26 Reply by jrbe (edited by jrbe 2018-08-27 01:28 PM)

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Re: Can't keep the Saab Cool

Car is obdii, so unless it's chipped removing the cat might make less power from it throwing a cat code if it goes into a limp mode. It might be fine with the check engine light on and making more power too, depends on the tune. Or chip the ecu with a tune that ignores the cat. If the cat is clogged or partially clogged that could be the extra heat.

You can vent the hood about 1/3rd of the way back from the front edge. You can also add a Gurney flap (aka 3/8 or 1/2" aluminum angle) to the front edge of the cut to help it suck the hot air out. Put it in the wrong spot and you will be forcing air into the engine compartment instead of out, so do your research before cutting.
http://i589.photobucket.com/albums/ss338/LeMons_panzer/2012/IMAG0444.jpg

I'll echo the mention of making sure there's no air in the system. Easy to get air trapped in some cars. Vacuum cooling system filling setups are great. Some have bleeders in the high spots to help purge air.
Some water pumps are junk. the impeller / bearings can feel good cold but the impeller can slip once they're hot.
Any chance you're running strange ignition timing or fuel out of the tunes window? Retarded timing dumps tons of heat in the cooling system. You could log obdii data and see how much timing it's pulling. Also worth looking at what it's doing with fueling and see if knock is happening in specific cylinders. Might be worth trying higher octane or a bit more ethanol in the mix if it's not going lean.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?

27 Reply by RSB

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Re: Can't keep the Saab Cool

rlchv70 wrote:

That is an old wive's tale.  Increased flow will lead to increased heat transfer.  Removing the tstat will increase the pressure downstream, though, possibly leading to hose failures, clamp failures,  or a failed radiator.

Well, its splitting hairs here, but its not the increase in mass flow that improves heat transfer, its the increase in turbulence, which causes 'more' of the water to be in contact with the radiator as compared to a laminar flow situation.

However, any gains in efficiency from increased flow rate/turbulence are modest and won't be as much as increasing the airflow through the radiator. So, as others have suggested, get more air to flow through the radiator (enlarge the bumper opening, reduce the amount of air bypassing the radiator, give the warmed-up air somewhere to exit the engine compartment).

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Re: Can't keep the Saab Cool

TheEngineer wrote:

So, the saab has always had cooling issues...

<snip>

- only other thing in the stack up is the intercooler which on the saab is the same footprint as the radiator.

</snip>

+1 to moving the intercooler if aero changes alone don't improve matters enough.

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Re: Can't keep the Saab Cool

Pulling the cat requires a tune in order to not piss off the car completely. I'd love to, but not yet. I may add a heat shield though to stop radiant heat moving towards the radiator.

Lots of good thoughts in here, thanks everyone.

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30 Reply by rlchv70 (edited by rlchv70 2018-08-28 04:18 AM)

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Re: Can't keep the Saab Cool

RSB wrote:
rlchv70 wrote:

That is an old wive's tale.  Increased flow will lead to increased heat transfer.  Removing the tstat will increase the pressure downstream, though, possibly leading to hose failures, clamp failures,  or a failed radiator.

Well, its splitting hairs here, but its not the increase in mass flow that improves heat transfer, its the increase in turbulence, which causes 'more' of the water to be in contact with the radiator as compared to a laminar flow situation.

However, any gains in efficiency from increased flow rate/turbulence are modest and won't be as much as increasing the airflow through the radiator. So, as others have suggested, get more air to flow through the radiator (enlarge the bumper opening, reduce the amount of air bypassing the radiator, give the warmed-up air somewhere to exit the engine compartment).

Heat transfer is directly proportional to the mass flow rate. See equation 18.26 here:

http://web.mit.edu/16.unified/www/FALL/ … de131.html

The temperature delta will decrease, but not as fast as the mass flow is increasing. There will be diminishing returns at some point, though.

As you stated, it's obvious on the air side of the radiator. The faster the air is flowing through the radiator, the more heat is transferred. Same thing applies to the water side.

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Re: Can't keep the Saab Cool

Thermostat thing is like asking what oil works best. There's engineering reasons to back both sides. Yes, more mass flow does on paper show more heat transfer, when you're talking in a specifically designed heat exchanger. But all engines are different, and on some when you force the flow too fast you get weird stagnation points that make things worse. My daytona for example. The head is designed poorly, and flow tends to stagnate around cylinder 4 letting that cylinder overheat. Increasing the flow rate won't really help the design flaw, instead you need to modify the flow path by routing coolant out of a freeze plug on the side of the head to fix the issue. All engines are designed differently and there is no blanket cure all. 

You'll find some people claiming that removing theirs made things so much better, and some saying that it made things worse. At the end of the day, there is a min temp you want the engine, and the thermostat helps ensure that. Since I race in a region that can be 95°+ with 90% humidity one race, and 30° in the morning at the next one, I'll leave the thermostat in place.

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Re: Can't keep the Saab Cool

We're in AZ so no thermostat.  One less thing to fail. And there's no inexpensive option for a lower temp thermostat on my car. The e46 runs right up to 180 where the low fan kicks on then stays there.

Owner/Captain of The 27 Club E46. Phoenix, AZ
and now the #95 Thunderbird

33 Reply by aventari (edited by aventari 2018-08-28 11:02 AM)

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Re: Can't keep the Saab Cool

I would do whatever you could to get rid of that cat. Then turbo blanket and wrap the downpipe.

Not the least of which is when a precat like that fails it could potentially damage the turbo or even the motor.  And racing seems like it would be really, really hard on it.

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34 Reply by gunn (edited by gunn 2018-08-28 12:56 PM)

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Re: Can't keep the Saab Cool

chaase wrote:
rlchv70 wrote:
RSB wrote:

There is also a school of thought that says its bad to totally remove the thermostat, because that increases the flow rate of the coolant in the system, which reduces the amount of time the hot coolant spends in the radiator, further reducing the efficiency of the cooling system.

That is an old wive's tale.  Increased flow will lead to increased heat transfer.  Removing the tstat will increase the pressure downstream, though, possibly leading to hose failures, clamp failures,  or a failed radiator.

We haven't run them on any car so far. The thermostat can also fail and not open causing an overheat condition. We take it out and haven't had an issue but that is us. I guess its pick your poison 8-)

We had a "fail safe" thermostat fail close. FU Stant, That killed an engine.
If you believe that increasing the flow rate of the cooling system is bad, you can always goatse the thermostat (remove the central body) OR for a few bucks just buy a restrictor ring set like this one. Either option is cheap/free enough.
https://www.amazon.com/Moroso-63440-Wat … B000COS5JM

---
Others have mentioned wrapping the hot bits and removing the cats which I would also encourage.
One other thought is to make sure that air is not spilling out over/under the radiator as it will take the path of least resistance. Examples:
1) I learned that selling the piece of plastic that goes from the bumper cover to the radiator to prevent air coming through the bumper cover from spilling downwards instead of going through the radiator was a bad idea. A piece of election sign fixed that (and I still made $30).
2) when I lightened the hood of my car, I found that I had inadvertantly created an air gap between the hood and the top of the radiator -- air was spilling upwards and over the rad instead of going through it. AT the racetrack, I fixed that with more election signs and duct tape. Afterwards, a pool noodle was sacrified to create a gap seal.

I've also done the mister thing using my windshield washer pump, a button on the steering wheel (very F&F), and a mister nozzle from Home Depot. It worked like a charm and you could see the temps drop by 15 degrees when you sprayed it on the track. Downside is that occasionally the nozzle will get clogged from crud in the pump tank and wouldnt spray. I haven't needed it since I went with a bigger radiator instead of the shitty 100K mi stock one we had.

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35 Reply by RSB

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Re: Can't keep the Saab Cool

TheEngineer wrote:

... Today I had the car at thompson for an HPDE ...

Which event was that? SCDA? Apex?

We tried to go to a Track Night in America event at Thompson. When I first contacted them, they said that even though the event was really designed for street cars, a Lemons car would be OK. But later when I tried to actually register for an event, they changed their tune and said NO race cars. Since our car is not street-legal, we have been looking for a way to shake it down in advance of a race weekend.

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Re: Can't keep the Saab Cool

RSB wrote:
TheEngineer wrote:

... Today I had the car at thompson for an HPDE ...

Which event was that? SCDA? Apex?

We tried to go to a Track Night in America event at Thompson. When I first contacted them, they said that even though the event was really designed for street cars, a Lemons car would be OK. But later when I tried to actually register for an event, they changed their tune and said NO race cars. Since our car is not street-legal, we have been looking for a way to shake it down in advance of a race weekend.

Track night does not want race cars, and I can respect that. Their whole point is to get people into track driving. They're more a novice organization than anything, and want it to be about getting on track with what you have.

We have always run with SCDA. They put together great events, and they were welcoming of the saab.

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Re: Can't keep the Saab Cool

TheEngineer wrote:

More question answering.

The fans are on a switch, we run them 100% of the time, so the OEM controller no longer applies.

i've never let it go above 217, I'm sure it would go higher if the opportunity was granted. I'm not comfortable with temps that high regardless. normal operating temps on the street are one thing, racing is another. Coolant temps climbing mean your oil temp is also climbing and the hotter the oil the worse it works. I would like to not see temps over 210.

there is no belly pan bast the radiator, the engine compartment is open to under the car.



Talking to eEurparts yesterday, their first suggestion was engine bay venting. They said venting the hood to their 9-3 race car made the biggest difference of anything.  So I think my plan of attack is as follows
1. Close up all gaps between the radiator and surround so all air must go through the radiator.
2. Vent the hood to allow more hot air to escape.
3. upgrade the OEM oil cooler to the RX7 model.
4. Install my wideband just for peace of mind
5. Start watching/recording a few more data points through OBD like EGT, Cat temp, what the car thinks the AFR is, etc.



Chris, I know you are not running the fan controller.  My points is your ECU may be adjusting the fuel mixture to try to get the coolant temp to the desired area, which in many modern cars is around 220.  You may be battling against the ECU programming.

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Re: Can't keep the Saab Cool

racinrob wrote:

Chris, I know you are not running the fan controller.  My points is your ECU may be adjusting the fuel mixture to try to get the coolant temp to the desired area, which in many modern cars is around 220.  You may be battling against the ECU programming.

This I honestly have never heard of. My 2016 Subaru doesn't do anything like that, it's happy to let the coolant sit right at thermostat temp. I don't think the saab is doing that either, because backing off a little bit allows the temps to drop right off back to thermostat. Playing with air/fuel to change coolant temp seems like a dangerous game. Additionally the eEurparts guys, who run a 9-3, haven't said anything like that when talking to them about this. They said that the engine bay just doesn't shed heat in stock form and you start heat soaking.

I will get my wideband on the car before october to make sure it's not doing stupid/dangerous things.

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Re: Can't keep the Saab Cool

Didn’t see it mentioned... Is it possible that your water pump is spinning too fast at racing RPMs leading to cavitation?  I’ve heard that street cars’ water pumps are tuned for street conditions and will fail to pump at high RPM which isn’t normally a problem on the street as redline driving is rare and momentary. Track is obviously very different. There was a related article on MotoIQ a long time ago. Good luck.

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40 Reply by gunn (edited by gunn 2018-09-17 10:34 AM)

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Re: Can't keep the Saab Cool

TheEngineer wrote:
racinrob wrote:

Chris, I know you are not running the fan controller.  My points is your ECU may be adjusting the fuel mixture to try to get the coolant temp to the desired area, which in many modern cars is around 220.  You may be battling against the ECU programming.

This I honestly have never heard of. My 2016 Subaru doesn't do anything like that, it's happy to let the coolant sit right at thermostat temp. I don't think the saab is doing that either, because backing off a little bit allows the temps to drop right off back to thermostat. Playing with air/fuel to change coolant temp seems like a dangerous game. Additionally the eEurparts guys, who run a 9-3, haven't said anything like that when talking to them about this. They said that the engine bay just doesn't shed heat in stock form and you start heat soaking.

I will get my wideband on the car before october to make sure it's not doing stupid/dangerous things.

FWIW, my 93 tbird's OBD1 era ECU (for a 5.0 V8) has separate fuel maps for a warm up mode and when the coolant is determined to be at temperature.
I believe it was called the "startup enrichment" table.

My suspicions are with this aftermarket radiator. Was this a new purchase or something acquired second hand? a clogged radiator that doesn't dispel heat well could very well be the culprit here.
-g

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41 Reply by TheEngineer (edited by TheEngineer 2018-09-17 11:21 AM)

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Re: Can't keep the Saab Cool

Radiator is brand new from a known quality manufacturer through a good supplier. There should be nothing wrong with it.

Warm up maps are standard, but they shouldn't do what Rob is suggesting, trying to manipulate coolant temp from thermostat temp up to 220. Most warm up maps are only used until the coolant is above 140 or somewhere in that general region. Basically when your idle drops to it's normal low point it's out of that map.


We've replaced all the hoses so far. And I'm planning on venting the hood before October along with better ducting the front end to the radiator.

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Re: Can't keep the Saab Cool

I definitely would not worry about the ecu leaning the mixture to try and increase engine temp. cold start enrichment is a thing but stops long before operating temp and all that go's out the window when you run at full throttle. ecu reverts to its max power map.  Also. I work mostly with German cars but I know of no car that removing the cats will put it in some sort of limp mode. I don't even run rear 02 sensors on my E46. if you want to have a functioning CEL  (something I have long given up on.) you can use 02 sensor spacers in the rear.  definitely ditch the cats. I sold mine for almost 300 bucks on Ebay and put that back in the budget.

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and now the #95 Thunderbird

43 Reply by jrbe (edited by jrbe 2018-09-17 06:53 PM)

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Re: Can't keep the Saab Cool

Late 2000's vag cars will throw an error in mapped coolant system code if the engine is running outside of range of programmed coolant temp. It's fixed by changing the thermostat to one that's working properly.
Some newer cars will hold a gear for a bit longer and retards timing to get the cats up to temp quicker.

Warm up "maps" are to adjust the fuel map to different efficiencies at different temps. They are to correct how much extra or less fuel it needs at that temp to run the correct a/f ratio. No voodoo there besides tuning it to what the engine requires. But warm up modifiers cover the full range of coolant temps. There is another for air temp typically. Some fancy ecus will even watch fuel temp and adjust for it.

Is your fuel pump keeping up? Can it maintain fuel pressure in boost? Running lean in boost? Is fuel pressure raising with boost? (Bad regulator or vacuum line?) Maf? Map? sensor(s) reading correctly in boost?

If your car came with a water to oil cooler the engine temp may be higher than you want to hear. They want water to boil out of the oil under normal operation. 220 isn't crazy high when the system is pressurized.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?