ausmini :: View topic - What are these bits?

They would draw air from the manifold, compress it and inject it into ports just below the spark plugs on the head into the exhaust. The supplied oxygen would burn off in the exhaust, supposedly improving emissions.

Mick wrote:

did it really pull air from the manifold? it'd always see vacuum there, I'd have thought it'd pull air from the air filter or maybe from a breather via the charcoal canister

They always claimed it burnt the fumes in the exhaust manifold, but without a catalyst that's pretty much a fantasy. All it did was dilute the exhaust with fresh air in the tailpipe so that when tested it was below the required percentage. It did nothing for total emissions apart from adding a bit of load to an already underpowered engine.

Tim

Thanks for all the replies. It seems I have a hose from the rocker cover breather to a breather on the lower back of the block.
Should these be connected together?

Timbo wrote:

The "pollution" heads have 4 pipes from the air pump so I assume one each for each exhaust chamber just after the exhaust valve, where the extra air would help the hot exhaust gas continue burning before it reached the manifold.
I agree that if the fresh air was only added to the tailpipe, it would not improve total emissions, but only one air inlet would have been needed.

Author:	ben23f [ Thu Jun 27, 2019 2:41 pm ]
Post subject:	What are these bits?
Hi All, Just a few random questions - 1. what is this bracket for above the alternator? Attachment: 20190626_144044.jpg 2. What is this bolt plugged hose for on the manifold? My guess is its for water heating/cooling but where does the other end go? Attachment: 20190626_144110.jpg Thanks

Author:	fuzzy-hair-man [ Thu Jun 27, 2019 3:42 pm ]
Post subject:	Re: What are these bits?
My 76 clubby has an air pump for emissions purposes, it looks like yours has been removed, probably explains the blocked hoses as well, I can't remember the exact plumbing.

Author:	simon k [ Thu Jun 27, 2019 3:56 pm ]
Post subject:	Re: What are these bits?
the blocked hose on the inlet manifold is a vacuum line - please please don't connect it to water because it'll go straight into your motor! leave it as is, or find something a bit nicer to block it off with, but it needs to be very well sealed you can safely remove the bracket

Author:	Mick [ Thu Jun 27, 2019 3:58 pm ]
Post subject:	Re: What are these bits?
There was a Pollution Control Air Pump mounted there originally. Not seen very often as they were pulled off and discarded. They would draw air from the manifold, compress it and inject it into ports just below the spark plugs on the head into the exhaust. The supplied oxygen would burn off in the exhaust, supposedly improving emissions.

Author:	simon k [ Thu Jun 27, 2019 4:02 pm ]
Post subject:	Re: What are these bits?
Mick wrote: They would draw air from the manifold, compress it and inject it into ports just below the spark plugs on the head into the exhaust. The supplied oxygen would burn off in the exhaust, supposedly improving emissions. did it really pull air from the manifold? it'd always see vacuum there, I'd have thought it'd pull air from the air filter or maybe from a breather via the charcoal canister

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What are these bits? https://www.ausmini.com/forums/viewtopic.php?f=2&t=98719	Page 1 of 2

Author:	Bill B [ Thu Jun 27, 2019 4:40 pm ]
Post subject:	Re: What are these bits?
simon k wrote: Mick wrote: They would draw air from the manifold, compress it and inject it into ports just below the spark plugs on the head into the exhaust. The supplied oxygen would burn off in the exhaust, supposedly improving emissions. did it really pull air from the manifold? it'd always see vacuum there, I'd have thought it'd pull air from the air filter or maybe from a breather via the charcoal canister "When the gulp valve opens, a small quantity of air is admitted directly into the inlet manifold to lean off the rich air/fuel mixture which is present in the manifold under the conditions immediately following throttle closure. This mixture, having been reduced to a burnable condition, combines with engine inlet charge for combustion in the engine cylinders in the normal way." Leyland Workshop Manual (1978). I guess it is meant to reduce richness on the 'over-run'. The air pump had its own filter so I assume it took air from the atmosphere around it (not from the manifold).

Author:	Mick [ Thu Jun 27, 2019 4:53 pm ]
Post subject:	Re: What are these bits?
Oh! Thanks. I always thought they drew air from the manifold.

Author:	Timbo [ Thu Jun 27, 2019 4:59 pm ]
Post subject:	Re: What are these bits?
They always claimed it burnt the fumes in the exhaust manifold, but without a catalyst that's pretty much a fantasy. All it did was dilute the exhaust with fresh air in the tailpipe so that when tested it was below the required percentage. It did nothing for total emissions apart from adding a bit of load to an already underpowered engine. Tim

Author:	Bill B [ Thu Jun 27, 2019 5:00 pm ]
Post subject:	Re: What are these bits?
For ben23f: check topic: viewtopic.php?f=3&t=97993&start=30#p1042846 photos of all the plumbing for your original setup. It is all a bit academic now; there can't be many minis with all this connected AND working.

Author:	Bill B [ Thu Jun 27, 2019 5:15 pm ]
Post subject:	Re: What are these bits?
Timbo wrote: They always claimed it burnt the fumes in the exhaust manifold, but without a catalyst that's pretty much a fantasy. All it did was dilute the exhaust with fresh air in the tailpipe so that when tested it was below the required percentage. It did nothing for total emissions apart from adding a bit of load to an already underpowered engine. Tim The "pollution" heads have 4 pipes from the air pump so I assume one each for each exhaust chamber just after the exhaust valve, where the extra air would help the hot exhaust gas continue burning before it reached the manifold. I agree that if the fresh air was only added to the tailpipe, it would not improve total emissions, but only one air inlet would have been needed.

Author:	drmini in aust [ Fri Jun 28, 2019 6:47 am ]
Post subject:	Re: What are these bits?
Those 998s were only rated at 30HP which is 4 less than an 850. So you burn more fuel for less power. Air pumps are NLA and they go harder without one, so good riddance.

Author:	ben23f [ Fri Jun 28, 2019 8:32 am ]
Post subject:	Re: What are these bits?
Thanks for all the replies. It seems I have a hose from the rocker cover breather to a breather on the lower back of the block. Should these be connected together?

Author:	gtogreen1969 [ Fri Jun 28, 2019 8:53 am ]
Post subject:	Re: What are these bits?
ben23f wrote: Thanks for all the replies. It seems I have a hose from the rocker cover breather to a breather on the lower back of the block. Should these be connected together? If you connect them to each other the engine crankcase pressure will build up and it may blow a seal. The crankcase breathers should go to either the atmosphere, carby, airbox or inlet manifold through a PCV. Due the the year of manufacture your car also used a charcoal canister between the rocker cover breather and carby. Here are a few engine bays with the Exhaust Port Air Injection (EPAI) system Attachment: 1977 engine bay with EPAI air pump.jpg Attachment: 1977 engine bay with EPAI.jpg Attachment: 1978 engine bay with EPAI.jpg I couldn't find a schematic for the EPAI but here is one for the earlier Evaporative Loss Control (ELC) system. Attachment: ELC schematic.png

Author:	ben23f [ Fri Jun 28, 2019 9:40 am ]
Post subject:	Re: What are these bits?
Thanks for the info! I might need to do some plumbing work on the weekend! I believe the larger hose connection on the top of my SU carby is to connect to engine breather system but it is blocked off. What is the effect on performance of having this blocked versus connected to the breather(s)? I don't know much about my engines history but the emission control gear has been removed from it.

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Author:	Timbo [ Fri Jun 28, 2019 9:43 am ]
Post subject:	Re: What are these bits?
Bill B wrote: Timbo wrote: They always claimed it burnt the fumes in the exhaust manifold, but without a catalyst that's pretty much a fantasy. All it did was dilute the exhaust with fresh air in the tailpipe so that when tested it was below the required percentage. It did nothing for total emissions apart from adding a bit of load to an already underpowered engine. Tim The "pollution" heads have 4 pipes from the air pump so I assume one each for each exhaust chamber just after the exhaust valve, where the extra air would help the hot exhaust gas continue burning before it reached the manifold. I agree that if the fresh air was only added to the tailpipe, it would not improve total emissions, but only one air inlet would have been needed. I stand corrected. My understanding was that by the time the exhaust gas had left the combustion chamber, the fire had gone out so there was no ignition source within the exhaust port. It turns out that its not combustion as such, but rather thermal oxidation (a chemical combustion reaction, without the flame) that can occur if the exhaust gas is hot enough for long enough. According to this source, it is difficult to do in a small 4 stroke, but if it can be made to work, it can substantially reduce emissions. Apparently it makes the exhaust pipe extremely hot. I suspect that in the mini the conditions were not ideal, but it might have had some effect. Not as much as the catalytic converters that Rover eventually fitted to the UK production though. Tim