My 131 abarth (never ending) story - 2017 season updates

[miro-1980]

Brakes update.

( see related discussion here : viewtopic.php?f=14&t=1901 )

The disks were machined to fit the hubs, the calipers and the wheels/

First, we had to add a collar to the hub face. This is to fit the hub tight into the wheel. The original disk had and fitting cut in space , but this is an adopted disk ( remember? )

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As you see the collar is welded top the hub face . This is a temporary test solution ( see plans : below)

The Ferrari disk has been slightly trimmed in diameter (from 305 to 304 mm) .

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New set of bolt holes has to bed drilled. Some old holes (too close to the new holes) were plugged . All of the old holes will be plugged this way before drive testing .

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We also had to trim the inner side of the disk to make sure the hub has sufficient clearance ...

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Ann aluminum distance disk has been made to get more clearance between the caliper and the wheel.

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Next set of pictures with caliper fitted and wheel bolted

Miro

[Guy Croft]

Clutch - spring washers under the 6 x M8 bolts.

Vent - that gauze has to go, far too restrictive. You might as well make the vent half the size and put no gauze on it at all. The thing with gauze is you have to consider the amount of metal area it presents vs the open area. Yours looks like 50%. To be honest you don't need anything on a rear-facing vent.

G

[Nobby]

Great stuff Miro.

If you didn't already know, the Fiat Coupe 20vt uses 305mm discs with a 4x98PCD (I believe the 131 is also 4x98?).

[miro-1980]

Chris ,

I nee disks with bell depth 74 mm ...

M

[miro-1980]

Clutch - spring washers under the 6 x M8 bolts.

Vent - that gauze has to go, far too restrictive. You might as well make the vent half the size and put no gauze on it at all. The thing with gauze is you have to consider the amount of metal area it presents vs the open area. Yours looks like 50%. To be honest you don't need anything on a rear-facing vent.

G

Guy consider it gone !

M

[Rallyroller]

Hello Gents.

Just spent an hour or two reading this thread. Great. This is why this is the best forum on the web.
Nice to see somebody enjoying their car as well. Re air flow over bonnet/ heat build up etc. As has been commented with a rally car (especially used in forests) it can be difficult to get heat out of the engine bay. My Stage 124 ST always suffered as it had a huge sump guard that covered the complete underside of the engine bay allowing virtually no air flow. Raising the rear of the bonnet did not really work due to the high pressure area.

Re air vents in the bonnets, I am waiting for the fibreglass bonnet for my 124 Spider rally car from Guy Morenhout. I have asked to have it without air vents so that I can position them myself. I notice that the works 124 Spiders had vents at the rear edge of the bonnet, but this was some way in front of the windscreen (due to the design of the scuttle. ) Does anybody know how effective these were? I had a link onto a Subaru web site where somebody posted results of tests that he had carried out regarding under bonnet temperatures and air flow through the engine bay. If I remember where it is I could post it. It was good.

On my new Spider it will have a large sump guard, but there will be a gap at both rear corners of the engine compartment to allow escape of air. The works cars had gap at the sides of the sump guard covered in.

Also regarding keeping oil temperatures down, the works Spiders had oil coolers mounted on the inner wing and ducted directly to the front of the car. This was (I think) a mod on the big wing cars, which had extra vents at the rear of the front wing to aid brake cooling as well. I notice that on Mick Woods 124 the oil cooler is mounted on the inner wing, but the older small arch extensions without the rear vent are now used. Does this still work ok? I would think that the ram effect from the air flow through the oil cooler would be sufficient. Any views?

Also regarding fan installation for the radiator. On our 124 ST rally car we had a manual override- as sitting at the stage start always saw the temperature start to creep up- just before you were going to thrash it. A light was fitted to indicate when the fan was running. – The manual override also worked with the engine off. Also we had a push button cut out switch to disconnect the fan. This would be operated by the co driver just before nay water splash. It was a momentary contact (or no contact) push button so that it could not be accidentally left in operation. The reason? Many years ago with my original stage rally spider I lost a lot of time after hitting a water splash at speed. The fan forced water up into the underside of the bonnet, and it then fell on top of the engine, filling all of the holes where the spark plugs sit with water- so shorting them all out. The distributor was fine.

The cam belt could cause some of this, but I suspected the fan.( Sump guard and belt cover do a good job on the cam belt I would think) It could be that some form of under bonnet shield could be designed to stop this water from the fan, but that would also restrict air flow. Driving slower through water would do it- but you know what happens when the red mist is down, and it always looks good in the photos! -so a simple button is the easiest solution.

[Guy Croft]

Good post Rallyroller! Some interesting, useful and constructive comments,

G

[miro-1980]

Here is a link to a youtube on board.

http://www.youtube.com/watch?v=jbFeBvM3PJE

Note 1: the track is extremely slippery when dry, When wet it seems to have more traction than ice. Actually most of what we see as a carting track ( very narrow ans with tricky double or triple curves.

Note 2: this is not a public clip ; only for those who have this link.

It shows the rear facing vent ( no net in it !) The paint was too fresh to put any stickers on it : it will have a black Abarth scorpion (in front of on the original air inlet) and a white Fiat wreath between the rear facing vent and the windscreen.

Actually when painted the rear facing vent does not look half bad. ( more pictures when weather improves -it is now raining cats and dogs).

This weekend we have a historic car rally with some interesting sports stages (one on track which has both tarmac as well as gravel parts ) should be fun !

Immediate impression - we have decreased the coolant temperature by 5 degrees - now it goes up only to 80 deg C. ( before it went up to 85 ) . So this made some difference !

With covering the bottom of the engine bay and putting in the brake vents we should reach the desired 75 deg C goal.


Miro

[miro-1980]

Dear Rallyroller,

Very interesting comments , Thank you .

As the saying goes : the deeper you go into the woods the more trees you see. The more of a competition car you build the more issues you have to deal with.

What we tend to forget is that any car but especially a competition prepared sports car has to be seen as a set of connected tubes. Almost all the systems seem to be interconnected and interdependent. You fix one issue and this creates another issu8e to deal with. It takes some time to get it all in line. As Guy says , the only way to deal with it is :
a/ to understand it,
and
b/not to concentrate on the symptoms but on the causes.

Incidentally I am really intellectually surprised by the complexities involved (like heat dispersion and air /gas/ dispersion, aerodynamics, etc.). This is what it makes competition car preparation so intellectually challenging and so much fun.

Re Override switch : My experience with 124 spider is limited as my 124 spider is purely "civilian". I read about the override switch only after I bought my 124 (from US). It already had the override switch installed. It is a standard flip switch (not a momentary action type). All I did is installed a control light ( used the belt warning light which I disconnected). Very useful i traffic !

I never had a problem with water flooding the engine bay by forcing water on top of the head ( in 124 or 131). What you describe appears to be caused by the large volume of water that got into the engine bay through the front grill.

The standard DOHC engine has a fan mounted into a fan guard - protecting the fan blades all around the edge of the fan circle. I would expect it to prevent water coming outside of the fan circle from being splashed on top of the engine. So the only water which I would think could be splashed over the engine by the fan is the water coming in through the grill in the fan circle. But It would have to get through the radiator. The radiator spaces that air travels through are too small for water to travel through the radiator freely. For sufficient volume of water to get through the radiator it must be forced with really very high pressure. In such case the fan would indeed have the tendency to splash the water all over. The water would bounce back from the bonnet and thus could flood the head. In this sense a fan kill switch activated just before you hit the water pot makes lots of sense. Very interesting idea.

RE: Tempt raising just before start. This is a very good point. I had the same observation. What we do now is keep the engine as cool as possible before the actual start takes place. This works very well. It is easier to prevent the coolant becoming too hot while standing than getting it down while driving at high RPM. Previously when we allowed the coolant temperature to raise to high while idling before the start , it took a fairly long time before the coolant got colder while we actually drove on the stage. Inadvertently the fan switch would activate the fan (sometimes several times) before the temp stabilized. This is why we adopted a strategy of pre-start manual fan activation and killing the manual override switch just before the start. This has virtually eliminated fan activation during the stage.

Miro

[Guy Croft]

while we're on fans and switches I would like to mention briefly the phenomenon (?) called 'heat soak' - where the engine temperature climbs even though the engine is switched off. Most 'modern' cars with electric fans have this and it is something worth building into the installation.

It can take many minutes of fan running at full power after switch-off to bring the engine temp down to a level where, on restart, you won't have immediate (bhp) power loss or a temperature so high that sudden application of high load might cause detonation and burst the head gasket.

G

[LanciaNut69]

Hi Guy,

Would you suggest a timer arrangement or leave the fan relays wired directly to the battery? I have gone that route, but I do have an issue with battery drain if the main cut-off switch isn't used for pro-longed periods.

On the Monte, I have added a number of relays, not only for cooling, but for headlights, windows, wipers and starter simply because the original loom doesn't have them and this results in burnt out switches and ignition, which are expensive to replace (depending on where you source them of course!).

Darren

[Guy Croft]

Perhaps the way to do this is to have a thermo switch in the radiator but also a manual over-ride on the fan.

You mention 'fans' rather than 'fan'. I don't think - given best effort at sizing - why you should need 2 of them excepting that of course if they cannot vent the hot air one might want more 'push' but that doesn't solve the fundamental problem.

BTW I recently bought what I'd consider a very lost and very powerful fan (you can get pull or push types) from Raceparts UK in Wallingford. Ties to the rad with special tie-wraps that you simply push thru the matrix. I had always imagined such a thing would be complicated to rig up but it is not. That lightweight fan is 12" diameter (from memory) and is easily capable of keeping the engine temp at 75 deg even with the engine running off-load at 3000rpm. I must stress that it can do that because the exit airstream is not restricted in any way.

Aux fans should quite simply NOT be operational over 25mph ie: not be needed, the airstream should be doing the job by then. Mine is manual for my bench-test rig but you can get temperature control wiring for these and of course the well-known Kenlowe systems.



G

[LanciaNut69]

Hi Guy,

Yes, I have 2 fans set up on my car, but to be honest, the second one is never used. The thermo switch is a dual type and the standard radiator has been replaced with a aluminium one, which fingers crossed does not get the car over hot. I could make the second fan switchable I suppose as a peace of mind factor if sat in traffic for a long time on a hot day, but no such problems to date.

I do have modern replacement fans to fit, which are 10" from memory - the 12" would be too big for the Monte radiator. Exit air from the fan/radiator is directed under the car.

Completely agree that fans should not be necessary over 25 mph.

Darren

[Rallyroller]

Hi Miro

Your comment about water through the grill is correct. The shape of the car front valance etc will have some effect ( as will speed and depth of water) . I have a picture of my 124ST going through the Sweet Lamb water splash in Wales, and the trajectory of the water is nowhere near the front grill, more out of the side. The original problem with the Spider is that with the front bumper removed, the bonnet forms a large overhang lip over the grill. There are holes in the box section on the bonnet and water could be forced up through there. Simple solution could be - don’t hit water so fast.

So is an ideal solution for the fan – electric fan- relay controlled. Relay Controlled with thermostatic switch. Warning light on dash to show fan on. Manual override switch ( possibly wired through a timer). Momentary break push button to stop fan when entering water. ( co driver to operate as well )

I am looking at an aluminium radiator (for weight as much as efficiency.) I will also put on a new lightweight fan. I have not looked in detail yet, but I think I will have to put it behind the radiator as the original. As Guy points out, once driving there should not be a need for the fan so the efficiencies between mounting in front or behind the radiator (if there are any) should not affect it.

Also your comments on developing the car and the challenge it brings are so true. That is why I am building the Spider rather than just going and buying an Escort. Half the fun is finding things out, learning new ideas, sharing with others etc. Again understanding the cause of the problem is fundamental. Also the old saying the strongest part is the weakest link. Certainly with any competition car the more you modify and push things to the limit, the more problems. As with anything if you throw enough money at it you should be able to overcome the problem. However there are limits, and in certain circumstances you have to accept the inherent weaknesses and make them easier to live with rather than eliminating them.

Good luck this weekend.

[Guy Croft]

http://www.youtube.com/watch?v=jbFeBvM3PJE

GC feedback:

1. I'm not suprised you got your hands crossed with that bloke talking all the time.
2. Is it just me or there some confusion as to what is 'left' and what is 'right'?! Mysteries of the Polish langauge no doubt 303 Sqn had the same problem with the RAF.
3. You upchange is too low in the rev band get your foot down.
4. Your braking is not aggressive enough.

No doubt you will tell me you know all this...!

G