31 replies to this topic

[Scoop77]

One of the many things the previous owner put on our car was a new inlet manifold and it appears to have connections fitted to it that I can only think are to flow water through. Am I correct?
If so where should this water come from and go to if I were to plumb it in (which pipe in other words) and why does it have it?
Cheers.

Edited by Scoop77, 10 December 2012 - 01:08 PM.

[Cooperman]

It has always seemed odd that as it's established that the cooler the input charge of fuel/air mixture the better the potential for an efficient burn, why have a water-heated manifold. Sure, the idea of better cold-start running is understood, but why pre-heat the mixture and thus reduce its efficiency when the engine is operating at normal temperature? After all, the choke or auto-enrichment device is there to compensate for a warm engine at initial start-up.
Most people who want to optimise engine performance by-pass the manifold with the water pipes and just ignore the hose stubs.
What a contrast to those who fit a 'cold-air box to gather the induction air from a cooler area than behind the engine.

[Ethel]

If it has 2 connections of about 12 to 15mm diameter that only connect to one another then you'll be right. Most inlets on road cars are heated: water is an improvement over just combining them with the exhaust as the temperature is better controlled.

If you plumb it inline with the heater you'll be able to turn it off, when neither you, or your engine, want more warmth.

[KernowCooper]

Yes mate its correct and the pipes are usually plumbed into the heater pipes left clutch side in and out from right side (from Front Of Car) to heater in pipe on the bulkhead. Some run it ( I Do) and some dont, see vizards book for the full info.
its also discussed here on the forum http://www.theminifo...inlet-manifold/

[sledgehammer]

Yep - they are to connect into the heater pipe - the manifold is heated by the engine coolant

a lot of people do not connect the pipe - saying it reduces performance - by heating the inlet air / fuel charge ^^ as above

I always pipe my ones up -

as in the summer - when inlet doesn't need any heat - the heater circuit is switched off by the cable so no heat to the manifold pipe

the additional cool water in the pipe 'may' keep the inlet manifold cooler in summer for a while

in winter the heater is used so water flows thru the pipe & warms the inlet air a bit - this can help when very cold

If I were you I would pipe it up without cutting any pipes (just add a small piece of pipe) - and see if the performance reduces -

- I don't think you will notice any difference in a road going std car

the original mini manifold had the exhaust manifold attached to inlet , to create a 'hot spot'

[Scoop77]

A correct assumption then. Thanks.
Why, was my second question but then I remembered that even now on my Civic type R they run hot water through the throttle body. Bypassing it is a common thing to do though.
I think I will connect for the colder months and bypass for the summer.
Thanks gents ;)

[SolarB]

I was always lead to believe that heating the manifold keeps it at a (reasonably) consistent temperature and this should make your rolling road results and set up more applicable throughout the year.

Intake manifold temperature affects the way the atomised fuel behaves. It the manifold isn't heated maximum and minimum temperatures throughout the year would be wildly different. With a heated manifold the temperature swings are much smaller.

[Gulfclubby]

This was never designed to help with cold starts. Unless you have a habit of heating up your water first before you start the cold engine. It was however designed to help with running in extremely cold temperatures and to prevent carb freezing. How effective it was at that is an entirely different story. I don't have mine plumbed up, as I don't drive in the winter time anyway.

[jaydee]

I was always lead to believe that heating the manifold keeps it at a (reasonably) consistent temperature and this should make your rolling road results and set up more applicable throughout the year.

Intake manifold temperature affects the way the atomised fuel behaves. It the manifold isn't heated maximum and minimum temperatures throughout the year would be wildly different. With a heated manifold the temperature swings are much smaller.

Very true, its also a design that helps fuel atomization improving fuel economy and emissions, at obviously the cost of performance (wont be noticeable on a road car though, on a performance car, just dont connect it).
It wont help against carb freezing, as it happens in the venturi so way before the manifold. The manifold and the carb are insulated and even with a hot manifold the venturi will be freezing cold.

[SolarB]

It was however designed to help with running in extremely cold temperatures and to prevent carb freezing. How effective it was at that is an entirely different story.

I was never convinced by the carb. freezing explanation for heating the intake manifold. How a water heated manifold can heat a carburetor that is upstream of the manifold and insulated by a plastic mount with only four small bolts to conduct the heat is puzzling.

[AVV IT]

I don't think that anyone is claiming that it helps to actually start the engine when cold. In my experience what plumbing in the inlet does is to aid smoother running more quickly after start up. After all the standard inlet is joined/cast to the standard exhaust manifold and therefore is heated by way of conduction of heat from the manifold. As aftermarket inlets are completely separate to aftermarket exhaust manifolds, the only heat comes from that conducted from where it joins to the head and convected heat that rises from the exhaust manifold below.

So if you use your car regularly over the winter then it's worth connecting your inlet up. But if your car only comes out in the summer months, or you're obsersed with cold induction because you're running a highly tuned monster, then it's probably not worth doing.

[Dan]

People confuse fuel condensation with carb icing as at first glance the effects of the two seem similar. Heated manifolds prevent fuel condensing on the inner surface, they do nothing to prevent carb icing (the manifold should be isolated from the carb anyway). Air has a poor thermal conductivity, the freshly refrigerated and fast moving inlet charge will not be significantly (or even detectably) heated in the small time that a small proportion of it is in contact with the warm aluminium.

[Scoop77]

Blimey. Thanks or all the info.

[finch661]

have a look here
http://www.minimag.c...read.php?t=1354

[Jamie_RoverMini35]

the heated inlet is to stop the fuel from "sticking" to the insides of the inlet manifold if you get what i mean