Hi Guys,
I own a 2007 997.1TT, manual 6 speed. I've had the car for a couple of years now, and it is my semi-daily driver. Over the last couple of years, the car has undergone several iterations of changes and modifications. I got the car with a decent set of GMG modifications, all done by GMG in-house in Santa Ana. When I bought the car, it had stock 3.6L internals with 63mm VTG's, GMG intercoolers, full GMG headers and exhaust (with cats), and a custom GIAC tune. It has the DSC suspension module, as well as GMG sway bars, lowering springs, etc. To make a long story short, soon after I bought the car, I had GMG do a full rebuild on the engine. We did a 3.8L conversion with Carillo rods, EVOMS headstuds, GT3 oil pump, and a few other things. I also had the VTG turbos upgraded to 68mm. I worked extensively with EVOMS on a custom tune and was running 91 pump mixed with e98 to make a blend of e20 or so. The motor ran beautifully. My 60-100 times were 3.1-3.2 seconds. 60-130 times were generally around 7.4 seconds- my fastest was 7.25 seconds. These were single 4th gear pulls with no shifts.

After around 5,000 miles and 18 months of seat time with the built 3.8L and the ethanol blend, I was getting a bit tired of always toting VP racing e98 around to mix in whenever I filled up with 91 pump. And like everyone who's reading this, I wanted more. More power, more torque, and more immersion while driving. I do not track the car (I have a dedicated track car). I wanted this car to be a reliable street fighter and daily driver. I love driving, and I view my car as my mental and physical sanctuary and therapy. After doing quite a bit of research and extensively communicating with Sam Ahdoot at ByDesign, I finally decided to take the final plunge and get rid of the VTG's and go for the conventional turbo swap, in this case, we decided on the latest version of the venerable XonaXR980- now called the XR1000.

My concerns about jumping from VTG's to the Xonas were many......would the lag be really bad, how would the daily drivability be with speed density tuning, would the EBC be a big hassle, etc. I discussed these issues extensively with Sam and he was very open and honest with me and also very reassuring. For those of you who have not interacted with Sam Ahdoot at ByDesign- I can tell you that his legendary reputation is 1000% well-earned and extremely well-deserved. He is simply awesome for lack of a better word!!!!! I am only a few hours away from the Los Angeles area, so it was the natural choice to drive the car down to him, and have him and his team of craftsmen and tuning wizards actually do the entire conversion and tuning on site and in house.

So here's what we did:
-Xona XR1000 with Tial WG's
-Tial Q50 BOV's
-HKS EVC
-IPD Plenum, Y-pipe (the big ones) GT3 TB
-Prometh methanol injection
-ID1300 injectors
-Protomotive twin disc conversion using sachs 487pp and GT3RS LWFW
-Full custom Tuning by Sam- including full Dyno and street tuning
-Tunes for 91 pump, 91 +meth, e85
-Retained my existing GMG headers, full exhaust, 200 cell sport cats, AMS Intercoolers

So here are the end results!!!! All dyno pulls were done at World Motorsports on their state of the art Mustang awd Dyno. This included the initial baseline dyno with my 68mm VTG set up- I had them dyno it with my 68mm VTG set up before they did anything.
-Baseline dyno 68mm VTG: 601 wheel HP/ 610ft-lbs
-XR1000 91 pump: 687 HP/654 ft-lbs
-XR1000 91 + meth: 800hp/776ft-lbs!!!!!! I rounded to 800 wheel HP. It was hot in the dyno room and the actual number was 799.567!!! This tune was a bit aggressive so Sam dialed it back a bit so as to not lean on Meth so much. See next line.
-XR1000 91 + meth FINAL street tune: 750hp/750 ft-lbs. This is my daily driver tune. 750 wheel HP. That should get me from A to B.
-XR1000 e85: 850 HP/809 ft-lbs. HOLY ****.

Driving Impressions: Holy crap this is car fast!!!!!!!!!!! I picked up the car last week and drove it home. I briefly drove the car on a lower boost setting (22 lbs) on e85 when I first picked the car up. I briefly got on boost a couple of times, and I knew the car was a beast when I hit a small irregularity on the street at 110 mph and a could feel the wheels spin and loose traction as my TC dash light lit up. The freeway was empty of course (Covid has helped in that regard). The rest of the time home, and for the past few days, I've been driving on the 91 + meth file, 750/750. The car is a monster. But it's also very very well behaved when off boost. It's almost too good to be true. How could a car that has such brutal acceleration and power be able to drive around town without a hiccup? Thank you Sam!!

Here are some observations that may be helpful to those of you who are thinking of this type of conversion:
-The lag and boost response is better and improved compared to my 68VTG's. Stange but true. The lag is not as bad. The 68 VTG were not particularly laggy, but there was some. I know turbo lag BTW. I have a hot-rodded single turbo 930.
-The car is ungodly fast compared to before. That's the obvious observation.
-Here's the one of the best aspects of these turbos compared to my 68 VTG's- with my VTG's, boost would fall off when shifting. When driving fast/aggressively for example, the 3d to 4th gear shift would result in a split second (around a 1/3-1/2 second according to my Racelogic curves) fall off in boost. You could feel it. You'd shift and sit there and wait for boost to start cranking again. This is now gone with these turbos!! The BOV's are quite noisy back there, so they are doing their thing very effectively. But man is it nice to shift and be back on boost essentially instantly. This is a huge huge improvement in my opinion.
-The twin disc Protomotive clutch is awesome. Just a little heavier feeling that my old set up (487pp and LWFW). I love it. It's a brute but feels almost like stock.
-I did a couple quick 60-100 pulls in 3d gear- 2.7 seconds on 91+meth. I did a lazy shift (0.6 second shift...still breaking in clutch) 60-130 and got 6.4 seconds. When I look at my 3d gear pulls of 2.7 seconds, and look at my 4th gear 100-130 time of 3.0 seconds, you get 5.7 seconds if this car were a PDK.... probably faster than that because the car would still be in better powerband up through 60 still in second gear. Either way, it is very fast compared to before.

In summary, I could not be happier with my decision to do the Xona conversion. The car is too awesome to be true. I cannot say enough about Sam Ahdoot and his team. This build is different than most because this was actually done in person by Sam and his team!! I am sorry for the length of this posting- but I hope it sheds some light on some of the potential questions and concerns in doing a non VTG conversion. I am very very happy with it, and I do not see a downside. If anyone is thinking about doing this, I would encourage you to take the jump. And if you are in the western part of the country I would also highly recommend you take the extra time and trouble to send your car to Sam!!!

I will be posting photos. I'll also do a post on Rennlist.

Keith

 

 

91, 91 Plus Meth, baseline 68VTG

 

The beast.

Clean Shop!!

Methanol Gauge- awesome!

Quality work by Sam!!

Meth Tank- beautiful workmanship


Look at that weld. Wow.

Huge turbos!

 

Again, a shout out to Sam Ahdoot at ByDesign. The tuning on this car is beyond phenomenal. Smooth as silk when tooling around town and a monster when let out of its cage. Sam was so great to work with, and the nicest guy in person as well. A true asset to our community!!!!

 

Awesome results! Glad to hear everything went well. Looking forward to seeing your pump boost curve . I'm up to 20psi and am training the ebc which is controlling boost quite well at this point.

 

Really nice results and extra nice being able to take advantage of a built engine. The torque its putting out for a daily must be quite fun . Even better is knowing there is more left on the table if you add more fueling

Enjoy it!

 

Sam is great. Did the tune on my XR980s. What boost are you at to get the 687whp on 91 without meth?

 

Do you plan to try any quarter mile runs? Sounds like a fun build. Those motor upgrades are expensive! Should be a high 9 second car on e85

 

On 91 without meth, boost is at 19lbs.

 

I don't plan on doing much quarter mile stuff. Indeed with you in the drivers seat it may be a 9 second car! With my drag strip skills......not so likely!

 

19psi (1.3 bar) is exactly what we are running.

 

Is 19psi on a built car "different" from 19psi on a stock engine? i.e. does the increased engine efficiency make more power from the same boost? I'm targeting 20psi and will then taper the boost up above tq peak to 22-23psi above 5500rpm. Haven't dynoed it yet...but based on the performance numbers I think I am still in the "safe" zone. Let's hope so, lol.

 

Bogg it's different in terms of their 2 cars have increased displacement, and at least pwdrhound also has increased VE. So we would expect them to make more power at the same pressure. Though everyone is aware just be careful comparing across different dynos.

Bogg your car won't be that far off from what they are seeing though.

 

I really was hoping to see ##s in the 1000s on kill • e85.