Stall speed vs. gearing
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
On The Tree
Joined: Feb 2013
Posts: 183
Likes: 7
Little loose could be not to your liking. I'll re-term it 'response time'. Sitting at a stop light, light turns green, slight pedal pressure to get car moving, a very brief delay. Sitting there in gear and take foot off brake and car doesn't move forward. Driving at, let's say 35mph, blip the throttle and car doesn't jump forward as you might be used to.
My Yank SS3600; take foot off brake and car starts to creep forward, no delay at a green light, blipping the throttle at 35- car lurches forward with that familiar slight front end rise.
Hope that explains it.
My Yank SS3600; take foot off brake and car starts to creep forward, no delay at a green light, blipping the throttle at 35- car lurches forward with that familiar slight front end rise.
Hope that explains it.
Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
A "loose" converter tends to have a higher flash rpm and more slip. A "tight" converter tends to have a lower flash rpm and less slip. A tight converter tends to be more efficient as far as fluid coupling but that comes at the cost of less torque multiplication... if that makes sense. A loose converter tends to hit the tires harder off the line, but doesn't MPH as well on the top end while a tight converter is vice versa. That's not an exact detailed description, but gives a good idea. The size of the converter, the stator used, and pitch of the turbine all factor into this, and it's all relative to the vehicle so a converter that's loose in one vehicle may be tight in another. The weight of the vehicle, the gearing, the torque input from the engine, the type and viscosity of trans fluid used, and other factors play into that as well. Naturally aspirated applications tend to like a looser converter with a high stall-torque ratio to "hit" the tires harder off the line. A lot of that has to do with the stator used in the converter. With boost or nitrous, you don't want that as you'll generally end up just blowing through the converter. A tighter converter, that places more load on the engine through better fluid coupling, is more beneficial there.
A suggestion. Find some locals with stalled car and ask for a city driving ride. Find out what converter and rear gears. Just sit in passenger seat and watch gas pedal movement versus what you feel sitting in the seat.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
Right. Laws of physics. The wider the diameter, the faster the edge speed at the same engine rpm, which means more fluid capacity and higher fluid pressure at the same rpm. This is also why larger diameter converters are limited on stall rpm.
TECH Fanatic
Joined: Jan 2017
Posts: 1,758
Likes: 442
CircleD makes a financially friendly 3200rpm converter which I believe is 278mm that is based off a trailblazer converter. I had it and it was very nice for a DD and was a huge step up from a stock converter. Couldnt even tell it was there other than the firm lockup. I do believe prices are higher atm but I'd give them a call and see what they can do for you. It was in that 500$ range when I bought it. Otherwise if max performance is what you want, you will have to pay for it and will run you 800-1200 bucks. This will get you a fully aftermarket converter in a smaller diameter. In regards to a 9.5 being too loose, this completely depends on how it was built. These converter guys know what they are doing and have multiple ways of setting up a converter to get it to do exactly what you want. All it takes is a phone call. And a lot of this "loose" feeling will be alleviated with shorter gears and a well built engine that has great low throttle response and torque. Even on a stock engine, a properly specced 3600 will drive great and after a while you will forget you put it in, until you floor it.
Launching!
Joined: Mar 2019
Posts: 267
Likes: 171
A smaller diameter converter can also increase that response. Smaller diameter means a lower moment of inertia through both less physical weight and the weight being closer to the crank center. Less inertia means better response.
Thread Starter
Launching!
Joined: Nov 2014
Posts: 234
Likes: 16
From: South dakota
Bspeck82, I did look into the budget friendly line prior . Just didn't know if 3200 would be worth while since 3500+ was suggested. Think I checked 3 or so companies but all there budget line offer up to 3200 stall
TECH Fanatic
Joined: Jan 2017
Posts: 1,758
Likes: 442
For your build, I'd recommend a 4000 stall and gear it shorter once you put in the 12 bolt. And I highly recommend an mwc or quick performance 9 inch over the 12 bolt. S60 will work too. You wont burn anything up. Put in a good trans cooler and call it a day.
Sounds like you have gotten the gist of what to look for in your converter in terms of parts and craftsmanship. Next step is deciding what stall RPM is going to be right for you. This is where people usually ending regretting there first choice as many above have mentioned. My suggestion would be to give companies X, Y, and Z (hopefully including us) and talk to them about your goals and what is already done to the car. Here's why; someone like myself who has been doing this for a hot minute and knows the converters will more than likely be able to help you translate your wants into an actual RPM range or SKU number. Everyone perceives drive-ability differently(many here LOVE a 4000+ converter while i have customers that think 2800 is WAY to loose) , part of my job is helping to make sure that perception is inline with the converter of choice.
__________________
FTI COMPETITION CONVERTERS AND TRANSMISSIONS
"IT'S NOT CHEATING, IT'S THE COMPETITIVE EDGE."
1-866-726-8358
info@ftiperformance.com
FTIPerformance.com
FTI Converter build sheet
FTI COMPETITION CONVERTERS AND TRANSMISSIONS
"IT'S NOT CHEATING, IT'S THE COMPETITIVE EDGE."
1-866-726-8358
info@ftiperformance.com
FTIPerformance.com
FTI Converter build sheet
^^^, Yep. A 2800 from one company could be very loose (TCI 2800 'Breakaway') where a 3600 from another company could be tight (Yank SS3600). I imagine FTI also has a range from loose converters to tight converters.
Based upon the OPs' original post, 'mostly street occasional strip', a good street friendly converter will also work well on the strip, a maximum performance strip converter probably would not be too friendly on the street.
Based upon the OPs' original post, 'mostly street occasional strip', a good street friendly converter will also work well on the strip, a maximum performance strip converter probably would not be too friendly on the street.
Just chiming in with my experience.
I've had a vigilante 3600 mated to my 4l60e with 2.73s out back for over ten years now. I also have a small 224 cam and I still love this combo. I've never broke anything, it IS considered a looser converter and I absolutely love it to this day. You need to ride or drive some to really see how they feel.
I've had a vigilante 3600 mated to my 4l60e with 2.73s out back for over ten years now. I also have a small 224 cam and I still love this combo. I've never broke anything, it IS considered a looser converter and I absolutely love it to this day. You need to ride or drive some to really see how they feel.
If you're set on a billet front, you can't go wrong with FTI, Yank, or Circle D, they all make great products. Some just seem to go the extra mile in terms of how they build things out per application.
As far as the gears go, if your 10 bolt is fine, don't bother opening it up and keep the 3.23s. Upgrade to a 3.73 when you get the 12 bolt. 4000 stall + 3.73s = perfect street setup IMO.
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
Sounds like you have gotten the gist of what to look for in your converter in terms of parts and craftsmanship. Next step is deciding what stall RPM is going to be right for you. This is where people usually ending regretting there first choice as many above have mentioned. My suggestion would be to give companies X, Y, and Z (hopefully including us) and talk to them about your goals and what is already done to the car. Here's why; someone like myself who has been doing this for a hot minute and knows the converters will more than likely be able to help you translate your wants into an actual RPM range or SKU number. Everyone perceives drive-ability differently(many here LOVE a 4000+ converter while i have customers that think 2800 is WAY to loose) , part of my job is helping to make sure that perception is inline with the converter of choice.
The STR is also a big factor in regard to feeling loose or tight... not just stall speed.
You guys should have Dalton explain the differences between the "Hard-Hit" (looser) and "Soft-Hit" (tighter) torque-converters; with both having the same (or nearly the same) stall speed.