DarrenW
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| posted on 3/5/06 at 08:47 AM |
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Bonnet vents - any ideas
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
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muzchap
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| posted on 3/5/06 at 09:02 AM |
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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 
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If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
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Hellfire
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| posted on 3/5/06 at 09:11 AM |
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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
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tim windmill
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| posted on 3/5/06 at 09:15 AM |
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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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DarrenW
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| posted on 3/5/06 at 09:16 AM |
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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
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DarrenW
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| posted on 3/5/06 at 09:25 AM |
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quote:
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
Interesting. Im pretty sure i have the cooling right. Fan kicks in at 98 and off again at 94. Coolant temp has always been consistent. Oil climbed to
1.2deg on the Motorway blat but caused me no concern. Im planning some exhaust wrap and possibly a fan override switch. Im about 4 weeks away with the
bike carbs (ZZR1100). manifold is getting made by a very good ali fabricator up North - watch this space as im sure he will be offering some excellent
cost conversions in thenear future.
I wont be fitting the bike carbs until i get the megajolt running correctly. Currently collecting the bits i need (short of trigger wheel and crank
sensor).
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Avoneer
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| posted on 3/5/06 at 10:59 AM |
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Hows about how I had mine on my avon.
Some pics floating on here somewhere.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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DarrenW
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| posted on 3/5/06 at 11:01 AM |
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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.
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jos
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| posted on 3/5/06 at 11:15 AM |
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My fan kicks in at an etb water temp indicated 85 ish
.: Motorsport / motor racing circuit / track wall art Apex Traxs :.
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muzchap
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| posted on 3/5/06 at 11:45 AM |
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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
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If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
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Hellfire
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| posted on 3/5/06 at 11:52 AM |
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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]
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muzchap
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| posted on 3/5/06 at 12:32 PM |
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Oooh they look lovely!
Fancy cutting some more 
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If you believe you're not crazy, whilst everybody is telling you, you are - then they are definitely wrong!
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02GF74
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| posted on 3/5/06 at 01:56 PM |
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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?
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Peteff
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| posted on 3/5/06 at 02:28 PM |
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For triangular holes drill the three corners then join them together with straight lines, you'll automatically have rounded corners all the same
radius.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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DarrenW
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| posted on 3/5/06 at 03:14 PM |
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i was really impressed by the Hellfire vents. Are they detailed on your website? Can you remeber what month?
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Hellfire
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| posted on 3/5/06 at 03:22 PM |
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quote:
Originally posted by DarrenW
i was really impressed by the Hellfire vents. Are they detailed on your website? Can you remeber what month?
They are in modifications...
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DarrenW
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| posted on 3/5/06 at 03:25 PM |
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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?
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Hellfire
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| posted on 3/5/06 at 04:50 PM |
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PU Adhesive
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TangoMan
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| posted on 3/5/06 at 10:16 PM |
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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.
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DarrenW
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| posted on 4/5/06 at 10:50 PM |
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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!!!
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DarrenW
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| posted on 5/5/06 at 10:17 AM |
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Here are the bonnet vents - just need some mesh to go in.
 
Rescued attachment bon vents cut.JPG
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DarrenW
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| posted on 5/5/06 at 10:17 AM |
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Ive also cut some holes in nose cone above number plate.
 
Rescued attachment nose cone holes.JPG
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ned
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| posted on 5/5/06 at 11:37 AM |
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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.
beware, I've got yellow skin
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Rob Palin
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| posted on 5/5/06 at 02:00 PM |
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Can i ask what the underside of your engine bay is like? Is it completely open or panelled under?
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DarrenW
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| posted on 5/5/06 at 03:03 PM |
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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.
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