running hot on freeway
- Ron LaDow
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Re: running hot on freeway
Apologies if this is too elementary for the folks here:
Engine coolant (water/oil) heat is the waste of the HP made, not the HP possible from a given engine; an engine capable of 110HP will not cause excess coolant temp if it does not make more than what is required to push the car down the road at X speed.
Assuming the engine fueling/timing/CR are in line, it's worth looking for anything which is requireing higher HP at X speed: Tire pressures, tire widths, brakes dragging, alignment, etc.
I remember R&T used to cite "Tapply Data" (sp?) in the road tests; it was more or less a coasting test to correct for such cofounders.
Back when this was a list-serve "List", I did a survey, and while it was a long way from what anyone would claim to be "scientific", it showed a very strong bias to 'overheating' in single-grille cars, even though the grille size is not the 'throttle' on the cooling air entering the engine bay.
Engine coolant (water/oil) heat is the waste of the HP made, not the HP possible from a given engine; an engine capable of 110HP will not cause excess coolant temp if it does not make more than what is required to push the car down the road at X speed.
Assuming the engine fueling/timing/CR are in line, it's worth looking for anything which is requireing higher HP at X speed: Tire pressures, tire widths, brakes dragging, alignment, etc.
I remember R&T used to cite "Tapply Data" (sp?) in the road tests; it was more or less a coasting test to correct for such cofounders.
Back when this was a list-serve "List", I did a survey, and while it was a long way from what anyone would claim to be "scientific", it showed a very strong bias to 'overheating' in single-grille cars, even though the grille size is not the 'throttle' on the cooling air entering the engine bay.
Ron LaDow
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- Martin Benade
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Re: running hot on freeway
Was a single grille a problem, or just perceived to be a problem?
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- Jules Dielen
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Re: running hot on freeway
I have a few sigle grill cars, only this one runs hot. I had 2 different engines in this car before this one went in, the other 2 did not run hot either. I am 99% sure it is an engine related problem.
Jules
Water pumps are for windshield washers only.
Water pumps are for windshield washers only.
- Ron LaDow
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Re: running hot on freeway
Dunno.Martin Benade wrote:Was a single grille a problem, or just perceived to be a problem?
When I did the survey, I asked things like tire size, carbs, exhaust, lowering, etc.
What was very clear (like a big difference) among those who reported elevated temps were those driving single-grille cars.
Sorry I didn't save the results, even though the sample size and randomization were far from optimal, but that result was loud and clear.
Ron LaDow
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- Ron LaDow
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Re: running hot on freeway
I'm not about to disagree. Do you have a dyno available to fiddle with the tune? If it is an engine problem, and not related to CR, you can find it there.Jules Dielen wrote:I have a few sigle grill cars, only this one runs hot. I had 2 different engines in this car before this one went in, the other 2 did not run hot either. I am 99% sure it is an engine related problem.
Ron LaDow
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- Greg Bryan
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Re: running hot on freeway
How about fuel ratio too lean, either from carb setup or fuel delivery?
Greg Bryan
- Vic Skirmants
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Re: running hot on freeway
OK; I'll mention it again; small oil pump versus large.
- C J Murray
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Re: running hot on freeway
As far as early vs later engines...when Porsche went from 75hp to 90hp they increased the size of the oil pump, added the velocity stack to the fan shroud, removed the wire screen, and changed to the 28 vain fan. In other words they needed more cooling to get to 90hp. Then they went to the twin grills. We race single grill cars but we also remove the rain treys which makes a giant difference as well as placing oil coolers where they get 120mph fresh air.
Higher compression in combination with shorter duration cams, very lean mixtures, and too little advance are to be avoided if you want to run cool.
So, in 1958, what did Porsche say about oil temperature? Here...
http://www.willhoitautorestoration.com/oiltemp.php
Higher compression in combination with shorter duration cams, very lean mixtures, and too little advance are to be avoided if you want to run cool.
So, in 1958, what did Porsche say about oil temperature? Here...
http://www.willhoitautorestoration.com/oiltemp.php
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- Doug McDonnell
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Re: running hot on freeway
CJ Add double flapper boxes to changes for cooler running. Jules try a run with the engine lid popped to open and see if it makes a difference.
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- Wes Bender
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Re: running hot on freeway
I agree with Vic that the small oil pump has some effect. Is it possible that you have a partial blockage in the new oil cooler? The switch from a stock cooler to the more modern aluminum ones usually results in a significant drop in oil temps.
Re. the oil, I would probably still be running a straight 30 wt non-detergent at the 1500 mile point in the break-in, but that's just my opinion. Others use different break-in regimens.
Re. the oil, I would probably still be running a straight 30 wt non-detergent at the 1500 mile point in the break-in, but that's just my opinion. Others use different break-in regimens.
Some days it's just not worth chewing through the restraints.....
- Craig Richter
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Re: running hot on freeway
Vic makes the point (twice for emphasis) that the early small-geared oil pumps aren't going to run as cool as big-geared later pumps. This must be directly related to pressure, because higher pressure will force a larger volume of oil thru the motor in a given time, and this faster "cycling" pulls more heat into the oil to be expelled by all the features you guys mention above. Jules, it's good your oil pressure light doesn't go on at idle, but have you actually checked the pressure at running speeds?
- Pascal Giai
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Re: running hot on freeway
Jules
Make sure to check your air/fuel ratio with the correct equipment.
You may fry your new pistons if the engine is running too lean.
It doesn't take long to destroy them, don't ask me how I know...
I never had any issue with small oil pumps, yet !
Pascal
Make sure to check your air/fuel ratio with the correct equipment.
You may fry your new pistons if the engine is running too lean.
It doesn't take long to destroy them, don't ask me how I know...
I never had any issue with small oil pumps, yet !
Pascal
- Thomas Sottile
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Re: running hot on freeway
I have a friend with the same problem for 1 year until he looked and saw his heat boxes were screwed closed.!!
- Craig Richter
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Re: running hot on freeway
Isn't it amazing all the screwed-up turkey s....tuffing found after all these years!
- Jules Dielen
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Re: running hot on freeway
I'll check air/fuel mixture again and change the oil. The partially blocked (new) cooler is of course a thought.
as to the big vs small oil pump and single grill talk... I had a different (small oil pump) stock 1600 engine in this car before i installed the rebuilt engine. I drove it back from Monterey, CA to Phoenix in 105F clear across the desert for a day on the freeway and did not have any problems. It also made the trek from Phoenix to Park City and back and I attended a NMS event without any issues. I put 12k miles on it with the old engine and the oil temp never even got close to 200F, although that one did have low oil pressure at idle/ operating temp running Brad Penn 20W50. No propped hoods needed with that engine, why should it with this new one?
as to the big vs small oil pump and single grill talk... I had a different (small oil pump) stock 1600 engine in this car before i installed the rebuilt engine. I drove it back from Monterey, CA to Phoenix in 105F clear across the desert for a day on the freeway and did not have any problems. It also made the trek from Phoenix to Park City and back and I attended a NMS event without any issues. I put 12k miles on it with the old engine and the oil temp never even got close to 200F, although that one did have low oil pressure at idle/ operating temp running Brad Penn 20W50. No propped hoods needed with that engine, why should it with this new one?
Last edited by Jules Dielen on Fri Apr 20, 2018 12:34 pm, edited 1 time in total.
Jules
Water pumps are for windshield washers only.
Water pumps are for windshield washers only.