Intercooler pipes 2.5 vs 3

[viper04]

I did a search and could not fine the answer. At some point in the GN-T-type live, front mounts came with 2.5 piping, spearco, CVS and so on. Now I think it's fair to say major of front mounts use 3" pipe if not all. I was just curious as to why? Was it found the 2.5 pipes where more restrictive, had more pressure drop? ect,. Just curious. Thanks for any input.

 

[viper04]

Anyone!!

 

[ijames]

Tony DeQuick of CAS posted several times back in teh late 90's on the gnttype list that down to the low 11's there was no need for 3" pipes and that some 2.5" pipes actually outflowed some 3" pipes because of the larger bend radius relative to pipe radius at the first bend leaving the turbo. In spite of that everyone kept asking for 3" pipes so first he sold them as an option and then he gave in and switched (the other big fm sellers at the time, PTE and Cotton, just started with 3" pipes).

 

[joe_schindler]

2-1/2 inch pipe should flow plenty for a 58 or 62 mm throttle body; but 3" looks cool.

 

[viper04]

ijames & joe schindler thanks for the reply
Joe, I did read it some where, the post was back in 83 if I'm not mistaken. I guess it as never been prove then, that a 3" would out flow or was more restrictive than a 2.5 piping. I really was more curious than on a fact finding endeavor. Anyone eles let me know what you think..

 

[joe_schindler]

I don’t remember what happened this weekend; so 83 is out of the question. The hot tip on exhaust tube used to be that 2-1/4 inch tubing flowed better than 2-1/2 inch; not because it did; but because that’s what muffler shops had.

The old (crush) style tube benders might have actually done a better job on 2-1/2 pipe than on 3 inch. Since most of the tubing is now bent on mandrel benders; you should have a 40% better flow with 3 inch tube. That doesn’t mean that you can take advantage of it if the engine can’t use more than what a 2-1/2 inch tube can supply.

 

[jasjamz]

I don't think that would see a big difference in going from 3" to 2.5". Well nothing that adding a little timing or boost wouldn't fix.

 

[viper04]

Thanks for the reply guys!

 

[TR Custom Parts]

3" is just sexier looking.:smile:

 

[Mike Licht]

We did a dyno test many years ago and the 3" pipes were worth about 2 to 3 HP on a 600HP car, this was within the run to run error range so we concluded they are worth little to nothing there. Consumers demanded 3" pipes however and they get whet they want in the end. However other than cost there is no down side to 3" pipes