146 replies to this topic

[VXT Tim]

This will crack you up. In the 8 + years I've had my car the cigarette lighter has never worked and I don't know/can't fix it

[VXT Tim]

Also I would definitely need a fast and furious style button on the steering wheel. Deploy cool water - head pushed back into seat

[techieboy]

Assuming the fuse in the boot is okay, is probably just the fact it's sh!t and lots of adapters don't seem to make proper contact for more than a millisecond before cutting off again.

[Zoobeef]

VXT Tim, on 18 Jun 2013 - 3:25 PM, said:

Also I would definitely need a fast and furious style button on the steering wheel. Deploy cool water - head pushed back into seat

I have those in the noble. They are horns fast as fcuk horns

[techieboy]

Sorry no can do with the steering wheel. I can do it in a flip-up top gearknob though, if you want?

[Zoobeef]

techieboy, on 18 Jun 2013 - 3:28 PM, said:

Sorry no can do with the steering wheel. I can do it in a flip-up top gearknob though, if you want?

Ooooooo go baby go

[VXT Tim]

Perfect

[NDT]

Ben_mk, on 17 Jun 2013 - 9:56 PM, said:

Question .. My friends evo has a mist kit that sprays water directly on the intercooler .. Would this make any difference to the cooling temp if fitted with a standard vx intercooler ?

 

It should do.

 

Water's latent heat of vaporisation is 2260kJ/Kg (thanks wikipedia as I'm in a hotel room in Germany and don't have any old engineering data books with me....)

 

So assuming that 50% [total and utter guess - reality is probably better than this?] of the water gets evaporated rather than simply dripping off, that gives you 1130kJ/Kg.

 

According to Winstar's earlier post, you need to reject 17.6kW to take enough air for 300bhp down from 110'C to 40'C.

So assuming our normal intercooler has got us to say 70'C [total guess, as above] rejecting 10.1kW, we need to reject another 7.5kW to get to 40'C.

 

If you had 10kg of water, using my massive assumption above, that would give you the ability to absorb 11,300kW.

Or 1,507 seconds of running at 300bhp.

That's 25 minutes.

 

Now someone tell me where my maths / assumptions are f**ked up before we all claim water sprays are the new chargecoolers....

[NDT]

NDT, on 18 Jun 2013 - 8:47 PM, said:

 

Ben_mk, on 17 Jun 2013 - 9:56 PM, said:

Question .. My friends evo has a mist kit that sprays water directly on the intercooler .. Would this make any difference to the cooling temp if fitted with a standard vx intercooler ?

 

It should do.

 

Water's latent heat of vaporisation is 2260kJ/Kg (thanks wikipedia as I'm in a hotel room in Germany and don't have any old engineering data books with me....)

 

So assuming that 50% [total and utter guess - reality is probably better than this?] of the water gets evaporated rather than simply dripping off, that gives you 1130kJ/Kg.

 

According to Winstar's earlier post, you need to reject 17.6kW to take enough air for 300bhp down from 110'C to 40'C.

So assuming our normal intercooler has got us to say 70'C [total guess, as above] rejecting 10.1kW, we need to reject another 7.5kW to get to 40'C.

 

If you had 10kg of water, using my massive assumption above, that would give you the ability to absorb 11,300kW.

Or 1,507 seconds of running at 300bhp.

That's 25 minutes.

 

Now someone tell me where my maths / assumptions are f**ked up before we all claim water sprays are the new chargecoolers....

 

 

And of course this ignores that some the water's temperature will be raised, absorbing more energy,

 

Water's specific heat is 4.187kJ/kgK.

So let's again assume that only half of the water does anything.

 

Let's assume the water is sitting in the boot at about 30'C. Say it gets to 50'C on average before evaporating (action of airflow etc).

So that's a further potential heat absorbtion of 837kW.

So we can turn the flow down on the water and make it last another 111 seconds.

[NDT]

NDT, on 18 Jun 2013 - 8:55 PM, said:

 

NDT, on 18 Jun 2013 - 8:47 PM, said:

 

Ben_mk, on 17 Jun 2013 - 9:56 PM, said:

Question .. My friends evo has a mist kit that sprays water directly on the intercooler .. Would this make any difference to the cooling temp if fitted with a standard vx intercooler ?

 

It should do.

 

Water's latent heat of vaporisation is 2260kJ/Kg (thanks wikipedia as I'm in a hotel room in Germany and don't have any old engineering data books with me....)

 

So assuming that 50% [total and utter guess - reality is probably better than this?] of the water gets evaporated rather than simply dripping off, that gives you 1130kJ/Kg.

 

According to Winstar's earlier post, you need to reject 17.6kW to take enough air for 300bhp down from 110'C to 40'C.

So assuming our normal intercooler has got us to say 70'C [total guess, as above] rejecting 10.1kW, we need to reject another 7.5kW to get to 40'C.

 

If you had 10kg of water, using my massive assumption above, that would give you the ability to absorb 11,300kW.

Or 1,507 seconds of running at 300bhp.

That's 25 minutes.

 

Now someone tell me where my maths / assumptions are f**ked up before we all claim water sprays are the new chargecoolers....

 

 

And of course this ignores that some the water's temperature will be raised, absorbing more energy,

 

Water's specific heat is 4.187kJ/kgK.

So let's again assume that only half of the water does anything.

 

Let's assume the water is sitting in the boot at about 30'C. Say it gets to 50'C on average before evaporating (action of airflow etc).

So that's a further potential heat absorbtion of 837kW.

So we can turn the flow down on the water and make it last another 111 seconds.

 

 

Which also goes to show that the temperature of the water is pretty insignificant. The evaporation effect is far greater.

Hence there being a reason that some Evos and Imprezas were fitted with water sprays as standard in the Japanese market.

[Ben_mk]

My brain hurts lol... My scooby was an import it had not mist kit lol Was running 380bhp

[NDT]

Ben_mk, on 18 Jun 2013 - 9:07 PM, said:

My brain hurts lol... My scooby was an import it had not mist kit lol Was running 380bhp

they didn't all have them but some certainly did. Type R's IIRC

 

Anyway, brain hurts WTF? this is basic GCSE physics, let alone engineering!!!

[Ben_mk]

Urmmm I don't have a national diploma in electrical and mechanical engineering (rolling eyes) :-)

[FLD]

I may be way off but the assumptions rely on an instant heat transfer.  The water will need to be on the IC for a while to absorb the heat.  There will be some maths about rate of heat transfer / heat gradient etc.  Beyond me!  I just know it takes time to get rid of the heat.

[Zoobeef]

Imagine waving a hot pan round in the air and another in water. The one in water will cool a lot faster! If that was what you were wondering :/

[hairy]

heat transfer to liquid >> heat transfer to gas

 

however, air is freely available but water can only be pumped around the loop (for air cooling)

Edited by hairy, 20 June 2013 - 09:33 PM.

[NDT]

FLD, on 20 Jun 2013 - 11:26 AM, said:

I may be way off but the assumptions rely on an instant heat transfer.  The water will need to be on the IC for a while to absorb the heat.  There will be some maths about rate of heat transfer / heat gradient etc.  Beyond me!  I just know it takes time to get rid of the heat.

Sort of.

I assumed above that half of the water just falls off without absorbing any heat and that the other half is around for long enough to absorb heat.

No idea whether that assumptions realistic or not.

[NDT]

hairy, on 20 Jun 2013 - 9:31 PM, said:

heat transfer to liquid >> heat transfer to gas

 

however, air is freely available but water can only be pumped around the loop (for air cooling)

Or squirted onto an intercooler...

[NDT]

Anyone know the total mass of a typical chargecooler, rad, hoses, pumps, header tank?

Not insignificant I would guess.

[siztenboots]

why not squirt water/alcohol atomised, in to the inside of the intercooler and use all the surface area to cool the charge, and reject heat via the fins to the ambient air, rather than try and cool ambient air first.