3.2 SSI internal diameter of primaries?
 

The more I search the more variation I find...

37.8mm? FVD Online Shop -

talk of 37mm id (1.46inches) after the switch to dansk ownership last year. SSI's on a 3.2? - Page 2 - Exhaust: Gas and Heat - Impact Bumpers

our host stating 35mm (1 3/8) 1984 Porsche 911 Carrera Coupe - Heat Exchangers and Hoses - Page 1

I assume it is 35

All SSI are 1 1/5"OD, 1 3/8"ID

1.5" or 1 1/2" OD. I believe this is what RarlyL8 meant.

According to the FVD info the new Dansk versions have 37.8mm ID primaries, it's true that all the older versions were 34.9mm or 1 3/8" ID.

If the FVD info is true then it looks like they finally redid the old SSI design w/ larger pipes that are more appropriate for the 3.2 -3.4 liter engines

My supplier just got my ssi's from dansk and is going to open the package and measure the primaries. I will let you guys know. I wonder if pelicsn is still selling old stock as they clearly state 35mm id

35mm with 02 sensor bung and thicker flanges.

I wonder if the 37.8 was externsl diameter, and someone just got it wrong on their website...

I emsiled dansk to try to put this to rest

Most product descriptions recite the outside diameter, mainly for effect (bigger is better). Strangely enough, the external diameter of exhaust tubes has no bearing on the size of the exhaust path unless the wall thickness is also included.

BTW, 37.8mm = 1.488", essentially 38.1mm = 1.5"

Sherwood

If you go to the FVD site they state
translation: OD 38.4mm, ID 37.8mm

I'll hold off on my calcs and comparisons until someone gets tech confirmation from FVD.

Meanwhile, here are a couple of conversion sites for reference:
Stainless Steel Gauge Conversion Chart
Sheet Metal Thickness Chart

Sherwood

I think we know the answer based on what is coming directly from dansk now (my order direct). 35mm, but i will post a response if i get one

Dansk bought all the tooling and a healthy supply of product form SSI. I doubt they changed the tubing size as that would require a complete retool of everything. That is one reason why John didn't do it.

Robert Diotte, the north america dansk rep just said 36mm.

Banging head on wall. I asked him to confirm.

So 35, 36, 37, 37.8. Again, i suspect 35 and the rest is misinformation.

good to know but realize where the 35 # came from
someone measured the pipes w/ a caliper probably in inches(That's what I did) there is a +/- on any measurement what ever the actual measurement 1 3/8" is close enough for most purposes

then somebody converted to mm by multiplying by 25.4 and rounded the result up. another source of possible error

The question is why is FVD saying differently

This is a bit off topic but... given a exhaust port size (in my case 35mm (early SC heads)) is it best practice to match primary header size to the exhaust port size? I'm going the 3.2SS route with likely 46 PMO's on the intake size and mostly street/AX use and 7K redline.

expanding gas flow doesn't like step transitions, the best situation is matched ports that taper from one size(the port) to the tube size which for a 3.2(long or short stroke) will be 1 1/2 to 1 5/8" the smaller size being better below ~5500 the larger better above, for street and/or A/X the smaller size will probably work slightly better. but cam selection and where the sweet spot of the torque curve affect this too.

Then is it ok to use ssi's originally used for a 3 L ok to use with 3.2ss (for street use)?

I have SSI's on a 3.2 SS, Stock Porsche (Bischopf) muffler.....great combo. Been running for 13 years, lovely sound and good power for sure.

Dennis

since the exhaust ports are 35 mm and the id of the ssi's being 35 mm then these are matched to the ports, correct?

I have some pre-Dansk 3.2L SSIs still in the box in the attic. I can dig them up and measure if needed.

jeff