Picked her up a few months ago. Great car but now at the point where it’s just not super thrilling anymore. Right now all stock except:

-Do88 Big Pack

-Cargraphic cats (I believe 200 cell…don’t know for sure installed by previous owner)

-Sharkwerks center bypass

-Sharkwerks metal water pipes and water lines pinned.



I don’t think I want to mess with E85. Hard to come by and don’t want an ECU switch that could possibly be switched to wrong position. Everything should be idiot proof and bulletproof, and not looking to do internal engine work. Not looking for HUGE power. 600-650 at the wheel on 93 sounds probably about right. We are only RWD on this car after all! Want to be able to take it to the track (road course) and not worry about hurting anything on 93. Call it 85% general street, 5% drag/straight line, and 10% road course, so power under the curve > top end peak power.

After a lot of lurking here, I think what I would most likely do is:

-Do88 inlet hoses

-63.5mm VTGs

-Proper tune to take advantage of this setup.



Does that sound like the optimal setup for what Im looking to achieve? Anything I should change on this setup or consider doing differently?

The turbos can be swapped without the engine having to be dropped, correct? How many hours should the shop charge for the swap?

Is there any advantage in already having a GT2 (housing is bigger I was reading somewhere) in the swap to the 63.5’s?

Will the stock injectors be sufficient for this setup? If not, what is involved labor-wise in swapping to larger ones?

Are the inlet hoses really that hard to install? Dont mind cutting out the stock ones.

I know that the stock clutch will probably need to be upgraded, but I suspect the previous owner already had it swapped. Trying to find out. Im thinking If the rest of this package can be installed without dropping the motor, wait until/if the clutch slips and then deal with that.

Don’t want to go to crazy with the modifications to this car and promise to otherwise stop here

 

Nice stable of cars!
The GT2 turbos have slightly bigger exhaust housing and clipped turbine wheel fins already.

I think some people have managed the inlet pipe swap with the engine still in but you could do just the turbos and tune now, and later on when the engine is down change the injectors, inlet pipes and clutch.

stock intercoolers are decent and probably okay. DO88 big pack better! check your intake temps at "typical" driving and you'll know if the stock ones are adequate.

 

Thanks for the reply! Wish I could say those were all my cars…pic was at dealer when I bought her.

I found from data logging that the stock IC’s were really inadequate for any sort of heavy use. The 997.1 GT2 uses normal 997TT IC’s and does not have the slightly larger 997.2 GT2RS IC’s, so I figured might as well get the big pack, even with the stock turbos, especially for track use.

So all that needs to be done with my stock GT2 turbos is to swap the intake housings then?

And turbos can be taken off and re-installed without dropping motor, correct?

Do88 has instructions for installing the inlets without dropping or tilting the motor:

https://www.do88.se/bilder/artiklar/pdf/do88-kit76S.pdf

Does not look *that bad* by scrolling through the PDF. I heard 4-6 hours total? Seems like a pain maybe not worth it just for 63.5mm

Don’t want to do the Xonas as don’t want to get too far away from a stock (looking) setup.

With just the 63.5 how much duty cycle are the stock injectors running? Would prefer to just get it tuned once with all the planned mods and be done with it (yeah, right I know how that does not work out!

 

Are the stock turbos not capable of 600whp?? I would think bolt on's with a Dyno tune would get you there no?

 

From what I was able to ascertain, stock 997.1TT compressors max out at around 480HP for the par, and stock 997.1 GT2s at around 530HP for the pair. Copied and pasted from elsewhere I found in my research to date:

997.1TT
5304 988 0060 & 61:
· Max HP limit – 480 HP for the pair
· Max compressor flow – 31-32 lbs/min
· Actual CW dimensions – O.D. – 56.1mm / Inducer – 43.3mm
· TH area – 4.05²cm
· S&W dimensions – O.D. – 48mm / Exducer – 44.5mm

997 GT2
5304 988 0080 & 81:
· Max HP limit – 530 HP for the pair
· Max compressor flow – 34 lbs/min
· Actual CW dimensions – O.D. – 56.1mm / Inducer – 45.1mm
· TH area – 4.26²cm
· S&W dimensions – O.D. – 48mm / Exducer – 44.5mm / with 15° clip for HCF resistance and higher flow

Edit: I believe these are quoted as wheel HP. 997.1 GT2's with just a tune and nothing else typically make just under 500 at the wheels. 530 sounds about right if you add all the other supporting mods.

 

Here are two STOCK TURBO 997's both making 600whp. One on 93 and one on e85. I think you can reach your goal considering you have a gt2 which comes with bigger turbos than a turbo.






​​​​​​
​​​​​​​

 

Those are two stock turbo 997"s both making 600whp. One on 93 and one on e85. I think you can reach your goal considering you have a gt2 which comes with bigger turbos than a turbo.

 

Hmmm..well I was aware that 600 WHP was easily achievable on E85 with Stock GT2 turbos and bolt-ons, but certainly not on 93. That is news to me.

Tom @ Champion said on another thread here that 65mm VTG's can give you just about 600 wheel HP on pump gas.

Are you saying that stock GT2 turbos are equivalent to 65mm VTG's? That does not sound right to me but I just dont know any better at this point in my research.

 

I'll throw in my $0.02...datalogged mass airflow from several different 997.1 turbos:

*1576 kg/h (~551 crankhp), GT2 ICs, IPD Y-pipe & plenum, FVD (M&M) exhaust (100 cell HJS cats, 70mm diam)
*1659 kg/h (~580 crankhp), do88 Big Pack (= ICs, Y-pipe, plenum, silicone hosing), unknown brand exhaust with 100 cell cats, ~70mm
*1598 kg/h (~559 crankhp), GT2 ICs, do88 Y-pipe, plenum, silicone hosing, unknown brand exhaust with 100 cell cats, 75mm
*within a month there'll be one with TTE750 turbos and do88 Big Pack / 75mm exhaust with 100 cell cats, very intersted in seeing how much it'll deliver
My own 996 turbo with 997.1 VTG turbos and do88 Big Pack / 75mm exhaust with 100 cell cats and center exhaust (ie short pipes) was dynoed 600 crank hp (1.2bar, 7200 rpm rev limit, +12C day) and datalogged mass airflow on the road 1702 kg/hr (596 crankhp, +20C day).

997.1 turbo's compressor wheel (BV50-2277) flows max about 872 kg/h. That multipied by 2 is 1744 kg/h and multiplied by 0.35 gives 610 hp.
997 GT2's compressor wheel (BV50-2280) flows max about 927 kg/h. That multipied by 2 is 1854kg/h and multiplied by 0.35 gives 649 hp.

610 crankhp x .85 (ie 15% drivetrain loss) is 518,5 whp. So over 520 whp claims with std 997.1 turbos (and gasoline) are, well, how would I put this...BS... Dynonumbers are dynonumbers, so easy to manipulate. Then again, if datalogged mass airflow is well below Porsche's numbers, my suggestion is to buy new MAFs and try again. They do degenerate during the years without throwing any CELs. I've seen several examples of this lately.

So sorry about the disturbance.

 

Pete, Not a disturbance at all. That looks like good research data. On the topic of the stock GT2 turbos, if im following you correctly, 649HP at the crank translates roughly to 552 at the wheels. That does not seem a far way off from the "just about 600 whp" that according to Tom, the 65mms are supposed to make, so it seems the 65mms are not much more capable than the stock GT2 turbos after all?

What should I expect to make at the wheels with just bolt ons and a 93 pump gas good tune?

 

Oh well, this a proper quessimate...on 997 turbos just a tune brings something like 520 crankhp. The exhaust is the largest retriction. On GT2...never had any tuned one at hand, but if in line with 7.1 turbos...up to 575 crankhp with just a tune. Maybe. They have better flowing turbines and apparently the exhaust too, but already higher boost pressure to start from.
Then adding a very free-flowing exhaust (100 cell cats) and a do88 Big Pack to really open the airflow you should be around 620-630 crankhp. There's one but,...you're close to maxing out your injectors. OEM injectors flow ~689cc/min @ 3.8 bar, which equals around 640 hp with 85% DC.

 

Probably not surprising there's not a lot of hard data out there owing to so few GT2s ever made, but based on the above, here's what we think we should be able to expect on pump gas:


If anything, I would venture to say that the stock GT2 VTGs would likely produce more than this with a tune and bolt-ons as I believe the 2011+ 997.2 GT2RS had the same VTGs but just slightly larger ICs and a hotter tune and was rated at 620 crank by the factory. Would love to hear from anyone who has firsthand knowledge of what they are capable of on pump gas.

 

I had the 63s on my 997tt and injector duty cycles were fine on pumpgas. When I had the Champion 68s the duty cycles on stock injectors were on the high side, and I upgraded to ID1000.
If you don't want to drop the engine then I'd suggest the 63s on your GT2. I thought the GT2 had the "upgraded" intercoolers. I ran those intercoolers for years even with my Champion 68s and they were fine
for street use and occasional track use. It all depends on how aggressive the tune is...more aggressive equals higher intake temps but below about 125mph it really wasn't a huge deal unless it was really hot outside.

You may as well be honest with yourself and ask yourself if you are going to want to do repeat stepwise upgrades...if so then go straight to the top right from the beginning! ie. get 68vtgs on your car with upgraded clutch, exhaust, intercoolers, injectors, intake pipes....and enjoy it. Should be fast enough for most people..

 

From how its been described to me, the driving feel of the 63.5’s, especially how im told they ramp up and respond to throttle inputs sounds more appealing than the 68’s to me, even if the 68s deliver higher peak power. Would be amazing to actually drive them both back to back to see for myself, but I can only go off of what others have said here and my discussions so far with the vendors / tuners.

So, in looking at the 63.5’s in more detail, they apparently aren’t so very different from the stock GT2 turbos, so I think what im going to do (at least for now) will be to keep the original stock GT2 turbos with bolt ons and a custom tune. Im told a good tune on those ought to yield about the same as what one could expect from the 63.5’s

I believe the previous owner already did the clutch. Don’t know for certain, so may find out if it does start to slip. If that happens, then we can talk bigger turbos and injectors, etc.

From the factory, the 997.1 GT2 (2008-9) came with the standard intercoolers, the 997.2 (2011) had the upgraded ones. I did some data logging and found that the temp on those stock units spikes pretty quickly and does not come down unless you let off on the gas. The Do88 big pack was the first thing I did to the car!

 

My recollection is that the 63s have a larger compressor inducer than the GT2 and that it would be worthwhile to upgrade the compressor side with the 63 wheel. Might not be that expensive these days.

I started off with stock car, then just tune, then 63s, then 68s and now Xonas. I documented the improvements at each stage and there were worthwhile improvements each time...the ramp up and "usability" of the 68s is really
quite good. I'm also not interested in just peak power, I daily drive my car.