Stupid question No 43276

[chris.richard]

If I use a swirl pot header tank, then I don't have any other tank in the system to accommodate volume changes, do I? So what would I do with the pipe draining the throttle body?Is this suitable for anything other than track use?

[Stratos]

Are you are talking water or petrol here?

[chris.richard]

Sorry, water.
(I said it was a stupid question!!):)

[Stratos]

I'm using a standard 164 expansion tank.

The bottom of the tank connects into the pipe going to the V. There are 2 small diameter pipes on the side of the expansion tanks, and I have the 2 pipes from either side of the plenum chamber attached to these.

Why not just fit a standard 164 expansion tank? It has a built-in pressure cap, and all the correct inlets/outlets.

[roger001]

As far as I understand the situation the hot water pipe to the throttle body is purely to warm it up, which is a good thing for a road car ie to help cold start and running, but a bad thing for a competition car which needs cold air rather than warmed air.

I have therefore dispensed with this circuit and have a simple engine-swirl pot- rad-engine setup without any other conections to cause complications.

[chris.richard]

Originally posted by Stratos
There are 2 small diameter pipes on the side of the expansion tanks, and I have the 2 pipes from either side of the plenum chamber attached to these.



Space is part of the problem - I'm looking for amaller solutions!
Two connections to the tank from the plenum? Now I'm confused - Surely the supply to the plenum comes from the cylinder head, then it empties to the tank; see diagram.:confused:

[Stratos]

Chris,

There's loads of space for a std expansion tank. You also have to consider that if you make the expansion tank too small, it will end up dumping water out instead of the water expanding into the space in the expansion tank then contracting when cooling.

On my 12v engine, I'm sure I have 2 connections, one either side of where the throttle is, on the end of the plenum chamber - about where the single one goes on your diagram. Just in case I'm wrong, and I'm confusing you un-neccessarily, I'll go and have a look this evening.

[David May]

If you ever plan on driving in winter (and not only below zero) you will need the throttle body heating. The air expansion at partial opening causes cooling and condensation which ices up the butterfly and the port - then you stop!

Dave May

[chris.richard]

Without the carburettor!:D

[chris.richard]

Originally posted by Stratos
On my 12v engine, I'm sure I have 2 connections, one either side of where the throttle is, on the end of the plenum chamber - about where the single one goes on your diagram.

You're not getting mixed up with the fuel vapour return pipe? See diagram - mind you, if you attached that to your header tank, you'd suck coolant into the intake. Hmm....

[rutthenut]

Originally posted by chris.richard
You're not getting mixed up with the fuel vapour return pipe?

I think that Dave was referring to the 'in' and 'out' connections on the throttle body.

On my car, there is a T-piece connector in/near the Vee of the engine. One part of this goes to/from the heater matrix and a smaller bore pipe connects it to the throttle body. A further pipe comes from the throttle body to the header tank.

That make sense?

[Stratos]

Yes, I checked and I do have 2 connections on the throttle body.

The way it's connected on my car doesn't make sense, because it just comes from the header tank to the throttle body/plenum, and back to the header tank. I was told to do it that way, when I was installing my V6, and, because I knew no better at the time, I just did it without questioning it, and it's remained like that ever since.

Now that we've discussed the subject, I reckon I'll be changing it.

[rutthenut]

Originally posted by Stratos
Now that we've discussed the subject, I reckon I'll be changing it.

I'd recommend doing that - the picture posted by Chris shows the correct routing. This method does provide for additional bleeding of any air in the block, which would migrate up to the header tank.

You could choose to miss out the throttle body from the water circuit, but that does pose the risk of icing as described before.

Do you have a heater matrix at all, or even just a heater feed and return pipe? I've got the latter, with a heater valve, so the plumbing is correct but I have no heating from it!