Intercooler question

[saurkraut]

Geez

If you say this:

“The smaller they are the less they will perform as RPM/psi goes up, you loose CFM and heat exchange capabilities, at some point you will reach heat soak and at that point all your doing is restricting your airflow and stuffing in warm air.”


How can you follow it with this"

“Anything is better than nothing.”

I would still contend that a crappy intercooler is worse than no intercooler.  Especially at higer boost.

[zukgod1]

Come on!

Just like it says, ANYTHING is better than nothing. There will be gains until it gets heat soaked.

[KTZed]

zukgod1

Dont worry im not offended or anything and I am equally appreciative of the people on this board and the civility with which discussions such as this are conducted. By the sounds of it you have far more real life experience with VW TD's than I so I can only theorize and state my own experiences.
Couple comments/questions...

That gas engine you are commenting on does not create the amount of heat our 1.6 TD's (Turbos) do and you know as to your comment.. Air flow pr engine aside the turbo the Nissan used was more efficient at the same PSI?

The turbo on the gas engine does in my example doesn't heat the air up as much because its only compressing the air to 7psi. As for the efficiencies of the 2 turbos themselves at different PR's/flowrates...who knows. We'd need the compressor maps etc. to figure that out. FWIW the turbos are similar in size the Nissan using a T28(I think) and the VW a very small T3.

The size of the IC is directly related to psi performance. The smaller they are the less they will perform as RPM/psi goes up, you loose CFM and heat exchange capabilities, at some point you will reach heat soak and at that point all your doing is restricting your airflow and stuffing in warm air.

I think this is more an application issue than anything. Your talking about 35-40psi  :shock:  In that application, you are putting a LOT of heat into the air, especially if the turbo is out of its efficiency range. If you are pushing air that hot through a small IC at high CFM and are on boost for long periods of time then yes I would definately be concerned about both heat soak and pressure drop.
My application is a daily commuter where even if I am making full boost ("only" 20psi) its for short stints with plenty of time for the IC to cool down between. And as I showed above, the stock application flowed more CFM through the IC than my engine ever will so im not concerned about pressure drop. I am also concerned about response and my goal was to have a low volume system with short pipes and a small IC to keep lag to a minimum...especially with the "big" T3. I did still notice a marked increase in lag when I installed this IC (with stock fueling...its much better now ).

As for the question of a bad IC vs. no IC...
Any IC is only detrimental if it is so restrictive that the pressure drop causes the turbo to work hard enough to the point of adding more heat than the IC can get rid of. For ex. if you want 30psi manifold pressure with no IC, the turbo only has to make 30psi. With a small IC say the turbo actually has to make 35psi to get 30psi at the manifold. If the IC cant get rid of that extra 5psi worth of heat and then some, theres no point in having it there. As for heat soak, almost any size IC can get heat soaked if you pump enough heat into it. It comes down to application again....think about what percentage of your driving time you actually spend at 20+psi of boost....unless you are racing or drive a semi it probably not very high.

[zukgod1]

I agree totally.


 

[saurkraut]

Ok, if you simply have to have an intercooler, and you don’t want to spend the money to get one that’s big enough to handle full boost, I guess it’s OK if you just cruise around.

If you don’t go there, why plan for it.

But, are you really getting a benefit from lowering an 800° F egt to 700° F?  Is there a gain in efficiency from lowering a low egt?  Is an intercooler yielding any real benefit?

On the other hand,I would suggest that some poeple do use full boost regularly (not naming names Mr. zukgod1  :wink: ), and are loosing performance when they do from having an intercooler that is too small.  They'd  be better off with no intercooler.

I go there all the time. I’m no stranger to high boost.  Every corner is the Carrousel at LeMans.   Every stop sign is a drag race.  And If I saw higher EGT, and lower boost that I could trace to an intercooler that was too small.  I take the blessed thing off, and run it over with my car.

As a matter of fact, I have a Ford Probe intercooler that is now for sale.  Actually, I haven't advertised it yet, so I may run it over with my car.  I was going to put it on my 1.5TD, but its going to get something else that can handle 20+ psi of boost and do the job right.


I guess it’s a matter of perspective.