I just wanted to interject to the thread starter that when you install the AMS intercoolers you do have to modify the plastic housings that the intercoolers sit in so going back to the stock ones will require some zip ties or buying new housings - probably not too expensive =left
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As far as an intercooler the AMS has proven to be world class in my testing - my AIT temps are always ice cold as close to ambient as you can get =left
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Only disadvantage is given the proximity to the turbos etc when you are not going through air - e.g. in traffic they do start to pick up soak which is quickly resolved as soon at you hit 60 mph or more they cool right down again =left
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I would not try and save money on intercoolers - the Garret cores in the AMS units are about as good as you can fit in the stock location - they are good for way more power than I will ever make =left
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Finally - unless you are going to build the motor and go with something than can spin much more than the factory rev limit or with a much larger displacement I would think that VTG turbos can get you all the performance you would ever want with minimal lag =left
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In my situation - even on my pump gas map I am blowing the tires off in 2nd and 3rd gear at 21 psi of boost and on E85 it is totally insane - pushing the limits of the stock rods with ease =left
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Here is a short video clip of my car in action yesterday

Car in the video above has poor boost control - you can hear it.

Care to clarify that statement and point out to how it would compare to “good” boost control?

If you listen to when it comes on boost, you can hear it oscillating. It's really common on VTG's and needs a lot of tuning to get right.

I would be happy to show a data log - the boost is very stable - if anything I think you are mistaking the sound of the tires spinning and grabbing which the car does in gears 1 - 3 in sport mode when it comes on boost - it is very hard to get a handle on anything as the car is all over the road in the rear end - (you have to have it pointed straight ahead)

Could well be wheels spin yes but it sounds like the vanes moving. If you have a log and it's all good then case closed :)

Update time

It's been a rather expensive month and a half, automotively speaking...
Unexpected additional maintenance on the 997.1TT,
a blown turbo on my S7 - necessitating RS replacement cores, of course :D,
and I've managed to total the wife's E70 X5 - first car I've written off in 20 years of driving. So that'll be an F15 X5 upgrade for her, thank you very much... :rolleyes:

So, the 997 went into the local Porsche indy shop to get all the parts fitted in the first week of April

All was well, until fitting the 2.5 clutch... turns out the chattering I'd heard coming from the engine bay was due to a sketchy dual mass flywheel - the sprung core had gone bad and when turning the secondary by hand, it felt spongy & very slow to return to the base position.

So, in went a lightweight flywheel (AASCO I think), sprung clutch disc + the supporting guide tube and release bearing... All for cheaper than the cost of an OEM DMFW locally (which would have run me around $2200)

While they were at it, I opted for replacing all the coil packs as well, as the car was still running the factory set from 10 years ago - most of which had started cracking where the shaft meets the body (that's what she said :p )... apparently a sign of impending not-too-distant failure.

On the bright side, all coolant lines are still firmly located in the block - so apparently there might be some truth to 09's being less prone to this issue.

So now, as it stands, the car's running the following:

Custom de-cat 3" exhaust
Do88 Big Pack intercoolers
Do88 Turbo Inlet Pipes
Do88 Y-Pipe + 82mm Plenum
GT3 82mm Throttle Body
BMC flat panel filter
Injector Dynamics ID1300x2 injectors
Lightweight flywheel, sprung clutch, 764 pressure plate
Cobb AP v3 with OTS Stage 3 1300 91 octane map

I've had it back for 2 weeks now, and I'm very impressed with the difference.

It's markedly quicker to spool the turbos, and way more responsive in general... acceleration is rather, uhm, brisk. I'd guess it's making in the region of 470-ish whp.

Frankly, I'm starting to doubt again whether to go all out for Xona XR980's or GT30's... a set of 65 or 68mm VTG's may be just what the doctor ordered - ultimate peak horsepower figures be damned.

Of course, there are a few niggles... mostly down to mapping. The Cobb off-the-shelf map is pretty darn good, but it's hardly perfect. The car is an absolute pig on fuel now, and initial throttle tip in can feel a bit "wooly", for want of a better word - particularly on the cold start map. Also, the accelerator input curve is a tad aggressive for my liking. I'm sure all of these things can be addressed with a custom map though, hence I've already thrown some cash Sam @ ByDesign's way for a custom map, that I'll start logging for over the weekend... hopefully there's another 20-30 whp on the table on pump fuel.

Also, the new flywheel and clutch setup has been a bit of a learning curve, necessitating finesse and steady feet with minimal throttle input to get off the line cleanly without either stalling it, or revving the engine up like some teenager driving stick for the first time - this is very much at odds with my former quick-blip-and-go approach on the stock DMFW - and it doesn't suffer poorly modulated 1st-2nd and 2nd-3rd shifts kindly when you've got your foot pinned and chasing the limiter

And of course, there's the stalling issue when clutching in at RPM or messing up a standing start - particularly when running the AC. It's immensely frustrating, but I'm sure it can be addressed through mapping.

I can understand why a lightweight flywheel on the 997.1 TT is so polarizing.... it makes you work harder and sucks in traffic, but also makes it more rewarding when you get it right.

All-in-all, I'm happy as things stand - the car is a hoot to drive, and will get even better going forward.

I'll post some pics when I pull them off my phone.

Oh, and as a side note... I'm pleasantly surprised with the Do88 intercoolers - I would imagine they'd remain unflappable up to some very high horsepower numbers.... I've logged inlet temps, and the efficiency is remarkable. Inlet temps will hover at around 12°C above ambient temperature during normal low speed driving, and will then actually drop down to around 4°C above ambient over the course of a 40-100 mph run...

Cool update and build though I think you have a typo in your hp # above (470) -- seems that setup would be throwing-down more like 670 or 770 (?). My car with lesser (stage2) mods dynoed at 547...

The upgraded S7 must be a blast as well. I considered an S6 or S7 as a daily a while back when my S4 finally gave up.

It's on stock turbos and 91, 470 is bang on.

Thanks!

Though, frankly, after reviewing some logs, even 470 whp seems a bit optimistic... judging by the MAF readings on a log I did last week (but only downloaded today) - where it only flowed around 410 g/s between 6000-7000 RPM, conventional wisdom of 0.8g per horsepower would suggest peak numbers of probably more in the region of 440 whp (520 crank hp)... so perhaps the Stage 3 OTS tune is a little more conservative than they're claiming - or other factors like timing and VE not telling the full story.

It feels significantly stronger than stock (410 whp for most stockers, give or take), subjectively speaking - but I've changed so much hardware in one go, and there's so much more torque from 3500-6000 RPM thanks to the mapping, that it's somewhat difficult to compare apples vs apples in peak hp numbers.

I suppose I'll need to go do a 60-130 run or a virtual dyno to get a more accurate guesstimate of what the car's making now. Or I could just go and slap it on an actual dyno. :p

Stock 997.1 turbochargers apparently max out around the 480-500 whp on pump fuel - and could probably push 530-540 whp when tuned aggressively on E85... at 5000ft altitude where I'm running it, and our relatively crummy 95 RON fuel, the upper limits are anyone's guess.


S7 is the perfect daily driver - I love that thing... APR Stage 2, full decat exhaust and SRM intakes saw it make around 500 whp. Oversize RS turbo's should make a bit more on the Stage 2 file, but should then be capable of up to 600whp on a Stage 3 map... Once again, the altitude variable might impact the ultimate number, so we'll see.

A bit of an update...

After a few map revisions, the the 997 Cabrio is pulling really nicely... Sam's a bit concerned about the high wastegate duty cycle, but given our crappy 8000+ DA's at 5000+ ft elevation, it's to be expected.

https://i.ibb.co/nmDDVyq/image1.png



A pretty respectable 100-200 run, considering it wasn't even done in Sport mode, and done 2-up in a cabrio... should make for a mid 8-second 60-130.

Truth be told, I think the Dragy's DA is wrong - actual DA should have been in the region of 7000 ft based on the TRC app's data at the time.

Even so, having done a bit more poking and prodding, comparing local Dragy results, etc, it seems even fast turbo cars are quite a bit slower at these kind of DA's than they would otherwise be at more reasonable DA's. A calculator I found claims that a 7000 DA corrected to sea level, would have seen this same 100-200 run completed in the region of 6.9 seconds.

I need to log it again so Sam can do another map revision with tweaked boost and timing - but I haven't even driven the car in nearly a month now.

Turbo upgrade plans have been shelved for the time being, as we're in the process of buying a new place.

Your mods are not much different from mine (mine still with stock fuel system) and my best 100-200 is 6.1s corrected. Also on pump gas only, poor 98RON. I can only see it related with weak ecu tune.

Keep in mind that stock VTG push almost the same than hybrid on pump gas because egt is already a issue. The hybrids just make it worst generating heat in the small vtg housing. You can only take advantage from it with race fuel or E85.

This car is on 95 RON equiv and at eleavation so can't be compared to 98 RON,

I've just done 0-186mph in 23s and 207mph on stock houings with larger comp wheels using 60/40 water meth so they do flow more than standard items.

207mph with what redline RPM? Stock size tires?

7300, stock tires. With meth I hit the limiter before the timing beams, without meth I'm just about on it at the beam. Looking to goto 20's now...