Heat Soak - Cods Wallop

[F6 UTE]

There's some talk of the mysterous 'Heat Soak' so here goes an explanation as to why it's bollox!

So it's been a while since I did 'my' times, but here's a tid bit I don't think I ever let out which helped my times.

Heat Soak - It's a falicy.

Keep the bonnet shut, keep the heat in.

Why?

Well here goes.

The intercooler doesn't gain squat from being iced / watered down, the head doesn't care if you put ice on it. NOS on the cooler, give me $300 and you'll get the same benefit.

Why?

Coz the air passes through those pipes so quickly it not got enough time to 'soak' any heat. The air passing thru the cooler drops the cooler temp so quik it's not funny.

So why shut the bonnet?

Because you want to keep all that heat in the exhaust manifold, the hotter that is the hotter the exhaust gas, the quicker it expels out the turbo.

But why does my car go slower after each run?

Because your tuner isn't worth her salt. Period.

Why?

Because she hasn't adjusted the charge temp correction tables, which pull timing out when intake temps rise. Intake temps rise to a point where 4 degrees of timing gets pulled out after ONE dyno run. Ford play it safe, your tuner might play it safer too..

It's a safe tune, but you want a drag tune... Get the temp correction figure bumped up - your tuner will know what point this is, because she has a logger. Even I had a logger, that's how we came to find it..

Once that's done you can run all night without your mph dropping at all.

There's another table there to play with, which has more impact on the rising temps - see if your tuner adjusts that one too......................

enjoy..

[spine]

fair enough, so how many back to back runs running consistent times could you run?

[typhoon_freak]

that's very interesting.. but makes sense but.. I still reckon there cud b a lil difference in the pipes being cooler.

[F6_jase]

ummm...would you like to explain your theory on the exhaust gases getting out of the turbo quicker cause they are hotter?

[typhoon_freak]

I sopose the molecules would be more spaced apart.. but then u would have more volume then cold air cuz it is hot. hmm I dont really know jase...

[F6_jase]

I see wot you are saying about the velocity of the air going through the pipes not picking up the heat but wot about everywhere else it goes? I used to have a digi temperature guage in my engine bay for that reason, and after a bit of fast driving then coming to a set of lights the temps would rise in/around my airbox from 30 degrees to 70+ degrees and it would soak into the airbox and surrounding metals etc. wouldnt this hot air have a negative effect getting sucked into the intake?

[ETM]

  F6_jase said:

ummm...would you like to explain your theory on the exhaust gases getting out of the turbo quicker cause they are hotter?

Hotter gas has more energy to drive the turbine wheel, it also has more volume than cold gas does so therefore will spin the turbine wheel harder.

This is something that can be felt on the street too, when your turbo is glowing red hot you can feel the response improve.

[XR6T 747]

Hi there,

Great theory - till it goes bang!!!!!!!!!! Playing with correction tables to overcome extreme temps is not a great thing - just speak to Simon from Nizpro, he'll confirm that!

How many back to back 11.80 did you run in your F6 - were they on a 35 degree day also?

C'mon mate your better than that.....

Race your turbo on a 5 degree night - dead cold and then race the car on a 40 degree day back to back, I guarantee there will be a diffrence - regardless of tuner - colder being better.

I'm sure some of our QLD racers/tuners will confirm this ...all I'm saying is racing in Bahrain and racing in Melbourne during winter will have an impact on turbo vehicles.

Just my 2cents

Kind Regards...

XR6T747

[howitzer85]

your absolutly rite 747 but how does that relate to heat soak?

your talking about ambient temps, not the temps under the bonnet.

F6 is saying that the temp under the bonnet won't effect the air because its being sucked in that fast it won't get a chance to heat up.

[F6_Tornado]

I think what Ben (F6 UTE) is saying is if you probed the temp of the air In the centre of the pipe and the external temp of the pipe there would be a huge difference. That being the case due to the velocity of the air travelling through the pipe the external pipe temperature would have little to no influence on the air travelling through it in such a small time frame.

A bit like having a small intercooler!!!! The air volume does not stay within the cooler long enough for the temp to drop to a notable degree. However by utilising a larger Cooler that same volume of air will travel at a much lower velocity (through the cooler) allowing a greater period of time to allow Heat to exchange ultimately reducing the air temp.

Once it leaves the Intercooler the piping does very little by way of heat absorbing due to the velocity of the Air within it.. What little effect it did would have minimal effect hence what he is saying above.

However a large intercooler is what’s needed not cooler piping.

Makes sense to me Ben!!!