Torque converter question

[ScottNM]

I will have a very streetable 500 hp engine soon. I want a street friendly tranny set up that can handle that power. I would like to maybe reach high 12s/qtr mi. Is there a stall speed and brand that would best fit this bill or is this a tall order? Question 2. When a TQ vendor advertises a 2k-2400 stall speed is there a probability that a very strong engine will stall on the lower end of that range?

[zmanabba]

I would call the the torque converter manufacturers direct and get their recomendations. Be ready for a slew of questions i.e. gear ratio, car usage ect. I have B&M in mine but it is the old style. I have heard that quality has fallen and there is more slippage than some others. Coan, TCI I have heard good things. Hughes not so good. But I have never personaly used any of them. The adage, you get what you pay for, applies. Good luck David

[zmanabba]

Oh and the stronger the engine (along with other factors) the higher the stall speed.

[dbreese]

^^^^^ What David said. I am partial to Coan and can tell you they have great customer service. I run this converter http://www.coanracing.com/Catalog.asp?ProductDetail=120 flashed at 3600 behind my mild 385 but because of the stator design was very efficient and you would never know that converter wasn't stock by just driving it on the street/highway. I'm using the same converter behind a 414 s/b that will flash around 4100 rpm but will still be just as streetable.

 

ATI is another good company. I don't think you would go wrong with either of these companies.

 

David

[Heckeng]

x3

 

You get what you pay for, and for an engine at that power level, I would not cheap out. Think about how expensive it would be if you bought a cheaper converter and it blew up and trashed your tranny. You are now buying a new converter AND rebuilding or replacing a transmission. You can get a good converter for $500-$700 from what I have found. I have a "tight" ATI converter. I asked for that, and that is exactly what they delivered. Like Dave said, you wouldn't really tell it had a higher stall unless you get into the throttle.

 

Coana and ATI seem to be the names I hear the most about going behind strong engines.

[ScottNM]

A very well known and respected engine builder is building my new engine. He is holding a early nova torque converter originally for a 6 cylinder unbelievably. He suggests I will love the match up of this unit against my bb 5oo hp engine. Imagine that.

[Heckeng]

Those 6 cylinder converters stall nicely behind lots of torque, but you might ask him about adding an anti-ballooning plate to it to keep your torque from shredding it. Most companies like B$M, TCI, Dacco, etc will reuse the GM converters but with making modifications to the insides like changing the blade angles and adding better components where necessary, so the stock stuff is a good start.

[FastClass]

Had a friend who swore by the old Vega 4 cyl. converters behind mildly modded V8`s.

 

Used to be a dime a dozen at any junkyard.

[680HPStroker]

It's been said a thousand times, or more that no two setups are exactly alike. No off the shelf/re-built stock converter for another car will do the job correctly. You have to have a converter build especially for your application, or you leave a lot of power and even economy on the table instead of at thw wheels. Not to mention the potential for disaster when the tranny, or converter blows up.

[zmanabba]

I seem to remember your builder is Mark (VORTECPRO). He is known for being able to use stuff that other people might pass up-he made his rep on his head work with iron oval ports. If he is willing to stand behind it give it a go. Buuuttttt-personaly I have seen the devastation that a blown torque converter can do. A friend of mine back in the day ran a vega 4 cylinder converter that probably ballooned on him if my memory is right(pretty sure but this was in 1980 lol). He was lucky that the shards from the stator took out the turbo 350 quickly so that he didn't have problems with the thrust surface of his crankshaft. I agree with what everyone else has said above (especialy me lol)the best way would be a converter from one of the aformentioned companies. I would be interested on how long it would last (the 6 cylinder converter). Of course it's always easier to gamble with someone elses money lol. David

[CrazyDavey]

I'm a little surprised Mark would suggest that but like Dave just said he is known for getting things out of stock stuff that a lot of people over look. Mark is an ATI dealer, we talk quite a bit and he just sent me a 8" to try with the Chevelle. On one of his 500hp 468's maybe that Nova combo has a good track record, a lot depends on the rest of your setup and intended use. With some other combo's he might not suggest that.....JMO....Davey

[Heckeng]

Dave, you'll have to let us know what the ATI does and how it's design is similar or different from your current one.

[ScottNM]

Feel free to educate me. A high performance Coan TC is around 6-800 dollars. I just bought a whole TH400 rebuilt with borg HP cluthes and a shift kit for 475.00. Now, it is built semi performance, with that expensive coan TC it would be better than the rest of the tranny. What if the tranny blew up, would if destroy the TC? I would rather have a TC cause me to do a 500 dollar performance rebuilt then have a 500 unit destroy a 700 TC. Does that make sense?

[zmanabba]

I can understand where you are coming from but in my experience I have never had a transmission take out a torque converter. But I have seen torque converters take out transmissions almost every time. If I remember the fluid flow correctly the transmission fluid will go through the filter before it goes to the cooling lines. But the trans fluid coming from the torque converter goes in to the trans directly. So any metal shavings go in to the trans and tear up the clutch seals. I may be wrong on that but I am tired and too lazy to drag out my old text books lol. The beauty of the turbo 400 is that they were built (some would say overbuilt) right the first time and will handle a large amount of power with a few simple mods. There were also millions made for many years so supply/demand kicks in also. The torque converter that came with it would probably handle the power fine but would be a dog due to the 1300 rpm (aproximatly) stall speed. What the torque converter manufacters used to do was take a core like your 6 cylinder or a vega converter slice it open and modify it to handle the increased power and weld it back up. But with the lack of cores due to attrition they are probably needing to make their own (just a theory I could be wrong). So there is definatly a lot of labor/materials/r&d tied up in a quality torque converter. I know the price sucks but unless you change your combination radically or are chasing another .10 or more in your 1/4 mile time. You should only have to pay the price once. I am running a B&M Holeshot that I bought in 1988. David

[Winston Wolf]

If the trans goes, you will likely have junk in the converter. You would have to cut it apart and have it checked/cleaned. I blew a trans last year and when they took apart the converter, ($1000 model) it was clean. They weld it up and send it back for a nominal charge, all is not lost. For me it was actually free, since I had them re-stall it, which my place does once for free. Spend the money for a good one, it's worth the extra money and can drastically change the way the car will drives vs a cheap loose one.

[CrazyDavey]

Feel free to educate me. A high performance Coan TC is around 6-800 dollars. I just bought a whole TH400 rebuilt with borg HP cluthes and a shift kit for 475.00. Now, it is built semi performance, with that expensive coan TC it would be better than the rest of the tranny. What if the tranny blew up, would if destroy the TC? I would rather have a TC cause me to do a 500 dollar performance rebuilt then have a 500 unit destroy a 700 TC. Does that make sense?

 

Coan always has specials, also talk to them about a refuribished one. The higher priced ones are usually custom converters that are built specifically for your setup. I'm not trying to sell Coan, there are lot's of good ones out there, they are just my experience.

 

here's a few from their site..

 

http://www.coanracing.com/Catalog.asp?ProductLine=SPECIAL

 

If you call them talk to Craig.....

 

 

[CrazyDavey]

Dave, you'll have to let us know what the ATI does and how it's design is similar or different from your current one.

 

Will do Scott...the main difference is I'm going from a 9" to a 8" and from 4500 to 5000. The new converter is also 10 lbs lighter so we'll see how that affects things as well. This is a spec converter that Mark has developed through ATI and has used with several of his high horsepower customers (not that mine's that high but maybe a little higher than most). He sent me a PM and offered it up, thinks it will pick the car up over the Coan so I thought I'd give it a try, if I can pick a 10th it's worth it. He is concerned that I'm going to blow my current 28x10.5's off and wants me to go to a 29.5 radial slick but I don't think I can fit it in there..I guess we'll see....

[ScottNM]

I must say the Torque converter is a challenging part of the equation when trying to get a street friendly 12second 4200lb car with a 500hp engine. I think my gear ratio is 273. I may go up to 330ish. What do you think for drivability? What about stall speed? Another thing challenging is they have these "pre made units for general applications near mine but yet some builders want cam card, wheel size, altitude etc. Makes you wonder.

[dbreese]

Coan 11" pro street converter 3.36 gears (8.2 rear) and some sticky tires with my mild 385 would run high 12's with no problem. Very streetable. With your 500 hp you should be golden. IMHO

 

David

[ScottNM]

I live near albuquerque at 5500ft above sea level. I believe the corrected HP here will be 380-400 approx. What stall speed do you recommend?

[Winston Wolf]

What is your peak torque RPM and what RPM do you shift at?

[Heckeng]

Getting a good converter won't be as hard as you think. The good manufacturers can hook you up with a "tight" converter with whatever stall speed you want. I would guess you will want something around 3000 rpm or so. When you hear people talk about "tight" and "loose" it doesn't just mean how high the converter slips. For example, on my Monte, I have only had 2 torque converters, the first was a B&M Holeshot 2400, and honestly was a great converter all in all. It was a loose converter for me though. Behind my engine it would actually stall to around 3000 rpm which was great, but the loose part means that it would allow the engine to rev more freely up to near the 3000 stall speed before it would apply the torque to the transmission. This can get annoying in town and cause heat to build up. When I ordered my ATI, I gave them my engine specs and told them that I wanted it to have around a 3000 stall, or slightly higher, but I wanted it tight so I wouldn't cook my transmission. That is exactly what they put together for me. My ATI converter doesn't feel much different from stock just driving around town. It is "tight" enough that it does send torque to the transmission below the stall speed, but if you apply full throttle, it will jump up to their projected stall speed and it stalls to around 3000-3200 rpm.

 

The B&M did great for an off the shelf converter. I figured it may be on borrowed time though as I ran it for probably 6-8 years. I sold it to a guy with a decent little 450 horse 350 and it blew up within the year. I got lucky by getting rid of it when I did!

[ScottNM]

My peak RPM is around 5600, I believe. As far as shifting, I want something street friendly. I am trying to find balance between drivability (mild shifting) and occasionally going to the track and getting the power to the ground. Not to much to ask for, is it. Not sure of the average rpm shift yet

[CrazyDavey]

Scott you should decide on the gears before you choose a converter, that will affect which one is best. That motor will probably not be happy with the 2:73's, I would pick it up to 3:08's or or even a 3:36.....