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Posted: Fri Dec 05, 2014 7:44 pm
by mgbv8
v8250 wrote:3xpendable wrote:Pics aren't showing mate, which ones are you referring to?
?? I can see them on the forum. They're the rad pics here
http://www.mgexp.com/phorum/read.php?40,2816332
1. with large black mounting plate
2. with mis-sized rad fans
If number 2 is the pic with the yellow fans in front of the rad. These are the stock fans for an MGB V8. They were ok for the smaller 3500 low comp engine (just) but in hot traffic they strugggled. I still have these on mine and they work ok for what I need them for
I would really like a big sucker fan like the one with the plate but there is no room to fit one on my MGB.
Posted: Fri Dec 05, 2014 10:38 pm
by v8250
mgbv8 wrote:If number 2 is the pic with the yellow fans in front of the rad. These are the stock fans for an MGB V8. They were ok for the smaller 3500 low comp engine (just) but in hot traffic they strugggled. I still have these on mine and they work ok for what I need them for
I would really like a big sucker fan like the one with the plate but there is no room to fit one on my MGB.
Perry, the #2 pic is of the two 7-8" black fans diagonally fitted. They're too small for an ideal set up. As you rightly say the originals are perfectly fine for smaller engines. I too would like one big sucker fan but there really is not the space between rear of rad and front of the water pulley, so can see myself having to go with 2x 9" blowers from Revotec. Despite this they still have a good cfm compared to many others; just a shame having to block the front of the radiator.
+++ I'm going to be using the well known MGB racing trick...carefully squeeze together the vertical slats on the chrome grille. This increases air flow by some 20%. Years ago I used to see all sorts of race cars with every other grille slat removed...MG's and XK & MKII Jaguars were the classic culprits. Nowadays it's not the 'done thing' as the scrutineers say no to such ungentlemanly behaviour. But the guys still reduce the frontal area and give them a squeeze! There's one well known FIA MG car specialist who even has a special pair of mole grips with long welded plates on the end specifically for this task
better start the welder up in the morning...
Posted: Sat Dec 06, 2014 6:26 am
by unstable load
v8250 wrote:mgbv8 wrote:There's one well known FIA MG car specialist who even has a special pair of mole grips with long welded plates on the end specifically for this task
better start the welder up in the morning...
Nothing special about them at all, he's having you on.....
http://www.wurtec.com/asp/product.asp?Item=8R
Posted: Sat Dec 06, 2014 7:45 am
by Ian Anderson
Do the V8 bonnets have "gills" or slots to release the hot air after it has gone through the rad?
You really need to get rid of the air after the rad!
Ian
Posted: Sat Dec 06, 2014 9:50 am
by v8250
unstable load wrote:v8250 wrote:mgbv8 wrote:There's one well known FIA MG car specialist who even has a special pair of mole grips with long welded plates on the end specifically for this task
better start the welder up in the morning...
Nothing special about them at all, he's having you on.....
http://www.wurtec.com/asp/product.asp?Item=8R
Now, I thought I'd seen these elsewhere too...
Posted: Sat Dec 06, 2014 10:01 am
by v8250
Ian Anderson wrote:Do the V8 bonnets have "gills" or slots to release the hot air after it has gone through the rad? You really need to get rid of the air after the rad!Ian
In std form, there are no bonnet slats. In fact, they're not the ideal as the bonnet is a high pressure area so heat struggles to escape especially the top half/rear of bonnet; though they do look good. The trick with heat dispersal is to use +ve and -ve air pressure to move the heat automatically out of the engine bay for you, so by doing the following one should not have overheating problems.
1. ensure total air output -ve area [rear of engine and inner wing exhaust manifold holes] is greater than input +ve area [through grille and radiator]
2. directly extract the heat, as above exit exhaust manifolds through the inner wings.
3. use good quality thermal exhaust wrap - this works in two ways, 1.to retain heat within the exhaust manifold and 2. accelerates the exhaust gas velocity.
3. make sure cooling system is in tip-top condition
if the above is done no overheating should be seen.
Posted: Sat Dec 06, 2014 11:03 am
by Ian Anderson
v8250 wrote:Ian Anderson wrote:Do the V8 bonnets have "gills" or slots to release the hot air after it has gone through the rad? You really need to get rid of the air after the rad!Ian
In std form, there are no bonnet slats. In fact, they're not the ideal as the bonnet is a high pressure area so heat struggles to escape especially the top half/rear of bonnet; though they do look good. The trick with heat dispersal is to use +ve and -ve air pressure to move the heat automatically out of the engine bay for you, so by doing the following one should not have overheating problems.
1. ensure total air output -ve area [rear of engine and inner wing exhaust manifold holes] is greater than input +ve area [through grille and radiator]
2. directly extract the heat, as above exit exhaust manifolds through the inner wings.
3. use good quality thermal exhaust wrap - this works in two ways, 1.to retain heat within the exhaust manifold and 2. accelerates the exhaust gas velocity.
3. make sure cooling system is in tip-top condition
if the above is done no overheating should be seen.
Ok number 2 why old technology?
Ceramic coat them and really reduce the under bonnet temps
Also not sure on your hi pressure in front of screen, sure higher than sat ambient pressure but I would imagine significantly less than Unser bonnet pressure
And as you say vent inside front wings put the gills on the outside of the wings in front of door hinges giving the air as much chance to escape as possible.
Just ideas
Ian
Posted: Sat Dec 06, 2014 4:54 pm
by v8250
Ian Anderson wrote:Ok number 2 why old technology? Ceramic coat them and really reduce the under bonnet temps. Also not sure on your hi pressure in front of screen, sure higher than sat ambient pressure but I would imagine significantly less than Unser bonnet pressure. And as you say vent inside front wings put the gills on the outside of the wings in front of door hinges giving the air as much chance to escape as possible. Just ideas Ian
Depends upon the type of exhaust wrap used. Thermal Velocity do some very special wrap made from volcanic lava, it's very effective. Ceramic coating is superb providing it's completed by the right company i.e. Zircotec...but I couldn't warrant the price for my project...may be in the future...
I found the bonnet high pressure levels surprising when running the calcs' but the downward pressure rolling return from the windscreen can be quite high, negating any heat output flow. The only effective time this genuinely works is as either low speed or when a forced air route extracts through bonnet vents. Either way, they do look good.
Posted: Sat Dec 06, 2014 8:30 pm
by mgbv8
I use the normal wrap on my pipes. I have vents in the bonnet that let hot air gush out when stationary. But as stated, when moving there is an area of high pressure on the MGB at the rear of the bonnet / bottom of the windscreen scuttle area. Some MG folk remove the rubber seal on the rear of the bonnet to let hot air out. But then often complain of engine smells being pushed into the air intake grille for the heater ?? My vents are at the outer corners at the rear of the bonnet and seemed to do the trick when the car was on the road.
Perry
Posted: Sun Dec 07, 2014 6:12 am
by unstable load
The high pressure at the rear of the bonnet is normal. A mate of mine used to race his P6 and he removed the heater box and fashioned an air box in it's place.
Posted: Mon Dec 08, 2014 9:16 am
by 3xpendable
I'd rather go puller too, but no worrm for it so I will try and go with 1 big pusher, I just don't want to lose too much area with a big motor.
I'll be going with the bonnet louvres too
Posted: Mon Dec 08, 2014 12:13 pm
by SimpleSimon
unstable load wrote:The high pressure at the rear of the bonnet is normal. A mate of mine used to race his P6 and he removed the heater box and fashioned an air box in it's place.
What the yanks refer to as "Cowl Induction"
Posted: Tue Dec 09, 2014 5:37 am
by unstable load
Thanks, Simon! I drew a blank at giving it a name.
