Vehicle exhaust extraction.

[Chris152]

We sometimes need to adjust a petrol engine in our single garage which, of course, fills with exhaust fumes, even with the garage door wide open. We've been looking into some kind of diy exhaust setup to feed fumes outside, through the wall.

The ones we see online are attached to or right over the exhaust, but we wonder if the reduced air pressure that creates will affect the running of the engine - mostly, it's 2 stroke engines. So any thoughts on that would help.

Rather than setting it up to take direct from exhaust pipes, we thought perhaps just set up a large cowl a foot or so from the exhausts with something like this attached:
https://www.machinemart.co.uk/p/clarke-cam200b-8-ventilator/

That one has 1500 m3/h - is that overkill or too little? And how much noise does this type of fan make - we need to be able to hear the engine running reasonably well.

Thanks for any thoughts,
Chris

 

[Spectric]

mostly, it's 2 stroke engines

So really bad fumes due to the oil content, and very influenced by exhaust systems so just some box arrangement to keep the fumes away from yourself. What is the application, horticulture or motorcycle ?

 

[paulrbarnard]

So really bad fumes due to the oil content, and very influenced by exhaust systems so just some box arrangement to keep the fumes away from yourself. What is the application, horticulture or motorcycle ?

My guess is motorcycles and tuning expansion chamber exhausts. Had fantastic fun with that in my younger days.

Use a flexible pipe at least twice the diameter of the exhaust so that it can suck in plenty of air past the exhaust and you should not have a noticeable impact on the exhaust and inlet tuning. I wouldn’t want to risk the fumes not going outside.

 

[Chris152]

That's great, thanks both. Yes, 2 stroke motorcycles, and the lad's plan is to work on them long term so yes, we need to get something working properly. Air past the exhaust sounds good, we'll have a go at that, and try boxes to see how that works. I suppose the advantage of 2 stroke is you can see and smell if the extraction's working properly!

How about the fan I linked to - I'm happy to get a larger one if that's what it takes. And what's the noise on them like?

 

[Chris152]

My guess is motorcycles and tuning expansion chamber exhausts. Had fantastic fun with that in my younger days.

He loves them - he's working on a Suzuki RG250 at the moment, and always fiddling with the Kawasaki KMX 125 that he uses daily for road and for hillclimb events, trying to get the most he can from it before moving up in power. He's doing welding and fabrication at college, and really interested in building 2 stroke exhausts, but not there yet! I've looked at it briefly with him, and it's way too complex for me.

 

[paulrbarnard]

He loves them - he's working on a Suzuki RG250 at the moment, and always fiddling with the Kawasaki KMX 125 that he uses daily for road and for hillclimb events, trying to get the most he can from it before moving up in power. He's doing welding and fabrication at college, and really interested in building 2 stroke exhausts, but not there yet! I've looked at it briefly with him, and it's way too complex for me.

Expansion chambers are surprisingly complex. I built loads of different variants for one engine while looking for the best power delivery for a two stroke grass track bike. My brother was a rider in a single engine class competition where there were no restrictions on how you modified the engine. It was quite amazing what could be achieved, including a few explosions
You can really make quite significant changes to power characteristics of the engine just by changing angles, lengths and diameters of the sections. I used a set of guides created by a racer/tuner Alf Hagon. I actually had one of his engines which was a work of art in terms of lightening, strengthening and tuning.

 

[Chris152]

Expansion chambers are surprisingly complex. I built loads of different variants for one engine while looking for the best power delivery for a two stroke grass track bike. My brother was a rider in a single engine class competition where there were no restrictions on how you modified the engine. It was quite amazing what could be achieved, including a few explosions
You can really make quite significant changes to power characteristics of the engine just by changing angles, lengths and diameters of the sections. I used a set of guides created by a racer/tuner Alf Hagon. I actually had one of his engines which was a work of art in terms of lightening, strengthening and tuning.

That's exactly the kind of shenanigans he's obsessed with! As I write, he has the RG running, it's a great sound. I'll get him to have a look at Alf Hagon. I think there are now programmes that calculate volumes etc, and even adjust them as you drag to pipe to the shape of the bike.

 

[paulrbarnard]

That's exactly the kind of shenanigans he's obsessed with! As I write, he has the RG running, it's a great sound. I'll get him to have a look at Alf Hagon. I think there are now programmes that calculate volumes etc, and even adjust them as you drag to pipe to the shape of the bike.

Yes times have moved on from dog eared bits of paper being passed around to full 3D dynamic modelling.
This kind of ‘fiddling’ is a great start to understanding how things work which will last a lifetime.
Your right to make sure of exhaust extraction. It’s easy to leave yourself open to problems later in life. Also make him wear ear defenders when the engine is screaming. That’s something you only get one set of too.

 

[Chris152]

Thanks Paul, I try to be the H&S person around here, I can't really help with the work apart from holding things, but clearly health matters above all else. And I'm not sure he's been wearing ear protection tho he has it - I'll remind him.

 

[Spectric]

and really interested in building 2 stroke exhausts,

They have always been a complex part to get right, the metalwork involved in getting a cone to also curve as it leaves the ports can be real fun. I grew up in the days when strokers were common and garages all had two stroke oil dispensers on the forecourt. The bikes were great in straight lines but could be somewhat lively when it came to handling and the sound of a two stroke tripple is amazing. I spent hours with rotary burrs working on the ports, making crankcase stuffing plates and then getting the exhaust to function at the right Rpm. One of my college projects for electronic systems engineering was a capacitor discharge ignition system for a two stroke based around an 8051 cpu that was also multispark to help get the mixture to burn without misfires at high rpm.

a set of guides created by a racer/tuner Alf Hagon

Also don't forget another two stroke wizzard, the late Roy Bacon.

 

[Jameshow]

Yes times have moved on from dog eared bits of paper being passed around to full 3D dynamic modelling.
This kind of ‘fiddling’ is a great start to understanding how things work which will last a lifetime.
Your right to make sure of exhaust extraction. It’s easy to leave yourself open to problems later in life. Also make him wear ear defenders when the engine is screaming. That’s something you only get one set of too.

WHAT DID YOU SAY!

 

[Chris152]

.

 

[Chris152]

They have always been a complex part to get right, the metalwork involved in getting a cone to also curve as it leaves the ports can be real fun. I grew up in the days when strokers were common and garages all had two stroke oil dispensers on the forecourt. The bikes were great in straight lines but could be somewhat lively when it came to handling and the sound of a two stroke tripple is amazing. I spent hours with rotary burrs working on the ports, making crankcase stuffing plates and then getting the exhaust to function at the right Rpm. One of my college projects for electronic systems engineering was a capacitor discharge ignition system for a two stroke based around an 8051 cpu that was also multispark to help get the mixture to burn without misfires at high rpm.


Also don't forget another two stroke wizzard, the late Roy Bacon.

I think it's a combination of what you describe that he likes about 2 strokes, the twin he has at the moment sounds amazing even to me, and I really don't like motorbikes. (Well, I don't like him riding them.) But the liveliness is the main thing, he was at Shelsley Walsh recently and managed to beat the time of a Hayabusa up the hill - that was all down to lightness and agility, his 125 has none of the speed. I'll add Roy Bacon to his reading list

 

[imageel]

This reminds me of a mate who restored an Ariel Arrow back in the day, the twin exhaust pipes were completely clogged and the only way he could get the oily baffles out was to chop the pipes in half. Seeing as the aluminium end casting when inverted, fitted the now shorter silencer he re-assembled the silencers with this modification and inadvertently found he had now tuned the exhaust and not only did it sound superb but it performed like a rocket..!

 

[Spectric]

This reminds me of a mate who restored an Ariel Arrow back in the day

That bike is a sad reminder of just what could have been for the British motorcycle industry and british engineering overall as we often had the technical expertise but lacked the marketing and production side. The ariel leader came first and then the arrow, both used one of the first two stroke two cylinder engines to hit the market and it has been said they were a forerunner to the Japanese invasion of two strokes, so why did we not keep up ? Also don't forget Ariel also had a four stroke overhead cam square four engine back in 1930, this would have been years ahead of any major competition from the japanese or Italians.

If you want a really quick two stroke bike then look for an RG500 Suzuki 4 cylinder but in race trim, the acceleration is mind blowing.

 

[Chris152]

If you want a really quick two stroke bike then look for an RG500 Suzuki 4 cylinder but in race trim, the acceleration is mind blowing.

Don't encourage him - have you seen the price of them these days?!
He's on about an RGV 250 once he's old enough to do his full licence, not quite as bad on price. As it is, he can't ride the rg250 on the roads he's working on as it's slightly over the power band of an A2 licence.

 

[Spectric]

Yes the licenses are all different today, we had it easy in that anything upto or looking like a 250 was ok but that did spawn some very imaginative bikes and of course back then no speed camera's !

The KH250 with the KH400 engine, the 250 Honda wet dream became a much better bike when it had the 400 engine merged into it and there were other specials people built. The prices are now amazing, £12,000 plus for a Kawasaki Kh750 and even the old GT750 kettles are making eye watering amounts.

 

[ChaiLatte]

That one has 1500 m3/h - is that overkill or too little?

An engine is a pump. It has a displacement and an rpm. The flow rate can be calculated from that.

It might be prudent to put some sort of atmospheric monitoring device (maybe a CO monitor as a minimum) in the place. Possibly the kind of monitor one would use if proposing to enter a confined space. If that goes off when you are working, your extraction system is not working properly.

The fan does not need to be connected within hearing distance of the suction pipe. When you have your septic tank pumped, the vacuum pump stays on the lorry and they run out 20m of hose into the tank.

 

[Chris152]

First three on here - eye watering.
https://www.carandclassic.com/cat/15/96/rg500/

 

[Chris152]

An engine is a pump. It has a displacement and an rpm. The flow rate can be calculated from that.

It might be prudent to put some sort of atmospheric monitoring device (maybe a CO monitor as a minimum) in the place. Possibly the kind of monitor one would use if proposing to enter a confined space. If that goes off when you are working, your extraction system is not working properly.

The fan does not need to be connected within hearing distance of the suction pipe. When you have your septic tank pumped, the vacuum pump stays on the lorry and they run out 20m of hose into the tank.

When I was working with wood, I had my dust extractor in an mdf box with baffle and exhaust to outside - so we could put the fan/ extractor in a box by the wall, and have a pipe run to the exhaust?

eta - I'd not thought of a monitoring device, we'll definitely do that. Thanks.
He won't be running it inside for long, just short periods - he can take it outside to warm up etc, and just start it up inside once he's ready to make any adjustments.