Morris Minor Owners Club

I have just fitted a useful bypass valve so that I can turn the hot water to the heater off whilst maintaining a flow through the Water heated mini inlet manifold which my car Jodie is fitted with.
It uses the solenoid operated valve from a Ford Ka. There are any number of these available new on e-bay.
It fitted quite neatly in the apertures (suitably opened up to rectangular) where the heater hoses passed through the bulkhead.
The solenoid is actuated, to turn the heater off, by a dashboard switch powered from an ignition auxiliary.[frame][/frame]

You get best power by NOT heating the manifold.........

but better economy if you do

metalmagpie wrote:I have just fitted a useful bypass valve so that I can turn the hot water to the heater off whilst maintaining a flow through the Water heated mini inlet manifold which my car Jodie is fitted with.
It uses the solenoid operated valve from a Ford Ka. There are any number of these available new on e-bay.
It fitted quite neatly in the apertures (suitably opened up to rectangular) where the heater hoses passed through the bulkhead.
The solenoid is actuated, to turn the heater off, by a dashboard switch powered from an ignition auxiliary.[frame][/frame]

'Neat', I was wondering how to get round this myself. Especially in v hot weather. Thanks Barrie

'Possibly' better economy - but not necessarily so! The engine will be most efficient with a cold inlet charge - it's a question of whether the slightly better fuel atomisation from the hot inlet in cool weather outweighs the cold charge. I'll be staying cool........ I'm interested to see how one valve can isolate the heater - yet still allow water to flow around the manifold.........

Presumably, and by the look of the valve, when closed it does not shut off water flow but redirects it back to the outlet. When open it allows unimpeded flow through the heater

It's only got two pipes........

No, it has four pipes, two go backward to connect to the heater. The Solenoid valve closes the topmost flow pipe which cuts off the heater but also opens a transfer port which returns the hot water directly back to the head. All fiendishly clever!!

Certainly the volumetric efficiency, everything else being equal, is improved if the air is cooler as the weight of air going in is increased. Presumably the manifold is heated to aid vapourisation and hence improve the balance between the cylinders. The designers must have known what they were doing, or did they?
I know that my tickover goes all to pot after a long hard run so maybe this is to do with heat soak in the manifold?? Have you tried both with and without heat?

Ah right - couldn't see the back pipes. The 'designers' would mostly be concerned with getting good 'emissions' figures - which are stupidly taken at idle........ What % of an engine's revs over it's lifetime are done at 'idle' - will it even be 1% ?? I doubt it!! So - nice warm evaporated fuel at idle = good emissions figure.

so in an ideal world you could fit one before the manifold so when the maifold is warmed up you could turn it "off" and divert the hot water directly to the heater or not as the case might be..

"What % of an engine's revs" quite a lot if you live in or have to travel through a large city.
I just spent 30 minutes at tick over creeping towards the Blackwall tunnel at a snails pace.

barrie102 just needs a flow meter to have the prefect test bed to prove if there are any benefits from water heating the manifold.
Running it on a rolling road would be very interesting.

Just reading through David Vizard's book . It appears that in periods of warm weather, inlet manifold heating is not required. therefore I assume it would be safe and efficient enough to follow a simple guide. 'if you need the heater then so does the intake manifold !'

The engine idles at ~ 500 rpm - but when running along probably averages out at ~ 3000 rpm ?? And most sensible people stay well away from Blackwall tunnel anyway My guess is the engine will spend at least 50 times longer 'running' overall than it will 'idling' - so that's 0.83% idling. I always switch off if I get caught at a traffic light or any other hold up anyway, and when going down hill of course. Most twin carb manifolds don't have any 'heating' - for very good reason!

I ran for a long time without the manifold plumbed in & connected it one winter the difference was immediately noticeable as the engine ran a lot more stable & the choke could come off sooner . little to no effect in the summer though

Sensible or not, London's population was 7,172,000 9 years ago so driving conditions there, and in other large cities are going to influence the actual statistics a lot more than you seem to credit.

"I always switch off if I get caught at a traffic light or any other hold up anyway"
Commendable behaviour, not really practical when traffic lights and hold ups are a LOT more common.

Ive got my water heated manifold disconnected at present but intend to try it in the winter with the water connected or maybe just visit my local scrapyard for a valve as above

That's exactly why I don't drive in cities - if I can possibly avoid it! Train (£1) or bus (free) if going into Glasgow! And I would never ever attempt to drive in London........ I dunno how you can do it !

If one is over 60 it's free, but the car is still more useful in most operations (Tesco for example).
Back to the subject: I suppose that the optimum temperature for the manifold is just below the vapourisation temperature of petrol. This is quite low, 70F comes to mind. So perhaps the manifold heating should be thermostatically controlled to that order of temperature?
I will try that next, using a bypass on the manifold, as there are many times when the heater is needed in warm weather. Last night 20/07/10 is a good example; lots of warm wet bodies get in and the windows fog up instantly.
There must be masses of theory on this subject, nearly all cars had heated manifolds when the A series was designed and I cannot believe it was to improve emissions as these were not even tested then. The A+ was supposed to be the pinnacle of design for the engine as regards power and economy and that had a heated manifold didn't it?

The water heated manifolds came along when emissions became an issue. As I said before - twin carb manifolds are not water heated - for a good reason. You want a freezing cold mixture - dense as possible - going into that cylinder. As it gets compressed - it heats up incredibly (Combined Gas Laws) - so don't worry about it not vapourising! In the case of the diesel (> 20:1 comp ratio) hot enough to ignite the incoming charge of fuel!