Jump to content

cooling


cast iron

Recommended Posts

Norman Verona

Interesting, I speed read it but one problem that I think happens to our cars is the high pressure build up under the bonnet. I believe this get so high that air cannot flow through the rad as fast as it should because of the wall of high pressure air behind the rad.

Link to post
Share on other sites

That was my understanding Norman. I guess that's where the ducted rad is useful. Would a flat floor under the engine bay help too? I suppose that doesn't exit air anywhere!

Link to post
Share on other sites
Norman Verona

I'm not sure. A flat floor may produce a NACA duct where it stops which would suck the air inside out.

 

I have glued centrel heating pipe lagging around my rad and the car runs much cooler. In fact on Sunday it was fine for the first 38 miles then the gauge started to rise. We were at our destination in minutes so I didn't worry too much. I thought it may have been because we slowed down for the junction.

 

However it was running hot on the way back - all the way. 

 

When I removed the bonnet and lifted the nose cone I found the foam tube on top of the rad and against the inside top of the nose cone had popped out. It was on the alternator and the end was mangled.

 

Got a new one this morning and will glue it to the nose cone this time.

Link to post
Share on other sites
Dave Eastwood (Gadgetman) - Club Secretary

A flat floor will potentially make matters worse unless you give the air somewhere to escape. This can be achieved by venting it out of the top of the nose - something that actually has some aerodynamic advantages too in helping reduce front end lift slightly at speed. (One of the packages of measures Caterham discovered on the wind tunnel tests and have subsequently used on CSR and some of the Duratec engined R models.

 

In Westfield circles, spitting the tub sides and fitting them in such a way that they flair out slightly towards the rear of the engine bay is popular.

Link to post
Share on other sites
Dave Eastwood (Gadgetman) - Club Secretary

I'm not sure. A flat floor may produce a NACA duct where it stops which would suck the air inside out.

 

Apologies, I may have misunderstood what you meant.

 

When I said it can make it worse I was referring to complete enclosure; panelling in the bottom of the engine bay, covering the underside of the transmission tunnel and then typically, fitting a diffuser at the back to enclose the diff and tank area.

Link to post
Share on other sites
Norman Verona

Same hymn book, me thinks.

 

I raised to rear edge of my non-vented bonnet and I think it helped. It's difficult to tell. But then I cut an oblong above the carbs so heat could escape in traffic. I thought I was getting vapour lock but as usual, the fuel problem turned out to be electrical. I had a faulty electronic ignition amplifier.

 

Anyway, the large oblong has, I think, destroyed the vacuum effect of the raised lip.

Link to post
Share on other sites
Dave Eastwood (Gadgetman) - Club Secretary

Yep, your mod is probably also the same effect the FW bonneted cars use, though whether the "nostrils" destroy the effect, I don't know.

Link to post
Share on other sites

very interesting thanks for sharing

Link to post
Share on other sites

Does anyone sell the side vented panels? That looks like a good solution for getting air out from behind the rad. Particularly if the car has been flat bottomed.

Link to post
Share on other sites
SootySport

Flared side panels are popular on Westfields but releasing hot air from the top of the engine bay is more effective.

Link to post
Share on other sites
Norman Verona

Bernie, as we wewre talking about you last night  :p I feel I can make a comment on he bit about releasing hot from the top of the engine bay.

 

From my research, using cotton wool stuck on various parts of the car and driving at about 60 mph the bonnet is under high air pressure over 30 mph. I guess that this pressure is higher than the under bonnet pressure so over 30 mph no air will get out the bonnet louvres, grilles etc. The grilles at the front, due to sloping down may release some air but the Caterham bonnet and nose cone doesn't have that degree of slope.

 

I've lifted the rear edge of the bonnet to create a NACA duct against the scuttle panel. It does work but not as much as I hoped. 

 

Fact is most of the hot air from the engine compartment goes down the transmission tunnel. As the area is very much smaller than the front grille air cannot get out as fast as it's rammed in. This slows the air flow through the rad.

 

And finally we were saying what a nice lad you were.

Link to post
Share on other sites
SootySport

So, is Brian there then? Did he get very wet on the way? and whats the "were" bit about? 

 

As for escaping heat, I was just under the impression that hot air rises and the best way to help it escape would be somewhere at the top of the engine compartment.  Interesting to know the bit about low air pressure under a bonnet, i find that hard to comprehend, never mind.       

Link to post
Share on other sites
Norman Verona

Bernie, Yes they're here and didn't get too wet on the way.

 

Mind you they're getting very wet now, on the inside!

 

 

I don't think I said "low pressure" under the bonnet, it's high as the pressure build up as the exit is slower then the entrance. It's "lower" that the pressure on the bonnet at speed so air from under the bonnet will not escape.

 

This applies to the Caterham, the sloping nose cone on the Westfield may be different.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Please review our Terms of Use, Guidelines and Privacy Policy. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.