How big is too big? IC piping

[always_broken]

I understand it varies with setup. But is 3" ic piping too large?

 

[Jagyr_97gsx]

Of course as with any part of the air system, running as big as you can with the least restriction will see you the best hp gains. 3" would be great as long as you can shoehorn it into your engine bay. I'm planning to run 2.5" on my front mount this winter when I get around too it, 3" will be more expensive for clamps, and hoses too. Plus unless you plan to have a LOT of HP, a smaller set-up should work just fine.

 

[always_broken]

I fabricated a larger hole under the air filter so I can work it in. Thanks bro.

 

[Splitpi]

Trade of a larger system is more turbo lag on the same size turbo versus differing size tubing. The reason is the turbo will take longer to "fill" the tubing to the same psi. However, this is usually unnoticed due to a larger turbo being added along with the larger tubing. Note though I am talking about a few ms of lag.... unless of course your going with something insane like 5" piping.

What the optimum tubing size per turbo is however, I don't really know. My guess is slightly larger than the turbo outlet size.

 

[DSMunknown]

I understand it varies with setup. But is 3" ic piping too large?

Look at that... you answered your own question.

 

[wret]

Trade of a larger system is more turbo lag on the same size turbo versus differing size tubing. The reason is the turbo will take longer to "fill" the tubing to the same psi.

This would seem to be intuitive but if you do the numbers, the time necessary to fill the larger volume is negligible. For example, if you compare the volume of 6 feet of 2.25” pipe to 6 feet of 3 inch pipe you’ll find there’s only about 1/10th of a cubic foot difference. Do you know how long it takes even a small turbo to fill 1/10th of a cubic foot?

 

[slipstream808]

Biggest notice would be the pressure drop from the TB to the intake as you step on it. But again... who cares??

 

[Lunch_Box]

I understand it varies with setup. But is 3" ic piping too large?

What size of turbo are you running? What is the size of the outlet on your intercooler? What size of throttle bodya re you running?

 

[2gGSX]

What people are getting at is that no matter how big your intercooler piping is, your TB, intake manifold and head will only flow so much and thus it comes to a point where your piping is no longer your restriction. Going any bigger at this point would not really help you.

 

[Splitpi]

This would seem to be intuitive but if you do the numbers, the time necessary to fill the larger volume is negligible. For example, if you compare the volume of 6 feet of 2.25" pipe to 6 feet of 3 inch pipe you'll find there's only about 1/10th of a cubic foot difference. Do you know how long it takes even a small turbo to fill 1/10th of a cubic foot?

As I said a millisecond (ms) or so of lag. Vol of 6' of 2.25" pipe = 0.166 cuft. Vol of 6' of 3" pipe = 0.295 cuft. Meaning the 3" pipe is 177.8% larger in volumn that the 2.25" pipe. The reason is because the radius is squared so the volumn grows exponentially as the radius increases. v=pi*r^2*h also bare in mind that 2.25" pipe is the inner diameter and so must be divided in half and changed from inch's to feet inorder to calculate cu.ft.

But that is neither here nor there... as you said and I said previously it will be negligable on a larger turbo, but could noticibly increase lag on a smaller turbo with a low CFM... ahm.. T25.... ahm...

One final point just for sanity sake... Say a T25 has I belive 440 CFM (cu.ft. per min) flow it would take ~40.2 ms to fill a 6' by 3" pipe or ~22.6 ms to fill a 6' by 2.25" pipe. Time (in minutes) = volume (cu.ft.)/CFM (cu.ft. per min) or if you had a turbo that flowed 650 CFM, it would take ~27.2 ms to fill a 6' by 3" pipe or 15.3 ms to fill a 6' by 2.25" pipe. So as you can see while the 177% longer time remains the same as the volumn difference, the actual amount of time is significantly less and not noticible on the larger turbo versus smaller turbo with all other aspects the same.

One final note while it may seem that it is ideal to just go smaller to decrease lag, there is a trade off where you cannot flow enough air through the smaller pipes to feed the engine to meet your power needs and thus doing more harm than good. So its a trade off of good versus bad to find the ideal size for the setup.

 

[J-VilleDivision]

So if I am running a Master Power T4 (70 A/R Compressor 68 A/R Exhaust side) I would want to run 3" piping?

 

[eboy0]

I'm running the stock t-25 @ 16 psi with one of those ebay FMIC(28x9x7* i think) with 2.5" tubing and it seems to be sufficient.
Though takes a bit of time to "kick in" since i've got a little too much tubing coming from the hot side.

 

[Fitz7099]

So if I am running a Master Power T4 (70 A/R Compressor 68 A/R Exhaust side) I would want to run 3" piping?

That should be enough. You could bump it up to 3.25".

What size is your FMIC?

 

[J-VilleDivision]

That should be enough. You could bump it up to 3.25".

What size is your FMIC?

The setup is not finished but i plan on running something in the area of 24 x 10 x 3. Like i said it is not finished and that size is just a guess.

 

[Splitpi]

So if I am running a Master Power T4 (70 A/R Compressor 68 A/R Exhaust side) I would want to run 3" piping?

What is the CFM?

 

[Fitz7099]

Three inches seems like it would be a good enough size for the size of the FMIC.