aarang Posted June 4, 2003 Share Posted June 4, 2003 I was just looking to get a few opinions on tubing size for I/C plumbing. Right now I will be using a stock 83 turbo engine with a stock T3 turbo, non-EGR intake, 60mm T/B, Jeff P downpipe, 3" exhaust, med NPR I/C. I have big plans for the car when money and wife permit. Is there a big advantage over using 2.5" as compared to 2.25"? I will eventually be upgrading to a T3/ To4e 50 and getting an SDS FI system. If I were to use 2.25" now, would it be too restrictive for the larger turbo later? I would like to do all the engine mods now, but financially it won't work. I am relatively new to turbos but have done alot of research on this board and other sites. Any help/opinions greatly appreciated! Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 4, 2003 Share Posted June 4, 2003 Either will work, although 2.5 would be my recommendation. It is harder to make fit of course, but worth the effort. I ran it on mine with the new intercooler, and I like it. I think I had 2 inch before. What are the inlet and outlet on the IC? I would match that, it would be crazy to go larger and then neck it down at the IC. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 4, 2003 Share Posted June 4, 2003 If I'm not mistaken the NPR has 2-3/4" inlets?? I agree with Lockjaw, no reason to go bigger than the IC inlet and outlet. In defense of small pipes, Shane ran high 11's at 115-119 traps with 2" tubing and a stock throttle body. I am running the same IC now, with 2" from the turbo to the IC, and take 2" out and gradually open it up to my 60mm throttlebody, which is bigger than 3" on the inlet. So don't get too hung up on pipe restriction, it's not going to make that much difference. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted June 4, 2003 Share Posted June 4, 2003 I used 2.25 mandrel pipes on my L28ET with a medium NPR. On the GNZ I run 2.25 on the turbo side with the turbo end using a 2.25" to 2" transition hose (turbo outlet is 2") and on the I/C end, the 2.25" pipe is expanded to 2.5" to match the I/C. On the TB side I use 2.5" pipe to a 62mm TB. This is supporting close to 500rwhp. Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted June 5, 2003 Share Posted June 5, 2003 I think that is what Topend recommended, what you are running Scottie. And I don't want to hear stuff about them, just saying they recommend it. I used a 2 to 2.5 in transition hose off the turbo, and I have a 2.5 to 2.75 transition hose to go from the intercooler line to the 60mm t/b. Sleeper I ran my 12.65 pass on the small 2 inch lines, so they work, but there was some spread sheet running around that made a calculation from Maximum boost, and I think 2 inch is really getting on the small side. I would have to hunt to see if i could find it though. Something about the air getting to the speed of sound or something. Thats why I ran 2.5, didn't want to have any problems. Quote Link to comment Share on other sites More sharing options...
Sean73 Posted June 5, 2003 Share Posted June 5, 2003 Maximum boost recommends keeping velocity below 450 ft/sec for intercooler pipes. Here are my calculations for 2.25" pipe (2.125 ID): Airflow = 600 CFM (400 HP) 600 ft^3 / minute 1 min / 60 sec ----------------- -------- PI(2.125/ 2)^2 (ft / 12")^2 = 362 ft/sec So, atleast according to Corky, 2.25 intercooler pipe should be ok for most turbo'd Zs. Quote Link to comment Share on other sites More sharing options...
aarang Posted June 6, 2003 Author Share Posted June 6, 2003 Thanks for the help guys. I think I will stick with the 2.25 for ease of install . After I do all the mods to the engine ( later down the road), I was looking to top out @ around 400hp, anyway. Quote Link to comment Share on other sites More sharing options...
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