Topic: Coolant Ratio

[chrisfranklin]

It never freezes where I am at. Lows in the deep of "Winter" are maybe 40F at best.  Running 50/50 coolant to water is probably overkill here. This 50/50 ratio apparently allows coolant to stay fluid to 30F below zero, which I am nowhere near reaching 

I flushed the system and have decided to go with a different ratio - probably about 70/30 water to coolant or maybe closer to 80/20 water to coolant.  Maybe enough coolant in there to inhibit rust. Am also using basically, close to a couple of gallons of purified water as the h2o portion.

Cooler engine temp is suppose to enhance performance slightly.  So far, so good on my end.  Am not going to mess with the water wetter stuff, low temp thermostats, etc.  You warm weather living guys done this?

[YJmechanic]

you should be fine but i would probably go 70/30 at minimum.  lower temp will increase performance but only to a certain degree.  engine are designed to run at a certain temp and if you go too low it will actually hinder the performance,  but a little lower will help some. 

[Jeffy]

I run 50/50.  It gets below freezing once in a while but never enough to snow.  Even when I lived in Hawaii (never got below 50), I ran 50/50.  One of the reasons is that the coolant has rust inhibitors.  Run it too watery and you risk rusting of the coils in the two radiator hoses.  The springs can break apart and float around in the system.  Worse is rusting the impeller.  The coolant will look brown if there is rust.  The other reason to be careful with the ratios is that the coolant not only helps prevent the fluid from freezing but it also helps keep it from boiling.  Since it does get hot in Socal. I'd be more worried about this.

Cooler temps does not enhance performance unless you're overheating.  MPFI's like to run on the warm side.  Run it too cool and it tricks the PCM to run richer.  If you're not setup to run richer you'll just be wasting gas and you'll see your mileage drop.

[chrisfranklin]

MPFI's like to run on the warm side.  Run it too cool and it tricks the PCM to run richer.  If you're not setup to run richer you'll just be wasting gas and you'll see your mileage drop.

Am not set up really to run richer.  But, I do have this 62mm TB that feels like it may need a little more fuel down low. Other than the spacer, the rest of the intake is stock.  I agree this will probably just end up dumping fuel.  Will try it for a few days.

Boiling point is another issue I should be on the look out for; PITA, but I'd probably change back to 50/50 or better if I was heading south to some desert areas - which might be twice a year.

50/50 or better is probably ideal for anti-corrosion.  And, yes, the mpfi engine probably tends to operate better on the warm side.   

[chrisfranklin]

you should be fine but i would probably go 70/30 at minimum.  lower temp will increase performance but only to a certain degree.  engine are designed to run at a certain temp and if you go too low it will actually hinder the performance,  but a little lower will help some. 

70% water/ 30% coolant is what I am doing right now.   You know the temp guage - its not a very precise tool.  But, it shows temp squarely between 180 and 210 marks - probably 190-200 degrees.  The needle was on the 210 mark for me with a 50/50 ratio.
Standard 195 degree thermostat is in place, so perhaps that's the temp it's at.

It seems to run better WOT; down low and mid-range seem to have improved; off-idle flat spot seems to have disappeared.  However, mileage is likely going to take a hit no matter how I drive it. 

   

[aw12345]

The skinny on coolant is this plain water transfers heat better than antifreeze. Antifreeze is used to eliminate or at least control corrosion as well as raise the boiling point of the coolant. Overall50/50 is best cools well, fairly high boiling point and good corrosion protection. Temp gauges are grossly inacturate, for most newer gasoline engines working temp in summer can be as high as 265 degrees fahrenheid which is fine as long as the cooling system is pressurized at 15lbs. Hence the pressure cap on your radiator. 30/70 will probably ok but you could get into boiling the coolant because of a lower boiling point in summer climbing one of our So Cali hills with the ac on.
Might be something to think about. that or simply stick a higher pressure cap on if all the coolant hoses are in good shape, since a higher pressure raises the boiling point of the coolant

Art

[gomi]

I'm lazy so the last time I changed my coolant I bought the pre-mixed stuff.

[Jeffy]

I'm lazy so the last time I changed my coolant I bought the pre-mixed stuff.

Premix is great.  Yeah, you're buying water but it makes filling it a simple task.  You don't need to mix then end up overfilling.  It's also great on the trail.  Many times you don't have a abundant source of water.

[chrisfranklin]

I've been driving it with the approximately 70/30 ratio for the last couple of days.  I can tell there is going to be about a 10-20% mileage drop - a 1.5 to 3mpg loss in the city.  But, I will have to say that the air/fuel ratio seems better; I don't have the occasional flat spots in acceleration  I had before and overall acceleration seems better.

Obviously, summer/desert, low-speed heat merits the higher boiling point of a 50/50 mix. 

[Jesse-James]

Soooo.....you're saying putting more water in your radiator made your Jeep faster? 

[chrisfranklin]

Feels slightly faster.  No timed runs, etc to support this though. But we're talking a couple of tenths off of a 0-60 of 12 seconds or something