VZ Engine Bay Airflow?

[routier1642]

Yeah, yeah, I know, forced induction is the cat's pajamas; I just can't afford the pajamas, so I amuse myself with this stuff.

 

[routier1642]

As an experiment, I re-fitted the top radiator shroud, which I'd previously removed to drop the intake temperatures.
Here are my observations:

With the top shroud:

1) When in motion for a while, coolant temperature is 2-5 degrees lower than without the shroud.
2) When you stop, coolant temp rises faster than without the shroud (heat soak).
3) IAT (intake temperature) drops more slowly in motion than without the shroud. And it takes a lot longer to get down to 2 degrees above ambient, which is normal for my CAI system. Most of the time it sits at 4-6 degrees above.
4) IAT rises more rapidly when stopped, than with the shroud.

So the top shroud only seems good for keeping the coolant temperature lower when in motion.
It makes heat soak worse, and badly affects intake temperatures.
Possibly it reduces engine noise a bit as well.

The auxiliary cooling fan I fitted has much less effect when the shroud fitted.

I like the idea of running the engine at 90 degrees rather than 93-95, so I'm working on keeping the shroud.
My next move is to replace the Alloytec 190 intake (with resonance tubes) to a 175 (without resonance tubes).
That should reduce heat soak of the intake system, since those tubes won't be in the hot air flow from the radiator.
There may be an increase in noise at certain RPM, and maybe a small gain (or loss) in efficiency.
I'll measure it and see.
I have an idea for a small heat shield to isolate the intake pipe from the hot airflow, but it's only in my head atm.

 

[XioiX1983]

I have been watching this thread with keen interest, as I have the v8 adventra, with otr, zorst and tune. When the big girls gets into the carpark and traffic is heavy as in stationary for 10 - 15 minutes (other wise known as the M4) the temp raises (no issues with system, all new) as a result the fuel mixture must become richer as I can smell fuel vapour in the car. (Although not all the time) But as soon as get moving, the smell is gone, I am assuming the ecu must lean the mixture out, adjusting for cooler flowing air.

My question is , can you post a how to for the fan that pushes the heat out of the engine bay? And have you toyed with the idea of bonnet flutes for heat extraction as hot air rises?

 

[routier1642]

.....My question is , can you post a how to for the fan that pushes the heat out of the engine bay? And have you toyed with the idea of bonnet flutes for heat extraction as hot air rises?

I'll get a photo and some destructions up later today.
Although it definitely works, it's still a bit crude; if I decide to keep it, I'll source better brackets etc.

I have considered vents/flutes, or even getting a Monaro style bonnet, but I'm on a budget, and also trying to keep everything I do reversible in case it doesn't work out. I love the car, and don't want to ruin it.

As a short-term experiment, try removing the rubber weather strip at the inside back of the bonnet.
It's easy to remove and restore - it just peels off.
The engine definitely ran a bit cooler both when in motion and stationary with the strip removed.
The car was outside for 4 days of heavy rain without the strip, and no water got in. I think it did increase noise a bit, though.

If you're serious about monitoring temperature or anything else, like air-fuel ratio, consider using an OBD2 adapter and a program like Torque.
It's a whole new world.

 

[routier1642]

In advance, I advise that everything you see here is intended to be *temporary*, for the purpose of the experiments.
For permanent installation, I would have better brackets and power connection.

As requested, here is how I set up the engine bay auxiliary cooling fan.

I purchased a Davies-Craig 8" thermatic fan.
I saved $23 by buying the no frills fan-only kit, without relay or wiring loom.
Mainly because at this stage I had no clue as to how I was going to power it, or how permanent it would be.

DCSL8 INCH SHORT (12 VOLT) PART No: 0135

UNDER THE HOOD
Because I had a Growler CAI fitted, I had some spare space immediately aft of the Growler, where the old air-box had been.
I used a spare mounting bolt on one side, and one of the canister clips on the Growler itself on the other side, together with some nuts & bolts left over from another project, and 2 brackets left over from a HKS (cheapo Hong Kong) earthing kit, to mount the fan. I had to be careful to keep it clear of the engine, and certainly wasn't going to mount it to any part of the engine, because - you know - engines vibrate!

Pic 1
P4130077a_zps86673bd4.jpg Photo by routier1642 | Photobucket

I mounted it in this position to try to draw hot air away from the air-box and air tube, blowing it out of the cavity at the bottom of the engine bay.
It also served to remove hot air from the engine bay generally when stationary, and blew on the passenger side of the engine block, helping cool that as well.
This last benefit was reflected in the decreased coolant temperatures, and lack of coolant overheat when stationary. It seems to have been more successful at the secondary aim than the primary one.

The Davies-Craig fan was used in its default configuration as a "pusher" fan, intended to be attached to the front of a radiator.
I don't know if this was the most efficient way to set it up, but it did keep the blades facing in a relatively safe direction.

This shot shows the power connection (as well as the dodgy brackets).
Where it almost touched the Growler, I added some rubbery adhesive insulation material (which you can also see on the aircon plumbing). This made contact with the fan, stabilising it, and gave the fan a bit of soft energy-absorbing suspension in case it vibrated in travel.
I made sure that the bolts were tight and that the fan had very little movement on the brackets. I didn't want it making vibration noises or - worst case - vibrating loose and bouncing around the engine bay.
The right hand bracket is actually using cable ties to attach to the fan. This is because I didn't have a bracket of the correct angle. They seem to work well, and will be OK in the short term.

Now for electricity:
Amongst my piles of useless junk, I found a 12VDC car power adapter for a laptop computer. This easily handled the 5 Amps that the fan draws.
You could easily purchase something similar, just make sure it can handle 5+ Amps. I just happened to have this one handy.
At the moment, the wires are just taped into the 12V laptop supply plug. I looped the wires in a knot around the strut brace so that they couldn't pulled loose from the other end.
The next step will be to replace the plug with spade connectors, insulated with heat-shrink tubing, and incorporate the thermal switch.

Pic 2
P4130078a_zpsf7aa91e3.jpg Photo by routier1642 | Photobucket

At the moment, the wires actually go outside the car & back in through the passenger door crack.
This is a small risk, but it's only for a few days.
The next step is to put the wires through a hole in the firewall rubber grommet that you can see just behind the strut top in Pic 1.
I'll need to remove the glove box to get to this from the other side, so I haven't done it yet.


IN THE CABIN
Using the car's internal power adapter socket (formerly known as cigarette lighter socket) had several advantages.
1) I didn't have to worry about a separate fuse or relay, or overloading another circuit. (socket is rated at 15A)
2) Because the plug is in the cabin, I have complete control over the fan and can connect or disconnect it manually at any time.
3) The biggest advantage was that it was controlled by the ignition. Ignition off = fan off.

I have ordered a cheapo Chinese multi-socket with individual switches (eBay can be useful for this stuff), so that I can just flick a switch.
I could conceivably fit a speed control as well, but I don't think it will be necessary.

Pic 3
P4130079a_zpsafc80485.jpg Photo by routier1642 | Photobucket

Looks like I need to vacuum the car again!
The 240V board you see on the floor there is connected to the inverter at the back of my Adventra, plugged into the 12VDC socket in the rear.
I use brick adapters plugged into 240V to recharge the Android tablet I've incorporated into to the console, and to recharge phones, since I found through experience that an ordinary USB connector from an adapter in the 12VDC socket couldn't supply enough current to prevent the battery draining if the GPS and/or wireless and/or Bluetooth is on all the time. It seems odd, going from 12VDV to 240VAC back to 12VDC to get an advantage, but it works really well. And I have the convenience of being able to run small 240V appliances without adapters. I really should move that power board off the floor, though.


DISADVANTAGES
The only real disadvantage of the fan is that it makes a clearly audible whine, noticeable when you're stationary.

ADVANTAGES
Ideal for stop-start driving, such as in heavy or city traffic!

The advantages are that by decreasing heat soak, it:

1) Keeps intake temperatures from rising so quickly when stationary
2) keeps the engine coolant temperature from rising quickly when stationary. Today, after I did a run where both the weather strip and the top radiator shroud were removed, when I stopped, it even stabilised the coolant temperature at relatively cool 93 degrees, which was pretty impressive. The effects do vary a lot, though, and I wouldn't guarantee it being able to do that under all circumstances.
3) Has a small cooling effect when moving at moderate speeds.

Overall, I think it's proving itself worthwhile, and I'll probably work on making it permanent.

 

[routier1642]

ANOTHER COOLING STRATEGY

During some research last night, I found a series of posts on a US LY7 forum about intake temperatures.
They confirmed what I had suspected; because the MAF body itself heats up during normal running (heat soak), the MAF/IAT sensor itself is heated, and often reports an incorrect air temperature under these circumstances.
Did Holden/GM take this into account in the air-fuel ratio programming?
If not, then once the engine bay is heat soaked, the AFR mix would be based on the wrong figures, adversely affecting fuel economy.

One solution is to move the MAF body - it's in a pretty bad place, right between the radiator (hot) and the engine (also hot).
There are kits sold in the US just for this purpose.

The way my Growler is set up, with the pipe going straight across in front of the engine to reach the throttle body at the front of the engine, I'd have to pretty much redesign the whole thing, moving the filter to the rear, attaching the MAF there, and then doing a 180 degree and a 90 degree bend just to get it back where it used to be.
I'm not prepared to be that radical yet, so I looked further.

I have been toying with the idea of a fairing/heat-shield to divert hot air from the radiator away from the MAF body, but that's only in the preliminary stages.

I read some other posts from a fellow who was concerned about how close the top radiator hose (the hotter one, returning from the engine) was.
Sure enough, on the Alloytec, it passes right under the MAF body, almost touching it. This must inevitably contribute to the heating of the MAF body, and the reported intake temperatures and airflow.

RADIATOR HOSE INSULATION
So today, I did something very simple - I insulated the radiator hose.
Nothing fancy - I just used simple hot water pipe insulation from Bunnings.

UNEXPECTED RESULT
The result wasn't what I expected.
What I expected was a decrease of the effect of heat soak on the intake temp, and possibly an INCREASE in coolant temperature, since waste heat was no longer being radiated from the hose itself. Logically, you'd expect that the radiator would now have more heat to deal with, so the coolant temp would, on average, be higher.

What actually happened was a modest , probably negligible decrease of the effect of heat soak in the intake temperature, but a measurable DECREASE in average coolant temperature!
It seems to be a good thing, but I'm still trying to figure this out. (Today was a little cooler than average - so maybe that was it.)
If anyone has a clue as to how this effect could occur, chime in!

 

[routier1642]

UPDATE:
Took the fan out & reinstalled it so that it would suck the hot air down rather than just blow down - subtle difference, I know, all to do with the pitch of the blades.
To do this, following the instructions, I reversed the fan, reversed the blades, and reversed the polarity.
Oddly, it didn't work as well - peak temperatures of coolant and intake air are both up when stopped (say at the lights) after a run, compared to what they were.
So I'll be undoing that.

I did install the temperature sensor - a simple Normal Open 35C thermostat switch, $5 from eBay. Works perfectly. Closes at 35C to turn the fan on, opens again to turn the fan off when temp goes down to 30C.
1x Thermostat KSD301 Temperature Thermal Switch 95°F 35°C Normal Open N O E1 | eBay