The V8 Owners Forum -

Does anyone know what the function of these ports are on Rover heads?

Most heads you look at have these areas as large flat 'blanks' - i.e. they look like they were designed with a purpose, but were never drilled/tapped.

The engine pictured is a 4.6 that I bought from someone - originally put together by V8D.

There are 4 of these (circled) on each head directly above the exhaust port.

Someone told me a story at work a while back about an old Land Rover engine (inline 6 I think) that used to have a problem with overheating exhaust valves - that had air blown on to them to cool - not sure if this is a similar thing from the past?)



http://thumbsnap.com/NMyBGY0A

my dads old carb'd 3.5 v8 in a rangerover had some sort of emissions control gubbins on it that recirculated exhaust gases somehow through those ports. i cant remember how it works but i know when the little pipes broke it sounded awful.

They're air injection ports for emission control.

That makes sense I guess. So you inject fresh air to weaken the exhaust gas - and pass emissions - nice solution. Not sure that's quite the point, but I guess it got them past the tests!! Was this for the US market?

Secondary Air Injection - indeed a US market device.

Chris.

I think I have a pair of those in the shed. Kiwi told me about the air injection for them. Seems to be a sneaky cheaty way of getting emissions down eh

But if it works it works I suppose. I guess these would make a neat way of tapping egt sensors in??

[quote="spratty"]my dads old carb'd 3.5 v8 in a rangerover had some sort of emissions control gubbins on it that recirculated exhaust gases somehow through those ports. i cant remember how it works but i know when the little pipes broke it sounded awful.[/quote

]

Jep i had the same on my 3.5 it blows exhaust back into the intake.

When the secondary air system on my Audi was playing up, turning on the engine warning light, the boss of the prestige Audi garage I visited told me that the tiny little secondary air pump pressurised the induction system heating the engine up quicker. When I asked him what the two turbos were doing at the time, he didn't have an answer He also couldn't tell me how pressurising the inlet manifold could warm up the engine quicker. I don't go there any more.

It turns out that on starting the engine the mixture is richened up, and some unburnt fuel can be found in the exhaust. The secondary air system injects air into the exhaust causing a second burn, and this heats up the cat(s) quicker. As we all know cats don't work well until they reach a certain temperature, so heating them quicker gets them working sooner, and also disposes of unburnt fuel, so a double winner on emissions.

That's how I understand anyway.

Richard

Very early form off exhaust gas recirculation system that has a valve which opens on a vacuum and the engine sucks the exhaust gas in to re burn the gas making it cleaner