I am hoping that one of our supporting vendors or another experienced individual can provide some information that compares 9.5" and 12" converters in 700R4/4L60/4L60E. What are limitations of each in terms of stall speed, horsepower, rpm, longevity, ability to drive on a daily basis (exothermic properties, etc)? Generally what are the pros and cons of each taking price and performance into consideration?

I know this is vague and covers a LOT, but if general conclusions can be made about any of the above I think it would be helpful to anyone trying to make a decision on a torque converter.

Also (maybe this should be a different thread) I would like some input on my current situation. My transmission builder is suggesting that I go with another 12" converter that stalls to 2500rpm. My mods are in my signature. When I mention a 2800-3000 rpm converter, he tells me that I will overheat my transmission, despite my pump and cooler. He also told me that 9.5" converters are "race only" and that they don't come with a clutch. I know he is feeding me some BS but I would like to know if I can have good results with a 12", if so how high can I go, and if anyone has any suggestions on sourcing a quality unit. Price is a concern, and since I don't want a very high rpm converter (always on street tires), I don't want to go with a 9.5" unless it is necessary.

Thanks in advance for the help!

 

Good lord, find a builder that is in tune with the current century...

For my bolt-on setup back when my car was a 100% daily driver I used to run a Vigilante 2800 9.5" converter with my B&M 24000 GVW trans cooler. Never an issue, perfect stall for a bolt-on car, and "not too much" for the street. Hell after a few days of driving it it doesn't feel any different than stock.

Yes, they have lockup clutches as long as you get the right one.

My Yank PT4000 has a lockup clutch and to me, is pretty streetable. So a 2800 is nothing.

A 12" 2500 stall converter is pointless and inefficient. Waste of time and money.

 

Did you ever go to the track on street tires with that otherwise stock setup? If so what kind of 60' did you pull on street tires? I take everyone's word that ~3000 is ok for daily driving, but how effective is the launch on street tires?
No skepticism here, but would you explain why a 12" 2500 stall converter is pointless/inefficient? Is it because of the stall speed or because of the weight associated with higher diameter converters (more rotational mass)?

Thanks for the input!

 

From what I've read raising the stall of a stock type converter (12") requires bending the vanes to the point where the fluid transfer process becomes inefficient compared to that of a 9.5" aftermarket. The weight is another factor in the lack of efficiency.

In regards to street tires on the track... there comes a point (to me) that street tires are pointless at the track, and that comes right around your power level. To hook you'll have to feather the throttle therefore negating the fact that you have a higher stall converter in there.

If you don't want to run around on drag radials all the time, a spare set of wheels with a set of drag radials is the best way to go.

My bolt-on car (longtubes, cold air, catback, mail order tune) with a 2800 Vigilante went a best of 12.9 @ 104 with a 1.72 60' on Nitto drag radials.

Hope that helps some.

 

I drove a car with a 3800 converter, I think it was tci brand, something like that? but anyways it felt very streetable to me, feeling the converter lock-up was kinda awkward(but something I could easily get used to), but if it weren't for that, and not having the prior knowledge, I would've never even guessed it had a 3800 converter in it.

 

I drove my 70 SS for 12 years with a 10" converter (non-lockup since it had a th350) and 4.11 gears. It didn't even have an aftermarket cooler on it and never had a trans problem.

 

9.5 inch converters can be built with or without lock up. They are approx 29 pounds dry weight. A stock 12 inch converter is approx 42 pounds. 13 pounds off the tail of the crank makes them desirable. The smaller size makes them more efficient making less heat in a given stall compared to a 12 inch with comparable stall.
The 9.5 incher will also feel tighter on the street. If you can fit the 9.5 incher in the budget, you will appreciate it more than the 12 inch model.

 

Here is what I hope you are looking for (if you have any other questions or need clarification, feel free to ask)...



Stall Speed Range-
12" - Stock to 2400 (Some will claim higher, but honestly, it doesn't happen)
9.5" - 2600 to 6000+

The 12" is limited by its size and it can't really see higher than about 2400 RPM stall speed. The 9.5" has far less limit and can see stall speeds in excess of 6000 without much work at all.


Ability to take horsepower-
12" - If well built, about 450 hp
9.5" - 450 hp to 2000 hp depending on build

With the addition of a ballooning plate, brazed fins, the possibility of a billet cover, and aftermarket internals, the 9.5" can see much more abuse in terms of raw power handling than the 12" could ever dream of.


Longevity -
12" - Out of the box, should last 100,000+ miles
9.5" - Similar, but a shift kit is a good idea to add to converter life along with removing PWM.

The 12" converter is built for longevity and will have a tendency to last for a very long time behind setups making modest power. The 9.5" in some cases uses a smaller clutch than stock and will need minor transmission modification to see similar longevity in those cases. If you get a 9.5" with a large clutch surface, it should exceed the longevity of a 12" without modification, but a shift kit is always a good idea.


Daily Drivability -
12" - Similar to stock
9.5" - Will feel a little different from stock and feel a little looser than stock depending on stall speed

Pretty much just that. Large diameter will feel more like stock and small will take a little more throttle to accomplish the same thing in normal acceleration. Most people get used to this in a couple days and swear they would never go back. Both can be daily driven with no real problems.


Heat -
12" - Somewhat similar to stock, I recommend a trans cooler
9.5" - Hotter than stock. Less fluid capacity means less dissipation of heat. I recommend a trans cooler.

With the higher fluid capacity of the 12" it creates less heat. However, with a transmission cooler, it is even possible to see a daily driven 4400 stall in Arizona, Utah, Texas, Florida, etc. summers with no problems. At about $50 and an amazingly simple 20 min. install, it is just good insurance with any converter, especially a higher stall.



Pros 12" -

Price - These converters should never cost more than about $350 for even an extremely well built converter.

Less Heat - These converters hold more fluid and generate less heat. This is good for a towing situation or in a very heavy car/truck/SUV.

Street Feel - These converters will feel somewhat similar to stock.


Pros 9.5" -

Performance -
Weight - Weighing (with fluid) more than 20 lbs less than stock, these converters give you the ability to spin the engine considerably faster. You can even see it when you rev the engine in neutral.
Adequate Stall Speed - These converters will give you the kind of stall speed that todays engine setups require.

Strength - If built right, these converters can take enormous amounts of power.


Cons 12" -

Performance - Not really a performance oriented torque converter. Will raise stall speed, but give little in performance.

Weight - These converters are heavy and more difficult for the engine to turn.

Strength - These converters are not built to take considerable power and tend fail under high performance applications.


Cons 9.5" -

Heat - With its small diameter, the converter holds less fluid. The lower capacity creates more heat. It is easily taken care of with a transmission cooler.

Looser - The small diameter will feel somewhat looser than the 12". However, with lockup, at speeds of about 35 and above, this will be gone and around town, most people actually end up preferring the feeling of having more control over what is happening with the RPMs.

Cost - Expect to pay about $450+ for a well built 9.5". They are more expensive to build and take many more aftermarket parts.







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Thread #2 (hehe)

I completely agree with you that a 2800-3000 is ideal for your setup. It will match your powerband extremely well and put absolutely violent power to the ground. Streetability will be great and with the cooler, heat won't be a problem. 2500 is inadequate for your setup and will really rob you of power.

9.5" converters are by no means "race only." I daily drive one and most of our customers do as well. In fact, the ratio of our builds for street driven vehicles of 9.5" to 12" is literally MORE THAN 100:1 in favor of the small diameter.

9.5" converters certainly are available with a clutch. In fact, some are available with a bigger clutch than the 12".

From a performance standpoint, you can reasonably expect .2-.5 better performance out of a 9.5". In your particular situation, I wouldn't be surprised to see .3 or even .4 better than a 12".

With your setup, I would actually go with the 3000, rather than the 2800. You will get a little more power out of it and particularly with your 3.73 gears (which make any converter feel considerably tighter), streetability will not be an issue at all.


I hope all of this is helpful, but if it needs clarification, please feel free to ask.

Thanks,
John Cameron
Fuddle Racing Torque Converters

 

well put! he just about nailed it...i heard if you go over about 2400 rpm with a 12 inch it becomes very inefficient! this will hurt you....even a 9.5 inch 2500 is a better idea because its more efficient...think this is due to how much the fins in the converter have to be bent over...anyways 9.5 is the way to go, its definately not race only...and i know guys here locally that daily drive 5100 stallls

 

I was in the same boat as you deciding what to get.
#1. Ditch your current trans guy.
#2. 2800-3000 stall from a decent company. (search)

I got a yank 2800 (used) and am extremly happy with it. Definatly the most noticable power mod for my car. If you go stall + gears do not foroget to get some awsome tires if you dont have them already. Street stock size tires wont cut it, they're barely enough for me without gears

 

1jfuddle, what can you tell us about 8" diameter converters? how do they compare?

 

I have a 3800 Fuddle converter, works great on my street car!

 

The 8" converter certainly has its place. It is almost always built as a track only converter though. You won't find one with a clutch, so that seriously limits its practicality with the 700r4/4l60 crowd.

Aside from that, both its advantages and its disadvantages lie in its amazing small size. The small amount of fluid that is able to move throught the converter pushes stall way up. You will have a difficult time getting an 8" converter to stall less than 5000. So, depending on how you look at it, that can be seen as an advantage and a disadvantage. The other disadvantage is price. They will run you well over twice the cost of a 9.5". The one clear advantage to the 8" is that it is amazingly light. Often able to weigh less than 25 lbs, this converter really lets the engine spin freely.

I suppose the bottom line with the 8" converter is that for someone who needs huge stall and really doesn't drive the car, it is a perfect solution. Just remember, it is pretty much a track only converter.