4 into 1 or 2 into 1 exhaust questions

[Richard Gibson]

I currently have a LHD 1600 Crossflow Sprint. I am planning on doing some engine work. My car currently has a rear exit exhaust system.

 

What are the differences between the 4 into 1 and the 2 into 1 exhaust systems? Is a side exit going to make a huge difference in volume versus the rear? Since I will be driving on the left verse the benefit of having the exhaust on the opposite side?

 

Any comments/advice very welcome!

 

Richard Gibson

 

Richard Gibson

[Graham Sewell]

I will probably find that I am incorrect, but my understanding is that for ultimate power 4 into 1 is the way to go, but for modest(?) engines a 4-2-1 gives better response in the mid-range.

 

Hence the choice is probably along the lines of - is this a race car (WOT for 90% of the time) or a road car (mainly 4000-5000rpm).

 

Cheers,

 

Graham

[Roger King]

As a general rule, a 4 - 1 system will give a higher maximum power output than a 4 - 2 - 1 system, but the power band will be narrower.

 

To illustrate this, race cars often have the former type, whereas rally cars have the latter.

 

It should be understood that exhaust design is something of a black art, so the above is a generalisation only.

 

Being such a light car, the Caterham can cope with a 4 - 1 system quite easily. If you are wanting to use one of Cateham's systems, my advice would be to stick with the rear exit system up to around Supersprint specification and use the 4 -1 system for more highly tuned units.