Howdy,

When installing a front-drive package in a mid-engine layout, keeping the radiator up front, you have to run more footage of plumbing. Has anyone ever had to run a "booster pump" to retain proper water flow?

TIA

Ron, with Steve and myself using MR2...ie. already mid-engined...then that only leaves KB who may have an answer...

My guess would be no...

Really hard to say since we have no way of knowing what minimum flow is required, and how much over that amount the pump supplies. And of course each added bend adds a restriction.
A variable which works in your favor is that if you use metal tubing, it acts like an additional radiator, plus I suspect us mid-engine people probably have much better air flow through the radiator since there's no engine blocking the exit. So I think that means you need less flow for the same amount of heat removal.

Anyway, theoretically yes I suppose larger pipe is needed... how much bigger is the unknown. Showing my excellent engineering talent I used 1.25" aluminum pipe, matching the original radiator hoses... giving no thought at all to the additional length I was introducing. In hindsite it *may* have been wise to go up to 1.5" for the main runs with 1.25" adaptors at the ends. I say "may" because I won't know if I'm a goof or brilliant until I take it out on the street. Of course I had very little spare space in the center tunnel for going to larger pipes anyway...

I used to work in the irrigation industry, if you use larger diameter pipe to run to the rad in the front (1.2-1.5x) the restriction will be less making your stock water pump more than sufficient.
it will take longer to warm up though.

Not if the thermostat is doing it's job circulating the water inside the block until it comes up to temperature.

with the increased volume in the largeer lines, the thermostat will open and move cold coolant into the block, which can cause the thermostat to close again, restarting the cycle untill its completly up to temp.

common thing to happen with rotary engines in a mid or rear engine application, (smaller amount of coolant chamber volume in the rotary block)

on a V6 It won't likely be a problem.

i would've assumed in my ignorance that the thermostat would ideally open slightly at first to allow a trickle of cold water into the newly warmed engine, rather than flooding it with cold straight away! did no car manuf every sort this?!

Sounds like if I keep eye toward efficient plumbing it just may work.

Thanks guys!

Guys,

Normally, a thermostat's job is to ensure the block retains 'cold' coolant until it needs to be released hot (this temp is determined by the thermostat setting) out of the block/head to the radiator, where it is cooled and returned the block.

I've never heard of a thermostat working the oppostite way round from this, unless someone knows something I don't...


Steve.

That's what I was trying to say...

I'm talking about problems guys have had from sticking watercooled engine in a beetle, the amount of coolant in the lines running from front to back was so much that when the thermostat opened the hot water in the block mixed with the cool water, cooling it off, and the thermostat closed again

the solution one guy had for this problem was to drill a small hole in the thermostat, this allowed some water to flow graddually heating the entire system, so that when the thermostat did open there wasn't a sudden surge of coll water snapping it shut again.

From what I understand about using water coolers in VW's is that the main problem has been more to do with the extra capacity overfiling the expansion bottle.
When engine and system get hot the original size expansion bottle is not large enough due to extra system capacity. This then overflows causing concern if noticed. This means that when the system cools down there is insufficient coolant to go back into the system.

I have never heard of the extra capacity causing problems for the water pump. It may not last as long as originaly, but it would hardly be noticable.

Terry

Well, the Libra system, as a concept, is a bit rough - but it does work.

In stock form you use the Rover Metro radiator (design for a 100hp 1.4) and you can at a pinch, run this with an unmodified 2.5 V6. It is joined by two long alloy pipes running down the centre tunnel. GTM retain the use of the Metro thermostatic switch in the rad, which means the system is a bit slow to respond, but it can cope.

We're using a custom three core rad and I'm going to rig in the PWM fan control from the engine management to control a solid state relay driving the fans.

The other key design issue with this is the ability to bleed air out of the entire system - the Libra heater takeoffs are very high which means it is very easy to get an airlock. I have three bleed screws in our system - one supplied in the rad, one I put in next to the heater because I knew it would be useful to see if there was air there, and a third as a drain at the lowest point.

Good luck with your design - I would say keep these things in mind for trouble free use and good flow:
1. Make sure your pipe internal diameters are consistent.
2. Maximise the radius of 90 and tighter bends.
3. Try to keep your heater matrix as low as possible.
4. Use the best quality hose clips you can afford, and make sure they're tight - choose to either do up none of them or all of them as you go. I left four of the most unaccessible ones partly done on our car, and got wet when we filled the system.
5. Drains and bleeds are very, very, very good ideas. Use you head when locating them.
6. Use Water Wetter - it's brilliant - but only after you've leak tested your system!

Mark.

(Engine cranks, but does not spark yet. Got some wiring to sort out...)