Hot under the bonnet
 

Hi everyone,

I'm getting the hang of this posting lark and it's an ideal pastime for my insomnia problem too!
Strikes me that a lot of SVX problems stem from the high under bonnet temperatures. I have had to repair the alternator wires (insulation gone brittle), the MAF/AFM terminals and the power steering pump O rings etc. In pursuit of a low frontal area Subaru leave very little clearance under the bonnet and of course it is well insulated being a type of plastic too. Has anyone tried putting on some sort of louvre or vent with any success?

Re: Hot under the bonnet
 

Hi Steve

A couple of things which I did to our SVX which improved matters slightly....... On the UK cars the central bit of the waterfall grill has a solid plastic psuedo hexagonal grill moulding, which is clipped onto the actual hexagonal grill behind. I removed the solid bit to allow some airflow into the engine compartment, it's not much but it allows some air into the front where the said PS pump and Alternator are.

I also used "waterwetter" in the coolant system. There is a lot of conjecture about it's effectiveness, you can read up about it on 'tinternet all over various forums, but in my personal experience it reduced warm up time and slightly decreased the indicated normal temperature on the SVX. I realise the gauge is only an indication, a "guess-o-meter" if you will, but the needle stayed noticably lower on the scale in normal use, and it didn't get hot so fast when "pressing on" shall we say !!

I realise these are only small measures and yes, the SVX motor does get blisteringly hot for some reason. There are all sorts of wonderful products to protect sensitive parts from heat, various sleaves and wrappings, but as you are on the bike circuit you'll no doubt be familiar with them !!

Welcome aboard by the way, I hope you are able to meet up with some of the guys at JAE later in the year as they genuinely are all as friendly in person as they seem in text here in the wierd world of the interweb !!

Phil.

Re: Hot under the bonnet
 

I have one of the carbon fiber hoods (bonnet) that was purchased during the group buy years ago. The scoop is not hooked up to anything, but just spills into the engine compartment under the bonnet. This area is then cooled and does not get as hot as the other SVXes I have. It doen't seem to run any cooler, but is just cooler when the bonnet is opened. :)

Re: Hot under the bonnet
 

That's interesting Earl, and you would expect that to happen once some of the heat can be "leaked" when stationary or pushed out of the way when on the move.

In another thread nothing to do with what Steve mentions here, I mentioned it would be nice to be able to duct some high pressure cold air into the space around the auto gearbox under the transmission tunnel.

As we know from consumption figures the auto gearboxes are less fuel efficient than a direct connection manual box, due to clutches slipping and the torque converter pumping losses etc, etc. Well this lost energy gets converted to a heck of a lot of heat :eek:. I became aware of this last summer as Jersey Girl needs the aircon re-gassed. Graham and myself were par-boiled with all the heat leaking into the cabin from the gearbox. With the aircon on and pumping chilled air, I never noticed the severity of this heat before. Without aircon it really heats up the cabin. Maybe even Phil's modification of taking out the blanking plastic would pump some cool air in there and shift some heat from over the gearbox. I must try that. Japanese grilles don't have that blanking plate for some reason.

Joe

Re: Hot under the bonnet
 

I suppose that without drastic metalwork, it probably isn't likely... but I wonder if an air extractor would work.

A slat in the hood just forward of the cowl, basically between the strut towers, that uses the laminar flow over the car to pull air out of the engine bay, into the low pressure area at the base of the windsheild, and then up over the roof as part of the airflow over the car.

several mercedes have such vents or slats in the hood, just ahead of the windshield.

I wonder if the cause for all the heat is the airflow through the radiator just has that much heat transfer, or if there is not enough airflow through the engine bay, and the engine and transaxle heat up the ambient air, which has nowhere to go.

Re: Hot under the bonnet
 

Our engine compartment is pretty full, lots of stuff in there and not alot of air space. I never thought about it being significantly hotter than any other car, but I don't doubt it. I know there is a practice in the honda community of adding shims to the hood so that the corners of it back towards the windshield are raised of the fenders. They say it keeps it cooler. I don't know if anyone has tried this on an SVX. Plus, I think it looks stupid. :lol:

Re: Hot under the bonnet
 

After reading the post about a low pressure area vent I thought, hang on, it's already got one where the wipers park. On inspection it is also well sealed from the engine bay so i guess this is, if you like, a 'still air box' type place for the heater system to draw on without having to compensate for 'ram air' variations maybe?
Also I couldn't help notice that after only a 12 mile drive home the motor was unbearably hot to touch 2.5 hours later. OK we are having uncommonly hot weather for the UK - over 20 degrees - it's like a fiery inferno to me and it isn't raining either.....
I am guessing that the problem lies with heat soak so a centre-ish vent like the one on the carbon group buy bonnets mentioned would help a lot without interfering with anything else.
There is a book on the subject of 'Manifold Cooking' and I have personally seen beautifully tender chicken portions come from a box over an old Rover exhaust manifold after a 2 hour journey. I would think we could stir fry stuff with ease in minutes on our engines!
Thanks everyone for your opinions and putting up with mine.
Steve.