4 into 1 Exhaust

[Tony]

My 1600 X-flow has the standard '4 into 2 into 1' rear-exit exhaust (where the '2 into 1' bit protrudes through the side panel). I've always thought it looked a bit puny compared with the '4 into 1' type you often see.

 

Does anyone know if I can change to the '4 into 1' type? Do the bore diameters match? Will the performance be affected (better or worse)? Will it sound better (i.e. louder)?

 

Engine is standard, running twin 40's, except I had the head gas-flowed (and hardened valve springs for unleaded fitted) by Roger King, plus the weber-alpha mapped ignition system installed by Chris Wheeler at the 7 Centre.

 

Any advice gratefully accepted...

 

[Casbar]

Yep, did the very same conversion, during the Winter.

 

Only thing you have to do, is make the hole in the side of the car larger.

 

Great sound, more power - better speak to Roger King on that one.

 

Only other tip, buy the exhaust gaskets from Roger King, the ones that come from Caterham and Burtons blow out quite regularly.

 

Robert

[Roger King]

Hi Tony,

 

If your engine is a standard 1600 it would be pointless going side exit for more power. If, on the other hand, you like the look/sound of it or you are going to upgrade the engine in future it would be worth doing.

 

As a general rule, I reckon that the rear exit doesn't really restrict power up to standard Supersprint power outputs (although subjectively the car feels quicker and seems more willing to rev). Beyond this, you are not getting full value for your money on engine work if you don't upgrade the exhaust too.

[Tony]

Thanks, Roger and Casbar. Just another couple of questions:

 

You seem to be saying there is no power advantage, but presumably no disadvantage either? Will there be any change +/- to fuel consumption (which improved a bit when the mapped ignition was fitted)?

Lastly, can I fit the '4 into 1' front pipes onto my standard rear-exit exhaust, or must I change the whole system to side exit?

 

[Roger King]

To be honest, we've never tried a back to back comparison with the two exhaust types on a standard engine. My gut feeling (which may be wrong), is that you will get a slight loss of midrange together with a slight increase in the willingness to rev.

 

The sizes are all wrong to mix and match the two types of system. We have also seen jetting problems when people have made hybrids.

 

Once jetted properly, I doubt that it will make much difference to the fuel consumption.

[PhilD]

Roger

I have a 1600 x flow and am interested in your comments, I have been considering modifying my existing rear exit to the side to try leave exhaust fumes behind !!

Is this likely to affect performance ?

thanks for any help

Phil D

[Roger King]

Phil,

 

There is probably no problem doing the conversion. Chris Wheeler here in the 7 Workshop has done this for someone before. You will probably have to move the silencer forward by cutting and shutting and then replace the tail pipe with a curved piece.