34 replies to this topic

[eriksher]

hi. gotta problem.
installed stage1 with heated inlet manifold.
but heater hose is much bigger in diameter than copper tubes on manifold.

what is solution?

[taffy1967]

You don't really have to connect it up?

[karl & his cooper]

You don't really have to connect it up?

Ok but what if I reallly reallly wanted to lol

[Broomer]

meh i wouldnt bother.

[Kerrin]

Mini spares do a hose adaptor from 1/2" (older minis) to 5/8" (newer minis).

Get one for each side and also a short length of 1/2" heater hose to fit on the manifold copper pipe, fit adaptors, fit hoses. sorted.

You should be able to get 1/2" hose from local motor factors, also dont forget you will need 4 more jubilee clips for the new pipes.

Or if you can find a MG metro/cooper inlet manifold the pipes will be right, but the manifold will probably need grinding down to match the exhaust flange thicknes.

However the concensus of opinion is dont bother connecting them up.

[panelbeaterpeter]

What make manifold have you got? Mine fitted fine.

[Dan]

Personally I'd always say connect it up. Hose size adaptors are avilable from most car tuning suppliers and a lot of auto electrical places.

[Strontium Dog]

Don't bother to connect it, it will only rob power and is one of the first easy cheap mods to do to any car for better power.

If you live in the Arctic you might miss it but not if you live in Blighty. It was installed to help get the car off choke quicker to aid economy marginally if you do lots of start ups and then short runs!

[Dan]

More myths and half truths....

[Ethel]

A water heated manifold is never going to get warmer than the engine that heats the water - that's why they're used on 'performance' engines in preference to just heating the inlet directly from the exhaust.

Plumb it in, you won't be able to notice the minimal power loss even if your inlet is 10 to 15 degrees warmer than optimum for power. You'll certainly notice the poor running and loss of power as it struggles to warm up, not only in winter. If the manifold pipes are copper you may find some 15mm copper plumbing pipe is a close enough fit to solder over it.

[Strontium Dog]

Now without getting too technical that's just not right.

It is down to rarifiying the intake charge and the manifold does not get as hot as when it is heated. Even when only water heated.

I run turbo cars and measure inlet temps and in that situation it is vital that you do everything you can to reduce inlet temps so water heated manifolds are out. What do you think we fit intercoolers for? As I said before the only possible reason to heat the inlet is to reduce the time that mixture enrichment is required from cold start. You might not notice much difference but a dino will show it and it could easily be a couple of horsepower even on a low powed engine like the A series!

[Strontium Dog]

More myths and half truths....

Oh yes and what part is a myth and which part is only half true? I've been doing this for 20 odd years and I don't know a tuner that would want to heat an inlet manifold!

[Ethel]

Lower inlet temperatures to a certain point yes...

You could probably squeeze out a bit more power on an injection engine or with a very high boost turbo. For a road going car, particularly one with a carburettor, having the inlet in the mid 70's celsius will help vaporise the fuel properly for maximum power. Bear in mind, at full throttle, the air will pass through the inlet pretty quickly and not pick up much heat. At part throttle the manifold depression will have a noticeable cooling effect and fuel is more likely to drop out on to the manifold surfaces since that's where it will get past the throttle disc.

A responsive (fast) road car isn't one that produces the most power; it's the one that produces the most torque when you put your foot down.

[Strontium Dog]

Funnily enough a few molecules of fuel adhering to the inlet tract walls is just exactly what you want. Fluid dynamics 101. The least resistance to flow will be caused by the fuel molecules slipping past each other and not from slipping over alloy molecules! The same as why you don't want a polished port but a matt finish.

Of course, personally, I like to extract all the power I can get especially for free. Pounds per bhp then not connecting the heated manifold pipes is a clear winner. If a rough idle at cold is a problem for you and power is not your goal then by all means heat away!

Just one more point. How hot do you think the coolant in your engine is. I think you'll find it is a bit hotter than 70 deg. That's why the cooling system has a pressure cap. Without one the coolant would boil around the cylinders and the engine would meet an early end.

Edited by Stronteum Dog, 19 July 2008 - 09:50 PM.

[Ethel]

That'd be great if the fuel stayed there (though an air meniscus works the same) sadly as you vary the pressure and temperature in the manifold it will vapourise and play havoc with your fuel/air ratio.

I'm happy to follow the lead of major motor manufacturers with multi million pound R&D budgets, if they put water heated manifolds and even thermostatic bypass valves on their intercoolers then I'm inclined to think controlling the inlet temperature rather than going all out to minimise it is a good idea on an engine that sees a wide range of operating conditions, like your average road going Mini.