW").

At idle speed, the mechanical fan draws very, very little power- all the work is in spinning the water pump and alternator. (that's why a 1/4hp electric motor will easily spin the stock fan at idle RPMS). Sure the mechanical fan is using more power at higher rpms, but it is moving WAY,way more air.

To match the air flow of the stock fans, you would need a much more serious electric fan and that means more power. Some cars do run big hoss electric fans, but they sure are not cheap or "energy free". They put a substantial load on the electrical system.

Millions of cars also run accessory electric fans along with a large primary mechanical fan to aid with low speed cooling and that is a good approach too. That way you have the incredible reliability of the mechanical fan and a smaller fan that kicks on when needed. Again, the accessory fan is somewhat unnecessary with a good radiator.

If you spend much time with electric fan systems on modern cars, you will see all kinds of failures...I replaced Mercedes,Nissan,Lexus and Subaru fans or fan components after overheating issues with all those marks. (and obviously those were pretty good quality oem components)

Anyone very familiar with electric motors knows you can't lump them all together in terms of efficiency. Yes, there are high efficiency multi phase motors out there, but those are expensive and you won't find that on an Autozone fan.

One other practical point for guys with stockish roadsters thinking "should I add an electric fan?" 15A is 50% of the capacity of the stock alternator.!
Flip on the headlights or a few other accessories and your stock alternator is maxed out. (that's a bad plan). If you add a big alternator, then again you have just transferred the additional load to the engine! Nothing is free, conservation of energy still applies.

If anyone needs a correct roadster fan, we have them and they are about as beautiful as a roadster fan can be...A few were also gifted at Solvang, but I'm not sure who got them.

[Bwk2000]

Steve.
Sounds like you cashed in some karma in managing to save that head. I find that driving a 1/2 century + old car, I have to ‘retrain’ myself in the old ways and remember to keep a weathered eye on the gauges. A simple little fuse, wire or belt that gives out can quickly become quite costly if not caught in time - Guess I’ve become too use to the bells, chimes, flashing lights and limp home mode being there to save the day if needed.

That being said, the electric fan has not let me down and does a great job of cooling the engine nicely!

I do really like the idea of upgrading to a three core rad at some point in the future. If mine ever gives up the ghost, I’ll likely skip recoring the original (pretty sure it has been done once before) and just order a new drop in one off of Dean - Would be money well spent I think.

[ppeters914]

Finally got my exhaust done this morning so that completes the chassis, engine and tranny. Happy with the end results. He did everything I asked him to do. Flex at the exhaust manifold, O2 bung.

Is this the O2 bung?
...

stevea_o2_bung.png

....
How will you route the wiring?

[Gregs672000]

Hopefully the sender isn't too tall and does not hit the trans (if that's what you're noting. Mine is more angled up). I route my wiring up along the firewall and through the stock openings into the interior and to the controller.

[ppeters914]

Hopefully the sender isn't too tall and does not hit the trans (if that's what you're noting. Mine is more angled up). I route my wiring up along the firewall and through the stock openings into the interior and to the controller.

Yes, although I think that picture might misrepresent the proximity to Steve's transmission. Is yours in roughly the same location, Greg?

Controller? Figured I'd be talking to you more about wideband.

[Gregs672000]

Yes, although my flex is now between the x frame. My sender is mounted a little closer to the header and at about 2 o'clock (or 10 o'clock depending on your position). "Controller" was in reference to the box to which the wiring connects that send signals to the gauge as well as the Microsquirt. That's how it works with my Glowshift wideband.

[S Allen]

The bung on both of my cars is tipped slightly up. No worries about hitting the tranny. Will run wires up firewall and then into the cockpit. I don't plan to install a permanent A/F gauge but will use it for checking the tuning and then pull it out.

Steve

[ppeters914]

The bung on both of my cars is tipped slightly up. No worries about hitting the tranny. Will run wires up firewall and then into the cockpit. I don't plan to install a permanent A/F gauge but will use it for checking the tuning and then pull it out.

Steve

Do you know what you'll be using?

[S Allen]

Probably something like this.

Air/Fuel Gauge

S

[Gregs672000]

I'm afraid a narrow band sensor will not provide you with much useful data for tuning, as it only reports 14-15 at best, and you really do want it in the 13s under load. As I recall there was someone on the list who offered a wideband one to borrow, or perhaps some folks local to you would be interested in going in on a portable set up for tuning. I understand not wanting to try to add another gauge; I was lucky in that my center console was already modified so adding one was fine with me.

[funkaholik]

You definitely want a wideband, and all are not created equal. I cheaped out and got an AEM gauge on Amazon and discovered when I was getting my chassis dyno done that my gauge was pretty far off the calibrated one at the shop. Even worse, mine reads rich, so if I tuned according to it, I would be running leaner than I thought. Scary.

Here is the one that Z Car Garage suggested, and said it's the only one they will use. Yes, its $210, but how much is accurate data worth when the health of your engine depends on it?

https://www.plxdevices.com/Wideband-O2- ... 002719.htm

[S Allen]

Duly noted. Thanks.

Steve