What is the best intercooler up-grade?

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04-14-2011, 05:38 PM

#91

DanaT

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Quote:

Originally Posted by sh944

Two points, Dana...

#1, your average street driven 951 isn't going to be driven hard enough for long enough to get to the point that intercooler becomes a huge factor, imo. .

But couldn't the same be said for a Cayenne so did the factory increase boost AND add different intercoolers? My theory is it may be somewhat about flow and not just size.

Quote:

Originally Posted by sh944

#2, in the instances where the intercooler does become a limiting factor, its my belief that the stock unit needs to be replaced with a different design, rather than being modified. Others disagree with that statement, hence some of the discussions. I might point out that the pictures of the F1 intercoolers posted in this thread show an even more extreme "reduction" than the stock 951 intercooler does, but no one has made mention of how "dumb" the F1 engineers are (and thats meant as a generic statement, not a flame towards anyone).

To your question about why wouldn't a 951 require more intercooler for 20% more power, that would assume that the stock unit as designed is already at 100% max capacity. If that were the case, wouldn't you expect that swapping out the intercooler with no other mods should show an increase in power? I am unaware of anyone ever successfully (and conclusively) demonstrating this. You don't need to increase the throttle body size by 20% to get a 20% increase in power, because it already flows more than enough air to support it. Same thing applies here.

But increasing boost and adding intercooler help. With Cayenne as an example, just putting on different intercoolers didnt make the power, it was increasing boost and increasing HP. Of course I wonder if the Cayenne needs different intercoolers or if its just they think someone may drive fast for sustained speeds and therefor may need the intercoolers. Or maybe the intercoolers have improved internal flow for the S?

I am not understanding yoru reduction comment? Are you talking about the size of the tanks and the tanks being very near the core? If that is the case, just looking at the inlet diameter and the size of the tanks, I would assume that the size and shape of the tanks was balanced with maximum airflow.

I would think huge tanks could hurt performance because of a large area of most stagnant air. The entire mass of air in the intake system must be accelerated before boost happens. The more mass inside there, the more air required to get moving.

Back to the original thread, I would think the 951 intercooler suffers more from the long tubes than the end tanks. My understanding of intercoolers is that if the 951 had the same size core (width depth length) but flowed in the top to bottom (or bottom to top) direction instead of the side to side direction it would be much better without increasing size.

-Dana

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04-14-2011, 06:07 PM

#92

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I think I agree with everything you just said.

First, how many Cayennes have even driven off asphalt, let alone come close to using even a fraction of its capabilities? The Cayenne the perfect example of "over-engineering" if one exists. Even so, it is a 500hp beast and I would imagine the flow requirements required some thought by Porsche, which they do fairly well, imo. Since I am not intimately familiar with Cayenne's, thats about all I'd offer to say on it.

Your comments on the F1 intercooler about balancing the size and shape with the airflow and on the huge tanks are dead on, imo, as well as your comment on the direction of flow on the stock 951 unit. Hence, I believe it is better to replace rather than modify the stock unit if you need more.

Besides, you are a Hayabusa guy, so you go for extreme performance without regard for reason anyway, right?

The *only* reason I chose to get involved with this thread in the first place is that it seems to be an accepted "fact" by a good number of folks that modding the end tank on a stock intercooler is an improvement, and I believe someone needed to speak up to stop that from being propagated as "fact".