Still running too hot
08-17-2011, 03:25 AM
#31
Paul,
Just a suggestion, you might consider re-routing your engine oil lines into a separate oil cooler. If you bypass the oil loop in the radiator, you'll get rid of a huge portion of the heat soak that dumps into the cooling system.
This solved my overheating problems. I mounted an external mocal oil cooler with a spal fan in the front driver wheel well.
Just a suggestion, you might consider re-routing your engine oil lines into a separate oil cooler. If you bypass the oil loop in the radiator, you'll get rid of a huge portion of the heat soak that dumps into the cooling system.
This solved my overheating problems. I mounted an external mocal oil cooler with a spal fan in the front driver wheel well.
08-17-2011, 04:38 AM
#32
Former Sponsor
Hi folks,
A while back I installed a Murf kit in my '88 S4. Not wanting to pull my louvers and louver motor, I went with two 11" pushers fans in front instead of the recommended 16" pusher fan. The kit comes with 4 8" (? or maybe 9") puller fans, but no pusher fan(s).
Anyway, since the install, the car's been running hot under most circumstances, and the six fans running, with water wetter in the system, still hasn't been enough to keep it cool in traffic in summer with the A/C on.
I was thinking of trying to build a 928Motorsports style air intake to try to reduce the amount of radiator surface blocked by the air intake box of the Vortech, but, after looking closer at the system, I don't think that's my real problem.
All of the electric fans are mounted directly against the radiator, with no shrouds other than the cage that's part of the fan itself. This means that the hubs of the fans, which don't allow airflow, are right up against the radiator. For the six fans, this adds up to 87 square inches of blocked radiator from one side or the other. I would think that this would tend to reduce the efficiency of the cooling system quite a bit.
I'm not sure whether I have enough room to offset and shroud both of the pusher fans... I may need to remove one and reposition the other; but on the back side, I certainly have room to back the fans up about 2/3" and shroud them with a bit of a box. What do you folks think? Would that be worthwhile, or does the hub blocking half the area of the fan not really make that much difference?
Oh, BTW, I did verify that when very hot, the louvers are fully open, and the fans are getting full battery voltage.
Thanks,
Paul
A while back I installed a Murf kit in my '88 S4. Not wanting to pull my louvers and louver motor, I went with two 11" pushers fans in front instead of the recommended 16" pusher fan. The kit comes with 4 8" (? or maybe 9") puller fans, but no pusher fan(s).
Anyway, since the install, the car's been running hot under most circumstances, and the six fans running, with water wetter in the system, still hasn't been enough to keep it cool in traffic in summer with the A/C on.
I was thinking of trying to build a 928Motorsports style air intake to try to reduce the amount of radiator surface blocked by the air intake box of the Vortech, but, after looking closer at the system, I don't think that's my real problem.
All of the electric fans are mounted directly against the radiator, with no shrouds other than the cage that's part of the fan itself. This means that the hubs of the fans, which don't allow airflow, are right up against the radiator. For the six fans, this adds up to 87 square inches of blocked radiator from one side or the other. I would think that this would tend to reduce the efficiency of the cooling system quite a bit.
I'm not sure whether I have enough room to offset and shroud both of the pusher fans... I may need to remove one and reposition the other; but on the back side, I certainly have room to back the fans up about 2/3" and shroud them with a bit of a box. What do you folks think? Would that be worthwhile, or does the hub blocking half the area of the fan not really make that much difference?
Oh, BTW, I did verify that when very hot, the louvers are fully open, and the fans are getting full battery voltage.
Thanks,
Paul
How old is your factory radiator and how many miles are on it?
What is your oil temperature doing, with this supercharger?
08-17-2011, 04:49 AM
#33
Former Sponsor
Both Brian and Davids have had failure with after market radiators.
https://rennlist.com/forums/928-foru...-2-cooler.html
https://rennlist.com/forums/928-foru...stage-iii.html
https://rennlist.com/forums/928-foru...adiator-3.html
I bought Davids old C&R with the hopes of figuring out a way to modify it with a little 'forward tilt'.
https://rennlist.com/forums/928-foru...-2-cooler.html
https://rennlist.com/forums/928-foru...stage-iii.html
https://rennlist.com/forums/928-foru...adiator-3.html
I bought Davids old C&R with the hopes of figuring out a way to modify it with a little 'forward tilt'.
To make radiators so that people will buy them, they use really cheap crappy cores. They last 2-3 years and then they leak. Really good coolant and grounding the radiator might help, but the basic problem is cheap cores.
To build a radiator with a decent core and high quality oil coolers.....well, a "high quality" core costs more than these guys are charging for their entire aftermarket radiator.
I've been working on building a decent "aftermarket" radiator, for about a year....but the costs of building a really high quality radiator, that will last, are very high....and I've questioned if the people in the 928 community will spend the money to buy quality.
08-17-2011, 05:39 PM
#34
Rest in Peace
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If you build a real quality, drop in product with more cooling ability than the stock one, some will buy them, I know I want one.
Yup. That's been the problem...and there is a really good reason why.
To make radiators so that people will buy them, they use really cheap crappy cores. They last 2-3 years and then they leak. Really good coolant and grounding the radiator might help, but the basic problem is cheap cores.
To build a radiator with a decent core and high quality oil coolers.....well, a "high quality" core costs more than these guys are charging for their entire aftermarket radiator.
I've been working on building a decent "aftermarket" radiator, for about a year....but the costs of building a really high quality radiator, that will last, are very high....and I've questioned if the people in the 928 community will spend the money to buy quality.
To make radiators so that people will buy them, they use really cheap crappy cores. They last 2-3 years and then they leak. Really good coolant and grounding the radiator might help, but the basic problem is cheap cores.
To build a radiator with a decent core and high quality oil coolers.....well, a "high quality" core costs more than these guys are charging for their entire aftermarket radiator.
I've been working on building a decent "aftermarket" radiator, for about a year....but the costs of building a really high quality radiator, that will last, are very high....and I've questioned if the people in the 928 community will spend the money to buy quality.
08-20-2011, 01:58 AM
#35
Three Wheelin'
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Sorry guys, been out of town the last couple of days.
The radiator looks good, but I haven't looked inside it, other than a quick peek when I replaced the hoses during the SC install. I don't think it's the original radiator. Its core is bare aluminum, not painted black. The car itself has about 94K miles on it. I don't have a temp sensor for oil temp.
I was thinking a bit more about Dan's comments about shrouds and pusher fans. I think part of the issue might be what I mean by a shroud for a pusher: I don't mean a funnel, like what's used for a puller fan; what I was thinking about was a ring (oval, actually, because of the shape of the fan frame), to back the fan off of the heat exchanger by 3/4" or so, but still seal the edge of the frame to the heat exchanger. The idea being to leave room so that the fan hub is not blocking so much air flow.
I plan to work on it tomorrow, probably experimenting with a small shroud for two of the four puller fans to see whether that helps, then maybe trying some things with the pusher fans. I still feel that the 87 square inches of 100% blocked radiator surface from these hubs is counteracting a pretty significant percentage of the benefit of having the six fans in the first place.
The radiator looks good, but I haven't looked inside it, other than a quick peek when I replaced the hoses during the SC install. I don't think it's the original radiator. Its core is bare aluminum, not painted black. The car itself has about 94K miles on it. I don't have a temp sensor for oil temp.
I was thinking a bit more about Dan's comments about shrouds and pusher fans. I think part of the issue might be what I mean by a shroud for a pusher: I don't mean a funnel, like what's used for a puller fan; what I was thinking about was a ring (oval, actually, because of the shape of the fan frame), to back the fan off of the heat exchanger by 3/4" or so, but still seal the edge of the frame to the heat exchanger. The idea being to leave room so that the fan hub is not blocking so much air flow.
I plan to work on it tomorrow, probably experimenting with a small shroud for two of the four puller fans to see whether that helps, then maybe trying some things with the pusher fans. I still feel that the 87 square inches of 100% blocked radiator surface from these hubs is counteracting a pretty significant percentage of the benefit of having the six fans in the first place.
08-20-2011, 09:26 AM
#36
Race Car
I was thinking a bit more about Dan's comments about shrouds and pusher fans. I think part of the issue might be what I mean by a shroud for a pusher: I don't mean a funnel, like what's used for a puller fan; what I was thinking about was a ring (oval, actually, because of the shape of the fan frame), to back the fan off of the heat exchanger by 3/4" or so, but still seal the edge of the frame to the heat exchanger. The idea being to leave room so that the fan hub is not blocking so much air flow.
Dan
'91 928GT S/C
475hp/460lb.ft
08-20-2011, 09:50 AM
#37
Not the sharpest tool in the shed
Rennlist Member
Rennlist Member
Yup. That's been the problem...and there is a really good reason why.
To make radiators so that people will buy them, they use really cheap crappy cores. They last 2-3 years and then they leak. Really good coolant and grounding the radiator might help, but the basic problem is cheap cores.
To build a radiator with a decent core and high quality oil coolers.....well, a "high quality" core costs more than these guys are charging for their entire aftermarket radiator.
I've been working on building a decent "aftermarket" radiator, for about a year....but the costs of building a really high quality radiator, that will last, are very high....and I've questioned if the people in the 928 community will spend the money to buy quality.
To make radiators so that people will buy them, they use really cheap crappy cores. They last 2-3 years and then they leak. Really good coolant and grounding the radiator might help, but the basic problem is cheap cores.
To build a radiator with a decent core and high quality oil coolers.....well, a "high quality" core costs more than these guys are charging for their entire aftermarket radiator.
I've been working on building a decent "aftermarket" radiator, for about a year....but the costs of building a really high quality radiator, that will last, are very high....and I've questioned if the people in the 928 community will spend the money to buy quality.
08-20-2011, 01:20 PM
#38
Three Wheelin'
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If you search for pictures of a ZFB9, all the pictures are wrong. They really look like this, with a frame/shroud that has a curved lip on the ends, but straight sides.
05-19-2014, 09:02 PM
#39
Race Car
Summer in Florida
Time to bring this up again I heard a rumor that Murf was working on a rear shroud for his kit to help with the cooling issues at idle with the air on.
If not has anyone tried to make there own or anyone found something that might work?
If not has anyone tried to make there own or anyone found something that might work?
05-20-2014, 01:03 AM
#41
Rennlist Member
Anybody try water injection/ cooling mist? That will help cool the SC and intake temp to reduce overall engine temp while boosting 5-10% more hp. Also changing to lower temp t-stat will help reduce engine operating temp.
05-20-2014, 03:33 AM
#42
Rennlist Member
pushers have an inherent problem of stalling the air of the fan, by the fact that the exit is kind of blocked. Pullers have a little bit of an edge to create a pressure drop in front of the fan, and at the rear of the radiator, to get a larger differential pressure from the front to the rear of the radiator.
I used the stock ac fan, with shorter stand offs so the fan was offset off the radiator front, by about 1". this seems to allow the fan to work, and then create a pressure head at the front of the radiator. this also makes the rear puller fans work much better, so if you can run both , you should have NO issues.
again, water wetter, etc etc, all make very small changes to how your engine runs temp wise. if its working, the engine sould run cool all the time, especially when moving . at the track, im amazed by how the temp is under 180, and im at near full throttle for 30-40min while the outside temps are over 100degrees F. air in the system, bad water pumps, or worse, can all cause overheating.
I used the stock ac fan, with shorter stand offs so the fan was offset off the radiator front, by about 1". this seems to allow the fan to work, and then create a pressure head at the front of the radiator. this also makes the rear puller fans work much better, so if you can run both , you should have NO issues.
again, water wetter, etc etc, all make very small changes to how your engine runs temp wise. if its working, the engine sould run cool all the time, especially when moving . at the track, im amazed by how the temp is under 180, and im at near full throttle for 30-40min while the outside temps are over 100degrees F. air in the system, bad water pumps, or worse, can all cause overheating.
05-20-2014, 10:51 AM
#43
Race Car
I am interested in a better straight fan blade 8" with more Cfm.
The pusher is running all the time, along with the 4- pullers. New radiator pump etc. seems like some kind of shroud should be available by now for the Murf kit.
The pusher is running all the time, along with the 4- pullers. New radiator pump etc. seems like some kind of shroud should be available by now for the Murf kit.
05-20-2014, 11:15 AM
#44
Nordschleife Master
I agree with almost everything below. Especially sealing the front of the radiator from the back of the radiator such that all the air must go thru the radiator, and about running the bellypans.
A comment about it being more complicated:
"Some people like it, and some don't, but there has been some testing done that shows the motorized air flap system that came on some model year cars increases underhood temperatures, even when it's working correctly, or the flaps have been permanently locked fully open."
Even if this is true, it could be due to two things with very different implications. First, it might be the case that the flaps even when open reduce the air flow and allow the engine compartment to heat up. Second, it might be that the flaps don't impact the amount of air flow but direct air flow such that the radiator removes more heat from the coolant which then ends up heating the engine compartment. The first would be a bad thing, the second would be a good thing.
A comment about it being more complicated:
"Some people like it, and some don't, but there has been some testing done that shows the motorized air flap system that came on some model year cars increases underhood temperatures, even when it's working correctly, or the flaps have been permanently locked fully open."
Even if this is true, it could be due to two things with very different implications. First, it might be the case that the flaps even when open reduce the air flow and allow the engine compartment to heat up. Second, it might be that the flaps don't impact the amount of air flow but direct air flow such that the radiator removes more heat from the coolant which then ends up heating the engine compartment. The first would be a bad thing, the second would be a good thing.
Assuming that the temperature gauge is accurate, some of the things that can contribute to warm running include:
Debris blocking the radiator. A lot of stuff can build up between the A/C condenser and radiator not really be that noticable if you're not looking for it.
Not having the aluminum air dam that's included with the supercharger kits installed on top of the radiator. It doesn't do much good if you drill a bunch of big holes in it either, like I saw was done on one car that did have it installed.
The sides of the radiator having openings that allow air to flow around it, instead of through it.
All of the fans that are supplied with the supercharger kits not turning in the correct direction, due to the wiring polarity being reversed on one or more of them.
Some people like it, and some don't, but there has been some testing done that shows the motorized air flap system that came on some model year cars increases underhood temperatures, even when it's working correctly, or the flaps have been permanently locked fully open.
Part of the spoiler/air directing system at the front of the car blocking the air inlet at speed. It may look fine when the car's stopped, but move at speed if damaged or not installed correctly.
The water pump impeller slipping.
Excess clearance between the water pump impeller and block, either from variance in manufacturing tolerances, or impeller to block contact having occured at some time.
A bad thermostat.
A bad seal behind the thermostat.
The radiator cap or some other cooling system component not holding the correct pressure.
An incorrect water to coolant ratio.
Not having the belly pan installed.
The inside of the radiator being partially clogged.
The effect of things like those on the engine temperature are cumulative. The more things that aren't working as well as they could be, the sooner the limits of the cooling system as it is will be reached, resulting in warmer engine temperatures. The outside temperatures that some of you guys have been seeing this summer sure wouldn't help the situation either.
Even if everything's not working as well as it should be, increasing the efficiency of even one part of the cooling system might be enough to raise it's capacity to the point where cooler engine temperatures can be obtained. I'd expect shroud's on the puller fans to help increase potential cooling system capacity to at least some extent. Whether it would be enough to make a significant difference on any particular car that's currently running warm is the question.
Debris blocking the radiator. A lot of stuff can build up between the A/C condenser and radiator not really be that noticable if you're not looking for it.
Not having the aluminum air dam that's included with the supercharger kits installed on top of the radiator. It doesn't do much good if you drill a bunch of big holes in it either, like I saw was done on one car that did have it installed.
The sides of the radiator having openings that allow air to flow around it, instead of through it.
All of the fans that are supplied with the supercharger kits not turning in the correct direction, due to the wiring polarity being reversed on one or more of them.
Some people like it, and some don't, but there has been some testing done that shows the motorized air flap system that came on some model year cars increases underhood temperatures, even when it's working correctly, or the flaps have been permanently locked fully open.
Part of the spoiler/air directing system at the front of the car blocking the air inlet at speed. It may look fine when the car's stopped, but move at speed if damaged or not installed correctly.
The water pump impeller slipping.
Excess clearance between the water pump impeller and block, either from variance in manufacturing tolerances, or impeller to block contact having occured at some time.
A bad thermostat.
A bad seal behind the thermostat.
The radiator cap or some other cooling system component not holding the correct pressure.
An incorrect water to coolant ratio.
Not having the belly pan installed.
The inside of the radiator being partially clogged.
The effect of things like those on the engine temperature are cumulative. The more things that aren't working as well as they could be, the sooner the limits of the cooling system as it is will be reached, resulting in warmer engine temperatures. The outside temperatures that some of you guys have been seeing this summer sure wouldn't help the situation either.
Even if everything's not working as well as it should be, increasing the efficiency of even one part of the cooling system might be enough to raise it's capacity to the point where cooler engine temperatures can be obtained. I'd expect shroud's on the puller fans to help increase potential cooling system capacity to at least some extent. Whether it would be enough to make a significant difference on any particular car that's currently running warm is the question.