996 starting troubles
08-29-2007, 03:22 PM
#16
Rennlist Member
So the 3rd radiator will not cool the operating temperature down, but will only offer a safety factor in the case of extreme conditions? Obviously it can't cool below the thermostat activation point, and I'm sure we (and Porsche) wouldn't want that, If I'm hearing right? If I'm reading this right, Porsche wants these engines to operate between 200-220 degrees?
08-29-2007, 03:27 PM
#17
So the 3rd radiator will not cool the operating temperature down, but will only offer a safety factor in the case of extreme conditions? Obviously it can't cool below the thermostat activation point, and I'm sure we (and Porsche) wouldn't want that, If I'm hearing right? If I'm reading this right, Porsche wants these engines to operate between 200-220 degrees?
08-29-2007, 03:29 PM
#18
Race Car
So the 3rd radiator will not cool the operating temperature down, but will only offer a safety factor in the case of extreme conditions? Obviously it can't cool below the thermostat activation point, and I'm sure we (and Porsche) wouldn't want that, If I'm hearing right? If I'm reading this right, Porsche wants these engines to operate between 200-220 degrees?
Whatever thermostat temp. Porsche has used is where the ECU is going to be most efficient to operate the engine fuel/timing.
I have seen cars run a lower thermsotat temperature than what the manufacturer used, and the cars lost power because the cars never made it out of warm-up mode.
Mostly carbbed cars in general can make more power with a lower temp thermostat.
08-29-2007, 03:39 PM
#19
Race Car
The high temps are purely for reducing emmisions.
Whatever thermostat temp. Porsche has used is where the ECU is going to be most efficient to operate the engine fuel/timing.
I have seen cars run a lower thermsotat temperature than what the manufacturer used, and the cars lost power because the cars never made it out of warm-up mode.
Mostly carbbed cars in general can make more power with a lower temp thermostat.
Whatever thermostat temp. Porsche has used is where the ECU is going to be most efficient to operate the engine fuel/timing.
I have seen cars run a lower thermsotat temperature than what the manufacturer used, and the cars lost power because the cars never made it out of warm-up mode.
Mostly carbbed cars in general can make more power with a lower temp thermostat.
Actually, the thermostat has nothing to do wth the final temperature of the coolant. You can put in one that opens at 150F and your coolant temps will be no different. The running engine temperature is the result of the high compression of the engine. Unless you increase your coolant flow and/or efficiency of the radiator, you will not get any lower temps. There is nothing you can do that will reduce engine temps to 180F on an 11:1+ engine.
08-29-2007, 03:49 PM
#20
Addict
Lifetime Rennlist
Member
Lifetime Rennlist
Member
I am having trouble re-starting my 1999 996 after it heats up(200), its starts to turn over but it seems like there is almost a hydraulic lock and it wont start. It starts fine cold, and will start fine after cooling down as well. The battery is less than a year old, and the alternator is charging fine.
Does the engine crank or does it seem like the starter is jammed and not turning the engine over?
08-29-2007, 04:05 PM
#22
Race Car
Actually, the thermostat has nothing to do wth the final temperature of the coolant. You can put in one that opens at 150F and your coolant temps will be no different. The running engine temperature is the result of the high compression of the engine. Unless you increase your coolant flow and/or efficiency of the radiator, you will not get any lower temps. There is nothing you can do that will reduce engine temps to 180F on an 11:1+ engine.
I differ the second part. I have been around plenty 12-13:1 engines on the street run at 160 degrees using 160 degree thermostats. This using Autometer gauges which are very accurate. It just takes a large radiator, simple as that. Water volume (relating to the water pump) is almost irrelevant, you can only flow enough water through a thermostat.
08-29-2007, 04:15 PM
#23
Race Car
Agree with the first part and I didnt state differently.
I differ the second part. I have been around plenty 12-13:1 engines on the street run at 160 degrees using 160 degree thermostats. This using Autometer gauges which are very accurate. It just takes a large radiator, simple as that. Water volume (relating to the water pump) is almost irrelevant, you can only flow enough water through a thermostat.
I differ the second part. I have been around plenty 12-13:1 engines on the street run at 160 degrees using 160 degree thermostats. This using Autometer gauges which are very accurate. It just takes a large radiator, simple as that. Water volume (relating to the water pump) is almost irrelevant, you can only flow enough water through a thermostat.
Water volume is a VERY important part of the effeciency of the cooling system. To little and you will run hot. Too much and you will run hot. There is no gasoline internal combustion engine on the road today that runs with a coolant temperature as low as 160F without chemical assistance.
08-29-2007, 04:24 PM
#24
Race Car
There is not an efficient enough radiator that will maintain a high compression engine at 160F. You either remember incorrectly, your gauges were inaccurate or you read the gauges on there way up before the engine reached normal temperature. Laws of physics dictate that to be factual.
Water volume is a VERY important part of the effeciency of the cooling system. To little and you will run hot. Too much and you will run hot. There is no gasoline internal combustion engine on the road today that runs with a coolant temperature as low as 160F without chemical assistance.
Water volume is a VERY important part of the effeciency of the cooling system. To little and you will run hot. Too much and you will run hot. There is no gasoline internal combustion engine on the road today that runs with a coolant temperature as low as 160F without chemical assistance.
2. A factory pump is usually sufficient for cooling as you can only flow as much as the I.D. of the thermostat permits.
08-29-2007, 04:45 PM
#25
Race Car
1. I am speaking of old muscle cars (carbbed) regarding temps (FI cars will run terrible at low engine temps), and yes, the gauges were accurate (Autometer).
2. A factory pump is usually sufficient for cooling as you can only flow as much as the I.D. of the thermostat permits.
2. A factory pump is usually sufficient for cooling as you can only flow as much as the I.D. of the thermostat permits.
Maybe you had the transmission temp gauge confused with the coolant gauge?
But, regardless, the engine's coolant temperture was higher than 160F. The volume of water through the water pump is determined by 2 things. Pressure and the size of the path. Increasing either will increase volume. The 996 water pumps flow less than required and these pumps were later redesigned by Porsche to allow for more flow.
08-29-2007, 04:51 PM
#26
Race Car
Me and my friends bought them by the box full (not literally) for our cars? It was an easy hp gainer for our cars. Yes, some cars would go over, say 165-170, but in general, 160 could be achieved as long as there wasnt stop and go traffic.
Look at Autozone, they sell several brands of 160 thermostats for older cars. They sell them for a reason.
08-29-2007, 04:55 PM
#27
Race Car
Ok, why would companies sell a 160 degree thermostat?
Me and my friends bought them by the box full (not literally) for our cars? It was an easy hp gainer for our cars. Yes, some cars would go over, say 165-170, but in general, 160 could be achieved as long as there wasnt stop and go traffic.
Look at Autozone, they sell several brands of 160 thermostats for older cars. They sell them for a reason.
Me and my friends bought them by the box full (not literally) for our cars? It was an easy hp gainer for our cars. Yes, some cars would go over, say 165-170, but in general, 160 could be achieved as long as there wasnt stop and go traffic.
Look at Autozone, they sell several brands of 160 thermostats for older cars. They sell them for a reason.
Like I said previously and you agreed to, the thermostat has absolutley nothing to do with the final operating temperture of the engine. All a thermostat does is determine when the coolant will flow to the radiators...nothing more. Remove your thermostat from your car and install a washer that has the same size hole as the thermostat did and your coolant temperature will not be even 1 degree different. The thermostat is designed to maintain a MINIMUM engine temperture and not a maximum and to get to the minimum as fast as possible.
08-29-2007, 05:13 PM
#28
Three Wheelin'
Not to step in or on any toes during your discussion, I just wanted to add my 2 cents.
I would hate my carbed or FI engines to run at 160 degrees, neither would operate correctly. Now cooling the air from a SC is a different story.
In regards to the meters, I love my Autometers on my race Mustang and they are all 'direct' reading gauges, meaning not electrical. For instance the temp gauge is a sending unit hardwired to the gauge, not an electrical sensor with a wire going to the gauge. The oil gauge uses a direct feed line from the engine to the gauge, not a electrical sensor with a wire going to the gauge. I trust the direct reading gauges much more than the electrical reading, but are they really that accurate still? It's like checking air pressure with one gauge and then the other to find out they read differently. Calibration of gauges should be done on a regular basis if you are truly racing at the high-end of your sport (OK any end).
I would hate my carbed or FI engines to run at 160 degrees, neither would operate correctly. Now cooling the air from a SC is a different story.
In regards to the meters, I love my Autometers on my race Mustang and they are all 'direct' reading gauges, meaning not electrical. For instance the temp gauge is a sending unit hardwired to the gauge, not an electrical sensor with a wire going to the gauge. The oil gauge uses a direct feed line from the engine to the gauge, not a electrical sensor with a wire going to the gauge. I trust the direct reading gauges much more than the electrical reading, but are they really that accurate still? It's like checking air pressure with one gauge and then the other to find out they read differently. Calibration of gauges should be done on a regular basis if you are truly racing at the high-end of your sport (OK any end).
08-29-2007, 05:26 PM
#29
Race Car
Like I said previously and you agreed to, the thermostat has absolutley nothing to do with the final operating temperture of the engine. All a thermostat does is determine when the coolant will flow to the radiators...nothing more. Remove your thermostat from your car and install a washer that has the same size hole as the thermostat did and your coolant temperature will not be even 1 degree different. The thermostat is designed to maintain a MINIMUM engine temperture and not a maximum and to get to the minimum as fast as possible.
Gotta go, I brought in old cars into the conversation. I dont care to talk about coolant issues anymore as we beat this horse enough, the 996 is pretty maxed out and limited because of the design.
