MLR's Bogan cruise ship

[GTSBoy]

It takes a few (like low single digits) horsepower to drive a car AC compressor. If you can gain more than that few HP back, it should be nett positive. It would seem like an interchiller should be able to be worth more than a handful of horsies.

Most importantly, it should be run when the engine load is less than 100% (ie, when there is spare power available, going unused at the tyres, when whatever power is used to run the AC won't take away from thrust.

 

[Kinkstaah]

I can see it being logical for pre-cooling the intake charge before it's actually being used. Kind of like dumping dry ice on an intercooler directly....

I.e waiting in line for your start at the drags, or driving around before you want to chop someone on the highway lol, and it would be a net benefit for @mlr's use.

However for say some dickhead who decided to supercharge his LS in a skyline, then wanted to do 30 minute hotlapping sessions, at 100% throttle for extended periods well and far beyond a drag run, in a very limited packaging situation with IAT's being extreme, (70+++). 

I can still see the subjective benefits of generally keeping IAT's lower rather than higher which is more than just pure power tbh. Keeping it lower makes sense. But I'm still curious as to whether it would actually increase RWKW in the long run and/or actually still _work_ when the engine is under load like that. Would the motor just generate too much heat for the AC system to overcome?

[The Bogan]

On 18/03/2022 at 10:11 AM, Kinkstaah said:

I can see it being logical for pre-cooling the intake charge before it's actually being used. Kind of like dumping dry ice on an intercooler directly....

I.e waiting in line for your start at the drags, or driving around before you want to chop someone on the highway lol, and it would be a net benefit for @mlr's use.

However for say some dickhead who decided to supercharge his LS in a skyline, then wanted to do 30 minute hotlapping sessions, at 100% throttle for extended periods well and far beyond a drag run, in a very limited packaging situation with IAT's being extreme, (70+++). 

I can still see the subjective benefits of generally keeping IAT's lower rather than higher which is more than just pure power tbh. Keeping it lower makes sense. But I'm still curious as to whether it would actually increase RWKW in the long run and/or actually still _work_ when the engine is under load like that. Would the motor just generate too much heat for the AC system to overcome?

For NA I couldn't see the cost being justified, you are just dealing with ambient temp and "possibly" a small bit of heat transfer 

But, I've done a little reading into IAT, CAI and heat transfer 

The IAT varies greatly dependant on the sensor location, and I cannot really see the air being "heat soaked" for the fraction of a second that the air is travelling from the CAI to intake valves of an NA engine.

5.7 x (6000 rpm ÷ 2) = 17100 litres of air a minute at 6000rpm (very roughly) #efficiency 

Thats 17100 ÷ 60 = 285 litres a second is getting sucked down its throat 

These rough calcs do assume 100% efficiency though, but even at half the volume, that is still near 150 litres a second.

What size is your intake and how long is it?

I'm guestimating that the air speed is exactly "really really bloody fast", too fast to heat up the ambient air to any noticeable degree....

 

For reference my post blower AIT goes up pretty much with the coolant temp, to settle at around 50°c, when its sitting in traffic or after a pull it gets to around 70°c, but after I shut the car down, it goes from 50°c to 70°c fairly quickly, but once the car is running and moving again it slowly comes down to 50°c

See pic for where my IAT sensor is in relation to the engine, it is basically bolted to the head, and this is why the spacers "lower" the IAT temp, it is really only stopping heat soak from affecting the sensor, actual IAT hasn't changed at all, from my research spacers alone seems to lower IAT between 10 - 20°c, the interchiller can get another -20° c

Meh, math and science make my head hurt

 

[Duncan]

With respect, if you can get more power our of colder intake air than the heat pump takes to drive, lots of racing classes would be doing it.

Also, while I'm feeling a bit ranty, you don't get "4kw" of heating or cooling power for 1kw input on a heatpump. You get 1kw. It's just that a radiator is only 25% efficient as a heater. Someone in marketing just decided to compare an apple to an orange

[Kinkstaah]

On 3/18/2022 at 11:36 AM, mlr said:

The IAT varies greatly dependant on the sensor location, and I cannot really see the air being "heat soaked" for the fraction of a second that the air is travelling from the CAI to intake valves of an NA engine.

In my experience, this actually does matter - The position of the IAT sensor doesn't matter with regards to the temperature when I have tested. I've tested it in the tube next to the TB, in the tube at the start. In the airbox, inside the pod filter, as well as in the manifold!

The biggest change was ducting cold air from the outside and making a sealed system. I agree - The air will not get heat soaked by the time it gets through the motor, but it will suck already hot air from the engine bay as a preference if it can, because that hot air is closest to the filter/intake.

(this is in N/A land). You can't duct your already compressed/hot air to overcome this, because well, it's hot due to the fact it is boosted. I now reguarily see air temps that are 0C hotter than outside. Went for a drive recently and my IAT's were about 12C while beating the hell out of the car. Ducting really does work. Removing the duct and letting it grab heat from the wheel well resulted in 38-40C air because oil cooler is hot, brakes are hot, and it'll grab the nearest air it can (round headlights and shit which is semi-engine bay hot)/through the rad hot.

Again not super relevent to your boosted setup 😛

[GTSBoy]

On 3/18/2022 at 11:47 AM, Duncan said:

Also, while I'm feeling a bit ranty, you don't get "4kw" of heating or cooling power for 1kw input on a heatpump. You get 1kw. It's just that a radiator is only 25% efficient as a heater. Someone in marketing just decided to compare an apple to an orange

No. Not true. The physical work put into the compressor is not converted into heat. It is converted into the transfer of heat from a cold location to a hot location. The heat comes from the environment around one of the heat exchangers and therefore violates no laws of thermodynamics. The work is sneaking the heat past what you think are the laws of thermodynamics because you're drawing your energy balance boundary too close to the heat pump.

Quote from: https://www.eec.org.au/for-energy-users/technologies-2/heat-pumps

Quote

Heat pumps can seemingly defy the laws of thermodynamics, because they can deliver much more than one unit of heat (or cooling) per unit of electrical energy consumed. This is because they are extracting heat from around the evaporator and dumping heat to the environment around the condenser. Electricity is being used to concentrate and shift heat, not to produce heat directly as in a resistive electric radiator or fan heater.

 

 

I wasn't at all suggesting that a chiller would be good for NA applications. Boosted applications are obviously even more sensitive to IAT and are also able to create more IAT so it makes sense to consider chillers for boosted applications first. I rather explicitly said that they would have to be useful at times when you are not using 100% of the engine's available power (ie do not need all the available power, owing to traction limitations, braking into corners, etc etc) and therefore they would likely be useful in more applications than people would give them credit for, because most people only think about the WOT case. They are certainly used in drag racing in the pre-WOT time, for exactly that reason. There's no reason why they could not be similarly applied in circuit or rally or some other types of racing, provided there is enough time off WOT to gain some of that power gap.

 

So, look at the math. If a car AC compressor takes about 3kW to drive, and can yield (conservatively) 4x that in cooling power, and you have air post intercooler (assuming a reasonable boosted application already) at say 50°C ....bugger it, let's say it's bad and you really need to think about a chiller, so.... 80°C, and you're making say 500 engine HP and using 350 cfm to do it. That 350 cfm is about 0.2 kg/s. Air spec heat capacity is about 1 kJ/kg.K (nice and easy). So, 12kW will decrease that air temperature by nearly 60°C. So, from 80°C to 22°C. ON A CONTINUOUS BASIS.

So, even if the car AC comp's leverage is only 3:1, you still get like ~45°C drop. And if it's better, like 5, you get really cold air.

On much more powerful engines, you would need a much bigger AC system. That's obvious. But at 500HP it already seems feasible with what's already lying around.

The real question becomes, how much more power can you make from air that is 50+°C cooler in a 500HP engine? It only needs to be >5HP to be positive, but you wouldn't consider all the weight and complexity for almost no extra power. You probably wouldn't even consider it for ~10HP. But, if it were worth say, 10% of the 500HP base, then it's probably looking attractive. And with the detonation threshold at 80°C being pretty scary, that might actually be possible. It would be even better if the system were well managed and could run the compressor more when there is spare power available and bank it in cold coolant so that you can actually use even more cooling power than the system produces naturally for short periods.

I think there's something in it and it just requires some dev work to make decisions about how big and how controlled and so on it needs to be.

[The Bogan]

For me it isn't about making more power, it is about keeping the power I have

I believe my ECM starts pulling timing from 50°c IAT and over that it pulls more pretty hard

I'm stagging at the drags with 70°c IAT, at the big end I'm at 80°c

Hence the car goes like a cut snake below "around" 50°c IAT, from 60-70°c IAT it pulls timing that hard that it is obviously noticeable from the drivers seat that the power has dropped its showbags

I don't believe a interchiller would be on any use on a circuit car, maybe, I don'tknow, and for "big" powered drag cars a reservoir is required to ensure that there is enough low temp coolant available for a full run

A Interchiller is just like an ice box, the benefit of this is you don't need to replace the ice, just idling down the return road will bring the coolant temps back down

For the street, it will always be super cold.

There are also ways to add efficiency to my 20 year old AC system by replacing and adding modern condensers, this also helps drop the intercooler coolant temp, and is relatively cheap to achieve 😀 

[The Bogan]

On 18/03/2022 at 2:56 PM, Kinkstaah said:

In my experience, this actually does matter - The position of the IAT sensor doesn't matter with regards to the temperature when I have tested. I've tested it in the tube next to the TB, in the tube at the start. In the airbox, inside the pod filter, as well as in the manifold!

The biggest change was ducting cold air from the outside and making a sealed system. I agree - The air will not get heat soaked by the time it gets through the motor, but it will suck already hot air from the engine bay as a preference if it can, because that hot air is closest to the filter/intake.

(this is in N/A land). You can't duct your already compressed/hot air to overcome this, because well, it's hot due to the fact it is boosted. I now reguarily see air temps that are 0C hotter than outside. Went for a drive recently and my IAT's were about 12C while beating the hell out of the car. Ducting really does work. Removing the duct and letting it grab heat from the wheel well resulted in 38-40C air because oil cooler is hot, brakes are hot, and it'll grab the nearest air it can (round headlights and shit which is semi-engine bay hot)/through the rad hot.

Again not super relevent to your boosted setup 😛

Cool ambient temp air is king 🥶

I would assume that my OEM, slightly modified, airbox would be getting near on ambient temps from just behind the headlight and where there is a hole in the body work for clean air and some plate blocking "most" engine bay heat, there are some improvements that I'm looking at, but it's got a pretty clean fresh air flow

The tricky thing with a top mount blower is getting an accurate IAT reading, actual IAT may be, say 40°c post the blower, but because of packaging and the resultant heat soak of the sensor, the ECM is seeing 60°c from the sensor....

Fun times 🥴

[Dose Pipe Sutututu]

You could chemically intercool the karnt, meth spray dis dat.

[The Bogan]

On 18/03/2022 at 5:26 PM, Dose Pipe Sutututu said:

You could chemically intercool the karnt, meth spray dis dat.

Cheap, but logistically troublesome with refilling and stuff, I would put in the same boat as an ice box

Possibly fine for turbo, or centrifugal front mount, but not for a top mount PD blower, shooting a mist at rotors isn't recommended

[The Bogan]

Wendsday: Drove to Goulburn to visit daughter for a few days, nice

Friday AM: Drove from Goulburn to Canberra to do some training, nice 

Friday PM: Went to Costco in Canberra for fuel for the trip back to Sydney.......cranks over fine but car wouldn't restart......pushed car away from pumps.....still wouldn't start......popped bonnet....looks good.....wobbled wires..... still won't start.....got angry....rang NRMA who I am not a member of......$560 later NRMA arrive......maybe Crank Position Sensor......called "mobile mechanic" no LS1 CPS in Canberra.....of course......NRMA tow car back to local military base to park it up and await the new day....and over night parts from Sydney...

Today: Awaiting mobile mechanic to arrive sometime today with new a CPS

Now: Hoping that it is a CPS....

SYMPTOMS 

Cranks fine

Tries to fire, but doesn't 

No tachometer signal

[Duncan]

that sucks, long walk home!

[The Bogan]

Thank god for mobile mechanics

It was a simple fix

Remove starter motor, R&R CPS

Put it back together 

Pay stupid amounts of 💰 for simple fix

Win

Sydney, here I come

Well soon.....the car spent the night under a tree where all the birds who have diarrhoea live, so it will need a trip to the wash point first

[The Bogan]

Nope

Car didn't start, the new "tridon" sensor is faulty

Mechanic went off looking for another CPS and luckily found another, different brand though, which could be good, or bad...at least it cannot get worse, knock on wood, I probably shouldn't have said that....

The funny thing is the car started before he started working on it

When the CPS sensor dies it stops working when the engine is hot, then works when it has cooled down, for a while anyway, I didn't want to risk a hwy run and possibly get caught out in the middle of nowhere when it fully dropped its showbags 

Meh, what can you do

In other news Jackie seemed a tad cranky after I told her the news this morning

Meh, life would be boring if it was rosey all the time, simple, but boring

Meanwhile 

[The Bogan]

This one works

 

[Duncan]

hell of a thing not to work out of the box. makes you wonder if it is a wiring issue in the car with an intermittent break...

[The Bogan]

On 26/03/2022 at 1:25 PM, Duncan said:

hell of a thing not to work out of the box. makes you wonder if it is a wiring issue in the car with an intermittent break...

Na, apparently the sensors are exactly the same, but, they wire the sensors differently for different makes and models

Well, that's what the googles say anyway, and it seems getting the wrong, right sensor is a common issue.

All is well now, it got back to Sydney and is all parked up.

What an epic adventure that was

[robbo_rb180]

Damn old holdens. Good its sorted and home.
Sure you could write a good book with all your adventures

 

[The Bogan]

On 26/03/2022 at 2:33 PM, robbo_rb180 said:

Damn old holdens. Good its sorted and home.
Sure you could write a good book with all your adventures

 

LOL, it's a 20 year old car, stuffs gonna break

If I did write a book you could call it "how to waste money on cars and motorcycles in 999,999 easy steps"

[MBS206]

On 3/18/2022 at 2:33 PM, GTSBoy said:

No. Not true. The physical work put into the compressor is not converted into heat. It is converted into the transfer of heat from a cold location to a hot location. The heat comes from the environment around one of the heat exchangers and therefore violates no laws of thermodynamics. The work is sneaking the heat past what you think are the laws of thermodynamics because you're drawing your energy balance boundary too close to the heat pump.

Quote from: https://www.eec.org.au/for-energy-users/technologies-2/heat-pumps

Youre confusing differences between amount of energy moved in terms of heat, and power gains here.

 

Just because youve gotten 12kw of cooling from 3kw of input, doesnt mean youre going to gain 12kw of power at the crank. And THIS is where the laws of thermodynamics will come into play.

 

The other part not directed at your comment, more other peoples logic, as everyone above is yacking about, IF the tubing in your air intake has the air go flying past and it doesnt have time to heat soak, how will it have time to cool soak...

 

 

This more goes into actual usable power gains

 

https://buildingspeed.org/2012/04/23/temperature-and-horsepower/