Ron240zxt Posted July 27, 2001 Share Posted July 27, 2001 Just Wondering what the ideal intercooler piping size is and why is it this way. I have to redo my piping and was trying to determine if there is a better way of doing this..Any suggestions please inquire... Thanks Ron Quote Link to comment Share on other sites More sharing options...
Drax240z Posted July 27, 2001 Share Posted July 27, 2001 Ron, it depends entirely on what type of horsepower you plan on producing. I am going to run a 2.25" pipe with my setup, but that leaves me room to grow. I'm not sure what the heavy hitters like TimZ and 240Z Turbo are running, but I don't think either of them are over 2.5", and thats for over 400rwhp. When you start getting too larger a pipe you'll start losing velocity, as well as adding a huge amount of volume to your intake system, which coul hurt throttle response, as well as causing a larger pressure drop from turbo outlet to manifold. I'd say if you are looking for up to 400rwhp, 2.25" should be sufficient. I can't say that 100% sure, however. I'm looking forwards to hearing others response. Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 27, 2001 Share Posted July 27, 2001 I run 2.5" and i don't have any problems with throttle reponse and pressure loss is only 1 to 2 psi from turbo to intake thru the ic.I think it's just right for what i'm doing right now.And if i want to expand the mods i don't have to do much to it. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted July 27, 2001 Share Posted July 27, 2001 One more thing I should have mentioned. A 2.25" mandrel bent system will flow around the same as a 2.5" press bent system. When I was saying 2.25" is enough for around 400rwhp, thats assuming that its mandrel bent. Quote Link to comment Share on other sites More sharing options...
Guest Tom Scala Posted July 27, 2001 Share Posted July 27, 2001 Here's something I posted a while back and never got a response to but it kind of pertains to this topic so I'll try again. Alot of IC pipe setups I see have the turbo to IC pipe smaller than the IC to TB pipe. Wouldn't you want the opposite? The hot gasses coming out of the turbo are expanded and need a larger pipe. Once they are cooled in the IC they contract and take up a smaller volume and wouldn't need as large a pipe to maintain flow. A smaller IC to TB pipe would help keep velocity up,and the slight pressure drop in the IC would also allow a smaller pipe to be used on the outlet without hurting flow but this effect may be negligable. I may try a 2.5" pipe to the IC and a 2.25" back to the TB. Whaddya guys think? Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 27, 2001 Share Posted July 27, 2001 I'm no pro like some guys,i haven't had any trouble with my set up.But i guess the only way to find out is try.The reason the pipe is smaller on my car on the output of the turbo is partially to the size of the output of the turbo it's self.If it was bigger i would of ran 2.5" all the way. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted July 28, 2001 Share Posted July 28, 2001 This debate has been going on for a long time and I have yet to hear what seems to be a logical explanation. However, here is another way to look at it. Take a look at many upgraded turbos, including mine rated for 580hp, and the compressor outlet has a 2" od, repeat OD. on the other end, we are scrambling to installing 60mm or larger TBs . I have a 2" to 2.25" hose on the compressor with a 2.25 pipe to the I/C where it steps up to 2.5" and 2.5" from the I/C to a 62mm TB. Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted July 28, 2001 Share Posted July 28, 2001 A typical size for most apps would be 2.25" turbo-intercooler and then 2.5" intercooler to TB. You always want the intercooler to TB as big as if not bigger than the turbo-intercooler piping. My current piping will be 2.5" turbo's-intercooler and 3" from intercooler to TB. The intercooler is also a reservoir which is why you want to the same size if not bigger from intercooer-TB. There is no reason to run a 2.25" pipe to the opening of a TB that is 2.5". You might as well have run 2.5". Quote Link to comment Share on other sites More sharing options...
TimZ Posted July 28, 2001 Share Posted July 28, 2001 Probably the best rule that I have heard for sizing intercooler piping deals with limiting the maximum air velocity in the piping such that excessive drag is not generated. The design guideline that I had heard was to keep it below Mach 0.4, or about 450ft/sec (I just lifted this from 'Maximum Boost'). From this guideline, a 2.25" pipe would generate air velocity of about 360ft/sec at 600cfm (~400hp), and a 2.5" pipe would be about 290ft/sec. So, at ~400hp (flywheel), either size should work just fine - the 2.25" pipe should give better response, but the 2.5"pipe has more headroom. That said I use 2.5" pipe - mostly because that is the size of the outlet of my turbo, and it didn't make sense to me to make the pipe smaller than the turbo outlet. Also, I think that somebody already mentioned it, but it's generally easier to make the IC outlet pipe match the throttle body size than it is to have a transition in the pipe itself. [ July 28, 2001: Message edited by: TimZ ] Quote Link to comment Share on other sites More sharing options...
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