pros and cons of a customized torque converter?
 

so it seems like a customized torque converter would be a good thing to do if you are looking to get some larger gains on an auto.

so i was wondering what are pros and cons of doing this. cost? gas milage? driveablity? being cool? :D:

Cons are cost and drivability.

The time between shifts is shortened, so shifts are not as smooth. Also the stall speed could be changed to launch at a higher RPM, but I am going to guess that would have an impact on a daily driven car.

Some manufacturers of torque converters advertise small gains in power and gas mileage but I doubt it.

And for the real question I think you are trying to ask, torque converters are made that reach crazy RPM's in cars with more power than the RX-8; so bumping up the shift points to 9000 RPM could happen.

I am no expert by any means, maybe someone with more knowledge would comment. I have been in 2 vehicles that had the stock torque converter replaced with an aftermarket sportier version, 1 was a truck, the other a camaro.

If you do get a custom torque converter please post the results. I'm sure many people with the 6 speed automatic would be interested in this.

And a little bit of required reading: http://www.converter.com/faqs.htm

thanks for the info thats the good type of info i enjoy getting here.

The trick is getting a higher stall speed without sacrificing too much drivability. Dragsters (big V8s) say to set the stall near the torque peak. This occurs at a fairly low rpm on these big engines. Obviously a 5000rpm stall will not work in our case. You could probably get away with 3000rpm without noticing too much of a difference in daily driving (assuming no FI mods).

Some benefits:

Torque multiplication. The converter can be manufactured to increase this to some degree. I don't know what it is, stock, but I imagine it's a pretty standard number. Note this will also affect stall speed to some degree, so it's not a single variable modification. Note 2: this multiplication only occurs when engine speed is much higher than the converter speed (eg launch).

Efficiency. The torque converter is what causes automatic transmissions to be so much less efficient than manual ones. A custom built converter should be significantly more efficient than the stock one. Therefor getting more power to the rear wheels, and likely increasing fuel economy a very small amount. Note: A torque converter is pretty much a turbine/pump combo, so it has efficiency ranges (much like a turbo would have). You cannot build a converter that operates efficiently over a 9000rpm range. It would be designed, most likely, to operate efficiently through the mid and upper ranges . (9000rpm is too high for the 4 port anyway, it can't breath up there)

Some negatives:

Drivability as discussed already.

Cost. Though not anywhere near a turbo system or anything like that, the $ to benefit isn't very high.

Pretty much nobody does this for rotary cars. So lots of Q&A sessions with the company building your converter over engine specs and output, etc.

If you plan on going FI, you might as well wait on the converter. Manufacturers base your converter on power and torque specs.

N Rider you soo want to max out your 8 AT's Hp dont ya haha.
Maybe you should whisper in RG or Zoom's ear about this since its been stated our Trannies came from the Rx-7's and someone has stated also about our Rev limiter that they have custom converters for that tranny for the Rx-7's. Surprised though no one else has thought of this sooner.

Oh yeah come spring with a friend gonna go junk yard hopping and go looking for some Crashed 8's hoping to maybe find a MT carbon fiber drive shaft hehe. (I hope its swapable. ><!)

Yup our AT trannies come from the AT RX-7.
Wounder what them AT RX-7 boys are putting out and if I could swap out there engine or should I just swap out there MT? lol what to do what to do =p

haha i do kinda want to max it out but im really just trying to get info. its not like im gonna just suddenly try to do all this. im just tryin to see whats out there. im still not gonna drop premium cash on this car right now. this is just fun stuff to talk about

im trying to find a nice auto rx-7 to mess around with.

This is interesting, I didn't know we directly inherited the RX-7 FD Auto tranny (talk about Mazda saving money). Now I will have to dig through the RX-7 club websites for info. too. Somebody, just had to have done it and we could see the results of some RX-7 Auto guys adventures.

I believe, feel free to correct me if I'm wrong, that close to 3,500 RPM is a good launch point for the RX-8 for a 0-60 or 1/4 mile. It keeps you in the appropriate power range. This is also where supercharger and/or turbo should be really kicking too. Right now, the RX-8 Autos can't really launch beyond 2,000 RPM or a little more. I know its suppose to be a little higher than 2,000 but I get worse results when going over it, as oppose to launching right at that number. Would really love to launch at 3,500 RPM without doing a neutral slam on my tranny. Combined with a Supercharger, I would expect that a customized torque converter would give some impressive results on the RX-8 AT.

I'm thinking that we should try to convince the twin-screw supercharger guys, Hymee and/or Pettit, to explore this avenue too.

They could possibly include a customized torque converter in their kits and/or have it done and demonstrate the performance results with their superchargers. I'm thinking RX-8 Autos with both mods would perform nearly equal to their M/T RX-8 supercharger brothers (if not better depending on the car) and take out anything lesser.

yeah if cost isnt crazy outrageous then hey it could be a nice thing to look into.

so if its the same convert. from the 7 then could we use the same thing that just bolts on with little or no modification?

before i would do any of this i would add another oil cooler and trans cooler too.

My guess would be that a custom torque converter would cost around $1,000.

Might drop .1 - .3 seconds in 1/4 mile drag. Maybe a little bit more out of the 2006+ automatic RX-8's due to a bump in RPMs.

But no one would know for sure until someone is brave enough to have one built and installed. Until then we can only speculate.

http://www.protorque.com/specs/ys.htm

Someone want to give them a call? I would but I don't have an automatic. :spank:

"Giant performance increases for import applications including: TwinTurbo 300ZX, Twin Turbo Supra, Lexus, Mitsubishi Eclipse, 3000GT and Eagle Talon, RX-7, Infinity, Honda, Acura, BMW and Mercedes.
"If you don't see it listed here that doesn't mean we can't do it. Almost all import torque converters will benefit from our modifications. Please call with your requirements" "


they do say rx-7 so its possible.... might shoot them an e-mail tommorrow. maybe....

I think you might see a slightly higher benefit because of the low torque. It literally takes 0.5-1.0 seconds to get to 3000rpm out of the hole (4AT). Starting at 3000rpm would completely remove this time. Now, I've never seen anyone do a converter on a low torque car like ours, so I'm just theorizing. It's not going to make it a fast car, but an improvement in its weakest area is great.

I have a high stall converter in my Turbo Shadow. I must say that I don't much like it. A higher stall converter just slips more at a lower rpm enabling you to launch at a higher rpm. Creates more heat etc... Great for drag racing, i.e. getting the turbo to spool up, but sucks on a street driven vehicle because of the added slip, it's much less responsive when you punch it.

Yeah I'm going to have to say I wouldn't get one of these.

I agree with therm8, you should see an .5 to 1 second improvement on the RX-8 auto.

If the stall limit is raised to 3,000 to 3,500 than this might not have any to only a little effect on it as a daily driver.

My understanding also, is that if you are going to go turbo or supercharger, than you need to do this first and add your various other performance mods beforehand too. Then have them customize your torque converter.

The benefit for launching is clear, so that leaves the daily driver and any slip issues. Again, this is something that RX-7 FD Auto guys should be able to help us with. Some of them should have went this route, would have experience with it, and it appears Mazda gave us their auto tranny.

If the RX-8(4AT) dropped a half a second in the 1/4 mile with a small impact on daily drivability then a custom torque converter is a steal for the price compared to other modifications you could possibly do. Maybe even beats out forced induction on a price/performance scale.

Still I'm a little more curious on the application on 06+ RX-8's. The extra RPM's could really pay off, but that would probably require modifications to both the ECU and transmission as well.

A customed torque converter would be great as it would probably makes the most of an engine and allows the drivers to concentrate on other facets of driving when racing. I've heard people thrashing an auto is useless but if you can drive a manual really well in a race where smoothness counts, you are better off driving an auto. Whether one is faster or not is a matter of gear ratios and most prefer a manual coz you feel more in touch with a car with one.

You know, I've played around a lot with the RX-8 Auto's manual mode. With the rev limit and speed limit cut, Trust me, the RX-8 auto manual mode becomes much, much more useful.

Its not bad and it lets you get in "touch" with the car too. When I do 0-60s, I use the manual mode. The great thing about it, is that the shifting is even more consistent than arguably M/T and clutch (I've played with my friend's RX-8 M/T too, but I own an Auto).

When we are talking supercharger or turbo, the issue of 4ports or 6ports, become less of an issue. It really starts to be all about whether or not the Auto tranny can handle the revs. If you can get an auto tranny to do it (ATF cooler, torque converter, etc...) than it can be superior to a manual transmission and clutch (of course die hard M/T people don't like to hear that). I strongly believe that there is no reason why the RX-8 auto can't perform as well or better than the RX-8 M/T. The Auto just needs the right mods.

Well done. The only thing about the AT is the power on demand and if a SC or Turb can fix that li'll prob we are set!