gerardvg

Hi guys
I have been getting my vette ready for summer here in Australia.
We get up to 47 deg c days here and last weekend was 30 deg c.
While my vette is modified, supercharged and intercooled the large intercooler (roughly the area of the radiator adds a lot of heat. It's fine in winter 10 to 20 deg c and up to 30 deg. It will get hot up to 120 deg c in traffic with the a/c on Fine on the freeway..
Last summer i got it up to 130 deg c and the radiator cap would let the vette coolant bubble

I have replaced the coolant (50/50) mix and purchased a 20 psi radiator cap and replaced any hoses that feel old
Was 30 deg on the weekend and the vette was well behaved only got to 110 deg c with the a/c on. I have an adjustable temperature controller set to maintain 95 deg (190-195F)

I had found last year that a 180f thermostat would not let the radiator cool enough and would gradually overheat even 30-35 deg days.
the 190F (standard) thermostat has helped a lot.

While i know a smaller intercooler will solve most of my temp issues,
standard the vette would run at around 115- 120 deg c on 40 deg days
so i feel the cooling system is a bit compromised with even minor horsepower gains.

How hot is too hot ?? i think 200-220f is normal for these vettes, will the radiator cope with up to 20 psi of pressure it is way over the top i know as the std 15 psi cap with correct coolant will raise the boiling point to 260f.

I tend to run the air conditioning for short periods of time above 35 deg to keep the coolant below 120 deg c (around 240F)
So far so good as it has not exceeded 220-230F
Going up a mountain in summer is another problem with all the heat from supercharging adding to the problem, i know i can solve a lot of this by having a intercooler half the size so the radiator can get some cool air. I just want to know what engine temperature i can safely run ?

Lower boost and smaller intercooler will help. (am running 8psi boost)

Let me know how hot your vette runs in summer with a/c on above 100F days?????
Thanks for taking the time to read this

blackozvet

gday gerard,
i put a new 15 psi cap on saturday, had to drive thru the city in 33c , by the time i got to showgrounds it was at just over 220f (113c) and venting into the overflow, not running a/c,
I took a look at my original cap and its got 17psi stamped on it ?
got a 195f thermostat too, but i must say the car ran cooler when it didnt have a thermostat in it, usually didnt go above 95c, even in 40c weather,
but must admit had the temp sender checked and it was 6c under actual temp, replaced with a new one on saturday, maybe its closer to real temp now ?

gerardvg

Hi Blackozvet
Maybe you need to check your coolant ? A 15 psi cap should prevent boiling to 160 deg. Saying that my vette would sit there boiling at 115 deg c. With the new 50/50 mix coolant and the 20 psi cap it is nice and quiet even at 115 deg so I suspect the 15 psi cap or the coolant was bad. Also check between the radiator and condenser.. All manner of crap gets picked up and deposited there. I highly reccomend you put screen mesh to prevent that,
Cheers
Gerard

XR_Strider_GuY

Hi Guys,
Good to see some aussie C4 vetters here.

Gerard,
We met on the Corvettes of Melbourne cruise last time. I was the guy in the Red 1990.

I am running a new 17psi radiator cap and I have a davis craig thermo fan over ride that allows me to kick one of the fans in earlier. I am running a stock thermostat.

Took mine out for a drive last Saturday and in idle stop go traffic the needle (I have a 1990 with an analogue gauge 100-260f) sat a little over half and this is with the air conditioning running as well so this means both fans are running. Once I start moving at say 60km/h it will go back to 1/4 to 1/2 on the gauge.

I would think (not an expert here) that 20psi will exert more pressure on the hoses, radiator and head gasket.

gerardvg

Hi
an update on the weekend the temp never went over 110 deg c (200-220f) was a 30 deg day so is looking good

Today i decided to bring it thru some peak hour traffic went via a toll road down then many traffic lights back.
On the toll road was maintaining 95-105 deg c (207F)

In heavy stop start traffic with a/c on and staying nice and cool the temp did not get over 110, an awsome result
sat around 195f with a slight rise to 207f while waiting at traffic lights and that dropped right back below 200f while in motion.

So my coolant must have been past its use by date as replacing it with a higher press cap has improved it greatly.
Putting a heater bypass hose has made the temp more stable (has a valve on it so i can adjust the amount of bypass back to the water pump) where it would ramp 10 deg for no reason, indicating there was not enough flow around the thermostat. Temp now very stable.

So i cannot wait for a high 35-40 deg day to test it some more
Maybe i can keep the large intercooler

The main worry about having a 20 psi cap would be the heater core,i did replace that 2 years ago with a new one as they are really hard to remove. Am a bit worried about the radiator plastic tanks, that will make me buy a nice 2 row all aluminum radiator if it spits the dummy. . (even though the radiator is only 4 or 5 years old)

So the heat of summer will be the big test 35-40deg c.
The callaway twin turbo vettes have the better idea by having their intercoolers bolted to the intake manifold, allowing the radiator to work at its best. but i do not want to put holes in my vette's hood

Oh i forgot to mention, i have re-enabled the Exhaust Gas Recirculation.
Not the air pump stuff just the valve on the inlet manifold.
Got another solenoid valve and connected it ... still works no EGR code on the highway now. it does lower the engine temp a few deg on the highway, i am sure of it as i was keeping it at around 195f

Ok i have talked enough... time to watch some television
Gerard

blackozvet

Hi gerard,
the green stuff is new, I had the radiator out during the engine rebuild so everything is clean in there too, I have a 'burnout king' brand radiator in mine, but I guess the easiest way to keep things cooler is another row on the radiator,
might try a new 17lb cap ?
xr strider talking about the gauge reminds me of when I had my zzr1100 Kawasaki, they ran hot like vettes and had a needle gauge which always showed near the red, owners complained about them running hot, so they simply re calibrated the gauge reading so it showed less than half, and everybody was happy ! maybe if we didnt have that digital readout in our face we wouldnt stress so much ?

gerardvg

Hi blackozvet
Yes they make a two row radiator the standard is a single one inch row.
The cap should stop the vette boiling if it is venting the cap must be bad or the coolant is not 50/50 blend. As I said a fifteen psi cap stops boiling to 160 c I cannot remember a time the vette didn't boil even at 110 c with a mew cap I have three or so, now I can pull up And there is sweet silence and no overflow / leak of coolant.

c4cruiser

One thing that you need to consider with C4 coolant temps is that they are designed to run hot for US emissions purposes. Later C4 cooling temps are typically in a range from 195 degrees F to as high as 238 degrees F.

One big way to insure proper cooling temps is having the radiator and A/C condenser free of any dirt and debris between the tubes and fins. Once the airflow is blocked, the radiator will have a hard time keeping temps down. Look up under the nose of the car and you can easily see if the A/C condenser has junk (leaves, dirt, twigs, small animals, Hondas...) between the fins.

Same with the radiator. look in front of the cooling fans down in the lower corners. On the later C4's there is a small opneing in the upper right corner of the plastic shroud where you can look down between the radiator and condenser. It's easy for dirt and debris to get in there, especially leaves.

A garden hose with a nozzle can be use to flush out a lot of this junk. Might help to spray a good cleaner on the debris first. Grab a cool one and let the cleaner sit for a few minutes, then direct a forceful stream of water from the fan side.

Old original radiators can be another problem. Afer years of coolant circulating through the fins, the metal gets worn away. This reduces the ability of heat to transfer from the coolant to the metal tubes where air takes the heat away. Sometimes a replacement radiator is in order; not a cheap fix, but probably the final step.

Old radiator hoses can be a potential problem too, especially the lower hose. If that hose becomes weak, it can start to collapse and cut the flow of coolant.

Flame Red

I live in Florida and know what you mean about heat, but I would not recommend anything over the stock pressure in these systems. If you go too high, you might ether be facing the dreaded replace part #1 - the dreaded heater core, or you might find yourself with gasket leaks.

I found that after I installed a DeWitts radiator it no longer runs hot. I also run a 180 thermostat and replaced the water pump with a high flow (Edlebrock) unit - but it is the radiator that makes all the difference. I also replaced the upper and lower radiator hoses with a set of universal aluminum hoses that can bend any which way since I cannot use the stock upper hose either because of my blower.

MK 82

Explain me to me please how replacing A 180 thermostat with a 190 helps the engine cool.

You do not need a 50/50 mix. In fact you could run straight water with water wetter. The water wetter stops corrosion. Water cools better than glycol.