Practically Classics Forum

tractorman wrote:There used to be a "diverter valve" that did just that - a sort of "Y" pipe with a flap that selected one side (going to the silencer) or the other (to open exhaust) for those who raced their road car (or as it's now known "Track days"!). I wonder how many of then "stuck" in the race position!

They are still available. Google "exhaust cut outs" and there will be plenty hits. They can even be operated electrically nowadays.

I seen lots of videos (motortrend and Stacey david spring to mind) of hotrods fitted with two exhausts, one set of side pipes and no silencers with electrically operated butterfly valves that close them off to send gasses under the car through a full system.
They would definitely sounds good on a v8, probably not so much on the 3 cylinder corsas which is almost certainly where most of the UK sales would go to

I regularly drive Transit customs all over europe for work, they are better than any car on the motorway, they even have cruise, aircon etc. I think it is the driving position which really helps, you can see miles ahead, past most cars.

History wrote:I had a Yamaha XS 750 that was 3 cylinder it sounded nice when pulling hard.

This form of setup on carbs has fascinated me. As we know,this setup is blow-thru. It's one of my pending projects to do a blow-thru on one of my Sierras,using a DGAV. I've heard that the manufacturers stopped building the blow-thru on bikes as it was too dangerous,as the boost kicked in,on inappropiate moments,i.e on a bend.
Big turbos do produce lag,but on my XR4i,it's equipped with a twin scroll turbo without an actuator. It does spin at low rpms,like a supercharger. Superchargers are better I find,as I prefer low rpm boost.

There is a video somewhere of a top fuel supercharger on a test rig, it takes 600bhp just to spin it up to full boost, obviously not a problem when your making well over 8000bhp.