Observations on the 308 cooling system

my car being a Canadian model, it has metric gages. Temp after cooling lap is 78C at 80 mph and slowing down over the 2.6 miles long track. I run around 85 degress on the highway at constant 70 mph. Reading is 90 degrees (193 F) in bumper to bumper traffic on the warmest day. This rad basically provides me with peace of mind and protects my investment in the rebuilt engine. I KNOW the engine will not overheat no matter the circumstances

this is worth the $900 invested in the rad!

Cheers and Happy Holidays

 

someone of F-chat gave this tip and i just tried it - cheap and good. Catch those drips without standing there with a rag or towel.
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The problem also lies with the design of the original radiator being a downflow style which is terribly inefficient. I designed and built a crossflow design which not only has 30% more cooling area, but the heat transfer itself is inherently more efficient.
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Interesting!!
Could you be so kind to explain us what the crossflow design means? Your radiator is the only one on the market with this design??

 

Good idea!!! So clean!

Thanks for sharing

 

I have an '84 QV, mid year build, with the smaller WP driver. The issue was airflow. I used a similar style fan as lperreault did (pancake style), but mounted pusher fans in the stock position in front of the radiator as I wanted to keep my front boot and spare tire. The additional air flow the higher capacity fans provide resolved the temp creeping up in slow traffic (never had an issue to begin with at highway speeds).

While I was at it, I added a puller style fan on the oil cooler, which is relayed off the same circuit as the radiator fans, so it turns on/off based on the water temp. This helps also, like when it's an August afternoon in NYC and you're in traffic on the BQE. In the winter, the oil temp takes a couple minutes longer to come up to operating temps, but nothing that causes me or the car any pain.

Then my best friend made the fan upgrade to his Pantera, and he experienced the same betterment as well.

Interesting to note that the Pantera has the a/c condensor mounted in the engine compartment, unlike our cars which have it in front of the radiator.

On my list of future projects is to find someone who can rewind the stock can fan motors in an effort to increase their rpm - thereby increasing their airflow, and then maybe mounting them back on the car instead of the Spal aftermarkets I've been using these last 10 or so years. One of these days I'll get to it.....

 

Exactly...and the 308 QV cars used this design.

And you can play with water pump pulley sizes until the cows come home. The 328 addressed the inherent problem and moved to sucker fans and a better radiator design.

 

This is really it, compared notes last weekend to the 328 installation and it was obvious.
Shrouded fans on the front of the 308 radiator would be a big improvement.

But not the Cowboy Way.....I use the knock off fans from Grainger. LOL!

 

These Ferrari downflow units in essence travel a very short distance north to south, but they have a significant quantity of liquid doing this as you will notice the tanks on the top and bottom of the radiator are quite sizable. There are two parts to this. First: the liquid travels 13" north to south which is just not a long enough path for much heat transfer to take place. Second: the coolant flows faster moving downward meaning it's not only traveling a short distance where it's not shedding much heat, it's moving that distance very quickly.

A crossflow design moves the liquid east to west (or west to east depending on your vantage point) in a similar volume a full 22" with only the pressure of the water pump moving the fluid along rather than a downflow radiators natural 'downward' progression. The tanks also do not hold as much capacity meaning the radiator is not constantly filled with extremely hot liquid. Too large of a tank is a heat retaining nightmare. You want water to come in hot, and leave cooler, and as quickly as the radiator can do so efficiently. I use 2 slightly larger elongated oval tubes in the core rather than the stock think copper core method. I still don't understand why Ferrari didn't do it this way but it is what it is right. Maybe crossflow cores were too expensive or they could not locate an adequate size? Who knows right.

The 328 radiator is still a downflow style but it is larger and the tanks are slightly smaller. Point is they fixed the issue I guess. A larger unit was not really the answer, but a more efficient unit was. For example, the radiator I made is almost the same size as a modern Corvette Z06 radiator. With crossflow design it doesn't take a radiator quite as big. Crazy right? Below is the Z06 radiator which cools a giant engine.

I don't really sell these or manufacture them in any quantity. I made a few for some fchatters a while back but I don't really have any interest in selling them worldwide etc. I keep it fun and help in the Ferrari community when I can which I really enjoy.
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Thanks for the explanation John. really interesting. Seems to be a very good improvement on our poor QV refrigeration system. I'm trying to improve my cooling system and the last solution will be to add a new rad -mine is a new aluminum one, but it seems not to be so efficient-. I need to work a little more on other areas and after that we will see. Thanks again for sharing.

Cheers

 

Much has been said about the 308-328 cooling system. I have 3 probably ignorant questions/observations:

1) in a not close to perfectly running 308 cooling system is the header/overflow tank too small?

I am looking to add a small extra tank below the current on so that any overflow from the overflow tank (quite often in this summer weather) is captured and returned. I hate when it pisses on the ground! But doesnt it makes sense to have one larger tank with lots of room for expansion while still holding a good amount of coolant?

2) could the overflow tank be located down near the radiator?

My pea brained logic suggests that setup would bleed the radiator and perhaps and autobleed could be incorporated at the t-stat housing (or in case of the older cars, just get a tstat housing with the bleed screw). note that Hans' GT4's PO installed a copper tube from rad through the tunnels to the header tank which autobleeds the rad - good thinking but kind of like bringing the mountain to Moses). There is room for a tank in the front - why wouldnt you put the tank there?

3) I look front on at my car and see an enormous A/C radiator blocking the rad. Surely neither are performing optimally like that. Are modern A/c radiators able to be smaller ie could you have one that doesnt block the whole engine radiator thus improving its flow?

Any learned thoughts?

 

1. The 328 cooing system is substantially different - 328's just do not overheat under any conditions - 110 degrees out, stopped in traffic, ac on, etc.

2. Location of the overflow tank in any cooling system is not particularly relevant to operation though extremes above/below are usually avoided. If too far below, it's more difficult for the vacuum developed as the engine cools to pull the coolant back in from the tank/bottle.

3. The ac condenser in front of the rad does restrict the flow a bit but this is the normal configuration on most cars (though not the 328) so obviously ON MOST CARS they size the radiator/fans to work satisfactorily on the hottest days with the ac on. It seems obvious that the 308's system was not so-sized. They basically just stuck the condenser in there with no real testing as to how it would function in really hot weather. They figured that out with the 328 so they moved the condenser to a separate location, with its own fan. Don't know if that actually improved ac performance at all but it certainly improved engine cooling when coupled with the more powerful pull-through radiator fans and revised hood venting.

 

There is this --> http://www.ferrarichat.com/forum/showpost.php?p=137719614&postcount=9

and, this --> http://www.ferrarichat.com/forum/showthread.php?t=373050

 

Yep, I have the auto bleeder on order and a small overflow tank arrived today. My question was more

Instead of having essentially two small overflow tanks (the oem one and a aftermarket one) could you have one larger one more able to handle more expansion/contraction of coolant without overflowing?

Secondly, would their be an advantage to having that tank up front near the rad?

 

These two are not the same...and the Ferrari uses an expansion tank. There are material differences on how these two similar but different systems operate. With an expansion-based system, the vertical position of the tank is critical to its functionality.

 

Thanks david, i regret that with my woeful knowledge I'm very easily out smarted in these discussions, but let me try and rephrase the question:

Could a larger expansion tank (larger than the little hip flask which is oem), with more capacity for...expansion...result in less (or no) coolant being dropped on the ground, thus obviating the need for another xxxxx?

Naturally, one has to try other things to get the cooling system to stop the engine spewing coolant on your drive, but that's another topic well covered.

 

Most folks use these terms interchangeably, even though they are very different.

No

This is the area we need to focus on. Coolant being expelled under certain conditions can be normal. Is this an ongoing problem, or only occasionally...or did it do it, then stop?

A few things to consider:
-Excess air in the system will exacerbate the spewing
-A defective expansion tank cap will exacerbate the spewing (90% of the caps I test will not hold pressure.)
-Coolant leaks and seeps will exacerbate the spewing
-If the tank is overfilled, it will spew until the equilibrium level is reached

This is different system by design and will not behave like a conventional car...hence, conventional wisdom doews not apply. Please not that I am not saying that this is a "better" system, rather just a bit odd.

 

"-If the tank is overfilled, it will spew until the equilibrium level is reached"

I think this is a really important point. The proper level of coolant in the exp tank when the engine is cold is quite "low." But it's easy to treat it like a radiator, filling it to the top and then installing the cap. Most radiators have an overflow tank so this works fine with a radiator. But, as noted, these cooling systems use an exp tank which essentially becomes the "top" of the radiator and there is no separate overflow tank.

When I had fluids changed by a well-known exotic car specialist in the local area, (I had no garage to do it myself at the time), they filled the tank to "full." The results were that it was spitting coolant for days until it got down to the correct level. This done by people who work on Ferraris and other exotics as their business. (!)

There is no need for a separate overflow tank if the exp tank is not overfilled. Even if it is, it will adjust itself to the correct level if you don't mind it spitting/dumping some coolant on the ground/floor for a couple of days if you overfilled it.

 

My bottom rad switch sensor has some odd numbers stamped on it but nothing clearly saying 195, 180, etc. How do I know what the temp setting is on mine? It is labeled as a Veglia and has "Made in Italy" stamped on it. It also has the following stamped numbers on the hex flats as well:

2G
73-0.2
85`/.76

What do these mean?

 

Bob, the only thing i know for sure is that (I tested it at home in a can of hot water.)

85' means 85' Celcius same as 185F thats when the cool ventilator starts working.
76' means 76' Celcius same as 168F thats when the cool ventilator stopts working.

the other numbers are maybe production numbers i'm not sure.

Rob,

 

Ah, thanks Rob! For now I'll keep it installed then.

 

David, that makes all the sense inthe world. Thank you.

I have just put in a overflow tank which can be removed in 5minutes while I sort out anything which is not just the tank being overfilled. For a more permanent install I would place it under the current header tank, out of the way, away from the heat and where the black tank would just blend in. For now, this do.
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I have a 1983 European QV that gets too hot in traffic. Case in point...coming home to NJ from Limerock ALMS races this past weekend. As usual there was an accident on the NYS Thruway and I crawled for about 20 minutes. The outside temp was 90+ and the gauge started climbing. I got real nervous when the gauge hit 105C but then I passed the accident and made it home okay. The temp after moving went back down to 90C.
I have done everything and would like to change the pusher fans to the Spals but have no idea what model to order.
Can someone help me out with a model number that fits the 308?

 

Short exhaust make for hot exhaust and long coolant flows make for hot coolant. Amazing what the rear engine layout does to these two systems.

One of the reasons I didn't end up with a QV was the numerous receipts I found in the QV's receipt envelopes for cooling system repair/upgrades. Every seller had a long spiel about how the cooling system was FINALLY fixed.

 

I am mounting two of these on my rad --> http://www.spalusa.com/store/main.aspx?p=itemdetail&item=30101522

They're 'true' pullers, designed to pull, rather than messing with fans blades and reversing connections etc.
They're thinner than the Hayden fans.
They're going on the back of the rad.
I figured I'd limit obstruction at the front of the rad/condenser, also copy the setup of the 328, which has a 'better cooling system'.




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