Hughs torque converters?

[Aarony85]

so its time to throw in a new torque converter. I have done some research about this on other forums and wanted to know your opinions on this. I am looking at a Hughs converter the 15XFM. this is going in an 89 w250 with the 727 trans. any thoughts?

 

[cerberusiam]

The little experience I have had was positive with the Hughes TC. The last one for a 518 I had custom built and it was pretty close to what I remember of the Hughes. Tighter fluid coupling and a little lower stall.

 

[Simplysmn]

Also look into Spec Rite converter's they are made in House and they offer some Nice stuff.

 

[Aarony85]

ok ill have to do that. i was hoping someone on here had a little more information on experience with a lower stall converter.

 

[cerberusiam]

Have all kinds of experience with lower stall TC's in multiple trucks, that is not what you asked though. Your question was specifically around the Hughes TC, not stall in general. Without asking the specific questions hard to come up with specific answers.

 

[Simplysmn]

I run a TCS low Stall and Love it . Even picked up the trans Used and have had no complaint's .

 

[Aarony85]

well what i was looking at is about a 1100-1200 stall.

 

[cerberusiam]

well what i was looking at is about a 1100-1200 stall.

That is not even close to realistic, at those rpms the engine is not off idle stage and is making no power. You lock in fluid coupling at that rpm and the truck will just sit here and chug.

There is a LOT more to TC than just a single stall speed, you probably should keep researching a bit more to understand the concepts and how they affect drivability.

What you want to understand is: Full brake stall, Flash Stall, Fluid coupling efficiency


Start with a stock TC and its specs:

Full brake stall - around 2200 rpms

Flash stall - around 1800 rpms

Efficiency - 70%


That is with stock power, when you change the input power you change the performance numbers, generally up. The stock performance is set to work wit the stock power curve, that means you won't get full fuel until after 1800 rpms or so and boost will not come up until fuel is up in the curve. Without boost it will be a smoky lag pig JUST leaving a stop light. The stock numbers allow the engine to rev and the turbo to spool to get the power input to the TC.

What seems to work best for all around usage is an efficiency around 85%, that will pull the flash stall down to around 1600 if they machine the impeller vanes correctly, full brake will come down around 2000 rpms. Go much lower than that will necessitate making turbo, injector, and pump changes to have some level of decent drivability. Push the fluid coupling efficiency too high and it will make it tough to overcome the drag, depending on the setup it may not be able to climb over a curb at 90% efficiency.

You have to consider gearing, tire size, and weight also. Too tight a TC in a 4x4 running 35" tires on 3.55 gears and it won't get out of its own way without a lot of coaxing. Change any of those will change the outcome.




To understand what you want, you will need to understand how you use your truck and the impact, this is not a 1 size fits all so you may have to compromise.