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MG MGB GT V8 Factory Originals Technical - engine bay temps FYI

well recently, after owning the motor for 9 years , I have tried out a coupls of Mods talked about here to reduce under bonnet temps
folding back the rear bonnet flange and folding down the bulkhead flange & Exhaust wrap
On the road there is no difference to the engine temp, if I give the engine a work out it still gets hotter - say 4 o' clock on the gauge, and normal runing just to the right of the N. - car has covered 60K miles and this has always been case.
At idle however the engine does cool quicker - this has always been a concern, although never boiled even in hot countries, so its a small step foward .

just an update for anyone interested.
Derek Watson

Derek,

Glad to hear it worked for you, it's surprising how much heat comes out of there.

I'm contemplating working on the fan to produce more waft, and also intend to do smoke tests to see where the air actually goes at standstill.

Mike
Michael barnfather

Derek,

Your results are what I would expect. The area at the back of the bonnet is a high pressure area when travelling - that's why the heater intake is placed there. So air will tend to ENTER the engine bay through the slot when driving, or at least the air at that point will be stalled, ie. you won't lose much of your heat via the slot. When stopped, the radiator fan(s) can make use of the slot to get rid of hot air and natural convection will cause heat to rise from there too.

I read in a recent thread that the optimum place for bonnet louvres is in the front third of the bonnet lid, as here you will get air extraction while moving. Look at some modern performance cars - that's where the vents tend to be. Of course vents there on your MGB might not be the visual effect you desire.

Mike
Mike Howlett

Anyone running louvres in the engine bay, say on the inner fenders? Ive been thinking of doing this, just want to see if ther eis any benefit. I assume the wheel well is a low pressure area when moving so hot air would tend to exit if given the chance.
Jake

Jake

The strengtheners inside the wings on mine have holes which allow the hot air to exhaust into the wings and out through large drain holes at the bottom. It's marginal help but prevents condensation in the wings.

The problemn with the mods to the rear of the bonnet and the water channel is the hot air which comes straight back into the cabin - not a problem in a roadster perhaps - not so good in a GT.

Agree with Derek - the system can cope with most temps so long as everything is in good nick.
RMW

Jake

The strengtheners inside the wings on mine have holes which allow the hot air to exhaust into the wings and out through large drain holes at the bottom. It's marginal help but prevents condensation in the wings.

The problemn with the mods to the rear of the bonnet and the water channel is the hot air which comes straight back into the cabin - not a problem in a roadster perhaps - not so good in a GT.

Agree with Derek - the system can cope with most temps so long as everything is in good nick.

Roger
RMW

Temp is not really an issue on the move only when stuck in traffic. As hot air rises then bonnet vents placed just behind rad and over exhaust manifold would be ideal.

Paul
Paul

This is a good time to report my findings on my engine compartment heat .
I put header wrap on and it seemed to help somewhat but what has really helped is putting 2 sets of louvers on the bonnet about 9 inches in front of back edge of bonnet and about 4 inches in from side.This places them over the headers. The louvers are 5 inches wide with 5 in each set. The heat just pours out when not moving which is where the hot condition was a problem . I was just in a 40 minute traffic situation and temp never went over 205.
i should mention mine is a 302 Ford V8 tends to run hotter then the Rovers or BOPs.
Hope this is of some help to someone
Gil
Gil Price

Jake

The first driving season after completion of my Rover 3.5 74 ½ conversion (Ford Falcon Rad, 3000CDM electric fan), the car was constantly overheating. I then added ducting to force the air through the lower rad and this alleviated some of the problem but not all. I then added louvers in the engine bay as high as I could get them and they exit into the lower pressure wheel wells.
I just got back from a 10 day driving vacation through Eastern Washington state where the temperatures were hitting 105 degree’s. The temperature gauge never left the ‘N’.
If you want some picture let me know.

Bruce Mills
Bruce Mills

Bruce
e-mail me the pictures
I'm reluctant to cut holes in the bonnet - have avoided it for the last 9 years-- I forgot to mention I have always run the motor on Forlife which is supposed to help a little - I only really got it as a long term antifreeze/corrossion inhibitor.

Derek Watson

Bruce,

I'd like to see those pics. This is something that I have been thinking about for years, but never got around to working on it.

Remove the "at" for my email to work. Thanks.
Carl Floyd

Derek,

Not sure about 4life as it has a high boiling point but no info on heat transfer, which could be same effect as antifreeze.

Also with 4life if you have a leak out and about (pause), then if you cannot mix with water do you need to drain out all the 4life?

Paul
Paul

Before installing louvers anywhere in your MGB check your mixture at idle and at crusing speed. the mixture should be 12.9 is an ideal at crusing speeds and at idle in the 13.9
to lean it will make the engine overheat same as engine timing. Most V8 should be time at 34 degrees at 2500 rpm and V6's 32 degrees at 2000 rpm.
this will fix must overheating problems then fine tune with louvers etc.
Bill Guzman

Forlife - err never had a leak (looking for wood to touch) + keep a 5ltr bottle in the garage - just in case.
As far as heat transfer well the temp readings never changed when I moved over to the stuff and have been stable ever since. I have changed it out once, after about 5 years - it supposedly has a life of 10 years.

Mixture_ recently had car on rolling road with mixture checked and adjusted at idle and then checked through rev range it was bang on. Thanks anyway for the advice

Derek
Derek Watson

I only have temp problems when stopped, louvres and removing rear lip has helped a lot, I have pics in X-power gallery (http://www.xpower-mg.com) under mikeb.

Subsequently I have removed underbonnet sound-proofing and added ducting underneath spoiler to force air through radiator. It's now plenty cool enought for UK summers, but I am considering fans underneath louvres wired wit rad fan to blow hot air out.....I did some temp tests (see earlier thread) and was surprised how hot the air is coming out of the engine bay.

Mike
Michael barnfather

This thread was discussed between 16/08/2004 and 18/08/2004

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