Intacoola speculation

[linuxman51]

So whilst brainstorming various IC options I have come across something I dunno the answer to.. Is it better to have smaller IC pipes or larger ones (for instance, the oulet on the turbo for most of us is considerably smaller than the inside diameter of the intercooler). Would there be an advantage to having smaller diameter plumbing? Or perhaps a better question is would there be a significant disadvantage to it? Starion I/Cs have tiny inlets and outlets compared to ours...

Speculation on my part. Ideas? :)

[Bishop]

Some cars used small pipes to reduce lag, really huge IC pipes are good on high psi turbo cars, but a pain on cars with lower boost.
Small IC pipes with intercoolers with very small volume end tanks makes for quick boost.

[Anonymous]

The exit of the compressor is smaller then the entrance of the intercooler, so the air will move slower inside the intercooler, so there is more time for it to cool.

The turbocharger can move so much air, that I don't think that a setup with bigger hoses will have more lag.

[ICE RCKT]

I'd brought this up a while ago... with reference to the Saab turbo's... the 9000 Aeros have much smaller diameter piping, larger compressors and make more power than we do. I realise there's more to a system than one individual part, but no one gave an answer worth more than :???: . would it make sense to keep the transitions as brief as possible, and maintain the diameter from the compressor outlet until the inlet to the intercooler... and the diameter of the intercooler outlet to the throttle body...
Food for thought...

[TRBO242]

Yeah, this topic of IC pipes came up in this post, check it:
http://forums.turbobricks.com/viewtopic.php?t=6577

I'm actually going today to get IC pipes form pick-n-pull. I understand that smaller ones on the turbo side are better, and then larger on the intake side. right? :e-shrug:

nick

I have been told small in, bigger out, by a few experts over the years. I am not enough of an engineer to explain exactly why this could be beneficial. On the other hand, Corky Bell does not mention this in either of his books, although he does discuss intercoolers and plumbing at length. I would not use significantly larger piping unless you are making double stock intercooled power or more. Something like 2.25 OD in and 2.5 OD out should be more than sufficient, but for the power levels of most of the people who use this forum, I there is any noticeable power difference between those sizes and the slightly smaller stock sizes.

In other words, this is not the secret that has been keeping everyone from making 300 hp at 15 psi.

[linuxman51]

no no, thats not what this was in speculation too :) I'm looking at a bunch of different intercoolers big and small (for various ideas floating around in my head) and ones like the eclipse side mount have significantly smaller inlets (As do starion intercoolers, and they're fairly well respected in the industry... altho thats not realy what I was looking at). I was wondering if the smaller inlet outlet would be a big problem or not.. I suppose one could always have bigger inlets and outlets welded on :)

[boostdemon]

technically the compressor to IC pipe only needs to be as large as the compressor tube ID. which is pretty small

now the IC to TB pipe needs to be fairly large in order to move the air out of the IC fairly easily w/o causing a pressure drop... however that has a lot to do with the design of the IC/end tank and the position of the outlet

[1 riktig svensk]

....just piggybacking off of what Philip said; it needs to be smaller on the IC in side, like a 2.25", and larger as it exits out of the IC, like a 2.5" or something alike. If it is the other way around, too much pressure will build up in the IC, and you wont see the power you were hoping for.....it'll be somewhat of a domino effect.....pressure rises, temperature rises, IC efficiency decreases, yada yada yada......and soforth......if you are planning on high levels of boost, you could look into stepping up a 1/4".....from a 2.25" to a 2.5", and from a 2.5" to 2.75".......

[the kick inside]

hmm, having been 'playing' with learning about exhaust design and learned quite a bit I really dont think its that simple....

Basically bigger pipe allows better airflow...and itsa a square thing...

but....where the pipe gets bigger is critical too...basically as it gets bigger you get low presure that 'sucks' the air following it... smaller pipe means higher velocity for the same flow - so more loading on the driving device (turbo) to maintain the same loading...but then again we know our turbo's can give far more boost than we need...

also as a pipe expands the air looses heat...so thats good going into the intercooler, but not so good when the presure is high as this gains heat...

smaller pipe will build presure faster, but flow less well (reducing lag, but sacrificing top end flow?) bigger pipe will take longer to presure up, but flow better...

I suspect that the biggest problem is actually the intercooler - it presents a restriction....

how about this for an idea ... a bypass pipe for the IC that flows at low presure, but that auto shuts out for high presure when the air charge picks up heat from compression & boost...just a thought...

I think a degree in physics, a computer, some fancy software and a lot of testing are called for!

[TurboBrick940]

In other words, this is not the secret that has been keeping everyone from making 300 hp at 15 psi.

Dammit and I thought all that I needed was to change my muffler bearings