Which direction should I go?, 6 speed or Paddle shift triptronic? Options

[RJMII]

I've been drooling over the Boxster S transaxles for a couple of years now, and told myself that when I got the Twin Turbo engine (with ridiculous amounts of horsepower for the 901) that I should upgrade my transaxle.

well, on my way home from Red Rocks I dragged a little trailer home with the new engine on it. It will bolt directly to my adaptor plate that I have now, while increasing my internal displacement by half a liter and adding another turbo. My winter project will be to get my car ready for Rt 66. (IMG:style_emoticons/default/smile.gif)

Which way should I go? Should I get the Boxster S automatic and add another cooler to my array and figure out the daunting task of setting it up to be paddle shifted; or should I go with a cable shifted Boxster S 6 speed?

[rick 918-S]

Chappy is running a 901 behind a 3.0? twin plug turbo. The power and torque come on after you have the clutch engaged so the theory is there is much less stress on the box. He hasn't broken his box....yet... (IMG:style_emoticons/default/biggrin.gif)

[ottox914]

Chappy is running a 901 behind a 3.0? twin plug turbo. The power and torque come on after you have the clutch engaged so the theory is there is much less stress on the box. He hasn't broken his box....yet... (IMG:style_emoticons/default/biggrin.gif)

I think its a 3.3 motor.

And I think, but could be wrong, that his 901 has a scavenge pump and the exterior has been plumbed to put sprayers on the gears/bearings to try to keep it together longer.

Crazy challenge, but I like the idea of the 6sp paddle shifter. When you master it, let me know, the 914T could use something like that.

[iamchappy]

Well your both wrong it's a 3.1, and the Big ? here is yet....... I do run a pump and cooler on mine but no spray bars(yet) and have short gears(MSZ) which helps reduce the torque loading between shifts and keeps the RPM curve linear, I also have clutch slipping problems so dont use my 901 as an indicator of how they hold up, but driven with care i do believe they will hold up pretty good.

As for shifters- paddle would be cool but i really enjoy using the shifter and clutch aspect of driving a car.

[pcar916]

To answer your question right off-the-bat. I'd go with a 914 transaxle first and then some other manual box if you wish. If the Boxster makes you tingle then go for it, but there are some serious mechanical issues to solve for that transplant, not the least of which is the starter placement. More on that from someone who's done it I reckon. As for your other choice, it's an individual thing but I don't like Tiptronics. When I choose to shift I want it right now, not after some undetermined period later. But that's just me and others really like them.

I've run a 914 transaxle with my 3.6L motor and a 2.7 before that for nearly 16 years now and the only thing I've replaced was a synchro while I had it apart to put install an LSD diff a couple of years ago. The synchro wasn't bad but I had another one on the bench that was a little better than that one. I'm plumbed for a cooler (-8AN) as well since the case was out, but it's a simple outlet/inlet (out: the drain plug / in: atop the diff compartment).

I've found that these boxes lubricate just fine without spray bars as long as the pump doesn't flow warm fluid any more than 3 - 5 GPM. With a big-flow pump and the oil at temperature, you would approach dry-sump conditions and that would require spray. Otherwise I think it's unnecessary. The big benefit is simply keeping the oil cool and that'll keep your box in fine shape. That said I have a few rules about our 914 transaxles.

- If you like to spin the tires in first gear then this box may break eventually. 2nd through 5th with the clutch fully engaged you can do pretty much whatever you want.

- Don't speed-shift. A 914 box in good condition will usually do that, but you're wearing out synchros, sliders and spiders, the latter of which are high dollar items unless you have spares around.

- Make sure the clutch is pushed all the way to the floor before shifting. This is true even for slow shifting. See the previous bullet for the consequences

If you really want to take this to it's logical conclusion you have a few options.
1. Don't shift... some folks would be better off with this option but it's a little extreme (IMG:style_emoticons/default/beerchug.gif)
2. Shift as little as possible. Most folks shift more than they need to.
3. Double-clutch
4. Match revs both up and downshifting.

Good luck

[Andyrew]

Seriously how much power are we looking at? Those automatics can shift quite fast, however they cant hold the power very well.

[RJMII]

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.3sx.com-8112-1285162503.1.jpg)

That looks like a good place to start. (IMG:style_emoticons/default/smile.gif) Take in mind, that is a dyno graph from a 5000+lbs car with awd.

[Andyrew]

Thats a nice little torque curve! What vehicle is that?

[RJMII]

It's a 3000GT VR4.

LOTS of upgrades are available, and serious hp potential. I've got the newer 3.0 (93+) that has the crank sensor and 4 bolt mains. We're going to pull the pan and see if I have a cast or forged crank... if it is forged, it could be a JDM unit. Right now it is a direct bolt in to replace the 2.5 single turbo v6 in my car. (IMG:style_emoticons/default/biggrin.gif)

[Andyrew]

5000lbs for a 3000GT VR4?

3800 lbs maybe, but 5k? I know they are pigs but they are 2 seaters... Hell my Audi A4 quattro is 3400lbs...

[RJMII]

You're right; Curb Weight, 3797 lbs.

I guess my 5k+ number represents more so how bad I am at guessing weight.

[Andyrew]

Funny 3800 was a guess!

Anyways no big deal, just thought it was odd! I thought you were talking about a turbo deisel or something (IMG:style_emoticons/default/biggrin.gif)

[RJMII]

They were heavy enough that they had to redesign the AWD system in 93. they went from an 18 spline split off shaft to a 25 spline. The transfer cases were too weak to handle the torque with that heavy of a car.

my 5k guess also shows how much of a pig I think they are - weight-wise. lol

nice guess! The engine is still sitting on the trailer; sitting there saying "put me in". I sure am looking forward to feeling better. (IMG:style_emoticons/default/biggrin.gif)

[Andyrew]

I hear you! My Audi is down because my aftermarket turbo is in need of a rebuild (after WCC 2010, coming home it started making a noise... I parked it when I got home).