I bought a brand new exhaust system for my B18CR motor in my EJ1 civic.

I asked 3 times that it was 2.5" before i bought it.

once i got it and measured the I.D of the pipe it was only 58mm or 2.28inches!
even if the O.D was measured it wldn't be anywhere near 2.5".

Now my testpipe and 2.5" 98 4-1's won't match up to the exhaust very well. THere will be a 3mm lip or more!

is this common for exhaust companies to say "2.5" system" when they really aren't!
brand is XSPOWER

 

happens a lot on ebay. xs power is an ebay brand, t1r and kteller both make true 2.5" exhausts.

 

That definitely false advertisement. Only a few companies make true 2.5" exhaust, T1R and Hytech are two that I know of.

 

So alot of japanese exhausts aren't 2.5" even. Like Buddy club, mugen, spoon, HKS etc etc.

I just don't want my 2.5" test pipe and collector to hit a bottleneck when they join to a smaller exhaust.

(I havn't got this system yet, my friend has it and measured it for me)

 

2.5" should be O.D. when it comes to exhaust. what did you measure as far as O.D. goes? some piping could have thicker walls than others but overall outside diameter should still be 2.5"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Coupe-R &raquo;</TD></TR><TR><TD CLASS="quote">So alot of japanese exhausts aren't 2.5" even. Like Buddy club, mugen, spoon, HKS etc etc.

I just don't want my 2.5" test pipe and collector to hit a bottleneck when they join to a smaller exhaust.

(I havn't got this system yet, my friend has it and measured it for me)</TD></TR></TABLE>

none of the exhaust you mentioned are true 2.5" they are all 60mm or 2.38"

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Casey &raquo;</TD></TR><TR><TD CLASS="quote">

none of the exhaust you mentioned are true 2.5" they are all 60mm or 2.38"</TD></TR></TABLE>

Correct...i think they just say 2.5" as its simpler than 2.38"

 

Almost every exhaust company advertises OD

If you take a caliper to the OD of your new piping, I'm sure it will be 2.5"

When you buy piping, it is measured by OD not ID.

T1R has a 63mm, 65mm (no longer in production) and 70mm (limited run).

ID of the 70mm:

 

As i said at the start
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Coupe-r &raquo;</TD></TR><TR><TD CLASS="quote">once i got it and measured the I.D of the pipe it was only 58mm or 2.28inches!
even if the O.D was measured it wldn't be anywhere near 2.5".

</TD></TR></TABLE>

The seller said that the flange by the cat is 60mm and the pipe I.D is 58mm.
so that means it has a wall thickness of 3.5-5.5mm Im having my doubts.

thanks for clearing things up that the JDM systems are 2.38" As long as this XSPOWER exhaust doesn't make a HUGE lip where the omni test pipe connects to it.
P.S so is a 2.5" omni test pipe 2.38inch?

 

Assuming a wall thickness of roughly 2.5mm, the piping could indeed be 2.5" and have an ID measurement of of 2.3" (which is quite close to the measurements you've provided).

 

Tubing is measured by the OD x wall.

Most stuff made in the US that is 2.5" OD has a 18g (.049") or 16g (.065") wall thickness.

ID = OD- 2*(wall thickness)

Most of the JDM stuff is 60mm (2.36") OD, I've seen this come in 1mm (.039"), 1.25mm (.049") and 1.5mm (.059') wall thickness.

 

as SMSP said the max wall thickness is probably 1.5mm

so that makes it I.D of 58mm + 1.5mmX2
0.D=61 or 2.4" so still NOT A 2.5" SYSTEM

QUESTION: What is the I.D of a omni power test pipe at the triangle exhaust cat back end.

 

Ok I have the exhaust now.

Its quite a bit smaller than a real 2.5" system

60mm O.D and 58mm I.D
if it says 2.5" IT SHOULD BE 63.5mm! not 60mm

I had a 2.25 system already (I.D I think) so this is pretty much the same!