: So I went on the highway in 2nd gear...



weister42
08-24-06, 12:49 AM
Just to try it out I kept going the same speed for a few miles and I can see the temperature rising higher and higher, it usually sits around 196 to 199 on highway but I got it up to about 220 and it was going to keep rising.

Doe this mean the factory cooling system is not designed to keep the motor cool in all situations?

GreenMachine
08-24-06, 02:50 AM
220 is well within the factory limit, the fans don't turn on until mid-20's.

Other than for "WOT" procedures there really isn't any reason to just simply cruise down the highway in second gear.

If you plan on using the engine for high RPM use make sure the radiator is clear of debris and such so that air can free flow threw it and assist in cooling it down.

There arn't many cars of there that will last long under those conditions simple because 3-4 thousand RPM constant operation isn't how it was designed to be used, they have made gears for a reason.

Premium fuel may also aid in this because as the engine termpertures rise detonation and pre-ignition can occur more easily.
:)

Ranger
08-24-06, 09:47 AM
Just to try it out I kept going the same speed for a few miles and I can see the temperature rising higher and higher, it usually sits around 196 to 199 on highway but I got it up to about 220 and it was going to keep rising.

Does this mean the factory cooling system is not designed to keep the motor cool in all situations?

No, the Northstar was designed to run at WOT for long periods and the cooling system was designed to handle it. Here is what the Guru had to say on the subject.

" The NS high speed endurance engines run for almost 300 hours at continuous full throttle, max load, max RPM. No idling, no part throttle...just flat out running. I have often, of late, seen a SC Northstar or LS7 in the dyno cell at full load/6500 RPM screaming away when I left for the day and it was sitting there, still screaming away the next morning when you come into work...and this happens day after day to accumulate 300 hours. By the way 300 divided by 24 hours is 12.5 DAYS at FULL THROTTLE!"

krimson_cardnal
08-24-06, 10:56 AM
Seems like weister has developed a test of the NorthStar cooling system. Might have continued on to see what might happen next. As ranger points out, the engine would most likely handle things as designed, or he could find a weak link in a how old car[?] and blew something.

What's not stated is the speed/rpm weister held it at. Also what possesed him to do such a thing in the first place.

It amazes me what owners of these fine automobiles will do to them. I don't say baby them, too ballsie an engine for that, and WOT is a fun thing, but to abuse a vehicle under any circumstance isn't right.

There is a thing called designed operational conditions. These are consumer cars meant to be driven on public roads under street legal conditions by everyday folks. Sure you can push the limits - but for what purpose???

I have always driven my vehicles hard [at times competitavely] - but well short of abusing them. I tend to respect and marvel at the technology - not test the limits or think I'm going to dicover what a major manufacturer might have missed up on.

Abuse anything and you stand a good chance of breaking something....

dkozloski
08-24-06, 11:14 AM
For years the design criteria for GM cooling systems was to operate at 100 deg.F outside temperature at 100 MPH with a 100 MPH following wind. You've got a long ways to go to reach those limits.

STS 310
08-24-06, 07:21 PM
Then again, I have never heard of anyone posting a thread with a major problem admitting to "riding it hard". Its usually just "I have a problem". Abuse of any kind is not readilly admitted, including autos.

I dont experiment with my car and those who do, surely dont post to the fact.

Let me back up, I did run my N* bone dry of coolant for a month back in Feb. It would go about a mile and half before approaching 245 degrees. I will never do that again.

Corroded welsch plug. $4.00 part, and $300.00 labor with engine pull. Its in the archives here.

JohnnyO
08-25-06, 02:30 PM
When you're going at a higher rpm for a given speed, the coolant is flowing faster and hence spends less time in the radiator getting cooled. This is also why sometimes an engine with no thermostat can run hotter than an engine with one, the coolant flows TOO fast. On the other hand, if you're going 100 mph you have 100 mph worth of wind chill coming into the radiator. So an engine running 4000 rpm at 50 mph will be hotter than an engine running 4000 rpm at 100 mph.

Cadillacboy
08-25-06, 03:59 PM
You wanna see what I heard....One 95 MB 200 Compressor owner is complaining about his cars performance especially at the launch or stop lights .So, he asked whether he might rev up the engine to 4000 RPM in N and then when the lights turn green , he might put the gear selector in D'n' go ...What an owner gee

krimson_cardnal
08-25-06, 05:02 PM
pop! goes the weasel!!!

JimD
08-25-06, 05:44 PM
.... On the other hand, if you're going 100 mph you have 100 mph worth of wind chill coming into the radiator...


Urban mythology.

Inanimate objects are not affected by wind chill.

chazglenn3
08-25-06, 06:36 PM
Darn...you beat me to it, Jim! :D

Ranger
08-25-06, 06:59 PM
He, he. I think he means more air flow = more heat disipation. No argument on the wind chill though.

STS-in-Nottingham
08-25-06, 07:05 PM
In the N* cooling system, less than 50% of coolant actually goes through the radiator, most of it is re-circulated around the engine to ensure uniform heat distribution.

chevelle
08-25-06, 11:03 PM
Running along in second gear is not a "test of the cooling system". Certainly the engine will run warmer doing that. Any engine will run warmer doing that. Nothing to do with the cooling system. Besides, 220 is still way way cool. Running at extended higher RPMs will always drive the oil temp up which drives the coolant temp up. Nothing wrong, just fact.

chevelle
08-25-06, 11:16 PM
When you're going at a higher rpm for a given speed, the coolant is flowing faster and hence spends less time in the radiator getting cooled. This is also why sometimes an engine with no thermostat can run hotter than an engine with one, the coolant flows TOO fast. On the other hand, if you're going 100 mph you have 100 mph worth of wind chill coming into the radiator. So an engine running 4000 rpm at 50 mph will be hotter than an engine running 4000 rpm at 100 mph.


Man...what a bunch of misinformation.

As mentioned previously, "wind chill" has no effect on metallic objects like radiator fins. Wind chill has only one application...human skin. Certainly the amount of air flow thru the radiator at 100 MPH is much greater so the cooling capacity is greater. But it has nothing to do with the idea of wind chill.

If the coolant flows faster and spends less time in the radiator getting cooled then the same logic would say that the faster moving coolant spends less time inside the engine picking up heat. Trouble is, it doesn't work that way at all. The faster the coolant flow the better the cooling. Period. The idea of "slowing down the coolant to improve cooling" is an old wives tale that continues to circulate. If an engine runs hotter without the thermostat (as a Northstar will) it is because the thermostat is an integral part of the coolant flow control, not because the coolant moves faster without it.

Most of the stories of "coolant moving too fast" causing overheating came from people that ran the engine at high RPMs and experienced overheating. They slowed down the water pump with a larger pulley and the overheating stopped. So...they figured it was because the coolant flow was slowed down. Wrong. The water pump was cavitating at the higher RPMs since it wasn't originally designed to operate at that speed. Coolant stopped flowing at all due to the cavitation. Putting the larger pulley on slowed down the RPM of the pump so that it no longer cavitated and coolant started moving again and the overheating stopped. High flow engines like the Northstar have water pumps designed to operate at high RPM so that they do not cavitate.

An engine running 4000 RPM at 100 will run cooler due to the extra ram air thru the radiator increasing heat transfer, not because of the wind chill. An engine running 6000 at 100 MPH will run hotter than one running 4000 RPM at 100 MPH because of the extra friction created by the higher RPM not because of the cooling system being inadequate or lack of coolant flow or anything like that. It is just making more heat at higher RPMs and the cooling system is nowhere near it's maximum capacity at those conditions so the slight rise in coolant temp is meaningless.

dkozloski
08-25-06, 11:42 PM
Man...what a bunch of misinformation.

As mentioned previously, "wind chill" has no effect on metallic objects like radiator fins. Wind chill has only one application...human skin. Certainly the amount of air flow thru the radiator at 100 MPH is much greater so the cooling capacity is greater. But it has nothing to do with the idea of wind chill.

If the coolant flows faster and spends less time in the radiator getting cooled then the same logic would say that the faster moving coolant spends less time inside the engine picking up heat. Trouble is, it doesn't work that way at all. The faster the coolant flow the better the cooling. Period. The idea of "slowing down the coolant to improve cooling" is an old wives tale that continues to circulate. If an engine runs hotter without the thermostat (as a Northstar will) it is because the thermostat is an integral part of the coolant flow control, not because the coolant moves faster without it.

Most of the stories of "coolant moving too fast" causing overheating came from people that ran the engine at high RPMs and experienced overheating. They slowed down the water pump with a larger pulley and the overheating stopped. So...they figured it was because the coolant flow was slowed down. Wrong. The water pump was cavitating at the higher RPMs since it wasn't originally designed to operate at that speed. Coolant stopped flowing at all due to the cavitation. Putting the larger pulley on slowed down the RPM of the pump so that it no longer cavitated and coolant started moving again and the overheating stopped. High flow engines like the Northstar have water pumps designed to operate at high RPM so that they do not cavitate.

An engine running 4000 RPM at 100 will run cooler due to the extra ram air thru the radiator increasing heat transfer, not because of the wind chill. An engine running 6000 at 100 MPH will run hotter than one running 4000 RPM at 100 MPH because of the extra friction created by the higher RPM not because of the cooling system being inadequate or lack of coolant flow or anything like that. It is just making more heat at higher RPMs and the cooling system is nowhere near it's maximum capacity at those conditions so the slight rise in coolant temp is meaningless.

Finally! Somebody that understands cooling systems, heat transfer, and thermodynamics. The greatest heat transfer comes from the greatest difference in the temperatures of the objects involved no matter how you accomplish it. Make the water flow high enough that the radiator is the same temperature as the engine internals and the radiator will disipate the greatest amount of heat.

STS 310
08-26-06, 01:13 PM
You really want to test your cooling system? Find some heavy stop and go traffic, run the A/C, and you will definately find out if you have a cooling system issue.

Make sure you have some place to pull over!

CadiJeff
08-29-06, 01:18 AM
A while back I did 65 for 15 mi on I70 temp never went over 230 deg. air temp was in mid 80's.

Wind chill, in general it should give you the idea that moving air at a constant lower temperature will allow a greater rate of heat transfer from the warmer radiator to the cooler air. Personally I don't have a problem with the usage of the words...Note...I have passed college level engineering physics courses that cover these concepts.

weister42
08-31-06, 12:23 AM
I wasn't trying to be a dumbass and abuse my engine, I just wanted to see what happens when the N* gets revved at a constant rate at high speeds, since I've never seen my coolant temperature go over 199 F on the highway. In the city it's around 197~235 F.

I did notice that my engine runs a few degrees hotter than before, time to clean the radiator and check the coolant.

krimson_cardnal
08-31-06, 10:48 AM
Generated quite a discussion didn't it weister. I certainly meant no offence - just seemed like a curious thing to do. Also seems curious you never see temps over 199F on the hiway. Your city driving temps are in line with what I see, well at least when the heater core is in place.

I've been driving with the heater core by-passed the past month or so and am seeing initial warm up temp takes longer and the engine seems to be running 5-8F cooler. I'll be putting the new core in shortly and will be interested in seeing if it was plugged up a bit interfering with flow. These cores run "open" all the time and I figure a blockege in them WILL effect engine temps. I'm also thinking that adding the tabs to the coolant flow might possibly clog in the core - upper lower hose - pure conjecture, however.

All speculation 'cause the temp swings I see and hear about and what I've seen with the core out of the mix has gotten my remaining brain cells working over time.

KC

GreenMachine
08-31-06, 03:50 PM
^I know if you use some of the no recommended stuff it may clog the heater core.

thats also why I choose to go with the tablets rather than powder, I suppose powder could flow for a moment in a big group where as the tabs disolve into the solution.

STS-in-Nottingham
08-31-06, 04:50 PM
Neither the powder nor the tabs will clog the heater core so long as the coolant is replenished when it should be.

If the coolant is left in the system too long,it starts to "gel", the gel then sticks to the suppliment and forms a thick sludge,then things get clogged up.

As long as the bars leak remains wet,it should not clog anything.