Bruce
06-05-2005, 05:12 PM
Since Oct when I installed my Cotton's, I've made a real habit of usually having my ScanMaster on CTS, and IAT.
But, before I begin, I maybe I should define a few terms, so we're all on the same page.
IAT, Intake Air Temp.. In GMese, it just means measuring the temp of the air coming out of the air filter.
MAT, Manifold Air Temp.. The temperature of the air inside the intake plenum.
CT, Coolant Temperature
OT, Oil Temperature
Normal operating temp., ie the *normal* temp of the CT, usually several degress higher then the thermostat opening temp.
Hot Running, the radiator fan is on, but no temp drop.
Overheating, the temp is increasing dispite the Radiator fan being on. It can lead to the engine *boiling over*.
PE, Power Enrichment. While it might mean WOT (Wide Open Throttle) it's not always true.
*******
First off, the TR were designed to generate ~250 HP. Once you go over that level, it should seem understandable, that the rad/cooling system might need work. If you want to make 500 HP you might as well figure you'll have to double the cooling ability of the design, to have the same reserve cooling as the oem setup. Just because the stock setup is so good, doesn't mean it was designed to handle a 500 HP setup. There are some systems where GM over designs their cars, so as to avoid bothersome breakdowns, and the TR reflects that in it's cooling/ oil systems.
In addition to CT's, are OT's. Make a long hard run, and a TR will put more heat into the oiling system, then a stocker, and that heat is just an addition load on the radiator.
On my car, I monitor the MAT. IMO, that's what's most important, temp wise. CT, and OT being a tie for second. MAT, is extremely critical as far as ignition timing goes. Giving the ecm the info. most closely related to what's actually going on in the chamber, is better then what the ambient air temp is. Ambient air doesn't account for heat soaking in the lanes, or time in PE.
Now a little about my car, and some *opinions*.
It's a 3.8L, Poston headers, 206/206 cam, 60 PPH injectors, TA-62, stock converter, AL Radiator, lowered, no air dams, and a reworked non-air-gap intake, Cottons F/M.
Through out the fall, winter, spring, and up until today the MATs when in cruise have always run within about 20dF of ambient (with the F/M), other then in extremely cold weather. In the past running without an Intercooler the temps were generally 30dF or so less then CT, and with the stock Intercooler about 50dF less. In a full pass on a warm day, the MATs without or with the stocker, would approach 200dF. With the F/M the temps might climb over ambient by 30dF or so (at 20 PSI of boost).
During the winter months, the CT would only rarely reach the thermostat opening temp of 185dF, and again in really cold weather not reach 185dF. Today in 90dF ambient temps it reached 193dF while in a sustained cruise. The MAT also ran at about 112dF, under the same conditions. At 203dF the fan would come on, while in traffic, and within mins, the temp drop to 195dF.
So what does that imply?.
IMO,
That those that claim to have a cooling problem when they put a F/M in, might have just been borderline to begin with. It's was the F/M that was really the problem, it was just the straw to break the camel's back.
So what does one need to do?.
IMO,
Reconfigure things for the amount of HP, and driving you go.
First be sure you have MORE then enough radiator.
If you think your dumping alot of heat into the oil (BTW, as HP goes up you do), consider an oil cooler, and possibly using an oil thermostat if you live in a cool/cold winter area.
If your running with EGR, be sure to have the cruise timing cranked back. EGR forces needing addition timing. Without EGR you put alot of extra heat into the oil, by running more timing then you actually need.
The TRs aren't economy cars, and trying to get the last .002 MPG is VERY hard on the engine. While you can run +46d, and get some great MPG numbers, it quickly takes it toll on rod bearings. IMO, I'd much rather run 36d, and pay a little more for gas, then constantly wear out bearing needlessly. Not to mention with the higher OTs from running the higher advance amounts, you also generate more oil fumes in the crankcase, that get sucked past the PCV valve. Which again, is not a good thing.
If your running EGR, remember that having the EGR blow thur the intake serves to heat the manifold, and incoming air. IMO, I wonder if the reason GM used an air gap manifold, was to help cool the manifold, due to the heat from the EGR.
If your out of injector and are having to run a 160dF thermostat, then you're just aggravating an already bad situation. While running a 160 has long been an accepted crutch, it's just not the best way to make an engine last on the street. If you're racing by all means run a 140 if you want, but for a street car, it's just not going to get you much when things are CORRECT.
If you're running a higher then stock stall converter then stock you're putting more heat into the radiator.
In closing:
A F/M is about dropping MATs. If you drop your MATs more then the increase in CTs, then your going in the right direction. In my case, dropping the MATs from about 155dF, to 112dF, in about the same conditions, shows that I've got it right.
If your running a 160 with a F/M then your wasting alot of energy, trying to maintain that temp., on a hot day. It's MUCH easier to cool an engine to 200 on a hot day then 160. Having a setup that's over designed by the same amount as GM did, allows for running in the worst of conditions, without having problems. IMO, with all the NASCAR engines running at about 200dF, there might be a clue, that it's just not that *harmful* for a properly setup endurance (street) engine to run that *hot*.
If you want to have a fast reliable, TR, you need to think about all aspects of it. With engineering, there is ALWAYS a *up* and *downsides* to any mods.. If you want more HP then engine life will suffer, if you want more HP, mileage will suffer, if you make (enough) more heat, sooner or later you're going to have to deal with it.
If you want to be able to run, in less then perfect conditions, they you HAVE to design for some overkill. If you have time to ice down your intake, and only drive in 60dF weather, then more power to you, but for most folks they just don't live in a perfect world, and IMO, should consider as many elements of design there are when they make a change or are planning to make a change.
HTH
But, before I begin, I maybe I should define a few terms, so we're all on the same page.
IAT, Intake Air Temp.. In GMese, it just means measuring the temp of the air coming out of the air filter.
MAT, Manifold Air Temp.. The temperature of the air inside the intake plenum.
CT, Coolant Temperature
OT, Oil Temperature
Normal operating temp., ie the *normal* temp of the CT, usually several degress higher then the thermostat opening temp.
Hot Running, the radiator fan is on, but no temp drop.
Overheating, the temp is increasing dispite the Radiator fan being on. It can lead to the engine *boiling over*.
PE, Power Enrichment. While it might mean WOT (Wide Open Throttle) it's not always true.
*******
First off, the TR were designed to generate ~250 HP. Once you go over that level, it should seem understandable, that the rad/cooling system might need work. If you want to make 500 HP you might as well figure you'll have to double the cooling ability of the design, to have the same reserve cooling as the oem setup. Just because the stock setup is so good, doesn't mean it was designed to handle a 500 HP setup. There are some systems where GM over designs their cars, so as to avoid bothersome breakdowns, and the TR reflects that in it's cooling/ oil systems.
In addition to CT's, are OT's. Make a long hard run, and a TR will put more heat into the oiling system, then a stocker, and that heat is just an addition load on the radiator.
On my car, I monitor the MAT. IMO, that's what's most important, temp wise. CT, and OT being a tie for second. MAT, is extremely critical as far as ignition timing goes. Giving the ecm the info. most closely related to what's actually going on in the chamber, is better then what the ambient air temp is. Ambient air doesn't account for heat soaking in the lanes, or time in PE.
Now a little about my car, and some *opinions*.
It's a 3.8L, Poston headers, 206/206 cam, 60 PPH injectors, TA-62, stock converter, AL Radiator, lowered, no air dams, and a reworked non-air-gap intake, Cottons F/M.
Through out the fall, winter, spring, and up until today the MATs when in cruise have always run within about 20dF of ambient (with the F/M), other then in extremely cold weather. In the past running without an Intercooler the temps were generally 30dF or so less then CT, and with the stock Intercooler about 50dF less. In a full pass on a warm day, the MATs without or with the stocker, would approach 200dF. With the F/M the temps might climb over ambient by 30dF or so (at 20 PSI of boost).
During the winter months, the CT would only rarely reach the thermostat opening temp of 185dF, and again in really cold weather not reach 185dF. Today in 90dF ambient temps it reached 193dF while in a sustained cruise. The MAT also ran at about 112dF, under the same conditions. At 203dF the fan would come on, while in traffic, and within mins, the temp drop to 195dF.
So what does that imply?.
IMO,
That those that claim to have a cooling problem when they put a F/M in, might have just been borderline to begin with. It's was the F/M that was really the problem, it was just the straw to break the camel's back.
So what does one need to do?.
IMO,
Reconfigure things for the amount of HP, and driving you go.
First be sure you have MORE then enough radiator.
If you think your dumping alot of heat into the oil (BTW, as HP goes up you do), consider an oil cooler, and possibly using an oil thermostat if you live in a cool/cold winter area.
If your running with EGR, be sure to have the cruise timing cranked back. EGR forces needing addition timing. Without EGR you put alot of extra heat into the oil, by running more timing then you actually need.
The TRs aren't economy cars, and trying to get the last .002 MPG is VERY hard on the engine. While you can run +46d, and get some great MPG numbers, it quickly takes it toll on rod bearings. IMO, I'd much rather run 36d, and pay a little more for gas, then constantly wear out bearing needlessly. Not to mention with the higher OTs from running the higher advance amounts, you also generate more oil fumes in the crankcase, that get sucked past the PCV valve. Which again, is not a good thing.
If your running EGR, remember that having the EGR blow thur the intake serves to heat the manifold, and incoming air. IMO, I wonder if the reason GM used an air gap manifold, was to help cool the manifold, due to the heat from the EGR.
If your out of injector and are having to run a 160dF thermostat, then you're just aggravating an already bad situation. While running a 160 has long been an accepted crutch, it's just not the best way to make an engine last on the street. If you're racing by all means run a 140 if you want, but for a street car, it's just not going to get you much when things are CORRECT.
If you're running a higher then stock stall converter then stock you're putting more heat into the radiator.
In closing:
A F/M is about dropping MATs. If you drop your MATs more then the increase in CTs, then your going in the right direction. In my case, dropping the MATs from about 155dF, to 112dF, in about the same conditions, shows that I've got it right.
If your running a 160 with a F/M then your wasting alot of energy, trying to maintain that temp., on a hot day. It's MUCH easier to cool an engine to 200 on a hot day then 160. Having a setup that's over designed by the same amount as GM did, allows for running in the worst of conditions, without having problems. IMO, with all the NASCAR engines running at about 200dF, there might be a clue, that it's just not that *harmful* for a properly setup endurance (street) engine to run that *hot*.
If you want to have a fast reliable, TR, you need to think about all aspects of it. With engineering, there is ALWAYS a *up* and *downsides* to any mods.. If you want more HP then engine life will suffer, if you want more HP, mileage will suffer, if you make (enough) more heat, sooner or later you're going to have to deal with it.
If you want to be able to run, in less then perfect conditions, they you HAVE to design for some overkill. If you have time to ice down your intake, and only drive in 60dF weather, then more power to you, but for most folks they just don't live in a perfect world, and IMO, should consider as many elements of design there are when they make a change or are planning to make a change.
HTH