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Cutting vents in bonnet?

Posted by spurs1canada 
spurs1canada Avatar
Barry Hotspur
Winnipeg, Manitoba, Canada   can
1972 Triumph GT6 MkIII "Mellow Yellow"
1976 Triumph Spitfire 1500 "Li'l Red"

My '76 suffers from hellish heat under the bonnet in our hot Summers and i have been thinking of installing vents,what worries me is the fact the paint on the car is in good condition and i'm wondering if the paint would craze or crack on a large scale from vibration cutting the hole if this was done? was thinking of buying vents that would overlap the holes.
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Falkkon Avatar
JP Robert
Calgary, Alberta, Canada   can
Dickie B Avatar
Dickie Brewer
Clover, South Carolina, USA   usa
1973 Triumph Spitfire MkIV "Rose"
1982 Chevrolet Corvette "Buddy"
1991 BMW 850i "Rocket"
2005 Nissan Frontier V6 "NIZMO"

Use a cutoff wheel on a grinder.
Mark the outside with tape.
Keep a wet cloth handy and every 1/2 " or so of cutting, cool it iff with the towel.
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dave-skip-fire-four-iv- Avatar
Dave Ertel
Oshawa, ON, Canada   can

hey barry louver he hood just my 2cents
johnniecab Avatar
John Edward Fothergill
Coventry, United Kingdom   gbr
1967 Triumph Spitfire MkII "Little Red Rooster"

Far to radical and risky .Have you not fitted an electric fan they work wonders
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ArcticOne Avatar
John Bulmer
Alberta, Canada   can

Seems like an extreme measure.

And will the benefit be noticable?

There had been another thread on here about whether the louvred hoods provided significant cooling at speed.

jb



John B
Alberta, Canada

DON'T DREAM IT .... BE IT!

In the Igloo:

1968 Triumph GT6 MK I
1968 Triumph GT6 MK I (FE O2)
1980 Porsche 911SC
Falkkon Avatar
JP Robert
Calgary, Alberta, Canada   can

Since we're adding personal opinion (I posted the thread link to show one of the many areas it's been discussed before), I would *personally* upgrade the water pump, radiator and fan. At least the radiator, as more and more people buy those Champion rads off Feebay and are happy with them, I'd look closely at that. Can't beat a 2 row aluminum rad for under 200 bucks as an upgrade. Apparently they slip right in without too much fiddling around, too!
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spurs1canada Avatar
Barry Hotspur
Winnipeg, Manitoba, Canada   can
1972 Triumph GT6 MkIII "Mellow Yellow"
1976 Triumph Spitfire 1500 "Li'l Red"

Thanks but coolant temp is not too bad i need to cool the oil a bit and there doesn't seem to be any way out of the engine compartment for the heat.
Remus Avatar
markus bewley
North West Englandshire, United Kingdom   gbr

Barry, before ye try any thing, take the bulkheed rubber strip off.
the amount of air that can escape out of there is quite a bit.

the more air that can get out, the more air that comes in thru rad.

Markus
1968triumphgt6 Avatar
Louis Boudreault
Montreal, Canada   can
1968 Triumph GT6 "Charlize"

Barry, unless installing vents is a modification that you actually wish to do, I'd say there are many other options.

The original hood on my '68 had only louvers on top. I got a '69 for the rebuilt, which as louvers on top and sides, and I can't say it changed anything as far as heat is concerned.

I'd start with the above suggestions and maybe an oil cooler before cutting through your hood.



Edited 1 time(s). Last edit at 08/20/2012 07:00PM by 1968triumphgt6.
weebestie Avatar
Tom Porter
Fellows, USA   usa
1963 MG MGB "Vivian"
1969 Triumph Spitfire MkIII "Caroline"

I have two electric fans and a aluminum radiator and my temp gauge still says I am running hot. I would like some side vents because when my car is standing still and the fans are on I can feel air coming out all around the rear of the bonnet. Seems like I could do with some more air flow. I took some readings with a info-red while the temp gauge was reading hot. Here is what I got... 131 @ temp sending unit, 120 @ rad inlet, 102 @ rad outlet, 221 @ block header side, 184 @ block other side, 125 @ valve cover. Does that sound like over heating?
cokerart Avatar
Bob Coker
Atlanta, Georgia, USA   usa
1973 Triumph GT6 MkIII "Spit-6 Or Dr. Frankenstein" ~ For Sale ! ~

If you remove the bulkhead rubber seal, hot air gets sucked into the fresh air intake vent at the base of the windshield. These cars are hot enough in the cockpit as is. I'm considering fender vents myself.
Bought an aluminum radiator off of eBay. No difference in cooling that is reflected on the temp gauge.

I'm thinking I should've bought Canley Classic's curved vaned impeller (read: "modern" ) alloy water pump. Would've been about the same price, but probably more efficient.



Edited 1 time(s). Last edit at 08/20/2012 06:29PM by cokerart.
Remus Avatar
markus bewley
North West Englandshire, United Kingdom   gbr

Bob, you got it wrong, trust me,
the heat could be sucked in if the heater fan was on, but not if it isnt, and the car is not moving forad. the lack of a strip will make the air prssure over the vent ..greater than the air pressure at the bottom of the windscreen
also as a bonus, the increased air flow thru the bonnet vent in the middle, will go along way to stopping floating middle wiper syndrome at high speeds.

the faster you go, the greater the air pressure under the bonnet, this will pass the air out,not into the car.
I have run this way for years, and my car is not hot. {and its a six pot, not a four pot.}
it is if the fan is on,or the heater is open, but not when they are off.
also reducd the under bonnet air pressure by about 11 PSI at 100mph.
reduced under bonnet pressure will lead to reduced front end float at high speeds.

Baz, just try it first.ye got nothing to loose.
others over here have ridiculed the idea, but thoses that have followed,all say it works.
its a win win set up. or I would no be running it.

Markus
carChips Avatar
Victor Harnish
Kelowna, BC, Canada   can
1933 MG Magnette
1973 Triumph Spitfire 1500 "Chip"
1989 GMC Sierra 1500 "Bush Truck"

Tom, all that sounds like is a wonky gauge. I have two such gauges in my car, the fuel, and the temp. If I flip the hazard switch up and down when they act up then they start working right again for awhile. With my big rad and dual fans the gauge goes up to the right side of the "N" then the fans kick in and the gauge goes down to the left side of the "N".



'S all for now
Vic
cokerart Avatar
Bob Coker
Atlanta, Georgia, USA   usa
1973 Triumph GT6 MkIII "Spit-6 Or Dr. Frankenstein" ~ For Sale ! ~

Markus,
I had horrible heat issues in the cockpit until I replaced the rubber seal. There was no seal when I bought the car.
If the cockpit fresh air vent was open, hot air would come in, even with the blower off. Seal installed: problem solved.
weebestie Avatar
Tom Porter
Fellows, USA   usa
1963 MG MGB "Vivian"
1969 Triumph Spitfire MkIII "Caroline"

In reply to # 836915 by carChips Tom, all that sounds like is a wonky gauge. I have two such gauges in my car, the fuel, and the temp. If I flip the hazard switch up and down when they act up then they start working right again for awhile. With my big rad and dual fans the gauge goes up to the right side of the "N" then the fans kick in and the gauge goes down to the left side of the "N".

She runs great, I just hate when the gauge reads hot and other people see it.

Sorry for getting off subject... I was thinking it may be the way I have the thermostat housing routed. Is the coolant inlet supposed to go in front or behind the temp sending unit?
grubscrew Avatar
grub screw
The suburbs of, Winfield, Maryland, USA   usa

While I'd never do it myself, I thought these vents looked OK and would actually be functional.
Dave



Dave
1970 Spitfire Mk3
FDU 78359L
34/11 (Jasmine yellow/Black interior)

Attachments:
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johnniecab Avatar
John Edward Fothergill
Coventry, United Kingdom   gbr
1967 Triumph Spitfire MkII "Little Red Rooster"

Bonnet vents will not help cool the oil .What you need is an oil cooler .Easy to fit available from immer bros in the Uk
69MkIII Avatar
Darrell C
Richmond, USA   usa
1968 Triumph Spitfire MkIII "Spitwad"
1968 Volvo Amazon (122) "Rollsie"

But we do this with an old boat sometimes - just cut it up and throw it in the dumpster piece by piece. Cut away if it makes you happy. Looks cool though even if it works or not.



Edited 1 time(s). Last edit at 08/23/2012 09:02PM by 69MkIII.
Remus Avatar
markus bewley
North West Englandshire, United Kingdom   gbr

Just to let folk see im no telling Porkies,
on Sunday, it was supposed to be the hottest day this year in Englandshire.
I had the bonnet strip off, and I also had this contraption still attached.
It was put on ,mainly for winter use,to get hot air directly of the ex manifold.

I had the heater on a fraction, as My legs were getting a cold waft, thru the heater outlets, was also wafting up into the nether regions to
So some where along the way, I either have got some thing that others have not got, or you Ladds are so used to having air con.

and its not just over there, folk over here complain they are hot.
I must be an Odd ball,with an Odd Ball car.smiling smileysmiling smiley



Markus
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