Torque Converter?

[ticopowell]

Ok so i have seen a lot of posts mentioning the Torque converter, but I am not exactly sure what it is, nor what it does. I know that it will lock and unlock depending on what gear you are in, and what your speed is, and how hard you are pushing the engine, but other than that all i can tell from reading is that my truck has it. I was looking at the gear selection display thingy on my gryphon and I noticed that sometimes, when driving steadily in 4th gear down the freeway, a lock symbol would appear. I assume this is the torque converter locking. So yeah any explanation would be great

[907DAVE]

Ok......So in an automatic transmission there is no mechanical link between the engine and tranny. The only link between engine and tranny is the fluid itself (without converter clutch).

Imagine for a second you set up two fans fasing each other, now imagine one of these fans is your engine and the other is your tranny. Now start the engine and rev it up a bit, fan starts spinning fast, which in-turn starts to spin the other fan. Now connect this other fan (tranny) to some gears and voila........work can be done.

A torque converter is basically two fans fasing each other, and using fluid instead of air.

Problem is that there is alot of heat created inside the converter, and it become inefficient because of the fluid coupling and the "slip" it allows.

The cure is to add a clutch inside that will lock the "fans" together at cruising speeds, or when you are trying to lay down some powa. This clutch now become a mechanical link, which means less power lost and less heat.

Of course there is much more going on inside a TC, but this should give you a basic idea and its about the best way I can think to describe it.

[ticopowell]

That makes sense, I knew about the "fans" inside the AT, so the torque converter basically locks the engine to the tranny. but why then does it only lock when I am going at a steady speed? if I floor it at 65 with it locked, it unlocks as the truck shifts to 3rd, or 2nd(forgot which), then it doesnt lock up again until I am cruising again... that normal?
oh and thanks for the quick reply!

[907DAVE]

Originally Posted by ticopowell

That makes sense, I knew about the "fans" inside the AT, so the torque converter basically locks the engine to the tranny. but why then does it only lock when I am going at a steady speed? if I floor it at 65 with it locked, it unlocks as the truck shifts to 3rd, or 2nd(forgot which), then it doesnt lock up again until I am cruising again... that normal?
oh and thanks for the quick reply!

Nope... the torque converter clutch locks things up.

When you stab the throttle you are demanding lots of power, which means you will need to get the rpms up into a higher range. If the TC stays locked all that will happen is you will lugg the engine and not get anywhere, unlock it and it will "free" up the engine to build some R's. I believe the main purpose of the converter clutch is fuel economy (emissions), with it locked in there is no more wasted energy.

Your truck is acting perfectly normal.

[ticopowell]

makes sense... now my question is why am i getting 13mpg's on the highway... my gryphon is set to 87 towing (canned... cant afford custom ones yet, plus im gonna do some more upgrades) and I previously had it on 91 perf, and both have shown about 13 mpg's... I measured the miles with the odometer and divided by gallons used when i filled a full tank each time, and the gryphon showed an average of 15ish. granted I havent had them on for very long, but the time they have been there they havent done anything for mileage ... any ideas? I did just put on a cat back gibson exhaust and that helps with weight and sound... but idk if it will do much for mileage...
any ideas? I am thinking of doing E-fans, and UDP's but those will wait for a bit, had to replace tires this week so im kinda strapped
thanks for the help.

[907DAVE]

Well anything you can do to help the engine breath easier should give you increased efficiency, which means more MPG's. Problem is with more power on tap it is very hard to resist using it. One the nostalgia of the extra power worn off you will start to see an increase in mileage.

I will have to let someone with more experience with the gassers to help you as far as programming goes. If its anything like our oil burners, custom tune are FAR superior in all ways.

Good Luck

[ticopowell]

Yeah i did to a Gotts mod and drop in K&N, and that seemed to help before the gryphon came, but i still think im getting really low mileage... even after the "holy crap i have power" effect goes away well ill see what others say, thanks again!

[Longshot270]

That is a good explination of the torque converter dave. Also search "torque converter" on YouTube. There are some very good videos on there.

For the mileage where do you fill up? I got a bad batch of gas this last time I went to HEB and the truck is barely making it down the roadright now. I usually run shell but I figured it would be worth saving 5 cents/gal because HEB usually has pretty good stuff. You would be suprised at how sensitive these trucks can be to fuel quality. You can try raising or lowering your most used gear (usually 4th). I have found that lowering the 4th gear can somtimes get better mileage but lowering the torque converter lock/unlock point to the extreme (-10 mph) can kill mileage because you have to give more throttle when it locks. The main thing to weigh is rpm vs load. Having high rpms are not the best for mileage (*past about 2100) but having high engine load (ex. result of making the truck shift ASAP) requires more throttle and more gas.
Here is a thread I started a while back based on compiled datalogs.
http://forum.gopowerhungry.com/conve...t-mileage.html
Also some tips that me and Jack have fount to be usefull for city driving that when you accelerate, go a little aggressive until you get up to speed. Then pull back on the pedal. I even installed a vacuum guage on my truck and so when I'm cruising I can balance speed with manifold vacuum (more vacuum means less throttle which means better mileage). I'd say that by adding that I can get at least 1 or 2 mpg by adjusting my driving.

[Jackpine]

One thing you can do, is monitor the Inst Econ (or Inst MPG). This tells you exactly what is happening at the moment, rather than looking at a "history" of what went on before. Now, I have no idea if the Inst MPG value is accurate, but it really doesn't matter, because all you really care about is "relative" behavior. If the numbers are "large" you know you're getting more miles per gallon than if the numbers are "small". In time, you can develop a "feel" for the engine sound, throttle position, and so on that matches the bigger numbers and, you should be driving economically.

Of course you still need to keep your eyes on the road, so don't "stare" at the Inst MPG gauge, which is going to be moving all over the place anyway. As pilots do, you have to develop a "cross-check".

Finally though, and I've said this before, wind is going to effect your fuel economy drastically at highway speeds. At 70mph, if you're driving into a 30mph headwind, the load on the engine will be ALMOST as bad as if you were driving 100mph on a calm day. You will see a drastic drop in economy driving into a headwind.

I don't even pay too much attention anymore to my mpg at each fillup. Instead, I'm more interested in the long term average over the last 1500 - 2000 miles. By taking that "long" view, you average out the headwinds/tailwinds, uphill/downhill, and city/highway driving effect. I've gotten about 14.8mpg averaged over the last 2600 miles (not towing).

And, to calculate your economy correctly, you need to make sure your odometer is accurate.

- Jack

[ticopowell]

Thanks for the Advice! I have the inst mpg up on my gryphon and the average mpg up as well, and I usually try and keep an eye on them (havent hit anyone or anything yet lol ) and I am getting a better feel of my truck after having it a little more than a month so far. For filling it up, there are so many gas stations around here I usually go for the cheapest. last time I filled up on base but who knows what kind of quality that gas has... but there are a few shell stations, and a couple conoco stations, but mostly I go to the random stations that are around. Even though my truck only has about 52000 miles should I worry about adding a fuel injector cleaner to the gas every once in a while? would/should/could that make a difference? or would it do more harm than good? Ive never had a vehicle with so low mileage so Im not sure what to expect
I also assume that my altitude has something to do with the mileage, i live at 7258 feet, and the springs is about 6000-6500 feet, so i guess i drop and gain a thousand feet every time I go to the movies...