heat affect on.........

[Nickm]

Hi John,

I'm sure that the actual rpm is measured from the crank, but that wasn't what I said!!!! I said that the ECU decides the revs from the engine load. These are probably displayed on the rev counter via the crank pick-up.

Nick

[Simon]

Andiroo,

with the diverter valve air is actually dumped back into the intake side of the turbo so is compressed again, this then gives the possibility that it is hotter than the ambient temp of external air being drawn in through the intake system.

Clive - no my car is not chipped - sorry I should have thought before I posted!

Simon

[Andiroo]

Yeah, good point Simon, probably will have an effect on temp - do you think it would be significant?

Andiroo

[runrowsam]

I would have thought that'd be a big difference, as it's pre-compressed air going through, so basically it's already at the stupidly high temperatures that it comes out the other side of the turbo at. But then that air's only going through for a short period of time. Even so, it probably brings the average inlet temperature up by a fair few degrees and heat up the intercoolers and all that jazz. Hmmmm, there must be a way to re-route it. Hmmmmm plan [img]images/graemlins/idea.gif[/img]

Rock on
Sam [img]images/graemlins/thumbs.gif[/img]

[Simon]

thinking about it logically air is only being diverted during gear changes - ie not for very long and not very often (in normal driving) so although it *will* have an effect I would think it would only be a tiny one.

Simon

[Simon]

having had a look at the piping between the intercoolers/throttleb body and the turbo and the relation of this to the diverter valve, all the diverter valve seems to be doing is releasing back pressure into the intake system - This presumably is to prevent the turbos from being stalled - so the amounts of air are smaller than I first thought so the temp effects even more negligable???

Simon

[PhilT]

I would agree. The DV(s) will have little to no effect.

[Paul-RS]

Clive...

I was Revo'd in the Red S3, and even running high boost i never saw temp (dash dial) above 90 degrees...

if you mean measuring with vagcom, for a more accurate reading, then i cant say.. not got vagcom/laptop.


often wondered if FMIC caused lack of airflow to rad, because it will also heat UP what air was going over the rad to cool it ...

Didnt WAK also fit an Oil cooler in the standard IC mount postion to help control oil temp too..

was this to help combat side effect of running a FMIC?

[Greg_S]

In a book i was reading recently they talk about different kind's of dyno's and recomened using eddy current dynos because you get better airflow with these. anyone got knowledge on them?

[Paul-RS]

eddy current is an electrical term.

shouldnt matter the type of dyno.

it has to be down to the cooling and flow properties of the cooling fans

[ChrisG]

a black surface gives off heat at a much faster rate than silver , so shouldn't the intercoolers have a light coating of black paint to help. I'm sorry I cannot remember how much better the heat dissipation is but it is significant ( my knowledge goes back to my VW aircooled days when barrels and heads were painted black , not by the factory, to help )
Rads are usually black !!
Andiroo 18 degrees is a substantial drop......let us know if it is achieved

[JohnW]

The important bit is it has to be MATT black, not gloss black.

Matt has a rougher surface texture, so greater surface area.
This is why all heatsinks on electronic equipment used to be Matt Black (now they get anodised when they can be seen purely for aesthetic reasons, but are increased in size to compensate).

There are a set of standard heat transfer values in still air and forced air for the different finishes, and matt black is nearly twice as conductive as polished alloy.

If I can find them I'll post them.

Cheers,
John.

[TimJMS]

Surely JohnW, that the best way of losing heat from an intercooler isnt to paint the surface with anything? (as long as the original surface is rust resistant, of course)If you start closing up the spaces between those vanes you are going to reduce airflow between and dramatically lose cooling efficiency. [img]images/graemlins/confused.gif[/img]

Radiation losses are surely insignificant when we are talking about a device which relies so heavily on a through - flow of air ... hence the gains to be made on an RS for example just by removing the fog light arrangement!

Cheers

[JohnW]

matt black etched/anodised coating are surface treatments microns thick. It is not like a layer of paint.

I agree with what you are saying about unrestricted flow of air, but if it were anodised/plated matt black it would give up more heat.

It is a tradeoff between unrestricted airflow and maximum surface area. Most radiators are sized to allow a given optimum airflow rate. To increase cooling you need to increase its size, as forcing air through it at a higher rate gives deminishing returns.

The only otherway to make things more efficient is to create a greater delta temperature.

I think the initial point was that these could be improved if they were black, but that's not to say the fogs etc should still be left in place [img]images/graemlins/wink.gif[/img]

[bem_ho]

AmD have got the Aquamist Water Injection running on my car now, pick her up Friday - let's see if there is a difference when she's logged against another modified car - hoping for an inlet temp drop of 18C on full chat.

Andy, what's your verdict with the aquamist for the RS4??