Rob

I did my own intercooler pipes many years ago.

gt37vgt

I realy like the pipes to be as nice as they can be but i challenge that 1% rule .... imagine a 3" bend compared to a 2" strait ?? there is only realy one 90 you can loose.
i still think the best solution is dummy them up in PVC (works fine for real on the cold side ) then have them made in silicone hose this way you half the number of hose clamps and realy feel clever

951_RS

Why would you compare a 3" bend to a 2" straight though... That is apples to oranges, you would compare a 3" bend to a 3" straight, or a 2" bend to a 2" straight

gt37vgt

becuase i may have 3" inlet pipes with 6 90 degree bends and you may have 2" with only 2, 45 bends but apparently the 2" set up will yeild 5% more power .
we all like to have nice strait as possible pipes I'm just saying you can't realy quantify it with any "rule a thumb" calc like that .. there are so many contributing factors .. bend type +radius flat spots etc on the tube .
i think its one of those mods that can often make a car a little more responsive in on off driving but yeild 's insignificant numbers on the dyno ..

Fluidplay

Off topic ? to Rob

Are you running a stand alone system?

951_RS

Apparently you've never read Corky Bell... As I said, you are comparing two completely different radius pipes, which does not work at all. Apples to oranges...
Nowhere did anyone every say that less bends equals more power no matter the ID of the pipes, that is just something you inserted on your own assumptions to make yourself feel better about your 6 90 degree bends in your 3" pipes.

Now compare your set up with less 90 degree bent pipes of the same diamter and you WILL see an increase in power. It's not just some arbitrary made up rule of thumb number. Corky Bell is a very famous mechanical engineer in motorsports. Try looking up the book maximum boost and reading it.

If it makes no difference then why don't we spell out 944 using our intercooler pipes for awesomeness since we'll make the same power no matter the radius of the bends as long as they are 3"

Rogue_Ant

Made me get out the nearly destroyed version of C. Bell's book... had it for too long, I really should pick up another copy.
Pg. 62.

Ok, two things. Firstly, this is a simple estimate, and there must be the fact of diminishing returns. I.E. if I have twenty-five 90degree bends, one single bend is not going to equal the same flow loss as if I have only five 90degree bends.

And secondly, more importantly. He states flow, not HP. If the stock piping can already flow more air then the throttlebody and intake manifold and head, then there wouldn't be much to gain by making the piping flow even more.

Finally, Corky Bell is a great reference. But, by no means the end-all authority on all things turbo.



-Rogue

gt37vgt

my only point was there is a bit more to it simply trying to knock out bends ...I read Corkys books about 12 years ago ..
So after several years working in wind tunnels and 30,000 barrel a day oil field infrastructure i still "apparently " can't imagine the physics behind a gas in a bend ..

951_RS

I think you both need to relax some... Nowhere did I say it was the word of god. It's an estimate, it goes to show that it is indeed worth straightening pipes if possible. I don't need to work with wind tunnels to understand the benefit of less bends in my intake piping... Maybe it's just me but ego does not equal knowledge.
Many people spend a crapload more money than that getting less power. On top of that having an open filter with metal piping instead of plastic is one of the worst things you can do for your intake once heat soak is considered, but that's another thread all together.

toddk911

Nice! I love data and especially from Mr. Bell.

One piece of his data that always stuck with me was "for every 15 degree drop in intake temps, you can safely run 1 additional psi of boost".

So I have always tried to get as much colder air into the intake as possible. And in the cold months when we get some boost creep it is safe because the increaed boost is offest by being much colder air in the intake.

Interesting though is Corkey is NOT a proponent of water injection, which is ALL about colder/dense air intake....

toddk911

I have used PVC also and on the hot side it is an issue as at the heat on the clamp gradually distorts the end of the pipe and thus leaks, etc.

But the cold side would probably be ok.

Actually, the hot side might work if you used some metal/SS adapters (2.5-3") on the ends at the hoses and then there would not be any distorting at the hose clamp ends.

But like I posted earlier, if you rotate the hose from the turbo counter clockwise, the end will line up with the IC inlet and a simple piece of straight pipe/exhaust pipe can be used.

Who makes custom silcone hoses?

I would have some concerns about the flexing of the hose if you used silicone as the IC "pipe" itself as boost lines should always hard lines or the could be flucuations in the boost pressure itself.

Mike Lindsey

Don't want to spoil all the fun and ideas, but your overlooking one important factor.
We thought we would save some of you the misfortune of finding out the hard way.

Several years ago we tested the intake temp drop between the turbo and the intercooler.
It was about 50F if memory is correct. That's huge! It was very surprising, and at the same time disappointing, because we had some ideas for product there but the fact that the pipe was doing such a good job already, we couldn't improve upon it as much as we thought before we realized the temp drop that was already occurring.

You would have additional cooling on the second pipe on the outlet of the intercooler, but not as drastic a temp drop because the temp differential would not be a high after the other cooling from the first pipe and intercooler had done their job already.

That was a aluminum pipe. Yes, read Aluminum. Very efficient transfer of heat material. If you build a hard pipe out of a material that does not efficiently transfer heat such as Stainless Steel or Silicone, your working backwards in what your seeking. Horsepower. Small gains from enlarging pipe size and straightening bends will no doubt be lost from higher inlet temps created. Stay aluminum or your being counter productive. The more aluminum surface the better and the less connector hose
the better.



On the car in this picture, we had 6 digital intercooler temp probes in the intake between the turbo and the valve. We tested stock pipes as well as what you see in the picture in various configurations. Looking at before and after performance data. These were very accurate aircraft instrumentation gauges. You can see some of the white lines which are sensor wires.

gt37vgt

fingers in ears LALALALALALALALA I'm not listening I'm not listening ..

. a bit soul shattering if you have put a fancy inter cooler in to find a significant amount of heat is just going out through a pipe .
i still like the idea water filled inter coolers and using the original unit to cool the water ...
a kg of water has more thermal mas then a kg of aluminum and is much cheaper ..
and i really like Julian edgers findings on paraffin filled coolers ....
have you guys herd of Julian Edger?? He can take Corky to school...

Mike did you do much data with how much water was displaced and heat transfered etc ..
there has been plenty of data proves much of the heat is simply put back into the lower pressure charge air in a street driving scenario...

67King

Corky Bell is a great reference. For high schoolers. If you want to go be an engineer about things, read CHarles Taylor. Even better, read a fluids text book. You want as few changes in diameter as possible.* You have losses increasing diameter, as well as decreasing diameter. You want any transition to a greater size to use a 7 degree draft (of 15 degrees counting both sides). You want your pipes to all be mandrel bent, not crush bent, and the radius of curvature needs to be 2X the ID of the pipe. I don't give a rip how big your pipe is, the air will fill the space, and if your bend is too tight, you WILL have separation. So honestly, without looking at things under the hood, I would be inclined to say a 2" pipe with 4" radius turns will flow much much better than a 3" pipe that has to cram a bend in with a 2" radius turn. Besides, when you get to the throttle body, you are probably going to get smaller again, anyway.

Having said all of that, your package space is always a huge limiting factor. From looking at it, the stock setup is quite nice. Without numbers to back it up, I think most aftermarket setups serve more of an aesthetic purpose than a functional one, unless you do something like change to a MAF, and can eliminate some of the tortuous nature of the bends.

* to an extent. Just like wiring, your internal resistence IS a function of length - to run longer distances, the change in diameter may be offset by the savings over distance. That relationship depends on your transition, and your total length.

gt37vgt

water filled inter coolers are very underrated i think ..It takes almost 4 times as much energy to raise a KG of water 1 deg than kg of aluminum .. and in an inter cooler system this thermal mas is very helpful ..
here is some very unconventional and interesting inter cooler experiments that realy make those Lindsey cool tubes look ok again.. fill them with wax ... don't bother with the pump etc ..
http://autospeed.com.au/cms/A_110772/article.html