Does the radiator fan help at 50mph?

[turbogrill]

Hi,

 

Does a radiator fan help at 50mph?

 

I am seeing some high temps on my NC, don't know if it's because it's 100F outside or if something is broken. 

 

Looking at the logs the temp goes from 208 to 214 pretty quickly in a uphill 50mph 'S' turn. Then on the next 100mph straight the temps slowly goes down again to 208-210. It's just this turn.

Could it be that the FAN wiring is glitchy in that specific turn? Or would a fan not help in 50mph at all?

Red circle shows the temp go from 208 to 214 in about 10-15seconds. 

 

 

 

This is the part of the track:

 

It's just this turn! (Going CCW, black arrow shows the direction)

 

Edited September 23, 2021 by turbogrill

[TiredBirds]

your fan might be restricting airflow. I like to use clutch fans.

[Team Infiniti]

Personal experience: the fan is little to no help above 40, as for @TiredBirds one can feel a distinct hp increase after removing the clutch fan, we ran for years with no fan but cautions and reds became issue if the driver was not on his game.

 

[turbogrill]

Thanks, so the fan does not help significantly at 50mph. So something else then.

 

I think 214 F is high for an NC, it looks like the ECU is starting to pull timing (22 vs 24 degress during WOT).

 

It's odd that it's just this turn. Maybe it's the slowest part of the track after a long straight so lots of built up heat and only 50mph flow. 

Will check the ducting friday, might be a birdsnest or something there.

Wish me luck! Got a race this weekend....

 

[MMiskoe]

Oil pickup getting dry due to sloshing and long RH into a long LH?

 

If you have the ability to run as a test, I would run a few laps as a baseline, then simply unplug the fan and run a few more.  I'll bet you a beverage that you won't see much change.

[turbogrill]

hmm..so oil stravation could cause it?

 

 

[Team Infiniti]

It would lead to glitter oil pretty quickly if so.

[mender]

2 hours ago, turbogrill said:

Thanks, so the fan does not help significantly at 50mph. So something else then.

 

I think 214 F is high for an NC, it looks like the ECU is starting to pull timing (22 vs 24 degress during WOT).

 

It's odd that it's just this turn. Maybe it's the slowest part of the track after a long straight so lots of built up heat and only 50mph flow. 

Will check the ducting friday, might be a birdsnest or something there.

Wish me luck! Got a race this weekend....

 

Basically the temp rise is because you don't have sufficient air flow to balance the heat generated just prior. 

 

As stated, the fan is an impediment at those speeds and above. Proper ducting before and after the rad will make a much bigger difference than a fan can. Use duct (!) tape to seal any gaps. Make sure the air has somewhere to go (hood vent, etc.) once it passes through the rad.

 

I ran a fan for the first couple of races back in 2013 and haven't since. About 10 degrees cooler without the fan in the way.

Edited September 23, 2021 by mender

[Hurljohn]

We don't run a fan(s), you likely have something blocking flow to your rad if you are still on factory setup.  We had this happen at Charlotte that cost us a win.  Upper factory ducting had broken loose from previous tire wall contact and started to hang down in the bumper opening diverting air away from rad.

 

Check that first.

[MR2 Biohazard]

Fan.  Fan is extra weight. Yuck.

 

My understanding is a fan is more restriction for the air go through after the radiator. I know Grant does not run one in his NC.

 

Also, when idling my Miata NC it stays at like 200F without a fan. I joked that I need to get and electric leaf blower for sitting in the pits if needed.

Edited September 23, 2021 by MR2 Biohazard

[turbogrill]

Sounds like a ducting issue! Maybe something is blocking, I can't remember us ever having over heating issue. Would 80F vs 90F vs 100F outside temp matter? 

 

As far as the fan, my team mates are a bunch of Neanderthals with learning disabilities. So I think keeping the fan might be good, however I haven't tried disconnecting it and see what happens during idle.

 

 

 

[turbogrill]

So where does the air go if there are no hood vents and such? The NC has a tilted radiator with some kind of "undertray" so it seems like it's attempting to push air thru the radiator. But there is no place for the air to go after it passes thru the radiator. 

 

Is it supposed to go under the car? Or just stay under the hood?

[Team Infiniti]

2 hours ago, turbogrill said:

 Would 80F vs 90F vs 100F outside temp matter?

Yuppers

1 hour ago, turbogrill said:

So where does the air go if there are no hood vents and such? The NC has a tilted radiator with some kind of "undertray" so it seems like it's attempting to push air thru the radiator. But there is no place for the air to go after it passes thru the radiator. 

 

Is it supposed to go under the car? Or just stay under the hood?

Generally speaking, under or anywhere there is a low with flow.

 

mender will be back in a moment

[Grant]

Correct I've never run a fan on any ChampCar. They're only useful when closely drafting another car of almost the exact same speed, which basically never happens.

 

At CMP in 95F? degree weather we saw a peak of 190F coolant temps. This is with the stock radiator, lots of ducting made from factory plastics, a non-vented hood (because no windshield), and a small inlet restriction in the form of a fairly fine metal mesh over the radiator. A car which can vent its hood should be able to do better on cooling (and downforce).

 

Aside from the sealed hood we don't have much blocking airflow out of the radiator though, relative to most NCs. I assume the air goes out into the fenders. If we'd kept running the car I was going to put a lot of time into reducing under-hood pressure.

[turbogrill]

7 minutes ago, Grant said:

Correct I've never run a fan on any ChampCar. They're only useful when closely drafting another car of almost the exact same speed, which basically never happens.

 

At CMP in 95F? degree weather we saw a peak of 190F coolant temps. This is with the stock radiator, lots of ducting made from factory plastics, a non-vented hood (because no windshield), and a small inlet restriction in the form of a fairly fine metal mesh over the radiator. A car which can vent its hood should be able to do better on cooling (and downforce).

 

Aside from the sealed hood we don't have much blocking airflow out of the radiator though, relative to most NCs. I assume the air goes out into the fenders. If we'd kept running the car I was going to put a lot of time into reducing under-hood pressure.

 

You moved a lot of stuff out of the way! Even cut that bar that goes across, was it heavy? Where did the ECU go?

Edited September 23, 2021 by turbogrill

[Grant]

7 minutes ago, turbogrill said:

You moved a lot of stuff out of the way! Even cut that bar that goes across, was it heavy? Where did the ECU go?

Yes of course we move as much weight backward as we can. The ECU is on the passenger firewall, as far as the bulk of the OE EFI harness would reach. What we have as a fuse box is near it.

 

The center bar was not heavy and was probably a mistake to remove, since it probably keeps the frame rails from bending inward in certain front end impacts. We originally did it because we wanted to seal the radiator to the hood vent in WRL.

Edited September 23, 2021 by Grant

[wvumtnbkr]

Love your new avatar.    Flat out.  That is how I drive...

[mender]

5 hours ago, turbogrill said:

So where does the air go if there are no hood vents and such? The NC has a tilted radiator with some kind of "undertray" so it seems like it's attempting to push air thru the radiator. But there is no place for the air to go after it passes thru the radiator. 

 

Is it supposed to go under the car? Or just stay under the hood?

 

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Edited September 24, 2021 by mender

[Rodger Coan-Burningham]

9 hours ago, Hurljohn said:

We had this happen at Charlotte

Champcar official: “So it seems your driver skipped pit out and drove directly on to the track”

Us: “No you don’t understand, he is like one of the best drivers in Champcar there is no way he did that”

Us after looking at the video: “hey, he did do that”

 

[Brian E]

If I remember correctly that turn is the highest point on the track. Could the heating issue be you are going up hill and have more load on the engine causing the temperature increase?

[enginerd]

Water flow rate through the engine will likely be proportional to engine rpm (belt driven water pump). If you are at some combination of high load and low rpm I can understand measured engine temp rising. 

[LuckyKid]

It could be that the car's yaw in that corner is impacting airflow through the radiator.  I could easily see outlets stop working or inlets reduce feed based on extreme yaw angles.  This is just a theory though.

 

We've been battling aero yaw issues a bit with our splitter. 

[turbogrill]

We are missing a bunch of OEM plastic undertrays under the car. I did a beautiful duct-tape job before the race and it might have helped. Didn't see the high 220 temps, but could have been the weather being slight cooler.

 

 

[Grant]

3 hours ago, turbogrill said:

We are missing a bunch of OEM plastic undertrays under the car. I did a beautiful duct-tape job before the race and it might have helped. Didn't see the high 220 temps, but could have been the weather being slight cooler.

You want all that stuff, and more. Especially if you don't have a fan. We saw a noticeable drop in temps just improving on the factory setup. There's a big piece of foam which sits under the radiator that commonly falls off, letting tons of air by...

 

Cooling system ducting is critical for reducing drag and lift.

Edited September 27, 2021 by Grant

[Grant]

On 9/27/2021 at 10:00 AM, turbogrill said:

We are missing a bunch of OEM plastic undertrays under the car. I did a beautiful duct-tape job before the race and it might have helped. Didn't see the high 220 temps, but could have been the weather being slight cooler.

By the way if you haven't seen it, check out the data available on racelouvers.com. They wind tunnel test a lot of different setups, and give you drag, downforce, as well as radiator airflow (via differential pressure).