97 ITR
GE 81.5mm block
9.1 CP pistons
Full Race rods
sc61
either an Inline pro mani or sidewinder.

I plan on running 350+hp on the street, high 400's at the track. I did a search and have heard to run either 2.25 or 2.5 inch intercooler piping. What size should I run with my setup? Thanks.

 

2.25

 

2.1/2

 

Damn, 2 different answers. Why one over the other?

 

I think 2.5" is the standard if for no other reason than availability, of both piping and couplers! I'd go with 2.5".

 

i run 2.5 and dont see any issues.

platinum.

 

2.5 inch we have a kit for the integra-civic (no gsr manifold) $295 with all the cuplings and the T-clamps, its powder coated black very clean its on Duc's car if you have seen that

 

i'd go with 2.25 i think most people are running piping thats too big.

 

IMHO if you are looking for high 400s at the track, definitely do not go smaller than 2.5" and you might want to consider using 3" piping at least from the turbo to the IC. Some people on H-T will say you want to keep the velocity high but here is the deal with compressible gas flow, velocity, and pressure. If you have high velocity then you used up some pressure to get it (conservation of energy and work/energy theorem, ain't nuthin fo free). Velocity goes up, pressure goes down. Velocity goes down, pressure goes up. Period, end of story. The aerodynamic drag in piping or the IC or whatever isn't a linear function of the gas velocity, it is a function of the SQUARE of the gas velocity! So double the gas velocity has four times the drag, and therefore four times the pressure loss, and remember that the energy lost to friction that caused the drag was converted into heat, so four times the heat added to your gas too. This is why it baffles me so much when people here say "yeah, use small piping to keep the velocity high"!?! These are the same guys who use a narrow 6" high IC that is 30+ inches long. Talk about pressure drop! It is much, much better to have 6" long IC tubes in a row 30" wide than it is to have 30" long IC tubes in a row 6" wide. And for those who are going to argue that the air doesn't have enough time to transfer its heat in the 6" tubes, it spends the same amount of time in the 6" tubes as it does in the 30" tubes, only it's going 1/5 the velocity, so only 1/25 the friction across an equal surface area! If you really want to have high gas velocity entering the intake manifold, which is the only place that it would matter, just use a small throttle body. That'll give you high velocity! Sounds stupid doesn't it? That's because it is stupid. And just like you wouldn't want a tiny throttle body choking your flow, you wouldn't want small piping choking your flow all the way from the compressor outlet to your intake valves. Some will say that the larger charge volume of the big piping will add lots of lag. Nonsense. Calculate the difference for yourself and you'll see that it will contribute an insignificant amount of lag. Unless you use 4" piping all the way to the trunk and back it won't be noticeable. Sorry for the long post. I'm just tired of some of the BS that passes for knowledge here in the FI forum. Cheers

 

i dont know why, but all the race bseries motors ive seen have all used 2.0 from the compressor to ic, then 2.25 to the tb. then if you look at kits i think most are like 2.25 straight through..

 

I just used 2.5 all the way...it's what the TB is, it's what both inlet and exit of my IC are.

 

depends how fast your turbo spools up.. having a smaler diameter piping from the turbo to the intercooler will help pressurize the system quick enough to not have a bad lag, you need to accelerate the air into the intercooler and from the intercooler to the TB is up to you....i would go with 2 1/4 from turbo to intercooler, and 2 1/2 from intercooler to TB, just blow into a different straw size you will understand then

 

Im not sure if this answers your question, but on the drag intercooler, the inlet is 2" and the outlet is 2.25".