[Mk2 Turbo] How much power....

[craig]

Is the stock Rev 2 intercooler good for? And when should it be uprated?

Cheers.

[Pitcher]

i would say it depends what you want from it, i have stock and for normal driving it is fine, it also see me 300bhp on the rollers...

[Fonzy]

Hi Red.

The cooler is the least of the troubles, its the super hot air created by a crap turbo that asks to much of it, if you are asking about a stock cooler with stock ct26 then 280-300 on a rev2 imho. If its a hybrid all that changes.

[craig]

Thanks for the replies guys, it's the stock intercooler coupled with a Greddy TD05 turbo.

cheers.

[JekylandHyde]

IMO, an intercooler upgrade should be an early modification.

There are too many benefits and no negatives:
1. Increased cooling
2. Increased air flow
3. LEss pressure drop so the turbo does not have to work as hard to maintain the same psi.

[Bender Unit]

3. LEss pressure drop so the turbo does not have to work as hard to maintain the same psi.

Thing is does a low pressure drop mean a good intercooler or actually a lack of ability to cool the charge?

My science is pretty basic but I though that if you took a gas under pressure and cooled it the pressure would drop? So if an IC has a big pressure drop then surley is cooling the charge properly compared to an IC that has a low pressure drop?

Never been able to work out the pressure drop statement?

Cheers

James

[JekylandHyde]

If the intercooler is truly an "upgrade" it will cool and flow efficiently.

In an ideal world, you could put 20 psi into and intercooler and get 20 psi out of it at a lower temp. Of course that doesn't happen.

But I will take 20 psi going in and 18 coming out over
23 psi going in and 18 coming out. If the IC is flowing more air efficiently, it does not have to cool as much since you do not need to throw a higher psi air at it to get the same end result (psi).

Hope that makes sense.

[Bender Unit]

Hope that makes sense.

Not really Its claimed that IC's with high pressure drops are bad, which goes against logic.

Any air from a turbo will be hot as pressurised air creates heat. It hits the IC and is cooled, resulting in a pressure drop (ignoring flow for the time being).

Based on that you can assume the greater the drop the greater the charge cooling. If the charge cooling is greater you can possibly get away with running more boost?

Fine if you need to ram 25 psi through an Ic just to get 18psi then thats an issue.

But if you had 2 IC's pumped 20psi into each and got 19psi out of one and 15psi out of the other then surely the one with the greater pressure drop was better at cooling?

Is pressure drop a measure of cooling ability or of flow ability?

Its just a see people stating Pressure Drop and I just dont know where the logic comes from as it dosnt make sense IMHO - unless the term has been twisted and sqewed though keyboard tuners?

Working on the pressure drop theory if you passed 25psi through an IC that was being heated with an electrical element then you could actually increase the pressure.

I know if I have a cold N20 bottle the pressure is around 600psi. If I heat that bottle its rises. If I cool it the pressure falls. Thats logical. I just cant see how a high pressure drop (as long as not being flow related) can be a negative?

Sorry been meaning to ask this one for ages ....

Cheers

James

[aaronjb]

I was going to say that I figured it was simply that the pressure drop due to temperature change was very small (<1psi) compared to the pressure drop due to the cooler impeding the flow..

However, I just worked out that a fixed volume of air at 20psi @ 75degC would be 18psi @ 50degC, which is a fairly big drop for a fairly small temperature change..

So I suspect my maths is flawed - I guess because the volume of the gas isn't fixed, because the turbo is always trying to output enough air to refill the volume..

Er.. if that makes sense.

Anyway, in short, I have no idea, and I'll be shutting up now

[JekylandHyde]

I *think* you are getting cofused because it seems like you are considering only a fixed quantity of air (which doesn't consider flow).

Sure, if you decrease the pressure of a fixed quantity of air you have most likely lowered temps, but what about a changing quantity of air?

(completely made up numbers folow!)
Let's say the OEM IC flows 500 CFM and pressures drop from 23 psi to get to 18 psi at the manifold.
Now, let's say aftermarket intercooler X flows 800 CFM and pressures drop from 20 psi to get to 18 psi at the manifold.

To get a full picture of the equation, we would need both the pressure drop and the intake temps.

I "know" my huge trunk-mounted IC is cooling better and flowing more air. I honestly do not know if I have more or less pressure drop for sure, but I would be surprised if there was not a decrease in the pressure drop.

But if you had 2 IC's pumped 20psi into each and got 19psi out of one and 15psi out of the other then surely the one with the greater pressure drop was better at cooling?

If they are flowing the same CFM.

Is pressure drop a measure of cooling ability or of flow ability?

Both

I just cant see how a high pressure drop (as long as not being flow related) can be a negative?

That's just it. The OEM IC has a higher pressure because it does have poor flow.

I just cant see how a high pressure drop (as long as not being flow related) can be a negative?

That's just it. The OEM IC has a higher pressure because it does have poor flow.

[Rory]

i would say it depends what you want from it, i have stock and for normal driving it is fine, it also see me 300bhp on the rollers...

Ahh but do you have any evidence that your car is running safely when your boost spikes and you hit 300bhp?

Rory

[jimGTS]

i would say that this should be your first mod fella........

[luthor1]

don't consider CFM, or pressure or flow, just consider molecules of air for a second.

Oxygen.

We get oxygen 1 molecule at a time all around us. if I want 10,000 molecules at 100 degrees that could be almost any volume or any pressure.

If I want 10,000 molecules at 100 degrees in a 10litre intercooler, then it is a specific pressure. If I reduce the temperature I reduce the pressure (20psi to 18psi), but I STILL have 10,000 molecules, so will *still* make exactly the same power.

Does that make any more sense??

[cantfindausername]

This one makes more sense to me. Can see James' logic thinking though.

Good thread this!

[JekylandHyde]

don't consider CFM, or pressure or flow, just consider molecules of air for a second.
.... If I want 10,000 molecules at 100 degrees in a 10litre intercooler, then it is a specific pressure. If I reduce the temperature I reduce the pressure (20psi to 18psi), but I STILL have 10,000 molecules, so will *still* make exactly the same power.
Does that make any more sense??

That doesn't make any sense to me.
Your first line makes everything else pointless.
We are not talking about a set system of only 10,000 molecules.
We are talking about a dynamic system that needs to consider CFM.
As the engine is running, especially at boost, it it constantly filling the intercooler and passing air throughit.

What you are proposing is like trying to measure the efficiency of a pait of doors in a shopping center but you only want to measure ONE person going through them. It doesn't matter if you have 2 doors or 20 doors, that ONE person will most likely get through just as easy .... now, let's consider 10,000 people trying to leave the store at the same time ...