I picked up my car yesterday from Sam at ByDesign! Holy SH**!!! It a damned animal now. I will do a separate forum posting here and on Rennlist to give a more detailed review. I think it will be useful for other forum members thinking about doing a non VTG conversion. My car (6 speed 2007 997.1TT) when I got it was stock 3.6L internals running 63VTG's, GMG intercoolers, full GMG exhaust and GIAC tune on 91 pump gas. Then about 18 months ago I had the motor fully rebuilt with 3.8L displacement, Carillo Rods, AMS intercoolers, and 68mm VTGs tuned for 91 pump and an ethanol blend (around e20). The car ran great and was a joy to drive. But I couldn't leave well enough alone, and I finally bit the bullet and had Sam at Bydesign do a full Xona conversion and also a methanol system. I upgraded the clutch to a twin disc Protomotive clutch. I had around 5,000 miles of seat time in the car on the built 3.8L and 68mm VTG set up. I picked up the car yesterday from Sam and drove home around 250 miles with the Xonas. I could not be happier. It's simply amazing. It is 100% dialed in and totally driveable. Amazing. 850hp/809ftlbs at the wheels on a Mustang dyno on e85, 750/750 at the wheels with 91 plus methanol. Again, I'm going to do a full write up as a separate posting. I had some big concerns and fears in going from VTG to non-VTG, as I imagine most 997TT drivers would. I can address those issues now that I have some seat time in the new set up. In summary- it is breathtaking, and I do not see a downside! I know I probably sound like a broken record on the forums here- but I can personally attest to Sam at ByDesign to being all that everyone says he is. He was absolutely fantastic, and his team of guys are true wizards and artisans.

 

Awesome news! Looking forward to hearing more about it...

 

Congrats on your car! Sam also did a fantastic job tuning my car with the XR980s. We went through 14 versions of the tune to get it perfect as we had a few hardware changes along the way. On very conservative 91octane file running only 19psi, we are putting 773hp to the wheels. We severely detuned the midrange from 720 ft.lbs to 610 ft.lbs in order to get a nice GT3 type power curve to make the car useable on the road course. Can't say enough about Sam, he did a hell of a job. Our plan is to swap in GT3 heads this winter to allow for a 8800 redline which should net closer to 830 at the wheels at 19psi.

 

Nice dyno plot, powderhound! Looks like it hits hard right from 3500rpm. Damn, I need a built engine, lol.

 

Fine tuning the ebc is going well. With 20psi target the deviation is plus or minus 5% and usually minus so I added a little offset...with a setting of 105 on the offset and target 20psi it slightly overshoots in a couple of spots but for the most part it tracks boost quite well. I think I will leave it at 105 offset and then add some targeted increases in boost to gently taper up the boost and then...done!

 

WOW! You have a VERY efficient set up there to be making that power with only 19psi on 91craptane!....and you guys backed it down from a street tune on top of that. Very nice & congrats!

 

What do you mean your done?!

You still have to go and do some 60-130 VBOX'ing my friend!...then your done....well almost!

 

Heh heh I know right.

I've noticed that with offset 105 it is more likely to slightly overshoot target in 4th gear whereas with offset 100 the boost was similar in 3rd and 4th gear. Maybe I'll try offset 103...

 

I decided that I prefer the way the car drives without any boost offset. It's a subtle thing but it seems that the off-throttle or part-throttle driving is slightly less smooth when the offset is used. Not a night and day thing but something that feels slightly less "oem like". The boost is more consistent between gears with no offset. I'm currently at the target of 20psi and am starting to taper up the boost by rpm. So far with taper up to 21psi the car is really starting to get near the "violent acceleration" point, which I like!

 

Best and fastest way to setup the hks is on a dyno. You can see exactly where it could use the extra boost. It will also make you aware how much torque it’s making considering your stock rods. You will find it needs a bit more after 5K then a little bit more after 6K to keep the power curve from dipping.

once your torque curve is set using the corrections, then simply changing the target will move that curve up and down the graph.

 

Where did the last 3 months go, lol. TT.brn, I do plan on finalizing on the dyno at some point. I am using an upward tapering boost curve, as you mentioned the power curve dips without it. From my fiddling I see that boost naturally rolls off above 5-6k rpm if you don't program in some taper.
I was struggling with just a slight delay in boost response around 4k rpm until I remembered that making tiny adjustments to the wg base pressure makes a difference and sure enough just changing the wg base pressure from 11psi to 10.7psi took away the slight boost delay, but there was a little overshoot in boost response. Quick adjustment to 10.8psi and looks like perfection so far...
Weather has been in the 40s to 50s in the morning so traction was a problem for 3rd gear datalogs. Even 4th gear is violent enough that I worry about losing traction. I'm 98% of the way there in terms of having the Xonas dialled in on pumpgas. It is vicious fast in the speed ranges I use, probably a little much for 5th gear pulls but I don't think that will affect me, lol.
The other night I had an opportunity...on the way to Mexico...3rd gear to 4th gear lazy shift, slight uphill and 3/4 gas in the tank yielded unofficial 60-130 of 6.4s. Times were taken from the datalogs so just provided for entertainment rather than a verified result. Once again I'd have to say that the Xonas were well worth the money over the 68vtgs I used to have...

 

Sounds like she’s running nicely! I’m glad you are getting some driving in- I’ve been unwilling to drive my car for the past few weeks due to the local wildfires here in CA. It’s literally raining (or more accurately “snowing”) ash every day and night. Everything is covered in fine ash all the time and I have stressful visions of ash plugging up the air filter and making it into the engine.

Indeed the Xonas are awesome, and I’m glad I listened to you and took the plunge. What’s awesome is that you get the old school analog 6 speed experience while keeping ahead of the newer cars- including the 992tt- in terms of raw power to weight. Drive safely and enjoy!!!

 

Yikes, sad to hear about the fires. Cali has certainly had it rough with Covid and now the fires. Hope things improve and you get to drive your beast soon. At least you don't have impending winter like me! I will drive the car until
the weather gets cold enough that traction suffers at which point the car goes into hibernation. No point in putting worthless miles on it since I plan on keeping it!

 

Well that's it for another season...got it back from the shop just in time before the snow and ice came. When I picked it up the guys asked me if I knew that my tires were worse than bald...I was like
"whaaaaaaat", they aren't that old. He showed me the places where the nylon bead was visible, lol. Looks like I'll be on the hook for new rubber in the spring, I think I will take the opportunity of getting
some new wheels and tires...maybe even "deep dish" as I've wished for since I first got the car but I think that style has passed. Here's what I really like:


I don't think this company is still in business unfortunately but I LOVE the look. Wife says they should be in black, lol.

I gave up on the dream of bigger brake discs...found a company that used to sell the caliper extension adapter to allow for bigger discs but they never replied to my inquiry. Besides, I don't know where to get larger discs without the whole kit anyway. I'll go with either Zimmerman or Sebro rotors and Textar/TRW pads.

I've unofficially started the penny jar for the 992 turbo S...finally something that makes me consider moving on from the 997tt, but not for another 5 or 6 years anyway...

Stay safe all!

 

Did you ever get your EBC set up to your liking? I think I have the exact same setup as you do, as far as turbos and mods, and also have the EVC6 2.4. My engine is out for a some off season maintenance.