Jump to content
SAU Community

Recommended Posts

Hey guys, Ive been looking at several intercooler kits for my gtst. The cheaper ones come with 2.5 inch piping but the more expensive ones come with 3. Is it really worth spending the extra few hundred and get the 3" piping? I mean i know that the larger diameter will flow better, but is it going to make a difference that will justify spending more money?

Come to think about it, anyone know the throttle body diameter for an RB25det off the top of their heads?

Link to comment
https://www.sau.com.au/forums/topic/120301-intercooler-piping-diameter/
Share on other sites

2.5" piping is more then enough... it will keep turbo lag to a minimum as well as give you an even flow with your stock intake pipe...

The FMIC core flow is what will cool the air and give you best perfoemance... Have a look at the Gktech FMIC kit in the group buy section...

http://www.skylinesaustralia.com/forums/in...howtopic=120149

Best value for money!

Cheers

while were on the subject of throttle bodies... :D

1. would going slightly larger be an advantage for rb25det ???

2. and wat size would u recommend :santa: ?

1. No, not until you are well and truly past the limit of the standard internals

2. See #1

:D cheers :D

T/body diameter should be the same for both.

There is no point going to 3 inch pipe work unless you are doing a major upgrade and seeking more than 400hp at the wheels. There is also no point upgrading the pipework if you are running standard cams as your hp limit will be around 230-240rwkw anyway and the 2 1/2 inch piping is more than capable of handling up to 300rwkw and over. The outlet on the turbo should only be around 2 - 2 1/4 inch as well so adjusting for some expansion would take you to the optimum diameter of 2.5

Similar type questions...

1. Does the 'fatness' of the cooler make a lot of difference...?? Ive seen them from say 65mm thick to 100mm?

2. Is the cooler only as effective as the the surface area exposed to the rush of air... (ie is the area of intercooler blocked by the front bar useless?)

Because I was thinking of just getting a cooler that wasn't as 'tall' as the usual 300mm and going for something half as tall.

the thickness of the cooler only really adds to lag unless u got mega horsepower, id say nething more than 75mm thickness is a waste for up to 20psi..

and yes a coola behind a bumper will not be as affective as a cooler with direct air flow... ie, is the reason u mite see ppl cutting up there stock bumper to expose more of the coola..

one thing i always thort but, wouldnt with beta flow ud achieve more horsepower?... like thru 3" at 15psi wouldnt the flow produce slightly more hp than the flow from 2.5" ??.. or does the 2.5" act in no way restrictive?

Edited by BiRDY

You loose airspeed with the larger pipe. it bottle necks when it reduces back down at the throttle body, and the larger area means more area to fill so can slightly increase lag. Your pipework should be the same size as your turbo outlet & throttle body. No step ups or reductions, just nice and smooth flow. in saying that the lag problem is easily sorted out if the pipework is shorter. If it is one of those cheap kits where the pipework runs up behind the radiator and then around into the throttle body, then no matter what pipe diameter, you have a large area to fill due to the pipe length, therfore increase in lag, and also heatsoke in the cooler pipe.

SMIC is more efficient but doesnt have the rice factor. There are kits where the cooler inlet and outlet are on the same side, this keeps the pipework shorter and cooler, therefore giving you a cooler charge even when you push a larger volume of air through at higher boost pressures. Do yourself a favour and spend the extra money on a kit that has been designed correctly.

the thickness of the cooler only really adds to lag unless u got mega horsepower, id say nething more than 75mm thickness is a waste for up to 20psi..

and yes a coola behind a bumper will not be as affective as a cooler with direct air flow... ie, is the reason u mite see ppl cutting up there stock bumper to expose more of the coola..

one thing i always thort but, wouldnt with beta flow ud achieve more horsepower?... like thru 3" at 15psi wouldnt the flow produce slightly more hp than the flow from 2.5" ??.. or does the 2.5" act in no way restrictive?

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

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...