Sparky Posted March 24, 2002 Share Posted March 24, 2002 just wondering....as i begin to modify my intercooler i wonder what size tubing i should run. my turbo outlet is 2" and my throttle body is 2". also i can get 2" tubing so much cheaper than 2.5". just wondering what size you guys are running and what you recomend. TIA Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted March 24, 2002 Share Posted March 24, 2002 I'm running 2" pipe that was cut up from the HKS kit and rewelded back together. Heres a pic. The smaller pipe will flow less air but, have less lag in the response time. I'm sure there is a formula but, I can't find it right now that will tell you the right pipe size for your HP goals. Lets see if some of the real turbo HP guru's will have it. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted March 24, 2002 Share Posted March 24, 2002 Not to confuse you, but with my VG30ET swap, I used 2.5" I/C piping. As far as what you should run?.. I'm not in a position to offer solid advice. I used the 2.5" because it fit with my I/C inlet/outlets, and also with my larger throttlebody I have on the intake. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 25, 2002 Share Posted March 25, 2002 What you're interested in is the flow capabilities and the air velocity (I presume). One thing you will want to know/understand is your cfm/hp goals.. your unboosted cfm x pressure ratio (boost pressure absolute/atmo pressure.. ie 15 psi= pressure ratio of 2). Cody is correct in that your initial spoolup (air being pushed through the tubes) will work faster with smaller pipes, and also lead to low end response, but lacking high-end. With a few querks think of it a lot like exhaust tubing. Knowing your HP goals, use a conservative 1.5 to get your approx cfm (200 hp= ~300cfm).. then apply a velocity formula V= (cfm/tubing area) so.. with a 2.25" (300 ft^3/min x 1min/60sec) / (pi(2.25/2)^2 in^2 x 1ft^2/in^2) = ~181 ft/sec with 2".. 229 ft/sec you'll notice in the formula that two 'ft's cancel out. Corky compares the drag in his book comparative speed of sound. 229/1100 = .208 mach. If your hp (cfm) goals are less than 400 cfm, I'd stick with 2" pipe, for 500, 2.25".. with 2.5" you'd better be making around 500 hp, or you're going to see some loss in intercooler efficiency (greater total volume of the whole i/c system from compressor outlet to t/b). Just use the formula and you aught to come out right. Just my .02. Good luck -980mak Quote Link to comment Share on other sites More sharing options...
Guest sabum Posted March 25, 2002 Share Posted March 25, 2002 ???? Damn. I saw this thread and watched with interest, as Im doing the same. Now Im more confused Is there a laymens term for this Quote Link to comment Share on other sites More sharing options...
Len Posted March 25, 2002 Share Posted March 25, 2002 Really if you think about it what 980 said is pretty straight foward. What da ya want? Ya want ta make ah 200 to 250 hp figure 2" pipe, 250 to 350 hp. figure about 2 1/4" pipe above that. You need to start praying your stock L-28 turbo engine will hold up. Also another thought is anything above 2 1/4" pipe is really going to be a motherbear to plumb from turbo/intake to in front of your radiator! Although I believe stock turbo TB is 2 1/4" and if you go with a 60mm TB upgrade you will be talking 2 1/2". Still since the turbo outlet is only 2", I figure on going with a 2 1/4" pipe(hey maybe my wife might get me a new T3/4 turbo upgrade for my birthday......NOT! ). Also I did what ZRED did and matched diameters with my current 2 1/4" I/C outlets. Still what Cody said concerning 2" (faster spoolup)is something to think about. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted March 25, 2002 Share Posted March 25, 2002 I use 2.5" to intercooler and 3" to TB. For most apps you can just run all 2.25". That is sufficient to flow the #'s you want and will not cause any problems for you. Don't try to read too much into determining the correct pipe size. Just do what is shown to work so 2.25" for everything will be fine. Quote Link to comment Share on other sites More sharing options...
Guest sabum Posted March 25, 2002 Share Posted March 25, 2002 I have a Mercedes 60mm to use and an NPR I/C which I have not measured. It looks to have at least 2 1/2" maybe a bit bigger. I cant wait to get this this car going faster! I would like to get into the low to mid 12's consistently. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted March 26, 2002 Share Posted March 26, 2002 FWIW, since my IC has 2" inlet and outlet, I'm running 2" from the turbo to the IC, then opening up to 2-1/4" and between the radiator and the motor I will expand that (with a long reducer cone) to 3" bending 90 into the Weber TB. I'm hoping I have the room - I'm making some more measurements before I buy the parts Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.