Why are the Vincent Egli Headers/down pipes swaged out to a larger diameter? Just asking as to what is wrong with the standard pipe sizes? The exhaust hole size in the head is still standard Vincent size, this is then adapted to a larger 2"? pipe, as the gas leaving the cylinder head is still restricted at source it hardly seems worth the bother ...... or am I wrong?
PT: Exhaust Egli Headers/down pipes
- Thread starter tom wilson
- Start date
When tuning exhausts in the header pipes we use inverted cones to aid scavenging and wave/pressure fitted into the header of the pipe at the head.
Widely available from Harley aftermarket pipe makers in various diameters.
I have a couple in the Rapide pipes which are straight threw.
Goldstar straight through end can/silencer.
Slip in to the header and re attach simple.
Proven on the dyno the results are notable.
Scruitineers look away now..
On a standard/superstock race bike they are undetectable by technicians as they are inside and out of view.
We mostly run race pipes with minimal silencing and on straight through pipes they are brilliant giving great results and cheap as chips, easy to make also.
Nice.
Widely available from Harley aftermarket pipe makers in various diameters.
I have a couple in the Rapide pipes which are straight threw.
Goldstar straight through end can/silencer.
Slip in to the header and re attach simple.
Proven on the dyno the results are notable.
Scruitineers look away now..
On a standard/superstock race bike they are undetectable by technicians as they are inside and out of view.
We mostly run race pipes with minimal silencing and on straight through pipes they are brilliant giving great results and cheap as chips, easy to make also.
Nice.
Some detail on cones from tuner friend I pulled out.
"Torque cones are tapered pieces of tubing that fit into your existing exhaust pipes, usually up near the port end of the pipe. They start at the normal pipe diameter and reduce to a smaller diameter in a very short distance. The object is to increase the exhaust gas velocity, which decreases the exhaust gas pressure at the downstream end of the cones. Having less pressure at the end of the cone helps prevent reversion, or exhaust gases traveling back up the pipe into the combustion chamber during valve overlap, or that time period when both intake and exhaust valves are open. Since the gases are at a higher pressure upstream, the lower pressure gases downstream can't flow backwards will be useful for you as the Vincent exhaust ports are to large really for this engine maybe an old design issue try them out go for it let me know."
This was a while ago since then we have been experimenting with them in various twins including my own Rap.
We recently pulled apart a well known French race twin and found they had beat us to it it already had from the factory race team cones inside the headers so good enough for them..
Allows you to have nice meaty down pipes with all the advantages of a narrower section pipe.
"Torque cones are tapered pieces of tubing that fit into your existing exhaust pipes, usually up near the port end of the pipe. They start at the normal pipe diameter and reduce to a smaller diameter in a very short distance. The object is to increase the exhaust gas velocity, which decreases the exhaust gas pressure at the downstream end of the cones. Having less pressure at the end of the cone helps prevent reversion, or exhaust gases traveling back up the pipe into the combustion chamber during valve overlap, or that time period when both intake and exhaust valves are open. Since the gases are at a higher pressure upstream, the lower pressure gases downstream can't flow backwards will be useful for you as the Vincent exhaust ports are to large really for this engine maybe an old design issue try them out go for it let me know."
This was a while ago since then we have been experimenting with them in various twins including my own Rap.
We recently pulled apart a well known French race twin and found they had beat us to it it already had from the factory race team cones inside the headers so good enough for them..
Allows you to have nice meaty down pipes with all the advantages of a narrower section pipe.
Interesting. Do You have any photos?
They are inexpensive, but I have not seen any back-to-back dyno runs that show an increase in anything except back pressure.
David
David
We found a racing twin (not a Vincent) on open pipes with cones notably easier to tune through the rev range on the dyno.
After 3500 rpm very noticeable.
Watched a tuner who specialises in land speed stuff tune a bike motor on a bed run without then run with, I had asked him about it which sparked my interest.
He had said that with it just made his task life easier to fine tune.
I am not a scientist he gave us the lowdown of wave pressure back pressure scavenging when it works best regarding intake versus exhaust onet hing which is clear after our use of for the last few years definitely doesn't reduce power does smooth out the tuning on open pipes.
At the time after some research we discovered they are very widely used in engines with short or open pipes.
Question for the aviation buffs wonder is this were they come from?
Al
After 3500 rpm very noticeable.
Watched a tuner who specialises in land speed stuff tune a bike motor on a bed run without then run with, I had asked him about it which sparked my interest.
He had said that with it just made his task life easier to fine tune.
I am not a scientist he gave us the lowdown of wave pressure back pressure scavenging when it works best regarding intake versus exhaust onet hing which is clear after our use of for the last few years definitely doesn't reduce power does smooth out the tuning on open pipes.
At the time after some research we discovered they are very widely used in engines with short or open pipes.
Question for the aviation buffs wonder is this were they come from?
Al
I would not think these cones in ex pipes had anything from the aero engine business. Would be quite illegal when not standard from the manufacturer. Experimental would be another thing but these stoneage engines have a max rev limit at 3000 rpm typically and fixed ignition at 23-25 degrees, twin sparks certainly. Overland rpm is mostly at 2300-2500 rpm and leaned for less fuel.
The Reno air races would be a source for info when Conti or Lycoming flat engines are concerned but common system is open pipes, no silencers - or alternatively turbo on these.
The more sophisticated engines were war and early post war engines with turbo radials and turbo-compound V 12 types. Again, Reno machines will be a good place for info but I would not think they´d add anything into pipes.
The Reno air races would be a source for info when Conti or Lycoming flat engines are concerned but common system is open pipes, no silencers - or alternatively turbo on these.
The more sophisticated engines were war and early post war engines with turbo radials and turbo-compound V 12 types. Again, Reno machines will be a good place for info but I would not think they´d add anything into pipes.