18 replies to this topic

[DUF2]

My Riley Elf has in the past been fitted with a 1988 A+ 1275 Metro engine. I need to replace the heater hoses. Currently the heated manifold is not piped into the cooling system.
I'm looking for opinions on whether to connect the heater pipe via the manifold as it would have been when the engine was in a Metro.
On one hand, I'm thinking BL thought the engine would be better with a heated manifold.
On the other hand, I was always lead to beleive that the colder the inlet air the better.
I look forward to comments and advice

[Cooperman]

A heated manifold is really only of use in extremely cold climates.

BMC never put heated manifolds on the Mini. If there is a risk of carb icing it is different, but that is not why the Metro had a water heated manifold. It was for quicker engine warm up and alleged better performance when driving off from cold, or so I was told, but others may believe differently.

[hhhh]

 

BMC never put heated manifolds on the Mini.

 

?

 

Only ever single carbed Mini they produced had an exhaust heated manifold, and they were heated much more than the ones typically used as replacements which are water heated.

[cal844]

As Cooperman's says, not needed in current climates(currently -6 overnight in Scotland 😁)

Edited by cal844, 15 December 2017 - 09:48 PM.

[skoughi]

How much is the engines performance reduced, b.h.p., torque and m.p.g, if a water heated manifold is plumbed in? Also does it get to a certain point that it's actually a water cooled manifold as the coolant flowing through it must help to reduce heat being transferred from the cylinder head and neighbouring exhaust manifold?

Edited by skoughi, 15 December 2017 - 10:13 PM.

[nicklouse]

the reason for it is purely one of improvement on the fuel economy. when they went from the one piece cast manifold to a cast exhaust and a separate cast inlet the economy dropped a little which is why the heated manifold was brought in.

 

also not the interior heater worked differently which meant that there was always a water flow through the manifold. not so on a Mini.

 

there is no need or point in connecting them up.

[skoughi]

So it doesn't reduce the engines performance then? If as you say it has a constant flow of coolant through it then it could lead to an improvement in fuel economy?

Edited by skoughi, 15 December 2017 - 11:20 PM.

[Retroman]

Nicklouse is right and I would never connect one, keeps the plumbing simpler... put the heat into the heater not the manifold.

 

Vizard p135 8.1

The cast type with hotspot you are loosing about 2 1/2 Lb of torque and 1 1/2 to about 4 hp on a 1275 with Hs 4 carb.

 

With a heated alloy manifold not 100% sure on the exact effects other than saying it will be negative from the power/torque side

[skoughi]

Thank you retroman for providing some figures, I'll have a check through the book later at the place you quoted. I'd have thought someone somewhere would have done a simple test on a rolling road with and without the manifold plumbed to see what actually happens.

[absx2]

Interesting debate on this one so just to chuck into the mix.

The factory produced a water heated inlet for the MG Metro that went on to be used on the carbed Coopers.

I try not to go near SPI and MPI mini electrics but do they have a pre heating element somewhere as a lot carbed and early injected cars did back in the day ?

 

It has been proved that the cooler the intake charge the better it is for torque and power but I guess a car used for a lot of short trips would be a little more civilised from cold start with a heated inlet charge.

I can`t see the manufacturers spending unnecessary money on something they don`t need but of course they sell worldwide so maybe every car would have got it weather it was needed of not.

 

If all out performance is not high on the list of priorities I can`t see any reason to not connect it if you have the plumbing as it may or may not improve the manners of the cold engines drivability. 

 

Back in the day i became a dab hand at separating the small bore inlet and exhaust manifolds without breaking through either as that hotspot was definitely a torque killer and when you didn't have a lot to start with every little helps.

 

My Rover cooper with around 85 bhp still has the water heated manifold connected.

[timmy850]

I connected mine up to see how it would go, and I also thought the water flow through the head might be different? 

 

It doesn't seem to make any difference to my 998 engine, I've been thinking of blanking it off again to see what happens. 

 

The other story I've heard is that the tune will be slightly more consistent as the intake air will be a similar temperature regardless of external temp. 

[panky]

The stubs on my manifold are corroded so just by-passed it with a length of 15mm copper tube to keep the coolant flow  through the head as it should be.

[Spider]

Keep in mind guys, this is not a Heated Air Intake, but heated after fuel has been added to the mix. It does make a difference.

 

In regards to any loss of power, while I've not done any tests, I'll say I seriously doubt it. The gases are going through here way to fast at wide open throttle for there to be any heat transfer from the manifold to the gases. In regards to Vizards Tests, he does say the he removed the hot spot, but likewise, he doesn't say what exhaust manifold he was using. When cutting these apart no matter how you try, you will always loose either the Inlet or the Exhaust (or indeed both !!).

 

Warming the Manifold reduces (or eliminates) the cool fuel settling on to and separation of the fuel from the air at low air flows, especially when cold. This will improve low RPM power and give better economy on the cruise as well as increasing engine life from reduced bore wash.

 

My 2 pence - for a road car, connect it up.

[skoughi]

Thank you! I've been thinking that these could even be thought of as "constant temperature manifold" rather than heated or even cooled manifold? The coolant going through the body of the manifold next to where it connects to the cylinder head has to keep down on the transferred heat thus keeping the manifold at a constant temp no matter what loads are being put onto the engine? I'd still like to see the results of a test being done on a rolling road though.

[Kev.jones]

Just turn the heater off to see the difference?