ALFAGTV6.COM

[Jim K]

In the recent hot days (>30*C) I noticed that when the twin fans came on, it took longer than I remembered for coolant temp to drop below 80*C. Since nothing has been altered in the cooling system, I concluded it must be dirt blocking the radiator surface. Sure enough, I found that ~40% of the surface area was blocked with crud and insects! Strangely enough, almost the entire blocked area is the part 'shadowed' by the bumper (Alfa 75). I would have thought this 'dark' area would be the clean one but its the other way around! Maybe there are turbulence forces playing there -no, I won't drill large holes in the bumper!
After about an hour with dishwashing fluid, soft brush, water jet blast and air pressure, the result is like new! The rad is again 'transparent'. Weird, but it only took 3 years and ~10,000km (no dirt roads) to get this bad! Just something to think about if you have a/c and hot weather! Oh, the rad with its twin fans are oem parts for the Alfa 75TD.

Jim K.

[KevinR]

Jim are these radiators man enough for a 75 with a 24v for track use ? My mate has been doubting this watching his temps not cooling off quick enough . Possibly thought the large oil cooler in front was adding to the higher temps .

[Jim K]

Kevin, I can't think of anything better for the V6, either 12 or 24v as far as rads go. I also have an upright oil cooler in front of the rad, although its only a 13 row unit. However, as temperatures go, I have never seen more than 82* in the track in our weather (~25-30*C) and 3 years ago I did 130 laps in a track weekend. In these past days we had up to 35*C here and in stop/go city traffic the fans turn on at 86*, drops to ~78 where they turn off. I'll find a fan switch that actually turns on at 82* at its supposed to. I have ~5 of these buggers (most are new) and I test them with a precision thermometer. Unfortunately, very rarely I find one that agrees with the spec (82-77) and if I do, they start slowly sliding away upwards in few months time. I'm at the verge of doing a small adjustable circuit for this job but its not a priority yet. Oh, the thermostat is a Calorstat 80*C item adapted to fit inside the std gtv6/75V6 housing and the expansion bottle cap is 0.7bar.
Regarding the fans, the 75TD ones draw ~11.5A each. I also have a set from a gta but those mothers draw >17A! I suppose they move more air also but my alternator is still the old V6 70A unit and can only be increased to 90A in the same housing. I therefore haven't used the gta ones, since I'm ok with the TD set. We have to consider that at idle the supplied current is much lower than 70A. What if the lights are on too (80W bulbs)... and the wipers, and....
If you want any relevant pics let me know!

Jim K.

[75evo]

Kev,

Your mates car is the black one with the 3.2? And he is racing in the UK right? Not exactly a warm place.

Believe me JK and I sometimes have 100F ambient temps at the track and the TD rad is absolutely fantastic. In fact last week the ambient temp at Buttonwillow was 110F and drivers were having problems.

I think if you clean them as per JK you won't have any probs.

[KevinR]

Yes Z , it is that black 75 . We ( owner of 75) work together and always dreaming up new mods which I must post on on another thread . This 75 runs standard thermostat but if it's going to be changed it might need some remapping as it was mapped at 90c . ( runs omex) .
I must say the 75 rad is really tiny compared to the rad specifically made for the SA GTV 3.0 but then it is aluminium . The SA 3.0 needed the large 4 core as most racing was in very hot temps . My rad in my track car is a BMW 7 series modified with custom side tanks and also mapped at 90c but extremely efficient even with standard thermostat . My oil cooler is the long thin horizontal type from the M3 which I think is pretty efficient as it sits in exact slot of the bumper . Anyway back to the 75 . Will try get some more accurate data on its cooling but it just did not seam correct . ( even with old 12v)

[75evo]

Kev,

Is your mate's car running a TD rad or a V6/TS rad? The TD rad is very good. I bought mine from OKParts 10 years ago. I was having problem with the stock V6 rad. It couldn't cool the engine enough during hot track days. I think the old rad had a lot of deposit inside of it.

But so far the TD rad has been fantastic. It's bigger and thicker than all other 75 rads. And if you use Evans cooling fluid, you won't have any problems with oxidation.

Here if I go to a track in Winter/Spring, the engine can't even reach operating temp in the morning sessions as I took the thermostat off. WIth winter ambient temp of about 40F and wind chill factor, getting the engine up to temp is a big problem unless you let it idle in the paddock.

[Jim K]

NO THERMOSTAT = DEAD WRONG!! I have been looking for a proper thermostat for quite some time and I believe I have found it. Its an 80* part which requires minimum work to use it in the V6 housing, after the std thermostat is removed and the pegs broken. Its a Calorstat TH1335.80 unit. All that needs to be done is to reduce OD from 54 to 51mm so it just fits inside the housing lip and the lower disc OD from 35 to 25mm. I use a chassis nibbler to easily do this. Surely enough, it opens at 80-81* (gauge dips) and holds ~75* highway temp. I've had it with this subject, I've tried many thermostats and this seems to be the best solution yet -until next time...
The TH1335.80 was apparently used in no less than 39 Ford vehicles!

Jim K.

[75evo]

Not for a road car, I wouldn't take out the thermostat for a road car.

For my race car, I see no point in a thermostat. Some of the thermostat I had were problematic. They either opened not per-spec or they leaked and didn't close per spec. Since the last one gave problems I never even bothered to replace it. Threw it out. 2 years later 110F weather, no problems. But cold weather will cause warmup problems. I seldom have time to run in the winter anyway. If I find a good thermostat I will use it. Will look into the Ford one you suggested.

[Jim K]

NEVER run without one. If it works well it won't impede flow at all. Warm-up phase is crucial for the engine. With cold oil, rings end up scraping liners!

Jim K.

[KevinR]

I used to run without thermostat in SA with bottom side blocked off BUT that because we could not get any in SA . Now that my car is in UK it's the first thing I have changed on both my cars . Importing was a nightmare - won't even go there . Jim thanks for info on that thermostat I'm definitely going to put one in on my carb GTV . As I can't program my fans on that car and prefer cooling running temps ie about 80c with those six carbs needing cold fuel .

[Jim K]

This is what you want, but these guys have crazy shipping fees! http://www.ebay.co.uk/itm/TERMOSTATO-FO ... Sw8vZXMbeQ

I'm sure someone sells these in UK for older Fords.
Kevin, if you want, you can stagger your fans to turn on at different temps by installing a dual rad switch and two relays as I have done. The relays are heavy duty as start-up currents exceed 25A for each fan.
In the first pic, the two white fused relays are for high/low beam and the black ones with 30A fuses for the fans.

The double switch on the left (FACET 7.5604) has two turn-on/off temps, 82/77 and 87/82*C. The one on the right is the std one.


Jim K.

[Jim K]

I believe that the city of Athens today was a giant stress test for cooling systems, cars and drivers! Temperature was >35*C at noon... The subway and the city transit system were on strike so everyone was driving to/from work. Sun blazing, ~1:30pm, stuck in traffic with the 24v (no a/c). The poor thing was idling for more than an hour and with both fans working, the temperature was stuck at ~84*C! Boy, was I pi$$ed! I hate traffic and I despise heat even more! When I finally got moving (3rd gear max) temp dropped to just <80*C as long as I didn't stop again. If this isn't a soak test, I don't know what is. I keep thinking about the gta twin high-current fans. Maybe I should try a bigger alternator and a second battery just for the test. They definitely move more air than the 75TD fans and I am trying to think of a cheap/quick way to compare airflow when I have both out of the car. What seems to make sense is a hard paper cone, the large end fitting tight behind the fan and the small end adapted to fit on an afm. Length of cone ~50cm (20"). I can then compare afm flap deflection ... How's that for cheap engineering? I could also use one of them wind-meters surfers have but I don't have one. I'll be back when/if any of this works!
.......
Ok, its 33*C in the shade and I had the urge to dig out the gta fan combo. Each fan draws 12A @ 10V and 14A @ 11V. I can't apply more voltage as my power supply craps out. Don't know how much inrush current is, the 20A meter goes off-scale for a second or so. These fans DO move LOTS of air....
Here is the std 75TD rad with the two different sets of fans. Top is the TD setup and bottom is the gta set with some mods to fit on the std TD rad mounts. You can see both sets leave a large blank area with no forced airflow in the bottom. Some time ago, I tried to solve this by buying two powerful SPAL fans and mounting them on the rad, but I never used this solution and finally sold the fans to a friend. This was the third pic below.




Jim K.

[Jim K]

Ok guys, this is probably the last cooling system upgrade for me. I installed the gta set in the car and tested it today in 39*C (103*F) weather. Highway driving, 76-78*C. Stop/go traffic jam, fans turn on at ~88*C (fan switch determines this) and temp needle drops FAST to 78*C where fans quit. These fans are very quiet compared to the TD set (~20years of evolution apart). Voltage drop from + terminal in engine bay (battery in trunk) to fan is 1.4V which I have to accept, judging from the results. In other words, the + terminal has 12.6V and the fans 11.2V. The only thing left in my perverse quest is to arrange for fan turn-on at ~82-83*C. This will take a small electronic cct, no sweat at all. Right now though... the hell with it!

Jim K.

[75evo]

Jim,

Have you looked into a soft start circuit? That would solve the inrush current issue and may prolong the life of your relays. Would be an interesting project.

[Jim K]

No and I don't care. No probs any more! Seems that with the ecu standardizing on 1000rpm idle, somehow everything works out ok. This type of ecu has a sort of 'learning' feature. If you drive it for a while (minutes? Hours?) it becomes more stable at idle. Even the factory manual advises driving for a while after reconnecting the ecu, for it has to store some parameters... I wouldn't know what. The relays are the 50A type, like the main releay in the 75 fusebox so no worries there. I really believe the 'cooling' chapter is closed for both my 75's! Only thing left now is mapping/dyno the 3.2 but in this heat I'm not going ahead with it.

Jim K.