Bg86 exhaust mod?

[Gerbutt]

Haha very good 😀 I wouldn't want it to loud, just thought it'd be fun! I may buy a second hand exhaust and do it to that.

 

I'm easily pleased! There's a vid on YouTube of a bloke whose fitted a race exhaust to his hand held blower haha!

 

 

 

 

Sent from my iPhone using Arbtalk

[Eddy_t]

Haha very good 😀 I wouldn't want it to loud, just thought it'd be fun! I may buy a second hand exhaust and do it to that.

 

I'm easily pleased! There's a vid on YouTube of a bloke whose fitted a race exhaust to his hand held blower haha!

 

 

 

 

Sent from my iPhone using Arbtalk

 

 

A piped exhaust can increase the revs considerably if the macho is ported. Those 3120's used on the gadget show race cart (see the APF thread) are pulling 21k rpm, so a blower at that speed would be like a tornado...

 

What do you recon spud, you could have your drive cleared in a second next time matty drops you a load of logs

[spudulike]

A piped exhaust can increase the revs considerably if the macho is ported. Those 3120's used on the gadget show race cart (see the APF thread) are pulling 21k rpm, so a blower at that speed would be like a tornado...

 

What do you recon spud, you could have your drive cleared in a second next time matty drops you a load of logs

 

That Gadget show dragster isn't ported, it has expansion pipes only, Our company exhibit there and I had a long chat with the fella that put it together. He was trying to get hold of adjustable H screw carbs for it last time I spoke to him!

[GardenKit]

It would be interesting to know how much more air velocity was produced by porting.

 

The backward curving centrifugal fan consumes most power producing air volume, but volume does not move leaves well. We need velocity, so we narrow down the spout at the end and the velocity increases, but the volume starts to decrease with the back pressure so the engine revs increase with the reduction in load. (put your hand over the nozzle to prove this, you can stop the velocity completely and the engine revs its nuts off under no load)

 

There is an optimum point which at which air velocity and flow is at its best. This is why the spout is designed as it is.

 

If more power is supplied then the volume will increase on a straight pipe, but put the nozzle on and the backpressure will increase and the load decrease allowing the engine revs to increase even more.

 

So its possible that adding more power to a standard fan will not actually result in more blow unless you change the size of the nozzle.

 

At least, thats my theory.

[MattyF]

Makes sense...

[spudulike]

One thing is for sure - a blower is the fastest way of getting a Chimnea, BBQ or fire pit going in record time:thumbup:

[Eddy_t]

That Gadget show dragster isn't ported, it has expansion pipes only, Our company exhibit there and I had a long chat with the fella that put it together. He was trying to get hold of adjustable H screw carbs for it last time I spoke to him!

 

 

Interesting, that's some serious speed for just a pipe then! When you say the bloke who put it together is he the husky bloke?

[spudulike]

Interesting, that's some serious speed for just a pipe then! When you say the bloke who put it together is he the husky bloke?

 

No, it is a third party engineering firm that were tasked with putting it together. The UK Husqvarna Sales Manager was trying to get some adjustable H screw carbs for the saws that they provided for the project. They are the same team that do the Robot War demonstrations at Gadget Show Live - that is where we met......nice bit of kit, some good work has gone in to it but those saws need a bit of fettling to get the power up!

[Eddy_t]

No, it is a third party engineering firm that were tasked with putting it together. The UK Husqvarna Sales Manager was trying to get some adjustable H screw carbs for the saws that they provided for the project. They are the same team that do the Robot War demonstrations at Gadget Show Live - that is where we met......nice bit of kit, some good work has gone in to it but those saws need a bit of fettling to get the power up!

 

 

Haha don't most saws nowadays?!

[spudulike]

A piped exhaust can increase the revs considerably if the macho is ported. Those 3120's used on the gadget show race cart (see the APF thread) are pulling 21k rpm, so a blower at that speed would be like a tornado...

 

What do you recon spud, you could have your drive cleared in a second next time matty drops you a load of logs

 

Where did the 21,000 rpm come from? seems damn high to me as even race tuned 125cc GP bikes don't get that high and these saws are not tuned to the pipes?

 

From what I know, the saws never had the adjustable H screw carbs and when I spoke to the guy that assembled it, he hadn't done any engine mods to the saws!