Rally Retirement
Discussion
Geoff Loos and I retired from the Carpetbagger Rally last weekend for an old reason we had probably forgotten about.
On a rather rought bit we hit a big bump with the result that the fan shroud, an early 2 piece one, moved relative to the fan and the fan blades and shroud stiffening flange all bent. This caused the fan/water pump pully to jam which then caused a broken fan belt. Thus 'game over'. The rubber grommet on the bracket allows up to about 1/8" deflection by the shroud.
On my car, and Geoff will now do this to his, I always mig weld the bottom of the shroud onto the radiator support bracket and then bolt this solidly onto the engine bracket. This has two advantages, the first as obvious on a rally car, and the second that it gives more clearance when fitting the fan belt. When fitting it may be necessary to shim up from the engine bracket and to get in to do this you need to cut away the inner wing at the lower edge. This helps with access to that area for changes of engine mounting as well.
On a rather rought bit we hit a big bump with the result that the fan shroud, an early 2 piece one, moved relative to the fan and the fan blades and shroud stiffening flange all bent. This caused the fan/water pump pully to jam which then caused a broken fan belt. Thus 'game over'. The rubber grommet on the bracket allows up to about 1/8" deflection by the shroud.
On my car, and Geoff will now do this to his, I always mig weld the bottom of the shroud onto the radiator support bracket and then bolt this solidly onto the engine bracket. This has two advantages, the first as obvious on a rally car, and the second that it gives more clearance when fitting the fan belt. When fitting it may be necessary to shim up from the engine bracket and to get in to do this you need to cut away the inner wing at the lower edge. This helps with access to that area for changes of engine mounting as well.
I guess a thin rad would be allowed, but I always wonder if the cooling is as good. Advice from experience would be good here.
Remember, on a proper rally car part of the rad could get a bit 'bunged up' with mud and reduce the cooling area. The problem we just had was really the 2 piece rad shroud. There is good and bad to using this set-up. The good is that you can change the fan without removing the rad or draining down. The bad is that you could have the problem we had. We were just unlucky that the joint of the two shroud pieces happened to be the point of minimum clearance and the bump moved the shroud & rad in the worst possible direction.
One point to remember if you feel that cropping the fan blades would be an answer. The Mini fan is what is known as a 'ducted fan'. With a ducted fan, the clearance between blade tip and shroud is quite critical in terms of air flow. Air flow is critical on a hot 1275 engine at the best of times, so I try to keep it to a minimum.
I once worked on the design of an aircraft wind tunnel. The diameter was 3 metres and the tip clearance for the huge fan was, wait for it, 3 mm to 5 mm. Any more than this and the efficiency dropped off rapidly. It amazed me, but the same logic applies to Mini fans and shrouds.
The answer is to set up the fan and shroud, then make sure that one cannot move relative to the other.
Off home now to get the engine of my 1292 'S' ready to go back in for my next event as a driver in Feb - The Gremlin Welsh Championship and Historic Championship qualifier.
Remember, on a proper rally car part of the rad could get a bit 'bunged up' with mud and reduce the cooling area. The problem we just had was really the 2 piece rad shroud. There is good and bad to using this set-up. The good is that you can change the fan without removing the rad or draining down. The bad is that you could have the problem we had. We were just unlucky that the joint of the two shroud pieces happened to be the point of minimum clearance and the bump moved the shroud & rad in the worst possible direction.
One point to remember if you feel that cropping the fan blades would be an answer. The Mini fan is what is known as a 'ducted fan'. With a ducted fan, the clearance between blade tip and shroud is quite critical in terms of air flow. Air flow is critical on a hot 1275 engine at the best of times, so I try to keep it to a minimum.
I once worked on the design of an aircraft wind tunnel. The diameter was 3 metres and the tip clearance for the huge fan was, wait for it, 3 mm to 5 mm. Any more than this and the efficiency dropped off rapidly. It amazed me, but the same logic applies to Mini fans and shrouds.
The answer is to set up the fan and shroud, then make sure that one cannot move relative to the other.
Off home now to get the engine of my 1292 'S' ready to go back in for my next event as a driver in Feb - The Gremlin Welsh Championship and Historic Championship qualifier.
I can't get the 'thick' 4-core rad into my 'S' as it is a Mk 1 with the metal frame on the inner wing carrying a rubber strip seal. I really have not had any problems with overheating since I fitted the additional electric fan.
It always seems with the modified 1275 and bigger engines that the temp is OK even on hot days until you go slowly or stop in traffic (or at the start of a special stage or test). Once the temp does go up, however, it is very hard to get it to come down again.
Yes, Phil, that was my car in the mag.
Your ducted fan idea for your 'B' seems a great idea and I love the thought of plant-pots as the ducts!
AS an aside, on my last rally the engine seemed down on power and was running very badly at low and mid range. I took it to pieces and could find nothing seriously wrong, but on starting to re-assemble last evening I found the twin pipe piece of the LCB to be badly damaged and squashed down to about 1/2 of its normal diameter just below the joint point. Now, this has never happened before, ever, and I think it may be due to the fact that for the first time I tried wrapping the lcb with a heat wrap tape. This, perhaps, caused the pipes to get too hot and bend/distort when I hit the exhaust over a bump (or two). I'm not going to heat wrap the new lcb.
Engine back in this weekend, I hope.
It always seems with the modified 1275 and bigger engines that the temp is OK even on hot days until you go slowly or stop in traffic (or at the start of a special stage or test). Once the temp does go up, however, it is very hard to get it to come down again.
Yes, Phil, that was my car in the mag.
Your ducted fan idea for your 'B' seems a great idea and I love the thought of plant-pots as the ducts!
AS an aside, on my last rally the engine seemed down on power and was running very badly at low and mid range. I took it to pieces and could find nothing seriously wrong, but on starting to re-assemble last evening I found the twin pipe piece of the LCB to be badly damaged and squashed down to about 1/2 of its normal diameter just below the joint point. Now, this has never happened before, ever, and I think it may be due to the fact that for the first time I tried wrapping the lcb with a heat wrap tape. This, perhaps, caused the pipes to get too hot and bend/distort when I hit the exhaust over a bump (or two). I'm not going to heat wrap the new lcb.
Engine back in this weekend, I hope.
Unfortunately we're not allowed an additional rad in Historic Rally Minis, only in post-Historic (i.e. 1968 onwards). I once did an Historic International event in Belgium where the outside air temp was 102 def F. I was in a 1071 'S' which does not get as hot as a 1275, but we had to run the heater full on to keep the temp down - and that was whilst wearing 2-layer Nomex racing overalls. I reckon I lost half a stone in 2 days. Worth it, we won our class and 8th overall.
As an additional rad on a road car, or a later rally car one can use a heater matrix. They will mount in the front and if you cut away the grille they mount next to the oil cooler. The heater matrix is much stronger than the radiator matrix as well.
As an additional rad on a road car, or a later rally car one can use a heater matrix. They will mount in the front and if you cut away the grille they mount next to the oil cooler. The heater matrix is much stronger than the radiator matrix as well.
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