Hotspot under the throttle butterfly: why??
Discussion
ed_crouch said:
Can anyone think of a reason why I shouldnt unplumb the silly coolant-heated bit underneath the throttle butterfly? All it seems to do is heat the charge air, hence rob a couple of horsepower, and make the coolant plumbing messy.
Anyone got rid of it??
Ta.
Ed.
You still have it plumbed in? Get rid, straight away! Anyone got rid of it??
Ta.
Ed.
(Just disconnect the two pipes that feed it, and connect them to each other or blank them off.)
Rightydoke. Sorry they're so EFFING huge, but if I make them avatar sized, you'l not be able to see the detail!! Veneer pic is worth clicking for a full size one.
coolant hoses going into hotspot by under throttle disc:
Pic of underside of throtle assy: hotspot casting can be seen here:
Camera seems to have focussed on my no3 injector plug: sorry!
And some other crud Im worling on at the moment. Anyone like me door strips?? No?? OK... Made 'em myself. Can yer tell??
Also fitting new carpets, hence interior is GUTTED! Even the heater box is out. Radio/centre console frame is a joke, so making one out of sheet aluminium...
Ed.
P.S. bet the pics dont come out...
coolant hoses going into hotspot by under throttle disc:
Pic of underside of throtle assy: hotspot casting can be seen here:
Camera seems to have focussed on my no3 injector plug: sorry!
And some other crud Im worling on at the moment. Anyone like me door strips?? No?? OK... Made 'em myself. Can yer tell??
Also fitting new carpets, hence interior is GUTTED! Even the heater box is out. Radio/centre console frame is a joke, so making one out of sheet aluminium...
Ed.
P.S. bet the pics dont come out...
Edited by ed_crouch on Tuesday 5th June 22:12
Edited by ed_crouch on Tuesday 5th June 22:19
Edited by ed_crouch on Tuesday 5th June 22:27
Edited by ed_crouch on Tuesday 5th June 22:28
...& are those the sill cover bolts? coz I think I've only got one It was to provide local heating to help fuel vapourisation under extrmely cold conditions. As in, about -50C.
You can disconnect the pipes as said, or you can unbolt and remove the hole unit. If you do that, you'll need to put two short bolts (with thread sealant) back in to the inboard mounting holes as they are drilled right through into the plenum and will allow unmetered air in. Result, car won't run. Guess who found out the hard way
Trouble was I'd done a few other jobs at the same time so I had to go back through everything (twice) before it dawned on me.
One side-effect of removing the heater casting is that you can get the nearside rocker cover off without disturbing the plenum. It also allows you better access to two of the injector plugs.
You can disconnect the pipes as said, or you can unbolt and remove the hole unit. If you do that, you'll need to put two short bolts (with thread sealant) back in to the inboard mounting holes as they are drilled right through into the plenum and will allow unmetered air in. Result, car won't run. Guess who found out the hard way
Trouble was I'd done a few other jobs at the same time so I had to go back through everything (twice) before it dawned on me.
One side-effect of removing the heater casting is that you can get the nearside rocker cover off without disturbing the plenum. It also allows you better access to two of the injector plugs.
Wedg1e said:
One side-effect of removing the heater casting is that you can get the nearside rocker cover off without disturbing the plenum. It also allows you better access to two of the injector plugs.
Wedgie - thanks for that tip - that has pi55ed me foo for quite some time... like everytime I adjust the tappets I have to lift off the plenum top 
I just had to go out to the car park to check mine. Of course someone has already chopped the throttle off the plenum. No hot spot on it, but you can still see the short bolts to seal the holes.
Unfortunately I still can't easily get that rocker cover off - the supercharger is in the way ;^)
Unfortunately I still can't easily get that rocker cover off - the supercharger is in the way ;^)
It's not just vapourisation problems that happen, there are problems with icing up.
When you have cold wet weather and drive on low throttle the act of forcing this air through a small orifice will supercool it as it expands on the other side of the gap so it may get below zero. This can cause a local build up of ice that may stop the throttle closing fully.
That is why this lot is built around the throttle disc.
When you have cold wet weather and drive on low throttle the act of forcing this air through a small orifice will supercool it as it expands on the other side of the gap so it may get below zero. This can cause a local build up of ice that may stop the throttle closing fully.
That is why this lot is built around the throttle disc.
Thanks TVR3X 
also.
That now gives me 2 choices.......
1. Take off said item for plumbing simplicity and ease of maintenance, but risk a frozen throttle on a cold winters morning.
2. Leave it in place but plumb it into the heater piping so it keeps it warm in winter when the heaters on, but not in summer when it's off.
Hmmmm? what to do?
also.That now gives me 2 choices.......
1. Take off said item for plumbing simplicity and ease of maintenance, but risk a frozen throttle on a cold winters morning.
2. Leave it in place but plumb it into the heater piping so it keeps it warm in winter when the heaters on, but not in summer when it's off.
Hmmmm? what to do?
TVR 3X said:
It's not just vapourisation problems that happen, there are problems with icing up.
On carbs, but have you ever known that to happen with EFI? The evaporative cooling happens a long way downstream and I can't see it producing enough of a cooling effect this far back to cause any trouble. It's not a problem I've ever experienced or heard of happening with EFI, and there are an awful lot of TVRs pootling about through the winter with the throttle body heater disconnected.I suspect that those who drive V8 wedges in icy conditions have a telepathic relationship with the back end and can tell in advance when its going to depart, hence will use similar superpowers to telekinetically de-ice the throttle plate.
All done at a pace approaching the speed of light, whereupon time dilates, leaving plenty of time for thinking about gears, heel-and-toeing etc...
:-P
Ed.
All done at a pace approaching the speed of light, whereupon time dilates, leaving plenty of time for thinking about gears, heel-and-toeing etc...
:-P
Ed.
adam quantrill said:
D1 MAD said:
Hmmmm? what to do?
3. Leave it in place but put a stop valve in series, so you can have it on in winter only.
However in reality, by the time I get around to sorting the exhaust and putting her back on the road I expect global warming will have taken care of any icing up risk! 
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