Blocked off most of my grill, no change in coolant temps

[91CavGT]

I blocked it off yesterday on my Colorado by removing the front grill and putting duct tape all on the back side of the grill. This keeps it looking decent, and it is easy to remove. There is still two fist size holes in the front bumper that redirect air up to the radiator and there is a gap all around the grill that allows air to slip past.

In 88 degree weather today in stop and go driving as well as highway driving I saw consistant temps that were identical to what they used to be. 190-191 degrees according to Scan Gauge.

I got some great results according to the Scan Gauge in this mixed driving today (31.9 mpg and 32.6 mpg)so I am going to continue to test the grill block the way it is for one more week. If I continue to see consistant coolant temps then I am going to block more of the grill off.


I'd like to get minimum of 30 mpg city and 40 mpg highway, that is my goal.

[jharbert]

40mpg out of a gasoline 2.8 would rock.

[ZugyNA]

Originally Posted by 91CavGT

If I continue to see consistant coolant temps then I am going to block more of the grill off.

I'd like to get minimum of 30 mpg city and 40 mpg highway, that is my goal.

Warning Will Robinson! Warning! I would be very careful blocking things off.

Good idea to have an indicator light set up on your elect cooling fan so you know when it runs...and when it typically doesn't. If it starts to run more and you don't know it...your testing will suffer...and so will your mpg.

[91CavGT]

Originally Posted by ZugyNA

Warning Will Robinson! Warning! I would be very careful blocking things off.

Good idea to have an indicator light set up on your elect cooling fan so you know when it runs...and when it typically doesn't. If it starts to run more and you don't know it...your testing will suffer...and so will your mpg.

Well, this is on a truck and as of right now there is now electric cooling fan. It has an older style mechanical fan that runs all the time, but it does have a thermo clutch on it. The nice thing about the thermo clutch is that when it engages, it is VERY noticeable. There is a VERY loud roar coming from under the hood when this occurs.

On a related note, this cooling system on this truck is overbuilt from the factory. In order to keep costs down, Chevy utilizes the same radiator, radiator fan, and thermo clutch on the 4 cylinder and the 5 cylinder motors. This means that the cooling system is designed to handle 45 more hp than what my motor is producing. So there should be plenty of cooling capacity even if air flow is reduced going through the radiator, in theory anyway.

[GasSavers_Ryland]

remember that the cooling system on a truck is also designed for when the truck is under load, half a ton of cargo, or 10,000 pounds of trailer, or whatever your vehicle is designed for, so if you are running an empty vehicle, and driving it lightly you shouldn't have any problems at all with over heating.

[Hockey4mnhs]

i dont think it will over heat at all just keep testing a posting the results

[MnFocus]

I had a lot of reservations about a grill block also , all for naught . You've got the right idea - block some ,test and repeat . Keep an eye on your SGII and you'll have enough warning to remedy 'too much block' before it gets out of hand .

[91CavGT]

Update!!

My truck was running at 190-191 degrees, so I decided to go ahead and block more. Low and behold, the coolant temps actually dropped down to 186-188 degrees!!!


My grill is now completely blocked (air can still pass by between the grill and the bumper) and I also blocked 2 of the 3 holes in my front bumper that lead up to the radiator area.

The only explanation I can think of is that the air coming up from the front bumper was adding turbulence to the air flow coming from between the grill and the bumper. Blocking off 2 of the 3 holes in the bumper has greatly deminished the turbulence thus allowing better flow through the radiator.

I have no idea if this is right or not. I am going to try to get some pics up as soon as I can, but with working and going to school Monday through Friday and moving, I don't think it will be anytime soon.


Ohh, also, according to Scan Gauge, I got 36.2 mpg on my way to school tonight!!!!! 37 miles, averaging 41 mph, max rpm 2015, max coolant temp of 191 all a mix of city/highway/rush hour traffic!!!

[MnFocus]

Good job! Keep on it - you'll see higher !

[91CavGT]

I'm getting REALLY curious as to how high this gas mileage can go!! Every time I take the truck out now I am seeing what makes the gas mileage go higher. I can't wait till I can drive with the A/C off and do some more aero mods!


For those that don't know the size fo the Colorado pickup trucks, it is basically identical in size to the early 90's base model Ford F150 trucks.

2006 Chevy Colorado
regular cab
2.8L 4 cylinder
175 hp
185 ft lbs
5 speed manual
3200 pounds