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

    • Newbie here, proud owner of an Autech 260RS. I'm on the hunt for wiring diagrams specific to the 260RS, particularly S1. I've ran my eyes through R33, R34 Diagrams, there are some similarities, however continue to find incorrect wire colours and pins on connectors in the 33,34 diagrams.   I was hoping someone could point me in the right direction? I'd be happy to pay for the originals in Japanese. I can translate them, at least they would be accurate.   Any help please would be greatly appreciated, never heard an RB26DETT before let alone driven one, and I've got a spaghetti monster of goodness to sort out.   Cheers Benny  
    • Hey all  im wondering if you can help me please I have put a rb20 box in my r34 gtt as my auto packed up and a friend had a spare box I know it’s not ideal but it will get me up and running for now. we have done the conversation and everything is working great but my Speedo we got a s13 speed sensor but my Speedo reads double now and I bought a speed converter but still not having any luck.  so I thought I’ll reach out and pick your brains  any help would be appreciated please as I wanna drive my car again 
    • Drain it. I got official Matic D but you can get whatever is listed as Matic D compatible.
    • Thanks guys,  Yeah I should at least have them dynoed, at least then I know what I've got as a starting point.  The springs on these are hard as rocks. I vaguely remember Russman saying he was going to sell the shocks to me with the rocks fitted, as he was keeping the softer springs for his new setup.  I didn't click at the time but of course that was to let me know the shock/spring wouldn't be matched.  I also remember pricing up new springs around 2014-15, but, house, money etc. it never happened. So that was another reason to have them rebuilt. I have rebuilt the forks on many motorcycles so I think I could handle the seals on these easily enough, but getting the valving right would be a rabbit hole I cbf exploring.  Duncan, interesting to hear RP was tuning these back then. I might give them a call.  In the mean time I have been busy fitting sway bars. The Whiteline rear sway bar I purchased 15 years ago finally got fitted, along with the Whiteline front bar that showed up last week. Just waiting on new links for the front sway bar to finish that off.  And my spare set of advan AVS VS5's should be back from the powder coaters in a Pearl White finish sometime this week, with a set of Hankook RS4's lined up for fitting.  And then I just have all the suspension bushes to do. A comprehensive kit is on the way... Lots to do before the Ararat hill climb. Cheers guys 🍻   
    • Nice car! I’m glad folks in the US have gotten past the FnF and are buying real cool cars like the 260RS I was with a bunch of mates in Portland about a year ago and spotted a green Stagea (just a regular 2.5T AWD) parked about 2 blocks away and they were like “a what?” So I made a bet with them for a round of beers and said “ok one of you run down there and tell me if the steering wheel is on the correct side” 5 mins later the American comes trudging back up the hill and goes “he’s right guys. Ok what beer do you want?”
×
×
  • Create New...