RonSSNova

My car hasn't had any real issues with temps until this summer with 90-100 degree days. I'm sure it will go down as one of the hottest summers in Portland history.

Inspire of regular cleaning if the radiator and AC condenser fins, stuck in traffic has yielded temps above 240.

And yeah yeah yeah, the stock high speed fan settings don't turn the fans on until 235.
I have set mine to 195 and 205 respectively. Thermo is the stock 197 unit.

The system simply does not have the capacity to cool to thermostat temp in hot weather.

Here is a case in point.
My Cobalt SS supercharged.
Ships with a 175 deg thermostat. It will sit in traffic all day at 100 degrees and run at 178. It has a bigger radiator than my Vette. Not to mention AC condenser and water to air intercooler sitting in front of the Rad.
In terms of high performance, 122 CID at approx 275 hp, it's light years ahead. Ships with Mobil one 5w-30. Seems Gm believes cooler running is a good thing after all.

I've heard nothing but good about the Dewit's. Mine is going in along with a 180 stat next week.

Might be able to add a degree or two of timing to boot. I'll test it on the dyno. I'm the operator.....

Ron

C5 Pete

Let us know with a detailed report. (The only kind of report you know how to do)

Scn1998

Looking forward to you write up on this. The Dewitts rad is the next thing to do on my list.

RonSSNova

Ok. Detailed report.
The radiator install was straight forward. I'd have to almost say removing the old one was harder than installing the Dewitt's.
Mine being a 2000, the fans come out the bottom due to the larger ABS unit.
Nice fitment on the new unit.

So, I really struggled getting the system filled. The Dewitt's holds a significant amount more coolant. And these cars can be a pain in the *** to fill.
Bled the steam vents, filled through the top hose. All the tricks.
Finally put a burp funnel on the reservoir shut the fans off and let it burp good!

Set my cooling fans at 185/195 assuming the 180 Stat would keep me right near 180.

Wrong again honey!

If I would have done my research, I'd have discovered that no one in history has had the so called 180 LS1 stat run 180.

Mine ran 198-201. Highway, city, driveway with the AC on.
So I guess I need a 160 to maintain 180 or so.

The good news is that the car does not go into thermal run away like it was. And we have been near 100 ambient. The radiator works.

Oh, I had the supplier (Tooley Racing, great folks) send me another 180 stat. Did the test on the stove. It cracks at 195. Open at 200. And the design is different from our stock units. The bottom disc has no holes for bypass. It's very odd.

Ron

neutron82

my full size dewitts radiator/dual spal fan setup has worked great for me for the last 2-3 years... I also installed a 180 stat at that time and high speed fans come on at 185... I also have a 3.5" thick frame rail to frame rail intercooler that is in the way and in the hot tx heat it's rare I see over 200 degree coolant temps... usually on those 100+ degree scorchers I will see high 190s and it might creep up to maybe 205 at the most if I'm stuck in traffic with the ac on... cruising down the highway it's usually 185-190ish depending on the temperature... case in point it does work... another thing to note is that I am still running an aluminum block, guys running iron blocks tend to have more cooling issues that are harder to rectify

RonSSNova

Perhaps your 180 stat is a diff brand.

Forgot to mention I'm 25% under driven on the crank pulley.

neutron82

it's a hypertech 180 and I have a 10% overdrive balancer now but I didn't notice any difference in coolant temps from when I had a stock diameter balancer

vettenuts

I modified my stock thermostat with a 0.045" shim and it runs in the 180-185 range depending on how the car is being driven in 90 degree weather. I am also running a DeWitts radiator.

RonSSNova

Thanks Bob. I found your mod article. My stock stat wasn't in good enough shape to modify. So to do that I'll have to buy a new GM one.

73Corvette

Stock radiator, Vararam CAI, Chuck CoW street tune 160 degree stat... I'm assuming Chuck used the 160 so he could advance timing without detonation...
Runs 181-187 almost all the time in town or on the hiway...
I also have NO side air dams and trimmed the middle one about 2"

Many folks use the 160 degree stat in the summer to keep temps down and put the 180 back in for the winter months...just sayin
OH yeah... Dewitts is the BOMB... had a Big Block 454 4spd 73... they were notorious for overheating... the Dewitts STOPPED that... it stayed on 190 all the time...

RonSSNova

I don't drive the C5 in the winter. So no issue there.