[OpenFlash]

Hi guys,
We've been working nonstop for the last 3 weeks on single turbo 6AT tuning. S Specifically how boost/throttle is controlled during short shifts (upshifts). It's during this specific condition that over-torques the 6AT clutch pack. So we developed Procede boost control code to manage torque during these mid-shift conditions. It's working quite well on the road (i'll post up logs later this week). But today was the dyno to see what it is currently putting down to the ground on the Dynojet at full boost.

We still aren't completely done with the WOT calibration (still have to do pump gas mapping) but we are getting close. So far, running 93oct+meth, it put down some good numbers at just 20psi tapering up to 23psi by 6300rpm.



On the dyno during a 4th gear pull, the 58mm turbo on the 6at spools up exactly as quick as the 62mm on a 6mt. But on the road, it has significantly faster transient response making it a good match for the 6at. And since we are currently rev limited with the 6AT upshifting at 6500rpm, there is little sense in going with the bigger 62mm turbo. In the end, running similar boost curves, the 58mm 6AT puts down nearly identical power/tq as a 62mm 6MT all the way up to 6200rpm. Above that, the 58mm 6AT power curve tapers off boost due to higher back pressure levels and in preparation for the upshift while the bigger turbo 6MT still keeps climbing and climbing:



The run duration on a 570+whp car is pretty short. So short that the dyno doesn't load up the car properly which means the turbo doesn't get a chance to spool up as fast as it would on the road. So I did a partial 5th gear pull which gives a better idea of what to expect on the street. In 5th gear, we mapped the Procede to reduce high RPM boost target a bit to compensate for the higher IAT and higher engine load (hence the power power number). We also had to stop the run early to avoid hitting the max speed limit on the dyno (160mph) which would delete the run. But the recorded low end is still very representative of real-world behavior (400lbft@3400rpm):



As time goes by, we will get more and more aggressive with these single turbo tunes. I have no doubt that we can achieve 600whp even with the small 58mm turbo. Especially once we are able to remap the TCU to shift at 7000rpm instead of 6500rpm. But for now the car runs fast, shifts quickly and doesn't trigger transmission codes/problems

Cheers,
Shiv

[D_Smiderreen]

Pretty impressive Shiv, great job. There is light at the end of the tunnel for us 6AT guys.

[WINGNUT]

I hope my wife doesn't find out about this. She's a speed freak and if she finds out that she can have a 335 with 600hp in an AT platform, she may buy a car and make it happen before I can, and she's spotting me a car. Lol

Keep it up Shiv.

[plague]

nice shiv! 600 whp on the 58trim should assume 700+ on the 62

[seoulmandmd]

So 58 only for 6at.
Not that almost 600 hp is anything to laugh at!

[Stucks]

Wow, that's pretty cool! 6AT single turbo 335i's should be rather easy to get into the 10's.

[Dr_Dirt]

What is the stock turbo sized at for comparison?

[chris b.]

[Mr_PharmD]

very impressive as usual.

How much meth is the 58mm turbo using and is the high back pressure due to maxing out of the turbo?

[themyst]

So you are saying don't short shift the auto? Not that I'd want to given that turbos flow characteristics. By reducing torque before and after the shift though you'd cost the car some acceleration time I would venture to state. I've done something similar by tapering off very aggressively after 6500 RPM but it simply reduces momentum and the car will perform poorly.

Or we could simply build the transmission, chalk it up to a requirement and not worry about it. The user picked the transmission, now the user can pay to build it.

[JMARS]

This all looks very exciting, I'm curious though if the AT kit would also fit a MT car? I'm planning on picking up a 6spd 335is e93 early next year BUT I'd love put this kit on whenever it gets released on my current AT 335i...

[cupertinosteve]

Originally Posted by JMARS

This all looks very exciting, I'm curious though if the AT kit would also fit a MT car? I'm planning on picking up a 6spd 335is e93 early next year BUT I'd love put this kit on whenever it gets released on my current AT 335i...

I'm pretty sure the kit is interchangeable ... its possible you may run out of breath on the 58mm turbo on the 6MT since you have nearly a 1000 rpm more to run.

[cupertinosteve]

Originally Posted by themyst

So you are saying don't short shift the auto? Not that I'd want to given that turbos flow characteristics. By reducing torque before and after the shift though you'd cost the car some acceleration time I would venture to state. I've done something similar by tapering off very aggressively after 6500 RPM but it simply reduces momentum and the car will perform poorly. ...

I know that the up top taper is there to the impending shift that will happen - whether user or TCU induced.

With regards to the short shift and non-desirable stress that is added from going to post-shift boost pressure to full boost ... there is something in the works to make it really sweet.

And yes, i have set aside budget for a new transmission. I'd like to see what a stock 6AT can do, so we will all know where the limits are.

[Eleventeen]

I have an auto, so I am most interested in how things develop with this kit, even if it's not as aggressive as the 6MT kit. What meth mixture are you running with this turbo?

That's some nice power, B.T.W.

[OpenFlash]

Yes, the turbos are all interchangeable and I think the 58mm will be a nice match for the 6mt for those who aren't going after big numbers. I suspect it will make 600whp on meth and 500whp on pump. Just speculation at this time as we have not tested such a combo.

[OpenFlash]

Originally Posted by Mr_PharmD

very impressive as usual.

How much meth is the 58mm turbo using and is the high back pressure due to maxing out of the turbo?

Currently spraying 1000cc/min using an 80/20 mix. The 58mm turbo definitely isn't as fuel hungry as the 62. Most of the top end roll off is caused by boost reduction in preparation for the upshift. It goes through the shift so quickly, you don't even feel or able to log any pre-shift boost drop.

[Bakeme521]

Originally Posted by D_Smiderreen

Pretty impressive Shiv, great job. There is light at the end of the tunnel for us 6AT guys.

Until the transmission pops

[onesuperboi]

Is there a smaller turbo that could be used that could offer similar power but even faster spool up?

[nafoo]

Originally Posted by shiv@vishnu

Currently spraying 1000cc/min using an 80/20 mix. The 58mm turbo definitely isn't as fuel hungry as the 62. Most of the top end roll off is caused by boost reduction in preparation for the upshift. It goes through the shift so quickly, you don't even feel or able to log any pre-shift boost drop.

When are you taking the AT to the track?

[OpenFlash]

Originally Posted by Bakeme521

Until the transmission pops

I'm pretty confident they should hold up well.

[Eleventeen]

Originally Posted by onesuperboi

Is there a smaller turbo that could be used that could offer similar power but even faster spool up?

57.99mm

Precision has quite a few turbo options, but the 58 mm seems to be delivering some nice power for it's size. For reference a GT3582R is 61.4 mm and is rated at ~600 HP.

Precision.pdf

[vereak82]

DAMN! Thats awesome i bet that A/T is a riot to drive