What Is The Internal Pipe Diameter Of A 3.5" Exhaust?

[R33-RB26DETT]

I just bought this exhuast.

It's a 3.5" Inch HKS exhaust but I don't know what the internal pipe diameter is.

When they quote an exhaust as being 3.5" does that mean that the internal pipe diameter is this width? or is it smaller?

[gotRICE?]

I think you will find the HKS is actually 3.75 inch

So a safe bet would be to get the 3.5inch

[mystery_kid]

lol even if the outer diameter of the pipe of a 3.5" pipe was 3.5" you'd only be losing literally a couple of millimeters of diameter due to the thickness of the pipe itself

in conclusion it's completely negligable.

[gotRICE?]

My girlfriend told me every mm counts.

Edited May 26, 2011 by gotRICE?

[R33-RB26DETT]

The reason I ask is because I want to know which apexi ecv will be compatible? Anyone know which one to get?

[gotRICE?]

If its 3.5 i would be confident in it fitting, like i said, the HKS is slightly over 3.5inch anyway. They are 95mm (for R33 anyway, 34's appear to be 85mm)

Have you considered measuring the pipe yourself? That way you will know for sure wont you.

[R33-RB26DETT]

Okay so i'm trying to find out which ecv to buy to match my exhaust.

Apexi ECV - http://www.nengun.com/apexi/exhaust-control-valve

155-A014

Nissan - Type A - ID 67mm - Bolt 105-107mm

155-A019

Universal - Pipe Type - ID 80mm - Bolt 105-107mm

Anyone have any ideas?

[R33-RB26DETT]

If its 3.5 i would be confident in it fitting, like i said, the HKS is slightly over 3.5inch anyway. They are 95mm (for R33 anyway, 34's appear to be 85mm)

Have you considered measuring the pipe yourself? That way you will know for sure wont you.

Thanks mate, but I cab by measure the pipe because its in transit. I've seriously got no idea which ecv will fit.

[mad082]

i can't answer your question, but i will just point out that if you are putting in the ECV to make the car legal, it technically won't be. if the car ever gets tested they test the exhaust with the valve open. if you are putting it in to at least reduce the amount of attention the car draws and make it quieter to drive, then go for it.

[R33-RB26DETT]

Yep, i know that it won't make my car legal.

The problem is that i don't know which ECV will fit my 3.5" inch exhaust?

Nengun supplied the attached info sheet, and i asked them what the internal pipe diameter is but they haven't got back to me.

You can see that i've highlighted in red the area i'm trying to figure out if it's 89.9mm (3.5"inches) to see if it will fit my exhaust.

Anyone have any ideas or experience?

Edited May 27, 2011 by R33-RB26DETT

[scotty nm35]

I think it says 67mm. You may have to go for the round slip on ones, the 80mm should be close to sliding inside the 3.5 inch pipe and the 95mm would be the only choice for larger than 3.5 inch, it would need adapters on each end. Perhaps you could hide it inside the cat body?

[blind_elk]

I believe pipe diameters are quoted as "inside diameter". So a 3.5" pipe has an internal diameter = 3.5".

[mystery_kid]

I believe pipe diameters are quoted as "inside diameter". So a 3.5" pipe has an internal diameter = 3.5".

this would make sense as different materials used for making exhausts would have different thicknesses depending on how strong they are

[R33-RB26DETT]

Ah well, i just ended up ordering this one

155-A014

Nissan - Type A - ID 67mm - Bolt 105-107mm

Fingers crossed it fits, i'll post back here to let others know because it was seriously painful getting the right answers anywhere.