Lazy performance with High stall converters...
#1246620
06/07/12 12:13 AM
06/07/12 12:13 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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I'm starting to wonder why we decide to go with these High stall converters. I dont drag race at the track. I do some spirited driving on the street and I DO intend to run the car on a few road race courses just for fun. Here is the combo: 440 based 493. 10.8 squeeze, MP '509 cam, 2" TTI headers, Edelbrock heads, 850 carb. 727 with 9 3/4" converter, Gear Vendors overdrive. 3.91 gears. The car will move off of idle, but it slips more than I like. If I lean on the throttle, the rpms go up but the car doesn't respond in direct proportion. In short, it slips too much before the stall rating. It feels like I'm leaving from a standing start in a manual trans car. The engine idles nice at 900 rpms. My 2007 Ram truck pulls nicely right from idle. The fairly stock 360/904 in my bro-in-laws 72 Duster also responds quickly right off of idle. I know... stock cams are designed for that. I just wonder if a stock converter might work for me. I am not as experienced as others in terms of torque converter science. My engine makes great torque and HP even at low rpms, so do I really need such a high stall unit? Freeway driving feels lazy too. If I'm rolling along at 65 mph and try to floor it, there is a noticeable lag before the car really responds. At 65, the car is going too fast to downshift to 2nd automatically, and for some reason, the GV will not unlock from OD until it slows below 45 mph. Yeah, I know... 65-70 is the speed limit and I shouldn't exceed it....Still, with the car rolling along in OD with a final drive of about 3.05, it feels sloppy. It feels loose from the standing start and sloppy at cruise speeds. I talked to the builder of the converter. He said that he could cut it open and change a few parts to lower the stall, but the question is... how much? 200 rpms isn't going to do it. I'd like the stall to be somewhere around 2000. Would it make more sense to look for a 11" converter? As is, the car will boil the tires if I just stab it from the start. I can fry the tires halfway through 2nd gear. I have no complaint about the performance at full throttle. My issue is part throttle starts and any other situation where the car is running "under the stall" rating. Thanks, Greg
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Re: Lazy performance with High stall converters...
[Re: DaytonaTurbo]
#1246622
06/07/12 12:29 AM
06/07/12 12:29 AM
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Joined: Nov 2011
Posts: 2,154 Its a TRAP!
DARTH V8Я
Oh No!! I just had a moron attack!
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Oh No!! I just had a moron attack!
Joined: Nov 2011
Posts: 2,154
Its a TRAP!
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Yep.. The 509 is a very lazy camshaft.
When it takes more than a sweet mullet to prove you rule at the trailer park..
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Re: Lazy performance with High stall converters...
[Re: Kern Dog]
#1246625
06/07/12 02:32 AM
06/07/12 02:32 AM
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Joined: Dec 2008
Posts: 27 Ca
speedy515
member
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member
Joined: Dec 2008
Posts: 27
Ca
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I'm no expert, but experienced something similar: The car felt like a manual transmission with the clutch pushed in part way until the stall speed was reached. Anything below that and my throttle felt "spongy". In cases where I spent some time below the stall and then mashed the throttle, the engine would rev and then it would feel like I "Popped the clutch" when the torque converter decided to catch. I went to several tranny shops who suggested swapping to a lower stall converter. A random person at a car show explained to me that the converter was "draining" faster than the pump was filling it when below stall. The "Laziness" was a result of the torque converter filling first and then doing what its intended to do. I took my car to a knowledgeable shop and mentioned this. They installed some sort of "Block-off plate" in the valve body. (This is what I was told). Now the car acts like it was supposed to: No more hesitation, No more spongy throttle. My
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Re: Lazy performance with High stall converters...
[Re: Hemi ragtop]
#1246627
06/07/12 07:19 AM
06/07/12 07:19 AM
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Joined: Oct 2007
Posts: 1,973 SoCal
jake4cars
top fuel
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top fuel
Joined: Oct 2007
Posts: 1,973
SoCal
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Quote:
Very interesting post. I have only put about 300 miles on my car since finishing it and I am wondering if a stock converter would'nt be more fun to drive. I have a 540 ci hemi with 10.8 compression, 248/254 @ .050 roller cam, 3.54 Dana and 3500 stall converter. I used the converter after much discussion with one of the top trans builders for the 727. Part throttle is just "mushy". Full throttle is not even possible on street tires so what is the point of all of that stall? I will wait until I get a chance to run it at the track on slicks to decide to go to all the trouble to change it. No doubt the et will be better with the converter I have, but I drive much more on the street.
Love this car
Joey
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Re: Lazy performance with High stall converters...
[Re: mikemee1331]
#1246630
06/07/12 01:58 PM
06/07/12 01:58 PM
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Joined: Jan 2003
Posts: 9,892 Weddington, N.C.
Streetwize
master
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master
Joined: Jan 2003
Posts: 9,892
Weddington, N.C.
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The best verts to me are fairly tight feeling stall (I call that "responsive" to throttle input) but can flash right into the meatiest point of the torque curve in high gear. I have always hated a part throttle 'slipping clutch' feel in a daily driver, won't ever have one that way. That's why I drove sticks all the time before converter science technology caught up. what's the part of all that juicy stroker "dyno" torque if you can't feel it until 4500-5000 RPM? That's why I don't chase top end HP with the cam, build the short block for torque and let the head flow put the HP where you want it. On the street you really want more of a road-race wide powerband, not a Drag Motor type torque curve....unless it's a really light car that can't hook what you have. The smaller diameter verts are more efficient and obviously less rotating inertia at high RPM. you've got to find the right balance for your combo but for strokers you're almost always better with a custom built unit.
Last edited by Streetwize; 06/07/12 02:00 PM.
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Re: Lazy performance with High stall converters...
[Re: Graham]
#1246633
06/07/12 03:17 PM
06/07/12 03:17 PM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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Quote:
What stall is this converter rated at? From what you've written, it appears that for street use, far too much stall speed. Properly applied, a higher stall converter is great, improperly applied, the worst performance investment you can do. Graham
Going back to 2005, I took my car to a shop that had a chassis dyno. The operator said that with my combination, the 11" converter was loaded against the motor at too low an rpm. I had the '509 cam advanced 4 degrees then and the car idled at about 1000 rpms. Since then I went with the 9 3/4" converter estimated to stall at 3000. I returned the cam to a staight up position which degreed at 1.5 degrees retarded. I've also added slightly larger headers and went from a 4.10 gear to a 3.91 with a GV overdrive. The motor now idles fairly smoothe down to 750 rpms. Raising the idle to help crutch the stall results in run-on dieseling on shutoff. Maybe these factors have all conspired to make the car feel lazy. No matter what, I want the car to feel tighter. The slip makes the car feel like a race car in bumper to bumper traffic: totally wrong for the circumstances.
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Re: Lazy performance with High stall converters...
[Re: DaytonaTurbo]
#1246638
06/07/12 06:15 PM
06/07/12 06:15 PM
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Joined: Apr 2010
Posts: 4,154 bethlehem pa
mikemee1331
master
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master
Joined: Apr 2010
Posts: 4,154
bethlehem pa
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Quote:
Watch out with dropping your converter too low. Too low of stall is going to give you one hell of an rpm drop from neutral to drive if you have too big of a cam.
Quote:
I've got a similar set-up in a B-body...
484;shift-kitted Torqueflite;street-hemi converter;3:91's...
Am experiencing nothing like what you're describing...
What did you have, trans-wise, in front of the 4:10's???
Your "street-hemi" converter is likely nowhere near as much stall as his.
exactly! right now i have to idle in park at almost 1000rpm, drop into drive and it's like 650-700 and so 'loopy' it still feels like it wants to stall out.
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