Caterham Exhaust manifold dimensions

[JohnCh]

I'm trying to identify the tubing diameters of the factory 4-1 exhaust manifolds for the 420R, R500, and 620R. I've been told that the measurements for the 420 are:

 

Primary tubing: 1-3/4"

Rear collector exit: 2-1/2"

 

Does anyone know the measurements for the other two or do you happen to have a set in your garage that you could measure?

 

Thanks,

John

[Renottse]

On ours (2013, 2.0 duratec)

 

All OD’s and approximate within a smidge…

 

Primary’s 1.724” Into a 4.75” collector that reduces to a 3” outlet (over approximately 4”) into a catalytic converter (inside the engine bay) that has a 2.511” outlet that runs to the 7” muffler. 

Can get you photos if that would help, realize that the catalytic converters tend to be outside the engine bay these days so may have limited use. 

 

 

 

 

[JohnCh]

Thanks Renottse.  I'm really trying to find the sizes for the 500 and 620 as those are both available new from the factory.  Given they list the 420, 500, and 620 as different parts, the assumption is that the diameters of the primary and rear of the collector/silencer tubing differ, but before I order the 620, I'd like to know what I'm buying.  

 

I posed the same question on BlatChat and had some interesting responses.  Someone with an R400D (precursor to the 420) replaced his silencer with one from a 620 and it was a perfect fit.  This tells me that unless the R400D had a larger diameter system than the 420, the 620 rear collector output should be 2.5" However, this seems undersized for 310hp.  I would have expected it to be in the 2.75" - 3" range.

[Renottse]

All good,

 

For reference on spec, according to Martin Phipps at Caterham ours is a 485. I would be thinking the same as you that a 620 would have a slightly larger diameter but apparently not?
 

All the best with the fact finding and cross referencing. 

[JohnCh]

I didn't realize you had the 485.  I would think that exhaust would be the same as the R500 system, but those measurements match the 420.  I think part of the problem is I'm trying to apply logic to something done by the Caterham factory   A local 620R owner has volunteered to take measurements of his exhaust.  I'll post those once I have them.

 

-John

[Renottse]

I had to jump through some hoops with respect to registration and had cause to get in touch with Martin and that’s what came through his search. 
 

Even then I would break out the salt shaker, I agree with you, only apply the smallest amount of logic necessary to get close to what might be in fact “true” … what happens on the floor vs. what the office records can be worlds apart. 
 

At my elevation (4,500’) it an’t a 485 and my wife couldn’t care less as 45-50 mph is her happy place. 
 

That’s excellent news about getting actual vs. theoretical measurements, the knowledge base grows. 
 

Cheers,

 

 Dean 

[S1Steve]

Hi John, Ten plus years ago I purchased a new in the box R500 muffler from the Caterham dealer in Canada . I also purchased a Caterham Zetec header from our member Skip Scannon. 2.50 x 31” long. So now this makes me a minority owner of a Caterham..   Seriously, hope this helps.. Steve🍻

[JohnCh]

Thanks Steve, I'll add this data point to my list.