What Torque Converter with an overdrive?

[PA Dodger]

I built a healthy stroker engine for my Charger.
Specs are: 400 blocks stroked to 470"/Lunati 60305 cam .533-.552 lift with 242-252 duration/Stealth heads/Eddy Torker intake/850 Proform carb.
Based on similar buildups I followed on this site I'm thinking 525-550 HP with 550-575 ft/lb torque. I plan on using 3.91 or 4.10 gears in the rear.
I bought a Gear Vendors overdrive for this car and now I can't find a converter that will work with both the engine and OD unit. Both B&M and Turbo Action recommended their 3000 stall converters but said the OD will cause slippage problems when engaged.

Here's what Gear Vendors says
"Yes, this is one of the most often confused questions (even when you ask people you would think would be knowledgeable). Here is the detail. Our example could be this 3.42 Chevy guy. In overdrive he is going to be a 2.67 final drive ratio. He is a Cutlass body with 27 inch tire and so at 75mph in overdrive the motor will be turning 2484 rpm and he has a 3500 stall speed on the back of a pretty nicely built 350ci motor making close to 400hp. 95% of the people you would ask (even tranny guys) would say no-way and yet we know this is an awesome package (drives wonderful, no high temps in the trans etc) why does it work? When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just crusing at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because he is not making 400hp. Car drives wonderful. If he romps on it while cruising then the trans is going to downshift to a lower gear and get him into the powerband. (note: read gear vendors passing gear in this section) So, this is why you never lie to you converter builder (because if you overstate your hp you will not get the stall you wanted).

Who's right and who's wrong? Anyone want to offer a torque converter suggestion?

[Chryco Psycho]

figure out using this http://vexer.com/automotive-tools/speed-rpm-calculator what RPM you will be turning given the average speed you travel at , tire size , OD ratio , it looks like about 75% , so you know what RPM you will be at , then we can see how close you can get to staying in the powerband with the converter locked up

[PA Dodger]

Tire size will be 28" dia. OD is .78.   Using the formula with a final drive ratio of between 3.0 or 3.2 in overdrive and a speed of 65MPH it looks like my RPMs will be about 2200-2500 RPM. B&M and TA said it will slip below 3000RPM. But what GV said about only putting a small amount of torque out at cruise speeds makes sense too.
Thanks
Dan

[firefighter3931]

The Turbo Action 11in "street hemi" converter would be my choice with that combo...it's efficient at low speed yet flashes up nicely when you hammer the throttle. Good balance between drivability & performance.



Ron

[elacruze]

Converter 'stall' speed has little to do with converter 'lock' speed. Stall slippage occurs when the converter output is static, launching the car. Converter lock happens when input and output are both moving and become effectively 'locked' hydraulically. You won't be using overdrive at the same time the converter is slipping. GV is right. Remember, the vast majority of GV units are behind automatic transmissions on RVs and tow vehicles, not 4-speeds like mine. They know what they're talking about.

[Challenger340]

The Turbo Action 11in "street hemi" converter would be my choice with that combo...it's efficient at low speed yet flashes up nicely when you hammer the throttle. Good balance between drivability & performance.



Ron

I second the above, talk with Paul down at TA if concerned about the application.

Convertors slippage, is one the "black art" aspects in Convertor design that requires alot of experience and know-how.....Paul is one of the best.

[68X426]

Consider giving a call to TCT Convertors (TCT is a division of Dynamic Transmissions).

http://www.dynamicracingtrans.com/tctconverters.htm

I didn't build my Road Runner's driveline, and can't profess to anything more than really basic knowledge on the trans/convertor/engine/GV combination. It was all built by pros for the previous owner. I feel secure saying the RR's build is top shelf.

Rick Allison at A&A Transmission worked with the engine builder and with Gear Vendors. The Hemi kicks out 660 hp, the trans is a bombproof A&A unit, and the GV is awesome, connecting to the Dana 4.10s. The convertor that they selected is from TCT.

It's the 10 inch TCT model 11732, stall is 2800. There was custom work done on it but I don't know what that entailed.

What I know is that this setup works perfectly. I feel safe saying that because A&A used the TCT then it's right. So give TCT a call, if nothing else to kick around ideas and options. (203) 483-9508

[PA Dodger]

I second the above, talk with Paul down at TA if concerned about the application.

Convertors slippage, is one the "black art" aspects in Convertor design that requires alot of experience and know-how.....Paul is one of the best.

Ironically it was Paul I talked to that said its definetly going to be slipping when the OD engages. He recommended I bump up the rear end to something higher than 4:10 that will put the overdriven RPMs into the 3000 range. Kinda defeats the purpose. He recommended the 17805ST 10" converter that stalls between 2800-3300 RPM.
I'll have to look into the TA Street Hemi converter.
Thanks

[MSRacing89]

I run Gear Vendors behind a 550HP 440 with an 11" 2800 converter and 3.23 gears.  There is definetly slippage that occurs in my situation.  You just learn to drive around it a bit.  If I know I am going up a grade for a while I just turn it off for a few moments.  At highway speeds turning around 2k, you apply load on an uphill grade and there for sure some noticable slipping.  I have considered going to a different convertor as I mostly only road course the car and it makes close 600 ft/lbs of torque.  No real need for a high converter in my case.   

[John_Kunkel]

Figure it this way, 3.91 gears with the GV will give you a final ratio of 3.05 which is still not as low as the factory 2.94 or 2.76 axles that were routinely used with 11" converters....the same 11" converter that would stall at 1600 behind a /6 and 2900 behind a Hemi.

[Cooter]

Unless you have some way of locking up a torque converter when it has a high stall speed, your gonna cook the fluid riding around in OD with a final drive of around 2.60:1....Notice the facotry OD transmissions have lock up feature? This is why, along wiuth better fuel mileage.

[firefighter3931]

Figure it this way, 3.91 gears with the GV will give you a final ratio of 3.05 which is still not as low as the factory 2.94 or 2.76 axles that were routinely used with 11" converters....the same 11" converter that would stall at 1600 behind a /6 and 2900 behind a Hemi.

Exactly  The 3.91 gears are steep enough (with the OD) to allow reasonable lockup with that particular converter. The TA hemi converter is VERY efficient at lower engine speeds and feels as tight as a stocker off idle. I wouldn't hesitate to use it in the combo listed above for one second ! 


Ron

[PA Dodger]

OK, its the 11" TA Hemi converter then.
When I was planning the drivetrain for my Charger I didn't plan on overdrive. I met a guy that pulled the trans and GV unit out of his Hemi Challenger convertible clone because he didn't like it. i got both for $1600. Finally in the right place at the right time!
Thanks all.

[RECHRGD]

I run a TA (tight) 10" converter with 3.55's, 28" tall tires and a GV unit.  In O/D it's about equal to 2.72 ratio.  The tranny has never heated up and runs great on the highway.  As said before, I just turn off the O/D if going up a long grade.  The converter stalls a about 3300 rpm behind my 440.

[Charge_her]

Hi guys,

Its been a while, but I'm back with a question with lots of variables. I have to replace my stock torque converter with something that is better suited for my engine/trans setup that now has a Gear Vendor O/D (been drooling over them for 10+ years).

I've done some research, and the big things I now understand is that when it comes to converters for the street, less is more, and you get what you pay for.

I'm thinking a stall between 2000 - 2200 would be suited to my setup, but I've been doing this for about *looks at watch*... 6 hours. I recall seeing much bigger numbers thrown around the forum, so am I missing something? What would you recommend for my setup?

Use: street cruiser and weekend getaway car
Engine: 451 stroker (400B w/ 440 crank), somewhere between 400 & 500hp
Intake: Torker 383 single plane
Exhaust: Heddman 2" primaries, 3" collectors
Hydraulic Cam: 230 duration @ .050 + 114 lobe separation, .490 gross valve lift, 274 tapped lift at .006
Gears: 3.91 locking rear + Gear Vendor O/D 0.78:1 OD gear, final drive at 3.04 (theoretically 2200 rpm at 60, 2400 rpm at 70)
Tires: 28.8" or 315/45/18

RPM   MPH in 1st           MPH in 2nd     MPH in 3rd      MPH in OD 2000   17.8953569   30.23698235   43.84362441   56.20977488 2200   19.68489259   33.26068058   48.22798685   61.83075237 2400   21.47442828   36.28437882   52.61234929   67.45172986

Should I try to approximately match the flash stall of the converter to the RPM immediately after each gear change so that its fully engaged when upshifting under normal driving conditions, or do I want some slippage?

Thanks guys!

Used these useful calculators to come up with some of the numbers:
http://vexer.com/automotive-tools/speed-rpm-calculator
http://users.erols.com/dmapes/GEARCLC.HTM

[BananaDan]

I put a GV on my car 4 years ago and re-geared my rear end to 3.91 at the time. Turbo Action was recommended by the folks here as well as my speed shop. I ended up going with their 10" #17805ST, that model number was based on Turbo Action's recommendation. They will want your engine and cam specs, your rear end ratio and will recommend a converter. I am very happy and it really woke up my engine and turned her into a tire shredding beast. I was also advised to make sure they gave me a unit with the stronger 7/16" bolts FWIW.

[Charge_her]

I just talked to them, they recommended a 3200 stall 10"! I've heard everything from 2000 rpm stall through 3200 depending on what company or expert I talk to. This really is black magic.

What stall converter did you have before? Stock?

[RECHRGD]

Sounds like the same one I've got.  Just be sure that it's the "tight" 10" and you should be fine.  It feels close to stock until until you mat the pedal.....

[Charge_her]

Did you have to add a cooler?

[RECHRGD]

I did just because, but I may not have needed it, as it has never overheated in the 8 years I've had it.

[Charge_her]

The guy at TA recommended a cooler.

Interestingly the new Transgo kit circulates fluid while in drive and with a 3 core aluminum radiator and big fans I'm hoping things will stay nice and cool.  Still, I think I'm going to be very conservative on the converter because I want a reliable cruiser and 3200 does not sound conservative. It does sound fun though.

Anyone following this thread who's running stalls anywhere between 2000 - 2400 rpm have regrets?

Also, what's the benefit to being loose? 

[RECHRGD]

Don't confuse the good guality TA tight converters with the cheaper everyday converters.  I had one in the past that was around a 3000 stall.  It was horrible for the street.  Very mushy pedal and didn't really want to move unless you gave it a bunch of throttle.  Just think of it as a clutch in a 4 speed car.  It will allow you to get up into your best RPM for torque before it hooks up WHEN YOU WANT IT TO.  Regardless of the RPM rating, they will stall differently behind different engine builds.

[BananaDan]

I had a stock converter and it was a dog out of the hole. Now she cruises great on the highway and is great out of the hole. I didn't put on a cooler, but I've thought about it. I drove her to Carlisle every year, about 175 miles each way, and maybe 600-700 miles per year. I've never had an issue. I don't recall anyone ever telling me I absolutely should have one.

[Charge_her]

I've been running a stock converter too, all I did was make noise. I'm thinking that at minimum I want at least 700 - 900 rpm higher stall than that 1500 rpm stock unit, but not be slipping while cruising and causing heat, poor fuel economy, etc.