At Stoneleigh the under bonnet temps after a motorway blat caused me some problems. I need to have more vents? Im not an expert on what looks nice. Please show me yours?


Here are some ive sketched on my bonnet. Constructive comments very welcome. i will have the same on both sides so which do you think look best or what else would you do? My idea is to put mesh behind just like infront of the bulge.

I think im favouring the rh side set but perhaps only the front 4.

[Edited on 3/5/06 by DarrenW]

[Edited on 3/5/06 by DarrenW]
Rescued attachment Bonnet vent idea.JPG

Personally I prefer the ones on the right.

Or whats wrong with 2 long strips with rounded ends? That'd look good - especially if you follow the lines of the bulge

I think further back as when you are moving quickly the hot air is being pushed towards the rear of the engine bay and down the tunnel not along the top.

If you do put them there the underneath will need significant reinforcing as it seriously removes any rigidity in the otherwise flimsy to start with bonnet.

The ones on the right I prefer.

Steve

darren,we are running the same pinto set up as you with the same bonnet and have no problems with the cooling, are you sure you have got the cooling set up right. we have done 2 pinto installations and not had the need for extra vents.
keep us posted on bike carb installation as were are going the same route, got some zx9 carbs and in process of getting manifold made up and sourcing parts for megajolt. we hope to have it all done for newark

Good suggestions so far. Main reason for the vents is to get cool air into the carb air filter (filter is currently 60% covered by the bonnet which is pressing down on it = high underbonnet temps and fuel vaporisation problems that i experienced at Stoneleigh) hence forward location. I dont want a normal air filter hole as i plan to fit bike carbs for which i will need a hole in the side for eg a pipercross filter to poke through. Im designing the vents on both sides to balance the look for when i no longer have the downdraught fitted.

I also have vents in side of the bonnet at rear which have helped air flow a lot as shown here.

I also share your concern over compromising the bonnet strength hence why im thinking of adding the ali mesh underneath as with current vents. Iam also concerned about how neat i can cut the vents with my rotozip.

[Edited on 3/5/06 by DarrenW]
Rescued attachment P2150665 resized.JPG

quote:

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Originally posted by tim windmill
darren,we are running the same pinto set up as you with the same bonnet and have no problems with the cooling, are you sure you have got the cooling set up right. we have done 2 pinto installations and not had the need for extra vents.
keep us posted on bike carb installation as were are going the same route, got some zx9 carbs and in process of getting manifold made up and sourcing parts for megajolt. we hope to have it all done for newark

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Hows about how I had mine on my avon.

Some pics floating on here somewhere.

Pat...

Waht about this as an alternative idea?

Im not 100% confident of being able to cut all of the traingles neatly using the rotozip but i do have a set of hole saws. So perhaps replicating the 4 holes in the side but with a smaller set on the top, starting small at the front and then progressively getting larger, but as said smaller than the side set.

My fan kicks in at an etb water temp indicated 85 ish

Hole saws are nasty things

I'd try to use a stepped hole cutter - you can get one from Car Builder Solutions - goes from 12 - 32mm (should be big enough...

I would imagine - fibreglassing in the ali vents would probably make the bonnet less flexy and a bit more resilient - but certainly it wouldn't be any worse

Here's a picture of our bonnet vents. More effective whilst stationary than moving, which is why we placed them here. Using a Dremel will make a very neat job of them.

Phil

[img][/img]

Oooh they look lovely!

Fancy cutting some more

triangulr holes; should be easy with roto-zip and steady hand.

what I would do is to make a wood block in the right shape and bolt it to the bonnet then press the body of the tool against the side of the block - easy peasy. the corners may be too big a raidus perhaps depending on the tool body.

re: air to carb - some ali plate to make a box to channel air from the front or side to prevent hot air getting to it?

For triangular holes drill the three corners then join them together with straight lines, you'll automatically have rounded corners all the same radius.

i was really impressed by the Hellfire vents. Are they detailed on your website? Can you remeber what month?

quote:

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Originally posted by DarrenW
i was really impressed by the Hellfire vents. Are they detailed on your website? Can you remeber what month?

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By heck you were quick - iwas just poting to say i found it.

How did you secure the ali darts to the top?

PU Adhesive

Darren,

I have vents but still have the same issue.

Even with vents you will be sucking hot air.

I have opted for wrapping the exhaust manifold and building an airbox fed from cold air.

I am also considering a high capacity core in the radiator as this is the real problem.

When caning the engine it creates a lot of heat which does not disappear just because you get off the loud pedal. Sufficient water capacity and flow should stop this being a problem. A shortfall in either will see raised temps.

As I am going to Le Mans in mine I don't want to take any chances of overheating.

I have found that backing off for the last mile of motorway driving helps quite a lot as my problem is only apparent when going from all to nothing.

I would check your oil level also as low oil will not help cooling.

Ive done 3 tringular vents on each side of the bonnet bulge tonight. Dead easy with rotozip - just slowly slowly steady away and clean them up with file and emery tape. Just need some mesh now to finish off.

Ive also cut some holes (5 x dia 50) in front of nose cone above no. plate.

Next up will be fan bypas switch and exhaust wrap.

Following that bike carb with filters sticking out of the side.


Damn these 60's designed cars!!!

Here are the bonnet vents - just need some mesh to go in.
Rescued attachment bon vents cut.JPG

Ive also cut some holes in nose cone above number plate.
Rescued attachment nose cone holes.JPG

Darren,

It looks like you've made a nice job of the holes but I am concerned that you should need them at all, it does seem odd to me.
The holes you have at the rear at the sides of the bonnet should allow the air fromteh front to flow through the engine bay nicely and draw the heat out.

I would also have thought that you'd have a lower rated rad fan switch fitted - 98 sounds very high before the fan kicks in to me.

nice job though.

Ned.

ps is it too early to cut the bonnet for the sausage filter? Even if you put some mesh behind it temporarily this would open up a lot of cooling to the engine bay. exhaust wrap as you've mentioned should help a bit aswell.

Can i ask what the underside of your engine bay is like? Is it completely open or panelled under?

Engine bay open at the bottom.

Cant cut filter hole yet cos i dont know what i will end up with or where it will poke thro.

Ive thought about fan stat but im pretty convinced the cooling system is working well. Its just the heat soak thatis an issue (but accept why you mention it).

Next up is exhaust wrap and fan override switch.

If it's mainly a heat soak problem when you're stationary then it might be worth checking for recirculation of hot air through the radiator.

It's a common problem in stuff like trucks and taxis(!) where there's little space behind the rad. The fan pulls or pushes flow through the rad but it then returns through either gaps around the sides or even back through the edges of the rad. You're then using 80+ degree air to cool the rad and the rate of heat transfer drops significantly.

For a simple check you could sellotape cotton thread or strips of wool to something like half-straightened paperclips and poke them through the vanes of the rad at the outer edges. Put everything back together, run the fan and see if the tufts go flat against the rad or point forwards out of it (probably fluttering around a lot though).

If they point forwards you could either use a cowl on the back of the rad (obviously better with a puller-type fan) or have some splitter plates which divide the back of the fan into thirds so the air going through the fan can only go rearwards and not get pulled back through at the sides. This second option leaves the rad more efficient when you're using ram-cooling, whereas the cowl will be better for fan-driven flows.

Simple way of dropping the coolant temperature by as much as 20 degrees for around £15.00 . Add a bottle of Red Line Water Wetter . Does what it says on the bottle

Darren,

To get a nice finish, may I suggest what I did to my grille?

Scribe the shape of the holes onto some hardwood - do male and female halves.

Put mesh between the hardwood and tap gently, until you have a formed mesh that can be bonded inside bonnet, but which is flush with the top of the vents holes.

ATB

Simon

Caterham rip off....