A stupid idea?
 

After giving alot of thought as to what would be a more complex mod as my next, I began to run though the various parts of the engine and trans (A/T....and no hatin :) ). I started to think of what some of my buds have done with their auto trans to make their cars quicker. So I was wondering.....would it be possible to replace the the stock torque converter to a high performance one with a stall speek around 2800 rpm. I am assuming the OEM TC has a stall speed in the range of 1800-2000 rpm. Now obviously I would not do anything till I can figure a good match based on rear end gear ratio and weight. As well as, finding out what the OEM converter specs are. I know there are some highly knowledgable rotary fellas on here like rotarygod that can guide me in determining if this a attainable feat or a potential disaster.

You have to love a thread titled "A stupide idea?"

Sorry mamccubbin but...I cannot resist...OK, so with the exception of me, do you have to be "stupide" to post in this thread? :D J/K

Well some might think so??? I'm just tired of waiting for performance mods for this car. We might see an Rx-10 before someone comes out with a SC or TC.

Too be honest, I've been thinking about this since my parents refuse to drive a manual, (i dont have the 8 yet. gotta wait till EARLY 2005!!!!!!!!). Why don't we just get a higher-end torque converter which can handle 9500 rpms. But of course we gotta change the gear ratios, the ECU, many other things. Doing a google search now.

Okay found some stuff.

There this company called PRO TORQUE which specialises in custom torque converters. They've also let you choose from a range of already tweaked converters for different cars which they've tested. And if you see here - http://www.protorque.com/prodln/pl_im.htm , it says it has a converter for the RX-7 although it does not list the product there.

That's what I get for being online at 1 in the morning.

Just teasing you a bit, that's what I get for being on at 1 AM too. I had to go back and correct my post after posting it the first time and finding mistakes in my own. :D

Hey, that's cheating! :)

But RX-7s only revved to 7.5K or so rpm anyway - that still won't be a converter that can handle 9.5K rpm!

Regards,
Gordon

The Auto redlines at 7.5k. I'm just lookin for a tried and true way to make the auto "quicker". I by no means think I can get the car to rev too 9.5k rpm. The torque converter is the reason why the auto has the lower reving engine.

Yup, but that 2K difference in redline is where ALL the extra power is. That's the reason why NONE of the MT mods will make the same power on an AT engine (well, that plus all the extra ports, extra intake path, and extra fuel injectors on the MT high-power engine to provide breathing and fuel for the extra revs). Have you read rotarygod's thread about why the AT low-power engine is not suited to modifications?

Regards,
Gordon

If the AT engine (which I think is similiar) can handle 9k RPM, and so does the converter, I think this is very possible.

Mazda Fould not find a torque converter that could handle the bigger engine. Hence we have the scaled down version.

There are many shops who can modify your factory converter for the performance specs you are seeking. Try calling the more notable companies such as TCI, B&M, and such. They will open up the converter housing and replace the bearings, vanes, one-way clutch, and impeller set(among other parts). The important thing is to have the info handy like engine torque, vehicle weight, rpm range, and desired "stall speed". Do a search on "Hot Rod Magazine"s website, as they had a great article on torque converter selection and performance. With our engines, if the aftermarket develops a version it is most likely to be in the 9" diameter range as our torque specs are rather low.

Charles

Since the RX-7 and the auto RX-8 have similar redlines, I don't see why you couldn't use a different one just fine. Yes you could gain some performance. I don't think the issue here is if he is trying to go faster than the 6 speed. He just wants to go faster period. Nothing wrong with that.

7.5K, and if the stall speed was higher on the FD, then there would be some benefit, but I would just look for an aftermarket solution such as level10. I've been trying to determine the stall speed myself and it appears to be somewhere between 1500 and 1800 rpm. That leaves alot of room for improvement. If you add an aftermarket converter, i'd recommend a custom tranny cooler as well ( i think there might have been a DIY here somewhere from quite a while back)

the point is not to rev higher, the engine won't flow much more air than its max at redline now, from what i've read in RotaryGod's posts. The point is to get into the torque band quicker.

huh?? the gain is in the higher stall speed, not that it's from an FD or anything. it's just to give you a better launch.

Well the gain would be a better launch, which would be a benefit. If you've ever driven an auto 8 or if you ever do, you'll notice this immediately. It's a fairly quick car once it's moving, but that idle to 2.5k start is really slow, and that is where the biggest improvement in 0-60 type driving can be had, short of big hp mods. I don't mean to come off like I know everything, especially since I don't :D , I just think an aftermarket torque converter might be a good idea, not sure how the warranty would be affected tho...

Here's what worked for me in the past: I determined that my torque peak was somewhere around 4K. So I installed a 10" t.c. behind a fairly well-built 350 Chev. w/a Powerglide and a 4.56 gear. In total, this package was not far off from that which we have with our 8's(with obvious torque output differences). This car launched on the torque peak and revved until 7.8K, then I shifted into second gear and ran it through the traps at 7.2K. With tirespin to 50 mph I still ran 13.3 @ 106. I would suggest that someone with an auto trans on their RX-8 do the same. Set it up to develop the "launch stall rpm"(which is different than the "brake stall rpm") at the torque peak and rev it as high as you like during the run. Any quality converter can handle the rpm's you deliver.

Charles

Cool....Thanks Charles. But...will it work? Any chance of screwing up the car if done right.

Exactly, I just wanna take off quicker/faster. I mean when you hit the gas in the auto it really doesn't get a good pull till 2500 rpm. I just wanna improve it. Everyone talks SC or TC...intake, exhaust, some nitrous. I guess I'm beginning to think about true mechanical/hydraulic improvement that hasn't been discussed so far with the auto. ?????

Well, how fast was the AT RX-7's take off? Fast enough?

first off, changing the tourqe converter will void your warranty, raising the stall will just give you lower rpm gains as described in other replys, the problem is that the transmission cases are not strong enough to handle the added tourqe, auto or manual, have seen the damage from tire spinners first hand, its not pretty, its not cheap, and its not warranty. I would recomend fuel and ignition enhancements, maybe check for an aluminium intake or look for more lbs, on the injectors, but at this time theres only research and development on performance. its still new to the world as is the computer design ect. mazda tech. 1000

Anyone know where this AT was sourced from? Level10 and a few others can beef the tranny up to handle more power and it's not all that expensive. They have kits available for Mazda cars but I don't know where the transmission comes from. I would think they would use the one from the Mazda 6 but the manual shift slots are on opposite sides(if that makes a difference)