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Tech Area => Transmissions => Topic started by: Scoobum on September 18 2017, 10:04:51 AM

Title: Torque Convertors
Post by: Scoobum on September 18 2017, 10:04:51 AM
Just my 2 cents, but I've come to the conclusion that torque convertors are the most important piece of the puzzle with these cars.

LU Convertors. The data I have on the best 3 are as follows. Norbs ran a 2800 Precision multidisc...an d the slip came in at 3 percent. He went 10.3 at 134.

Grumpy went 9.98 at 138 with a 9/11. No slip numbers...but the MPH tells me it was coupling well.

Jasons convertor slip was 7.3 with Jakes convertor.

NL convertors. Our very own Bird...and Rich is one of the nicest guys going went 9.69 at 138 with an AC 19930. Joe went low 10's for years with an AC 19930 in the low 130's. When I ran the 1/4 I'd run 11.5 all day at 120-121 with the slip checking in at 8.9 percent with my 16930. Tons of data out there on the PTC race convertors. They speak for themselves.

Brandon went 11.01 at 123 with an off the shelf 2800 PTC NL on 20 PSI...pump gas...109...wi th a 6131...and TA heads. He's quietly one of our brightest stars.

My own data shows I have to have this convertor flash to 3950-3975 to garner a 1.5 launch. Murph mentioned in his thread that the convertor he was running flashed to 39xx to achieve a 1.5 launch. My theory is the convertor has to flash fairly high to get these car moving...due to the weight. It'd be interesting to get more data to see the RPM and short time from other members.

RPM drop. Steve has mentioned these engines work within a small window in regards to RPM. You need a convertor with enuf RPM drop at the shift points to keep the engine in its 'wheelhouse'. This convertor is giving me a 600 RPM drop...keeping the RPM's between 5200-5800...right where this cam/heads work best. Too much RPM drop...and you'll drag the engine down...too little...and you'll just be buzzing the engine. Norbs lightened this governor...and it shifts at 5800...and I hit the 1/8th mile traps at 5500 and the 1/4 traps at 6000.

In GENERAL...a looser convertor will get you off the line quicker...but will slip more at the top of the track. This AC 16930 is an absolute dog off the line on Erics low gear default fuel and timing defaults. Add low gear timing...and drag the low gear 02's below 800...and it's a whole different animal. I'd rather have a tighter convertor that will couple well at the top of the track...and tune it in to get it to launch.

I see guys complaining of their car not launching well...but the convertor seems well matched for the turbo. Their instant solution is to go with a looser convertor...wh en I'm betting tuning could wake it up.

Once again...just my 2 cents.


Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 10:28:13 AM
I will add another criteria.  If it costs less than $900, it probably is not worth installing....:D
Title: Re: Torque Convertors
Post by: TurboCajun on September 18 2017, 11:16:16 AM
here is a log from a 10.99 pass, PTC 10" 3000 LU. dropping 400rpm at shift

Title: Re: Torque Convertors
Post by: reality on September 18 2017, 11:48:22 AM
https://www.svtperformance.com/forums/threads/torque-converter-stall-torque-ratio-str-guide.1113661/ (https://www.svtperformance.com/forums/threads/torque-converter-stall-torque-ratio-str-guide.1113661/)


Higher stall doesn't have to mean less efficient. Str is only 1 part of the puzzle.


Off the shelf converters are a compromise.
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 12:00:48 PM
here is a log from a 10.99 pass, PTC 10" 3000 LU. dropping 400rpm at shift

Keith, is the speedometer showing the correct speed?  Or is off about 8% because you have tall tires and did not change the gear in the speedo?  Looks about right to me
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 01:08:49 PM
hmm, that rpm should be about 146 mph.  Given the time, I am going to guess that the converter was not locked?  And that the speed of 125 is the correct speed ?  Looks like about 14% slip if that is the case which is not bad for a LU converter that is unlocked.

Not enuf info to make a good guess from :)  I guess that the speed is correct because the car ran 10.99 which would be hard to be that slow if the mph was actually 135 mph after correcting for tire size.
Title: Re: Torque Convertors
Post by: TurboCajun on September 18 2017, 01:10:59 PM
I did change the gear but i still think that it may be about 2 mph off

Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 01:25:15 PM
It may be on top end. It's hard to compare speedometer speed with trap speed.    Was the converter locked?

What was the speed on the slip?
Title: Re: Torque Convertors
Post by: TurboCajun on September 18 2017, 02:35:03 PM
conv was not locked and the speed on the slip was 121.58
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 02:43:45 PM
That means the speedometer is pretty darned close...You can check it with a gps speedometer on your phone...but, the timing slip time is an average speed over the 66' trap before the line so the actually speed at the moment you cross the line is a bit higher.  I picked 125 which would have been after you crossed the line from the spot immediately before you lifted.  You were probably doing more like 123 at the line, I would guess
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 02:45:22 PM
Slip is about what I would guess for a good lock up converter that is not locked.  You might gain a couple of tenths if you locked it around 85-90 mph
Title: Re: Torque Convertors
Post by: good2win22 on September 18 2017, 06:51:40 PM
My 10.98 pass at 125.96


RPM drop 1-2 shift 6030 to 5066 = 964
RPM drop 2-3 shift 5714 to 4818 = 896
I am locking the converter at 90 mph. RPM drop 5256 to 4818 = 438


I let off and RPM was 5553


I guess I need to lock it just a little bit later in the run. But she is still pulling hard
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 08:51:16 PM
Converter still looks a bit tight to me.

I forget, are you still spraying alky?
Title: Re: Torque Convertors
Post by: good2win22 on September 18 2017, 09:42:50 PM
Converter still looks a bit tight to me.

I forget, are you still spraying alky?
I agree Steve. I would like to have the converter I had in my white T. It was a tad more loose on the bottom end. Of course, I have no specs on it. It was Jake built too.


Yes sir, spraying that alky
Title: Re: Torque Convertors
Post by: Steve Wood on September 18 2017, 09:55:51 PM
That definitely makes the tuning a bit complicated...
Title: Re: Torque Convertors
Post by: Scoobum on September 21 2017, 01:31:38 PM
Found a post from Paul from last year. 4100 for a 1.4x launch.
Title: Re: Torque Convertors
Post by: nocooler on September 21 2017, 07:19:59 PM
Most people don't know how violent these cars can become with some low gear timing and fuel adjustments. 

My 9/11 was terrible inefficient and had to be locked.
Title: Re: Torque Convertors
Post by: Steve Wood on September 21 2017, 08:20:28 PM
Mine was too....terribl e...I thought it was a bad converter...an d eventually it broke so I was right
Title: Re: Torque Convertors
Post by: Scoobum on December 02 2017, 05:36:25 PM
A source I trust says the Pro Torque 10.5 in LU with the Kevlar clutch can withstand being locked at WOT and is good for 4mph on a 10 second combo.
Title: Re: Torque Convertors
Post by: reality on December 02 2017, 10:30:47 PM
As compared to what?
Title: Re: Torque Convertors
Post by: Scoobum on December 02 2017, 10:55:43 PM
As compared to what?

No comparison was made.
Title: Re: Torque Convertors
Post by: reality on December 02 2017, 11:32:18 PM
Where did the 4 mph figure come from then?
Title: Re: Torque Convertors
Post by: earlbrown on December 03 2017, 12:13:09 AM
locked .vs unlocked
Title: Re: Torque Convertors
Post by: good2win22 on December 03 2017, 12:10:27 PM
Everyone I've spoken with is saying that once you reach the 11.0-ish ET, locking the converter will only slow you down and tear things up inside the tranny.  At least on a 200R4.  I'm not certain of the new technology inside the converter.  I can tell you that the lock up converter I had from Jake had no heat marks on the clutch surface or the mating surface of the converter but the clutches were worn and the steels were discolored on the high gear set. I had 11 passes on that tranny.


I have no experience as to the lock up side of things going slower or faster but I can tell you that my tranny was hurting by locking it up at my power level.
Title: Re: Torque Convertors
Post by: TexasT on December 03 2017, 02:31:25 PM
What did you go with for direct clutches the second time? Were more clutches added? Did Jake use the thicker steels? Lots of things can be "fooled" with inside the trans and converter.

I'm not a believer in locking the converter. Just too hard on it imo. To me that lock up is for cruising and not accelerating and that is how gm designed it. Those multi disc units just add weight and I'm not sure they work, but I've never tried one out. They sure sound like $h/t. If I had a dedicated track car I would go non l/u. Plenty of tech these days to get it launched and be tight on the big end. 
Title: Re: Torque Convertors
Post by: Scoobum on December 03 2017, 02:45:03 PM
Each time I've had my transmission freshened up over the years it's been the high gear clutch pack that's been worn. The rest has had minimal wear. NL convertors are the way to fly. Guys buy LU convertors and then immediately ask why their MPH is off at the traps. Torque convertor selection is the most important piece of the puzzle...and most get it wrong.
Title: Re: Torque Convertors
Post by: Joe Buick on December 06 2017, 12:02:32 PM
I will add another criteria.  If it costs less than $900, it probably is not worth installing....:D

You got that Fxxx right!
Title: Re: Torque Convertors
Post by: nocooler on December 08 2017, 07:31:11 AM
Here is a good post I came across. Slip isn’t always everything.
http://www.yellowbullet.com/forum/#/topics/2121025?page=4 (http://www.yellowbullet.com/forum/#/topics/2121025?page=4)
Title: Re: Torque Convertors
Post by: Steve Wood on December 08 2017, 08:52:05 AM
Here is a good post I came across. Slip isn’t always everything.
http://www.yellowbullet.com/forum/#/topics/2121025?page=4 (http://www.yellowbullet.com/forum/#/topics/2121025?page=4)

it took me to the forum home and not to the post...what section is it in?
Title: Re: Torque Convertors
Post by: nocooler on December 08 2017, 10:42:59 AM
Odd - takes me straight there. It’s under the transmission section, when to use a lock transmission or torque converter. None of us make the power to need a lockup transmission, but all the info is good
Title: Re: Torque Convertors
Post by: Steve Wood on December 08 2017, 01:19:31 PM
I missed the tranny section when I looked down the home page.  After reading that, I am just as confused as ever  :)
Title: Re: Torque Convertors
Post by: Grumpy on December 08 2017, 07:16:15 PM
Here is a good post I came across. Slip isn’t always everything.
http://www.yellowbullet.com/forum/#/topics/2121025?page=4 (http://www.yellowbullet.com/forum/#/topics/2121025?page=4)


Come on those guys are making some real power !!! nothing like our cars. Our 9/11 LU worked awesome. Yea we locked it to. Just sent it back a year ago to have it checked out . We have had it since 2006 from what I remember. Russ did go to a PTC non LU to try out. Worked great on the track.  9/11 to us is hard to beat on a street car goin to the track every now an then in my opinion (Mazda is a perfect example) The new PTC Melissa is working great in her car as she has gotten quicker (9.5s) still 3700# car . 6'0s in the eighth.
Title: Re: Torque Convertors
Post by: ULYCYC on December 09 2017, 08:26:35 AM
 It's like 99% of the women shopping in the Victoria Secrets Catalog and think it will make them look like the models. Put the book down and go back yo your trusty old  JC Penny Plus Size  book.  Whats good for the 6 and 7sec guys doesn't apply to us.
There is a more to locking up a converter then just jumping the A-F terminal and stepping on the gas.
When I did it years ago with a Vigilante converter I found locking it right after the 2-3 shift. Less strain and rpm pull down. If I remember right it netted me a ¼ sec. and 4-5 mph.  You also need to keep your rpms in your cams power band. If locking or less/more converter slip knocks you out of it your fighting a losing battle of tuning.
Title: Re: Torque Convertors
Post by: nocooler on December 09 2017, 09:28:47 AM
I was trying to get the point across that a locking up a converter typically only increases mph and you can’t alway judge a converter by slip percentage.
Title: Re: Torque Convertors
Post by: Scoobum on December 09 2017, 10:48:48 AM
Again...conver tor choice is all important. Flash stall...correc t RPM at the shift points...slip percentage...e verything comes into play. I've seen a crapload of PL files with RPM drop from a shitass convertor of 2 to 300 RPM. Shitass lockup convertors seem to be all the rage these days.
Title: Re: Torque Convertors
Post by: gusszgs on December 09 2017, 08:23:36 PM
I run Dave's 3021 LU and was seeing 7-800 drops between shifts before my pump slide took a dump.  Not saying it's the rage or anything, but seems to work ok for what I'm doing.......mi x of street and track. She's all fixed and ready for next years breakage  :icon_lol: 
Title: Re: Torque Convertors
Post by: Joe Buick on December 20 2017, 03:14:10 PM
I love my ATI Converter and wouldn't change it for anything else.... :rock:
Title: Re: Torque Convertors
Post by: Steve Wood on December 20 2017, 07:29:01 PM
I love my ATI Converter and wouldn't change it for anything else.... :rock:

A real converter!
Title: Re: Torque Convertors
Post by: Scoobum on December 21 2017, 03:49:23 PM
I love my ATI Converter and wouldn't change it for anything else.... :rock:

Do I know you? Merry Christmas to my friend/engine builder/head porter. He's the best kept secret in the Buick community.
Title: Re: Torque Convertors
Post by: Joe Buick on December 22 2017, 01:50:31 PM
I love my ATI Converter and wouldn't change it for anything else.... :rock:

Do I know you? Merry Christmas to my friend/engine builder/head porter. He's the best kept secret in the Buick community.

I think you know me!! I see you once or twice a year.... :cheers:
All the Best Wishes Dude...
Joe
Title: Re: Torque Convertors
Post by: ss/gn on February 10 2018, 08:36:24 AM
I love my ATI Converter and wouldn't change it for anything else.... :rock:

Do I know you? Merry Christmas to my friend/engine builder/head porter. He's the best kept secret in the Buick community.

Secrets out ! :D
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