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

    • Yeah pretty impressive hey, good to see quality products not over-shooting their prices. That's what drew me to buy the hypergear turbo, just a shame I've never got the chance to see it in action
    • Thank you GTSBoy and MBS206 I have done the compression test with the motor out of the vehicle, reason for the test was to see if I needed to remove the head and do rings etc while its out. I'm in the process of respraying the vehicle and tidying up a few things. Story behind it all is I've just purchased the skyline and it was running when I got it, never drove it on the street though as I wanted to pull it down and do it all up again before registering it. the gentleman I purchased it from told me the motor has a forged bottom end and has a decent tune through it but I was going to pull the sump off anyway to see if it is a forged bottom end. that's why I thought id do a compression test beforehand. 
    • Man, I'm kind of amazed that the price of the turbo has not changed in 7 years. Everything else is inflating beyond reason, but not this? Good on Tao / hypergear I guess? Anyways, good luck with the sale!
    • I'm selling my brand new, in the box, never used Hypergear ATR45 - and I had some additions I paid for a few yrs back when I purchased it. Never ended up having the rest of the money to add all the mods at once, so I just ended up slowly selling each part. I originally had it internally gated, with the dump pipe, however I found it was incompatible with what I was going to use it for, so I contacted (I think Ken) from Hypergear, and he and I messaged back and forth & he got me to ship the turbo back, where they modified it & made it externally gated, and gave me the 5 bolt dump pipe attachment for custom welding. (Photos below) This turbo like I said has never touched the inside of an engine bay, it's completely brand new, never used, been sitting in the same box it arrived in, covered in plastic & all. Below are the photos of it: And while the guys at Hypergear were making it in-shop, they sent me some photos of the process: I'm looking at selling this just because I'm in need of the money right now, and don't have plans on modifying the 34 anytime soon - and from reviews & peformance sheets, this turbo had amazing results back when I was researching. The turbo was purchased in 2018 for $1.9k, with the mods I got added on. Looking at the website now, for the same turbo they sell (ATR45SAT), with the current addons it adds up to $1830 for the turbo Current addons included: - Bolted dump adaptor - Ball bearing CHRA - Braided oil feeding line So I'm looking to possibly sell it for around $1800, with shipping included in that 1.8k, It cost me around $120 to ship - so yeah thought I'd throw it out there and see if anyone was interested in purchasing. Cheers!
×
×
  • Create New...