High stall torque converter question

[beekppr]

If I am running a 3000 stall converter and I typically cruise under 3000 on the freeway and on back roads, does this mean my converter will constantly be slipping? I assume it does.

If it is in a state of nearly constant slippage, is there some drawback such as increased heat buildup?

I have been plagued with intermittant overheating issues and I have tried everything in the book. Lately I have been wondering if this is part of my problem.

Secondly, I have noticed an odd loss of power while crusing and I am not sure of the source. I have had two different carbs of different sizes and tried varying the jetting on each from rich to lean but no help. The loss of power is just that the car begins to slow slightly while keeping the throttle steady at 2500 rpm. The engine doesn't speed up or surge, the car just slows slightly as though it is going uphill. A bit of extra throttle immediatly fixes this until I go back to cruise mode. I have also wondered if the torque converter is part of this problem as well since I am not over 3000 rpm.

Without writing a book here, the story is the car sat at a body shop for many years. While it was there, I redid the engine from pure stock (and running perfect) to hot cam, increased compression, aluminum heads, improved intake, high stall converter, higher rear gear, etc. Under full acceleration, the car is incredibly fast but at idle and slow speed, I now have overheating issues. At cruise, the car doesn't want to run clean and smooth, it just wants to run full speed ahead. Since I made all the changes at once and so long ago, it is hard to attribute my problems to a specific mod.

I am ready to pull the engine and go back to pure stock but before I do, I am hoping I can make this combo work reliably.

Can anyone educate me about torque converters and what I can expect from continued use of this 3000 stall spedd unit?

[6packCuda]

Sounds to me like you're running too high of a gear ratio for the engine/converter setup you have. What gears are you running? The way your engine is built, it's going to be a lot happier running lower gears to get the RPMs up a bit. If you're cruising at under 3000 rpms, yes the converter is always slipping. This creates a ton of heat in the tranny. With a higher stall speed like that, you really need to run a large external tranny cooler. The over heating issues could be related to the increased compression. Hard to say without actually knowing what compression you're running.

[Cooter]

Well, I can tell you this, a 3000 Stall Converter shouldn't be all that bad as far as slipping goes going down the highway..Most stalls aren't rated as such..They are rated at what's called "Flash" stall speed. Meaning when you romp on the car like your gonna "Hop" it, the RPM will only go to a certain point, then the car begins to move. Power braking to find out flash stall usually ends up in the rear tires going up in smoke before you reach the stall speed...I personally, haven't had a major problem with heat build up in a higher stall converter until I tried to run a 4500 Stall on the street, with 3.73 gear...THAT one burned fluid in about 25 miles...
I'd be more concerned with your Cruise RPM's...And whether or not your pulley set is matched..I too have a 440 overheating problem...One of them won't run over 180 Degrees I don't care what I do to it and it's "Cammed up"....The others run anywhere form 195-230 depending on heat of day..NONE have actually puked out into the overflow, but by the guage, it says running hot...

Higher compression relates to higher combustion temps, therefore, more heat to get rid of...Are you running a fan shroud?

I'd hate for you to pull out that Converter only to have the car still "Run hot"..BTW: What's overheating to you?
200 degrees? 210 degrees? Does it puke coolant when you come to a stop and shut it down?

[beekppr]

Well when I say intermittant, I have had it not overheat on a hot summer day at times but then have it run hot when the air temp is only 45 degrees.

I have 10-1 compression. The rear gear is 3.55. It lauches great and if I want, I can smoke the tires for what seems like weeks at a time.

I have been hoping to get around 190 temps and yet it frequently tries to run 210-220. I always shut it down at that point so I don't really know if it would continue to rise.

To cure my overheating, I went to a super thick aluminum radiator and try not to run too much antifreeze. I have a flow cooler on it and recently swapped out the stock seven blade fan with dual electric fans. They work way better than the solid seven blade fan I ran with no clutch. I have tried a variety of thermostats and finally settled on a restriction plate instead. It seems to be doing the trick but I had to make my own and vary the hole until the engine found what it liked.

This last mod of using the restrictor plate in place of a thermostat has seemed to make the biggest impact but it still seems like I am only masking symptoms of a larger problem.

When I was jet tuning the new carb the other day, I noticed the loss of power during cruise and it made me think more about the torque converter. The best way I can describe it is as though the car feels like it's going up a slight hill and losing steam. Only applying more throttle fixes it. 

[beekppr]

Forgot to mention, It does puke collant out onto the ground and I have used a thermo gun on the engine to confirm temps so I know the gauge is accurate.

What did you mean by pulley ratios? I am using the stock pulleys but I am thinking of changing the water pump pulley to the a/c unit since it is an ince smaller in diameter and will spin the pump faster at all speeds.

[Cooter]

Moving water too fast is as bad as slowing it down too far...I take it you DO NOT have a puke tank on it right now, and are running it like the factory did? right out onto the ground? Bad idea..I'd put an overflow tank on it at least to save the coolant...A little puke out is normal, but I'm referring to blowing it out for like 10 minutes or so....

You need to reinstall a thermostat, as the water is moving too fast through the block to cool it...Those restrictor things are for the birds IMO...I know it sounds crazy, but a thermostat in the engine will actually help it run cool. And NOT a 160 degree. I'm talking like a 180-195...You have to remember that the newer cars with ALUMINUM heads run 227 Degrees BEFORE the electric cooling fans even come on, so I wouldn't worry too much bout 210...What is the timing at at cruise? Are you running Vaccum advance?

[nqkjw]

Mate,this is one area I'm sure I can help.
I live in tropical Nth queensland,Australia where it's always hot so we get pretty good with our cooling.
Diagnosis is pretty easy.

Does it get hot when sitting still idling and/ or in stop/start slow moving traffic?
If so your cooling system is probably fine and you've got n airflow problem.

Does it get hot at highway speeds?
If so you've got a cooling problem which could(but not necessarily)be mechanical such as head gaskets.

Make sure the tune is right.Have the timing right for your engine and tune a little rich till you sort the cooling.Remember - lean means hot.

Please get back with info as I've helped a heap of Aussies sort cooling issues.

EDIT : It's unlikely your convertor is the problem as it'll only slip when you have full hp going through it.That is,WOT.
          FWIW my 69 barracuda with 440,3.55 gear and 28" tall tyre has a 4500 stall and runs around 172deg on the highway.

[beekppr]

Well the problem has not been as consistent as I would expect it to be. Once I put it the thick aluminum radiator and was using stock seven blade fixed fan, it would run ice cold down the road and by ice cold, I mean like 130-150. I found it got hot quickly once I went below 30 mph even though my fan had no clutch and seven blades. I switched to a 180 thermostat and it would run 170 down the road and again quickly climb to 210 as I slowed down. My other radiator wouldn;t even do this so I concluded it was a flow problem at slow speed.

I removed the stock fan and replaced with super duper dual electric unit. Now it would idle all day at 190 with fans going on and off as expected. Once I started moving, it climbed to 210 and would not cool down at all. This made some sense to me because the electric fans create some blockage compared to the stock fan and shroud and the engine naturally would generate more heat at 2500 rpm than at idle. In fact, right after putting in these fans, I drove 40 miles to a car show, leaving at 4am and driving in 40 degree cold and it ran 210 all the way.

I started playing with thermostats but nothing I did made a difference. I finally replaced it with a restrictor plate and this made a difference. I cut the guts out of a regular thermostat and now I could see changes. The last thing I did was closed up the opening a little more to about 3/4 inch and this seems to be a good balance. I have not seen any problems at any speed but it's winter so we shall see when it gets warmer.

I know this thick aluminum radiator is capable of removing a tremendous amount of heat but why is the engine creating so much heat in the first place? My other 383 is using a stock 2 row radiator and working perfect.

I'd really rather not bolt on a coolant overflow tank if I can help it although I realize the value in having one.

[beekppr]

Couple more thoughts...I am running a large tranny cooler and it is directly in front of the radiator. Someone I know suggested that I find a new location to mount the cooler so that heat from it does not have to go though the radiator afterward. It doesn't feel that hot to me and I run it through the radiator in addition to the cooler anyway so is this overkill?

I am beginning to accept that my tranny and torque converter are not part of this problem. I was hoping it was the missing part of the puzzle but it doesn't seem to be.

I'm still not sure why I get the loss of speed during cruise as though I'm losing power. The jetting seems to be fairly close and it runs strong at WOT. I am not feeling any surging or other stuff at cruise so I had hoped it was converter related but I guess not.

At some point or another, if all these nagging little things aren't solved, I plan to yank the motor and go back to pure stock no matter how much trouble it is. I have the original components.

The motor was bored 40 over and another person suggested that maybe this block was always a tad bit flawed during the casting process and not capable of handling that much bore over. I can always have it ultrasounded during the rebuild and find out once and for all. Never had this problem with any of the other motors I have used.

The challenger I just picked up has a fresh rebuilt 383 and it is pure stock in every way right down to the original 2 row radiator. It does not have any of these issues.

[nqkjw]

Well the problem has not been as consistent as I would expect it to be. Once I put it the thick aluminum radiator and was using stock seven blade fixed fan, it would run ice cold down the road and by ice cold, I mean like 130-150. I found it got hot quickly once I went below 30 mph even though my fan had no clutch and seven blades. I switched to a 180 thermostat and it would run 170 down the road and again quickly climb to 210 as I slowed down. My other radiator wouldn;t even do this so I concluded it was a flow problem at slow speed.

OK,I'm using this paragraph as a baseline as it appears to be the most conventional setup you've tried.
Based on the above info I'd say it's an airflow problem.You've proved it can run cool so I'd say there's no issue with your cooling system.

You mentioned a big tranny cooler in front of the radiator.That can't help.Relocate it if you can.

When you had the mechanical fan did you have a shroud?They do a lot.Placement of the fan in the shroud can affet effectiveness too.
Desirably you want most of the fan's thickness within the shroud but some (say,25%?) should be sticking out.The diameter of the fan should be big enough to fill most of the hole in the shroud(leaving enough to allow for engine rock of course)
Also the shroud should be well sealed to the rad so that all the air pulled is being drawn through the rad.
If you didn't have a shroud then the fan needs to be abt 3/4" from the radiator.Otherwise it's useless.
Another one which helps a little (but certainly won't cure everything)is to seal up all openings in the radiator mounting panel.This helps ensure that all air entering the front must pass through the radiator.

When you mounted the electrics were they in front or behind the radiator?
And are they wired right?Sorry if it seems insulting but seen MANY times where electrics have been pushing air the wrong way.
Electric fans need to be mounted very tight to the radiator,otherwise with a good shroud.

Can you post pics of your setup?
I'm sure we can solve it.

And just out of interest,our overnight minimum temps are currently around 78-79F
Daily temps are fairly mild at around 90F
January to early february will see our hot weather at around 96-98F days with the occasional day reaching as high as 110.
Never seen it hotter here than 115.

Had my challenger out today.It's abt 420hp 440 auto with no auxilliary trans cooler.It's got a mechanical steel flexi 7 blade fan in shroud mounted behind 26" wide 4 row std copper radiator.In front it has a 10" and 12" electric mounted to the aircon condensor.
Today was  90F here and temp didn't go over 185.

Two weeks ago I had to participate in a pre-race 3hr cruise in my 440 barracuda.It was a blistering day.Probably abt 105F.I held it down to 195 by keeping the front of my car in clear air wherever I could.
It has a big 4row ally rad with two 16" electrics.One pushing and one pulling.

Hope this info is of help.Keep us informed.

Regards Ken

[nqkjw]

so I concluded it was a flow problem at slow speed.

Just to clarify I'm agreeing if you mean AIRflow.
I don't believe it's a WATERflow problem.

Oh,and PLEASE put a thermostat back in.
You have no idea how quickly you are shortening the life of your front cylinders.
Particularly in your cold climate.

[beekppr]

Yes, I meant airflow.

I took some photos of the current setup. I don't have any photos of my previous setup with the old radiator, or old fan and shroud.

I have always used a shroud but lets be honest here, the Mopar shrouds I have seen never fit very well either to the radiator or the fan placement within the shroud. The old fan and shroud fit was weak at best.

I don't know how well the photos show this but the new electric fans have a really nice soft rubber seal which is just perfect. The fans are like 1/4 inch from the radiator. They are definitely spinning the right way (no offense taken). I can feel fairly good airflow being pulled from the front of the core. These fans are the variable type and spin faster as the temp goes up.

By the way, I think I cured the strange loss of power thing at cruise. I raised the float level in the carb slightly and that seemed to take care of the problem.

[nqkjw]

Good to see you solved your cruising power problem.That will have to help cruise temps a little as now it shouldn't be leaning out.

Pics are good enough to see what's happening.

Once again,please don't take offence at any comments I make.Just trying to help in my usual blunt manner LOL

Firstly,that's a nice looking fan setup!!!Wish we could get stuff that neat looking over here!!!
However,I'm not a big fan(no pun intended) of shrouds on electrics as I reckon they limit open road airflow.Maybe this could be contributing to your heat?
However,there are MANY cars over here successfully running much the same setup as yours.
Also I prefer a large single over duals.All things being equal(same manufacturer,same mounting distance,etc)the largest single you can fit will outflow the largest pair of smaller diameter fans you can fit on.
Were the fans expensive?Fans aint fans.Generally what you pay for them is a fair indicator of quality.Over here you can buy cheap fans which are next to useless.Buy a more expensive better quality fan and they blow like a cyclone!!!(hurricane in northern hemispere)
Check the cfm rating of each fan against what else is available.
Another way of guaging how good a fan they are is by current draw.This also should be specified by the manufacturer.
FWIW the two 16" fans on my barracuda pull 21 amps each.

That trans cooler is about the same size as most heavy duty units.I would,however,mount it further away from the rad.As close to the grille as you can.This will allow air to flow around the cooler instead of having the cooler block off 20% of your airflow.

You also have to realise that although it's a big,thick rad with lots of cooling potential,it's a lot harder for the air to flow through that thick core which means more fan power required than for the 2 core with your other 383 challenger.

I reckon you just need more airflow.Can you borrow a good 16" fan to temporarily munt and hard wire just to try it?

 

These fans are the variable type and spin faster as the temp goes up.

Never had anything to do with these but one thing worries me.How are they calibrated to the temperature?
I assume there's some kind of sensor but are they intended for modern cars that DO run hotter?Like about as hot as yours is now running?See where I'm going with this?
Can you bypass the sensor and hard wire the fans just to try it?

Hope I'm helping here.

Regards   Ken

Just for refence,here's the best 2 pics I could find showing my 69 notch barracuda




 



 

[beekppr]

I think you are absolutely right about the shroud blocking airflow at speed.

Before I installed the electric fan, I ran the car down the road with the stock fan and shroud and it was nice and cool on the highway but in town, it warmed up fast. The same afternoon, I switched the fan to the electric setup and it cooled it at idle but as soon as I ran down the road, it ran much hotter than before. I concluded that the shroud on the electric was cutting down airflow at speed.

The electric fans are very nice and unfortunately were very pricey. They draw heavy current and came with a special relay setup to handle it. They do their job at idle and that is something the stock fan could never handle.

If I had it to do over, I would have tried a large single fan. The manufacturer claimed this dual fan moved more CFM than the single unit.

I wonder if there is a way to open up the shrouds a bit or maybe I just need to keep an eye out for a single unit.

[mopar12372]

stock fanclutch will work just as good or better . electric fans put a huge load on the electrical system. the factory wireing cant handle it . when doing this there are some things to take into consideration (amp draw) . you should upgrade to a current style alternater . 90 to 145 amps should be considered depending how many electrical components are being used in the car .
also think how much a person REALLY  drives his or her car when they say " my electric fans work with out fail and i NEVER have a problem with anything". i have seen this time and time again , ask your self , what gains am i getting from this ? what problems could come from doing this mod ?
  imop i would use a stock shroud and a viscouse setup . Bill