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Intercooler Piping

HKSgtst

By HKSgtst,
in Engines & Forced Induction

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zforce Enthusiast

zforce

Posted
Posted

Well my theory is that the turbo to IC pipe should be bigger then IC to throttle for 1 reason:

1. Hot air takes up more space then cold air (i.e. is less dense, therfore requires a bigger space to flow the same volume of air)

There are more reasons (and theories) to why i think this setup is better, however that is the main reason.

I just can see how having a smaller pipe (say 2") from the turbo to IC and then a massive (say 3" pipe) from IC to throttle. Why would this setup be better if it is? Can anyone shed any light on this?

MM2death Grand Master

MM2death

Posted
Posted
Originally posted by zforce

Well my theory is that the turbo to IC pipe should be bigger then IC to throttle for 1 reason:

1. Hot air takes up more space then cold air (i.e. is less dense, therfore requires a bigger space to flow the same volume of air)

I thought it was the other way around

Ronin 09 Grand Master

Ronin 09

Posted
Posted

zforce is right with hot air taking up more space than cold air - hot air particles are agitated and thus expand. However, i believe that the reason the piping from the cooler to the throttle is larger than piping from the turbo to the cooler is for a couple of reasons:

1. the smaller the diameter of the pipe after the turbo (within reason, that is, not to try and force it through a maccas straw), the higher the pressure and the faster the fluid velocity. Fast velocity = good for flow to the cooler. While it will be hotter than in a pipe of larger diameter (remember that as air cools it reduces in vol and as air is warmed it takes up more volume), the cooler is designed to shed this extra (if any) heat.

2. After the IC, if the cooler has done its job the air will be significantly cooler than before the cooler. This air hence takes up less volume, and is slower in velocity. However due to the vacuum effect of the intake when the throttle is open (ie. how a N/A car 'sucks' its intake air charge), this reduction in velocity is minimal.

3. Now for point 2 i've said that the air takes up less volume, and the less volume it takes up, the less pressure it is at. This may have a 'pulling' effect on air travelling through the intercooler - remember that air naturally moves from high pressure to low pressure - effectively helping flow of hot air through the cooler.

Hope that is clear... bye :wavey:

JNR24 Proficient

JNR24

Posted
Posted

Thanks Ronin 09,

Sorry to jump off topic,

I am running a "cut & shut" RB26/25 intake manifold, (il post some pics later)

would that type of setup cost more, than say the standard RB25 Intake setup? Or will they be about the same?

Also will the price inlcude silicon joiners & clamps?

Ronin 09 Grand Master

Ronin 09

Posted
Posted

Unsure if that includes silicon joiners, but it is complete. I would guess that if you want silicon joiners it may cost a bit more (they're about 100 bucks each!).

I would again assume that your cut n shut should cost (marginally if any) less as the piping is shorter. Either way they'll have to hack a hole anyway.

Sydneykid Grand Master

Sydneykid

Posted
Posted

Hi Guys, I have a very good reason for gradually increasing the size of the intercooler pipework as the air moves from the turbo to the throttle body. Nissan do it, and they spent heaps on research.

Everybody explains airflow like it's in slow motion. At 4,000 rpm an RB25 at 1 bar will swallow all of the air in the inlet system in less than 1/20th of a second. At that velocity I don't believe 80 degree air (before I/C) is much different to 30 degree air (after I/C). Taking pressure reading proves this to be the case, there isn't any difference unless there is I/C restriction. If the hot air vs cold air made any noticeable difference in pressure, then you would be able to see it, and I never have. So in my opinion too small to worry about.

MrRB20, asked "how much on average would it be to pipe the cooler seeing it is a custom intercooler and the intake and outtake are on different sides unlike the standard cooler which is on the same size ??"

I do my own in aluminium (straight and donuts), silicone (hose) and stainless steel clamps, the materials usually ends up around $500 including about $80 for welding.

Hope that helps

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