KB Tech Article RE: Dyno and T/C Lockup

[HwyCruiser]

I posted this link in my dyno thread but thought it deserved its own thread since there has been some torque converter discussions going on as of late.

Kenne Bell's Tech, Tuning Tips & Dyno Tests (http://www.kennebell.net/techinfo/ford-techinfo/46gtTechTips_2200.pdf) is pretty good reading for someone trying to figure out how dyno testing results differ with the torque converter locked vs. unlocked (specifically the last page).

Now I can only presume Kenne Bell's testing regarding this is accurate, so my question is: why lock the converter on the dyno at WOT if it gives such good results and not do it on the open road?

Comments?

[Rkammer]

I posted this link in my dyno thread but thought it deserved its own thread since there has been some torque converter discussions going on as of late.

Kenne Bell's Tech, Tuning Tips & Dyno Tests (http://www.kennebell.net/techinfo/ford-techinfo/46gtTechTips_2200.pdf)is pretty good reading for someone trying to figure out how dyno testing results differ with the torque converter locked vs. unlocked (specifically the last page).

Now I can only presume Kenne Bell's testing regarding this is accurate, so my question is: why lock the converter on the dyno at WOT if it gives such good results and not do it on the open road?
Comments?
Kenne Bell and thousands of turbo Buick owners have been locking converters for years for faster ETs and trap speeds. It's very common, and true on my own turbo Buick, that locking the converter in 2nd or early in 3rd gear will give at least 2 10ths quicker in the 1/4 mile and 2-3 MPH trap speeds. I haven't experimented with my MM yet but plan to lock the converter any time I want max accelloration. I'll be playing with the tune on my Xcal2 to see where the car likes lock up best. Maybe the tuners can give us some comments.

[HwyCruiser]

RKammer, a few of us with the Precision Industries single plate Stallion torque converter found that locking the t/c during WOT had some rather disconcerting side effects with certain tunes (aka 2nd gear WOT pause). See this link for more info:

http://www.mercurymarauder.net/forums/showthread.php?t=11197

I had never felt anything like it with the stock converter. Maybe the slippage of the PI is so much greater than the OEM t/c that the lockup becomes noticable. The fix was to keep the converter unlocked during WOT.

What type of t/c's do the Buick's run? Single plate? Any idea of the stall speed?

Interesting comment, thanks.

[SergntMac]

I'm going to suggest a caution here, a caution that is founded in my view that dyno driving and race track driving are two different worlds which share no convergence. We think they do, and we love it when they do converge, but in reality, they do not. Dyno driving and race track driving are two different sciences, each requires a certain skill level and talent all it's own.

The dyno produces results that are an index of power, expressed in RWHP, RWTQ and AFR. Perhaps one or two additional parameters could be included today, now that we can read OBDII port stuff live. But, all that would mean nothing more than adding likewise indexes to the dyno pull. From these indexes, we can detect areas where tuning can improve performance, and we can see the changes (hopefully beneficial) certain mods we have invested in bring to the table. Nonetheless, when it's all said and done, the dyno is just one big test tool. While your performance stats from a dyno provide some expectation of performance on the race track, the track is your next big test tool.

The race track is the final test tool. It also produces performance indexes, the most popular and important of which is the 1/4 mile ET. We also see 1/4 mile top speed, along with 1/8th mile ET and speed, 60 foot times, and our reaction times measured in two significant ways, Pro tree and Sportsman tree. All of this is performance stats too, but it's the data that could put money back into your pocket, if you are so inclined.

Because these two mediums produce such different, yet, controversial performance indexes, they will be forever linked in our minds as related to each other. But, in reality, they are not. I've seen dyno champs blow it out their azz at the tree, and I've seen dyno wimps turn around and flip you off while doing a back-stroke throught the gates, and I have seen and done both with my own MM.

I haven't read the stuff from Kenny Bell yet linked ^ there yet. But, I'm going to do that right now, and see if there is any new 411 on this we need to learn. I doubt it, but I'll check back here later, K?

[Rkammer]

RKammer, a few of us with the Precision Industries single plate Stallion torque converter found that locking the t/c during WOT had some rather disconcerting side effects with certain tunes (aka 2nd gear WOT pause). See this link for more info:

http://www.mercurymarauder.net/forums/showthread.php?t=11197

I had never felt anything like it with the stock converter. Maybe the slippage of the PI is so much greater than the OEM t/c that the lockup becomes noticable. The fix was to keep the converter unlocked during WOT.

What type of t/c's do the Buick's run? Single plate? Any idea of the stall speed?
Interesting comment, thanks.I read this thread last week and don't know why it became an issue with some of the MMs. The stock Buick converter is a single disc with about 2200 stall from the factory. With age it will loosen up to maybe 2500 stall. Even the high horsepower cars using 2800 to 3500 stall TCs are benefiting from lock-up. I don't know of any Buick which had any issues with a locked up converter but have heard of some guys who claimed no improvement between lock-up and non lock up. Not many, though. But the Buick turbo is quite a different animal from the MM ln that it weighs about 800 lbs less and is a much torquier motor than the MM because of the turbo. I can see the possibility of a 4200 lb car getting bogged down if, all of a sudden, the engine is loaded down by a locked TC. How about the high horsepower guys with the 4.10 gears. Were they also having this problem? Or was it mainly the less modified cars?

Has anyone done any data logging either on the dyno or at the track? It would be interesting to look at things like, knock retard, spark advance, engine load, RPM drop, etc. when the bog occurs. I'll report on my findings when I start locking the TC on my car. I'm still at the beginning of the learning curve with my MM and have a way to go and lots to learn. :)

[JohnE]

Take a look at what happens with a late 2nd gear lock in red.
http://home.houston.rr.com/eiswirth/Pics/HRPJanApr.jpg

G's
http://home.houston.rr.com/eiswirth/Pics/HRPgJanApr.jpg

[Rkammer]

Take a look at what happens with a late 2nd gear lock in red.
http://home.houston.rr.com/eiswirth/Pics/HRPJanApr.jpg

G's
http://home.houston.rr.com/eiswirth/Pics/HRPgJanApr.jpg
If I'm reading this right, it looks like the lock up came at about the 6 second point and about 5000 RPM. It also brought about a slight increase in acceleration. Can't explain why the trap speed was over 2 1/2 MPH slower but the slower ET looks like it started before the lock up point when the car was launched from the starting line. It didn't have the same acceleration as the faster run.

[JohnE]

There was a delay to lock of 3 seconds in the red graph. That's 3 seconds from the time the 1-2 shift was initiated. Notice that the black trace is close to a straight line after the 1-2 all the way up to the 2-3. And if you draw a line from the portion after the TC lockup of the red trace, the unlocked portion falls below this line. Yes, when the TC locked late there was additional acceleration. Actually it felt like another gear change. But this lasts just under 1/2 a second and doesn't add back for the loss 2 1/2 seconds leading up to the lockup. You have to give somewhere to get it back.

The torque multiplication an unlocked converter produces when it's flashed doesn't come for free. The engine has to put that power in as it spins up faster than the input to the tranny. From a stand still or high differential, this charging period of time allows the engine to get up to better power production. So it can be a win win. Notice that it takes about 1 second to flash the converter on launch. This allows the engine to store energy and rise 2,000rpm to get moving. And a reward of 0.9g was had too. The best part in the 1/4 is that some of the time spent flashing the converter is prior to crossing the start line.


A locked converter will transmit more power to the ground. An unlocked looses energy to heat. And of course an unlocked converter allows the engine to spin faster. If a lock occurs too low, the engine may not be in its poweband yet. So, on the street if you're in OD and want to accel from 45mph, an unlock (or possibly downshift if press hard enough) is a good thing. But after the engine was spun up to max in 1st gear, an upshift to 2nd shouldn't drop the engine out of its power band. In my case an immediate lock in 2nd produces best results.

John

[Rkammer]

There was a delay to lock of 3 seconds in the red graph. That's 3 seconds from the time the 1-2 shift was initiated. Notice that the black trace is close to a straight line after the 1-2 all the way up to the 2-3. And if you draw a line from the portion after the TC lockup of the red trace, the unlocked portion falls below this line. Yes, when the TC locked late there was additional acceleration. Actually it felt like another gear change. But this lasts just under 1/2 a second and doesn't add back for the loss 2 1/2 seconds leading up to the lockup. You have to give somewhere to get it back.

The torque multiplication an unlocked converter produces when it's flashed doesn't come for free. The engine has to put that power in as it spins up faster than the input to the tranny. From a stand still or high differential, this charging period of time allows the engine to get up to better power production. So it can be a win win. Notice that it takes about 1 second to flash the converter on launch. This allows the engine to store energy and rise 2,000rpm to get moving. And a reward of 0.9g was had too. The best part in the 1/4 is that some of the time spent flashing the converter is prior to crossing the start line.


A locked converter will transmit more power to the ground. An unlocked looses energy to heat. And of course an unlocked converter allows the engine to spin faster. If a lock occurs too low, the engine may not be in its poweband yet. So, on the street if you're in OD and want to accel from 45mph, an unlock (or possibly downshift if press hard enough) is a good thing. But after the engine was spun up to max in 1st gear, an upshift to 2nd shouldn't drop the engine out of its power band. In my case an immediate lock in 2nd produces best results.
John
John, I'm still having difficulty understanding why the "red" run had lower acceloration off the line which, I believe, contributed to the higher E.T. This occurred long before the converter went into lock-up.

Have you tried only locking the converter after the 2-3 gear change?

[SergntMac]

IMHO, Kenny Bell's remarks about locking the TC are for test purposes. Their goal was to glean out power numbers, and it so happens that they got higher numbers from locking the TC during the test.

As I posted earlier, you should not expect the same results when driving the 1/4 mile. Moving a real car down the track, against the elements, is quite a different task than turning dyno rollers. With the tuning talent and toys we have available today, shouldn't be to difficult to stage your own back to back test on a race track. Get a hand held programmer and have twin tunes installed, one locked, one not locked, and drive. You answer will be on the timeslip.

[Rkammer]

IMHO, Kenny Bell's remarks about locking the TC are for test purposes. Their goal was to glean out power numbers, and it so happens that they got higher numbers from locking the TC during the test.

As I posted earlier, you should not expect the same results when driving the 1/4 mile. Moving a real car down the track, against the elements, is quite a different task than turning dyno rollers. With the tuning talent and toys we have available today, shouldn't be to difficult to stage your own back to back test on a race track. Get a hand held programmer and have twin tunes installed, one locked, one not locked, and drive. You answer will be on the timeslip.
Absolutely the best test. Timeslips don't lie. :coolman:

[JohnE]

John, I'm still having difficulty understanding why the "red" run had lower acceloration off the line which, I believe, contributed to the higher E.T. This occurred long before the converter went into lock-up.

Have you tried only locking the converter after the 2-3 gear change?

For the run in RED, I eased into the pedal slower than in Black. I also had better tires for the Black run. Can not just drop the hammer at the line, I have more torque than available traction. Now at the 1-2 shift through the 2-3, the conditions are the same and that's where I'd focused my comments for locked vs. unlocked converter.

Haven't tried performing a unlocked WOT 2-3. Actually the delayed 2nd gear lock was something that got into the tune by mistake.

[RoyLPita]

Nice article.

Judging by what they are talking about when it comes to lockup, Would the Trilogy S/C benefit from more lockup, hence more HP & TQ?? Lidio's tune doesn't activate the converter until 63MPH.

['03BlkMM]

I had a thread a few months back about this. Lidio gave some of his reasons for locking/not locking the TQ conv. Here it is.

http://www.mercurymarauder.net/forums/showthread.php?t=17823&highlight=shift+point

I have since moved the 2nd gear lockup point up some to get it closer to the peak power point. Now its locking at closer to 5K rpm's and there is no discernable hesitation or loading of the engine when it locks. I haven't been able to go to the track and see if it made any appreciable difference but it feels better! My main concern was with wear on the conv clutch locking it at WOT all the time.

[Smokie]

I don't think that there is a right or a wrong way to dyno a car, however over the last 3 years of experimenting with our cars I believe the concensus we have reached as to a protocol for consistent results that can be duplicated and compared across the country are as follows.

1.Chassis Dynomameter.
2.3rd gear pull (because you have a 1 to 1 transmission ratio)
3.Locked torque converter.
4. PCM program does NOT allow downshifting in 3rd gear.

This is how Dennis, Aric and Lidio perform dyno runs and perform dyno-tuning***


*** It is not my intention to speak for these gentlemen, I am simply stating how events took place when they worked on my car, or posted on this forum.

[cyclone03]

I don't think that there is a right or a wrong way to dyno a car, however over the last 3 years of experimenting with our cars I believe the concensus we have reached as to a protocol for consistent results that can be duplicated and compared across the country are as follows.

1.Chassis Dynomameter.
2.3rd gear pull (because you have a 1 to 1 transmission ratio)
3.Locked torque converter.
4. PCM program does NOT allow downshifting in 3rd gear.

This is how Dennis, Aric and Lidio perform dyno runs and perform dyno-tuning***


*** It is not my intention to speak for this gentlemen, I am simply stating how events took place when they worked on my car, or posted on this forum.


Smokies got it right,
and I'll add the reason to lock the T/C in 3rd on the dyno is so the pull can begin at a lower RPM,in my case 1600rpm all the way to 6000 one strait pull without any down shifts.

[HwyCruiser]

No doubt that what has been discussed is the way to dyno test. True 1:1 power ratio through the tranny in 3rd gear, ability to gather lower rpm data without the effect of torque multiplication, no lost power due to converter slippage... no arguements here.

Assuming KB's data for the 4.6L 2V supercharged Ford he illustrated that put out 507 hp w/ tc locked vs. 469 hp w/ tc unlocked is typical for that power level for the 4V's also, that seems like a pretty amazing 8% gain in hp with just a tweak to the software.

That is a lot of power left on the table at the drag strip unless someone can come up with just the right rpm values to take advantage of it. I read Lidio's responses to 03BlkMM's thread and it seems like its not just theory at blown or NOS power levels and/or running a loose converter.

Also knowing whether the tc is locked or unlocked when evaluating a dyno graph is good to know when comparing two side-by-side when that one variable has such a large impact.

Good info!

[JohnE]

Remember the more power you make into the same converter, the higher the stall and the more the losses. I have a positive displacement supercharger and a higher stall than stock converter. For me lockup nets a gain over unlocked.