Ladybug83

Cool race Mark! Thanks for posting the video

FredR

Mark,

When your cooling system pukes coolant out of the expansion tank your system is out of control. The air above the coolant level is your friend and provides a compressible non condensable buffer space. When the system boils the pressure rises suddenly and dramatically because of the volume of steam formed and when the expansion cap lifts the first thing emitted will be the air quickly followed by coolant and ultimately steam. If you continue running like this something catastrophic will likely happen before too long. You know something is wrong so you back off. The heat load reduces and the system reverts to normal operation but now it has less coolant in it. As the system cools, the steam condenses, the pressure drops and eventually it tries to pull a partial vacuum and thus the cap allows air back into the system- by now the hoses will be soft and stay that way unless you go back to racing mode and then the coolant heats up again but this time the temperature difference is not much so the compression factor due to higher temperature is minimal to not noticeable- the hoses remain softish unless it boils.

Puking out coolant is abnormal- it should not happen and when it does you are going to see the phenomena you have described. If the system is under control this cannot and should not happen. When my car is cold the hoses are soft. When it is up to operating temperature the hoses are firm and stay that way until the motor has cooled down- that is because it is working correctly.

You can take various [drastic?] measures to improve the heat exchanged but it is clear to me that you have found the limit of what you can do with your system and now you are relying on luck as to whether you do any serious damage. A good oil will give you more protection against overheating but even that eventually has its limits.

Now you need to give serious consideration to taking that oil cooler out of the radiator and into an external and effective oil cooler. That alone may be enough.

Bottom line: when the coolant hoses are flaccid on a hot engine there is something wrong/abnormal going on. That is the point I have been patiently trying to convey in our extensive dialogue.

Rgds

Fred

mark kibort

Fred, i think you now understand what is going on based on your first paragraph above.. dead nuts correct.....,with one exception being your last comment. there is NOTHING wrong with the system when you puke out coolant,( which is a result of overheating with the very hot track temps and exceeding the limits of the system) and then the system is cooled by not using full power capability and the hoses then become soft with no internal pressure.
Again, this happens because the over pressure pushes out the coolant due to internal boiling creating steam, which takes up VOLUME. when cooled sufficiently, the steam condenses and the water which is being pushed out the overflow , stops exiting, and then air is drawn back in .... it does this until there is no pressure differential. this is how i come into the pits and the hoses are flacid, yet the car is at operating temp (water gauge near middle ).

think of it this way. say you put 200F (95C) water in an empty engine and filled it... would you have pressure? NO! it would be at operating temp but there would be no pressure ... the system would not go through expansion as it does taking the water from cold to operating temp, which creates pressure. this is what basically is happening. the lines will stay soft until the engine started to boil internally.

does this make sense, or do you see any errors in my logic above?

Now, i just took the car out last night for a drive in 95 degree heat . i beat on it and it stayed cool . bellow middle temp point. oil was going to just above normal 200F for a hot day. i turned off the fans and continued to drive.. still cool.. it wasnt until i stopped , with fans off, that it got to operating temp.. then beat on it some more... WOT, 40-80mph . it started to slightly climb, (with no fans) but by the time i stopped, it was back at half way. hoses were FIRM solid as rocks.. (cooling working perfectly) went to the gym..... came out after 15mins ... Hoses still hard as rocks. 30min later, they were softer and temp was barely off the low mark. 1 hour, hoses were soft. THIS is normal..... do you not agree? the cap has been pressure tested. there are no leaks . coolant rose to near top of the container. (remember I've overfilled it to simulate the same conditions). this morning, its exactly where i stared .. 1" below the top ... so no coolant loss .

so, the bottomline, is that on that racing day at 105F, i exceed the cooling capabilities of the system and need to remove the oil cooler from the radiator, or just not race at laguana on any day over 95 degrees. As a note, ive run at Thunderhill in temps over 100F but the car has 4x the time spent at 20% higher speeds , so the car doesnt overheat at all. however when i start out with air in the system, alll bets are off. poor circulation due to air in the system , causes overheat that cant be overcome . I should also note that 6 years ago, i was overheating at thunderhill, and then cut holes in the front bumper below the nose, to add to the air inlet size. this fixed climbing temps i was seeing that day. That was the holbert car. now ive made smaller ones, but i might make more of them like John Veneger did on his car. Probably just take the oil cooler off. it makes more sense.
and yes, the good quality oil probably saved the engine.

EDIT: question. does the cushion of air with the overflow container being half full, create any benefit to the system having the " compression area"? is the only benefit being that fluid is not ejected during boil over or normal expansion?

FredR

Mark,

I have been trying to advise you since the previous incident that there is something wrong with your cooling system- now you tell me that "at last I understand what is wrong- except the last sentence of the first paragraph"? I sincerely hope you might chip in to the surgery bill that I am about to get to repair the hernia I just acquired laughing my nuts off!

Puking coolant out of the expansion tank is not normal, it is anything but - it is your poor little car crying for help before it self destructs- it is the cars equivalent to throwing the towel into the ring to stop the opponent beating the snot out of the boxer.

The expansion tank cap is the last line of defence- as it blows it allows the coolant to boil off and that alone soaks up a lot of heat [as the latent heat of evaporation]. Trouble is it cannot sustain that for too long before there is nothing left to boil up. Besides being the last line of defence it is also meant as a visual cue to tell the driver to pull over and switch off as he sees steam pissing out all over the place [as you did to some extent]. Once the coolant reaches boiling point it cannot go any higher as it boils at a uniform temperature.

Knock the throttle off, cut off the excess heat source and the system can then quickly stabilise- as you saw.

However, now the problem is that you are drawing in air with the system at a high temperature, the system now has a lower level in the expansion tank and it can only settle at atmospheric pressure because being fully heated, there is no further liquid expansion available worth talking about to pressure the system and now there is more volume to compress anyway so your coolant will now boil at 212F [normal atmospheric boiling point] and the hoses will remain flaccid -as you saw so once it has boiled basically you are buggered if you cannot cool below that temperature and then the thing will start boiling, it will thus pressurise quickly and in no time will puke again if you put excessive heat in. Does this sound familiar?

Now you report that last night you checked it and low and behold the hoses remained rigid for quite some time just as I advised you they should until things cool off. This is exactly what should happen when you are tracking. That it does not tells you what is wrong.

Your system just does not have sufficient cooling capacity for the conditions you are trying to run in and that is the case every time you puke coolant. Until you can get your head around that concept then you will not be able to solve the problem. When you had to back off did your fellow competitors back off?-no- Clearly they did not have cooling problems. Do your fellow competitors puke coolant out and if they did would they consider it normal?- I somehow doubt it.

The only reason you saved your motor was because you had the nouse to back off before it grenaded.

As to what you can do- well for starters you can get an all aluminium higher capacity welded radiator, get yourself a new expansion tank or Carl's aluminium racing version and stick one of his higher pressure thermostat's on the expansion tank. You also need to get the oil cooling out of the radiator. Remember if you are generating 30% more power than stock you also have to cool 30% more than stock. I doubt the stock radiator will take more pressure.

Alternatively you can carry on what you are doing until the day your luck runs out. How much would it cost to get another motor built to your current spec- $30k?

You also suggested increasing the glycol content- going to the stock 50% formulation reduces the specific heat by about 15% or put another way you need to increase the flow rate by 15% to get the same heat flux and that is not going to happen so you overheat that much quicker.

"Chance favours the prepared mind"! I think you need a visit from my pal Dirty Harry to slap you around some and hopefully knock some sense into your grey matter!

Regards

Fred

mark kibort

Fred, i guess we have a "definitions" issue between us. glad we both are speaking the same language as to what is happening. you could have summarized your speech with one line. " You have an over heat problem due to the air flow and capasity of your system".

there is nothing wrong with the coolant system, its just too small.. just like if i removed the rev limiter of the engine, and ran to 8000rpm, and blew it.. there was nothing wrong with the engine, just the operator was an idiot!
so, our definitinos are off. "nothing wrong" means the system is functioning normally. everything that happens is normal for the conditions. it was supposed to overheat, and the hoses were flacid because of how it overheated and then cooled of as i entered the pits.

Im trying to use the engine in a capasity for which it cant perform normally.

now, you get a few facts wrong below. my engine HP is only 15% higher than it was when i regularly visited 100+ day tracks, so, the 50/50 glycol mixture raising boiling point by 15% would solve that issue. here is why.. sure i get the fact that i need 15 % more flow too, but thats not the issue. its more than able to keep temps in check, if the water didnt start to boil. the boiling was the problem, because the water doesnt circulate correctly. but, the high oil temps due to 250F water doesnt help, the 280F levels, so your right.. time to dump the stock oil cooler which is probably heating the water and throwing it over the edge.
OR, if i got 15 % more air flow... (thunderhill has about this gain in higher average speeds vs laguna), it could be the reason it has survived in the past. (or opening up the front bumper a bit more too should help)

the net net is that im boarderline. if one factor is altered just a little.. air in system, too low of water level, etc... it overheats and this is not good for a racer spending ungodly amounts of time and money in prep for a race. therefor, i will be getting rid of the oil cooler and make that external as the next project. also opening up the front bumper should help as well

Keep in mind, the car worked flawlessly at laguna last month with a warm day as it usually does (sears point too was 90F). the water temp never got above horizontal! the 100 to 105 temps at laguna were just too much......

so, i think we agree.. the system is not suited for laguna 105 or probably even any track at this temp and works well otherwise... its failure at Laguna determines it cant work properly at those temps to keep the engine cool.

EDIT: just checked my racing logs. july 2009, i had a hot 103F day at thunderhill with the holbert car and cut a large hole in the front bumper . It fixed the issue. since then, several 95 degree day races where there was no overheating . only last season with the air in the system to start.

dr bob

Hi Fred --

This discussion has happened before, and it's like arguing with an alligator. All mouth, no ears, and a single-thread one-bit brain the size of a walnut. The alligator has already decided what it's going to do. No amount of explaining the real physics is going to help. Mark already knows everything about what's happening. I'm not really sure whey he even mentions it here, since it's so obviously normal (for him).

Part of the discussion that's lost is that your alligator treats the engine as a single exothermic lump, with no regard for having localized hot spots and heat transfer issues due to state changes there.

Again, waste no time on this.

FredR

Mark,

I see light at the end of the tunnel! The elements of your system are working just fine but the system as a whole is not for the conditions you are exposing it to.

I had no clue as to what power your system is making- that was just a wild *** guess to make the point that there are limitations as to what you can expect to get the system to do.

Whatever you do, do not run 50/50 coolant mix. All that will do is make your engine overheat quicker thus raising the pressure quicker and chucking out of the expansion tank cap quicker. There is a reason why racers run lean coolant mix and you did what others before you have done and continue to do to this day. Try finding a NASCAR that runs on anything but water & a surfactant in the cooling system- maybe NASA have come up with something that carries heat better than water but I have yet to hear of it.

Oh and 105 F is as hot as it has been here the last month! Racing in such conditions is no joke! That is why Abu Dhabi F1 and now Bahrain have lights- they run regular events at night time during the summer.

It's a hard life in the Third World!

When it comes to circuits then indeed the circuit itself can play a role and the key factor is probably how much time you spend directly up your competitors butts ingesting their hot effluents. That is a big problem in F1.

mark kibort

Agree! yes, I've been a huge proponent of running the distilled water and water wetter... however, it was a thought that even with less cooling capacity, maybe the lack of boiling , could stop the major overheating factor due to boiling and steam replacing water stopping circulation. not going to do that.

yep, it does depend on the traffic, chasing the nascar around, certainly not a great thing to block air to the radiator! Speaking of nascar, and other racing..... water is the only thing allowed. no antifreeze. very illegal. if you get a leak or have a crash, its hard to clean up, AND, if you are leaking, it can be death to cars following behind you. antifreeze is very slippery!

thanks for chiming in. sounds like what i saw was expected for a system that has been exceeded by racing temps.

now, figuring out how to disconnect the oil cooler in the radiator and use those fittings for an external cooler......

mark kibort

You now understand we actually figured it out and we don't need to "scratch our heads" if there are no issues with leaks or the cap. ...........all I saw was normal and expected and makes sense. now we know the system is not at fault, its just too much external heat to deal with. the discussion of this was just a learning exercise and a discussion.

im a little insulted by your comments. i brought the subject up because i haven't had the issues or seen this problem before. if you recall, "before" it was the "experts" saying the pump was bad and was the cause,. that air in the system is impossible , or that there is no need to burp.. All of which i was able to show yet again. the system is fine, the soft lines are a product of overheat, coolant being expelled by steam, condensing, and then lack of pressure in the lines while at operating temp.....so, i dont know why you just posted this. we all learn through these extreme use cases. and as note Bob, i treat my car and engine so badly, yet it keeps on running relatively problem free in normal racing conditions. all your prognostications of what should happen with no tensioner oil, or reusing inner bearing races up front, or the temps i run the engine at, somehow , I'm still racing and nothing happened! BTW, still "beating" on the car at the limit 20 years later. you of all people should be amazed of how tough these engines really are.....especially the ones that have bottom ends made by Todd and Tim.

Btw: Fred said this (since you addressed this post to Fred)So, you see, we did need to discuss the physics and it turns out we dont need to "scratch our heads" we know why the system could have soft lines and operating temp after an overheat and cooling period before i came into the pits. hot, but no pressure in lines. I also just tested yesterday, the engine at operating temp, and the long , normal decay of pressure in the system. (proving no leaks) did you miss that? just curious.

Now, if you want to help, can you steer me on an oil cooler or dependable oil lines that i can mount into the stock locations and feed a remote cooler?
Mk