Jump to content
SAU Community

Recommended Posts

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?

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

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:

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?

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.

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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Interesting, I haven't read about the issue with oil getting into the speedo in the cluster before. I'll have to take more notice with mine. The speedo on my R32's when I've run factory diff and tyre size have never been accurate as far as I can remember. The non Type-M GTS-t did come with 15" 5 stud wheels and smaller brakes, but that's less than 5% of them.
    • Good to hear the condenser you picked up off my brother worked all good. Do you think there could be an issue with your AC compressor itself or the clutch on it then? I don't know a lot about them so I can't really help but keen to hear what it ends up being. Keep the build thread going man, it's nice to look back on over time.
    • This is a story of my life things, I learned eventually (thanks to someone calling me out) that my enthusiasm for discussing and sharing ideas that it came across as arrogance and I'm like... WTF?!    One thing I'm pretty sure I justifiably pride myself on is knowing that everyone will have things they can teach you, and you're always going to find out that something you think you know turns out wrong - you just don't know what it is until you get there.   Just the bursting enthusiasm that comes with ADHD when you hit something that gives you dopamine dumps can come across like you think everyone else is wrong or don't matter. But yeah, I'm a software engineer by trade and also do tuning in weekends and 100% have long had a reputation for  quickly making connections when resolving problems or forming solutions that I've sometimes had to take people form a long walk from start to end to explain how I ended up where I did when it's seemed "too simple" when I've stated my initial case, and had the "WTF" type reaction when they've realised how much was actually considered haha.   My reward is that I get all the curly problems thrown at me.
    • Wives never seem to find things funny. Especially when they're trying to sleep, and you've found the new funniest thing ever. I've never seen someone be able to get try and be cranky with me, while they're holding back fits of laughter... 😛   Also, I tell mine it's payback anyway. She has BiPolar. So the household can get quite emotionally wild at times 😛
    • I'm not up to date on the latest, but for basic modifications like pod filter, lower springs etc you can get a modification permit at the time of inspection.  For more serious modifications you will need engineering.  Intercoolers used to fall into the mod permit rule but its been a long while since i looked it up.   Either way you will be able to get it registered, just a case of $300 vs $3k . 
×
×
  • Create New...