95' Junker Drag Truck

mondtster said:
That's all the difference I've ever seen out of it. Were you running the thick or thin HyGard?



Your reasons cited are the only real reasons anyone should consider running it. There's just not enough difference in stall to make it worth experimenting with in an attempt to change converter characteristics if you ask me.
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I have only tried the Thick HyGard.

Update:
This morning I finished installing a new looser converter. There is a slight difference at idle because the truck doesn't push so hard in Drive or Reverse. Once moving, the looser 2300 RPM stall converter feels almost the same as the old tighter 1700 RPM stall. Under load, this converter does shift about 250 RPM later than the old one. Basically, since the TV valve is wired WOT, the truck shifts based purely on MPH as increased MPH creates more governor pressure. This converter is loose enough to allow the engine to reach 250 more RPM before it shifts at a set MPH.

What's amazing is when I power brake with the new converter, RPM flashes to 1750 or just 50 RPM higher than the old converter. But if I continue with the brakes and throttle routine, the converter loosens up and lets me gain RPM up till about 2200 RPM where the turbo starts to build boost! It's mysterious how a converter can be built to flash stall at 1750 but then loosen up enough to brake stall much higher.

About 2500 rpm the turbo is making 7psi-10psi and pushes through the brakes.

Anyway, the Junker is Back! It feels good with the new converter and I will be at the next track day, in about 10 days.

Huge thanks to the man who built this torque converter!

I'll do a full write up with results as soon as I make my next track appearance. I'll give credit where credit is due when I come back with some quicker ET's!
 
Big Blue24 said:
I have only tried the Thick HyGard.
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That's all I've tried to date as well. I've used the thin stuff for other applications, I think it would be much closer to transmission oil viscosity than the thick stuff. Should change the stall speed even less.

Big Blue24 said:
...What's amazing is when I power brake with the new converter, RPM flashes to 1750 or just 50 RPM higher than the old converter. But if I continue with the brakes and throttle routine, the converter loosens up and lets me gain RPM up till about 2200 RPM where the turbo starts to build boost! It's mysterious how a converter can be built to flash stall at 1750 but then loosen up enough to brake stall much higher.
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I think you're confusing what flash stall is...

I'm not surprised at all with your findings. Converters will stall at different speeds depending on how much torque the motor generates. It sounds like you're reaching a temporary plateau in your torque curve for a short time and then it continues to climb. Maybe the turbo starts to build boost there? Is the aneroid set tight and restricting rack travel at that point?

IMHO it is a fine art to have the skills to build a good converter for a turbo car. You want a loose enough converter on the bottom end to get up on the turbo but you don't want it too loose or you'll blow right through it once you get moving and just create a lot of slippage and heat.
 
People have been doing that kind of stuff for years, ask an older tranny builder that was around in the '70s and '80s what oil they put in all automatics and their response might be surprising...
 
The one or two brands of synthetic ATF I've rubbed between my fingers felt too slippery. I seriously wonder if the only benefit of syn ATF over traditional ATF is durability under high heat.

There is definitely a noticeable friction difference between Tractor Fluid, Type F, and Dexron 3 with Tractor Fluid having the most grip/friction.
 
Kinda off subject but got my brain going about the whole ATF discussion. Has anyone ran it through the engine as a fuel additive? It would lubricate the pump and other interparts great, clean your injectors and probably give you a tad more power.
 
TTR 21 said:
Kinda off subject but got my brain going about the whole ATF discussion. Has anyone ran it through the engine as a fuel additive? It would lubricate the pump and other interparts great, clean your injectors and probably give you a tad more power.
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Considering ATF has additives that increase the flash point and retard burn rate, basically meaning it's designed NOT to burn (easily), I don't think that's a great idea. It doesn't cost all that much to buy a bottle of Power Services and that stuff is chemically engineered to do all those things you're looking for. Plus it raises the cetane rating a few points which increases burn rate to help increase power (up top mostly) and reduce smoke.

Big Blue24 said:
The one or two brands of synthetic ATF I've rubbed between my fingers felt too slippery. I seriously wonder if the only benefit of syn ATF over traditional ATF is durability under high heat.

There is definitely a noticeable friction difference between Tractor Fluid, Type F, and Dexron 3 with Tractor Fluid having the most grip/friction.
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The other bonus of HyGard is that it won't break down at 250+ degrees like ATF. Fact is search for Deere's test of how well it holds up to heat and you'll find that they used TH350s running at about 350 degrees fluid temp for a while and then they tore them down... The Dexron one had been burnt to a crisp while the HyGard trans you probably still could have read the Borg-Warner or Raybestos on the plates :Cheer:
 
TTR 21 said:
Kinda off subject but got my brain going about the whole ATF discussion. Has anyone ran it through the engine as a fuel additive? It would lubricate the pump and other interparts great, clean your injectors and probably give you a tad more power.
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People have run diesels on waste transmission oil, it can be done. I personally feel that on a truck and a pump that I actually care about I'd never run anything but diesel and the correct additives. On a motor I don't care about - that's a whole different story.

BlackSkyRacing said:
The other bonus of HyGard is that it won't break down at 250+ degrees like ATF. Fact is search for Deere's test of how well it holds up to heat and you'll find that they used TH350s running at about 350 degrees fluid temp for a while and then they tore them down... The Dexron one had been burnt to a crisp while the HyGard trans you probably still could have read the Borg-Warner or Raybestos on the plates :Cheer:
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The durability at high temps is why most guys running it do so. A turbo motor can be brutal on a converter and trans, sitting on the t-brake for a long time building boost will do a number on the trans oil. The tractor oil helps out quite a bit in these applications.
 
Track day is this Wednesday, Sept 22nd. With this new converter, spool-up should not be a problem.


Based off of some mathematical extrapolation, I think the 95' Junker is going to show a MPH increase that reflects about 40-50 rear wheel horsepower, or enough power to run 13.1 or so. I have not touched the fueling setup so this will be a great test comparing HX35 airflow of 50-55 lbs per minute vs GT4294 airflow of 80-88 lbs per minute. The forecast high is 95*F and I'll be running at 6:30-8:00 PM so should be mid 80's for air temp or nearly identical conditions to when it ran 13.68 @ 100.8 late at night back in June.
 
srt cummins said:
So can you use the tractor transmission fluid in a dd truck?
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Yes, but there's not much point in doing it unless you need the advantages that tractor oil provides over type F. Make sure you run a screen filter if you decide to do it.
 
mondtster said:
Yes, but there's not much point in doing it unless you need the advantages that tractor oil provides over type F. Make sure you run a screen filter if you decide to do it.
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I wonder if that is necessary with the low-viscosity HyGard :poke:
 
BlackSkyRacing said:
I wonder if that is necessary with the low-viscosity HyGard :poke:
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I've actually run thick hygard with a dacron filter in -35 degree weather and routine temps of -20 degrees, no problems on my truck. Other peoples' experiences have varied a bit however.

Most of the shops building performance valve bodies that I've talked to have recommended running a screen instead of a dacron filter even in trannys using normal ATF. I'd personally take that as an indicator that you might run into restriction issues with the standard filters. It's more of a CYA thing as far as I'm concerned, put a screen on it right away and avoid having problems that would require dumping the oil and replacing the filter at best, at worst causing you to rebuild the tranny prematurely.

I really want to try the thin HyGard, I might have to give it a shot when I change the oil in it this fall. I'll still be using a screen on my trans though.
 
mondtster said:
I've actually run thick hygard with a dacron filter in -35 degree weather and routine temps of -20 degrees, no problems on my truck. Other peoples' experiences have varied a bit however.

Most of the shops building performance valve bodies that I've talked to have recommended running a screen instead of a dacron filter even in trannys using normal ATF. I'd personally take that as an indicator that you might run into restriction issues with the standard filters. It's more of a CYA thing as far as I'm concerned, put a screen on it right away and avoid having problems that would require dumping the oil and replacing the filter at best, at worst causing you to rebuild the tranny prematurely.

I really want to try the thin HyGard, I might have to give it a shot when I change the oil in it this fall. I'll still be using a screen on my trans though.
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Where would you go about getting a screen filter?
 
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