Hi,

I've had my 996tt tiptronic for 2 months now and I'm finalising my mod plans specifically with a goal to improve the driveability of the car around town. In its stock form I find the 996tt a little "constipated", by this I mean the motor does not seem as free revving or eager to get up and go compared to other turbo cars I have driven.

To improve the way the car drives around town I figure I have to concentrate on the following for mods:
- Turbo spool up as early as possible.
- Select an ECU flash / tune that improves the low end torque and improved throttle response
- Try to improve the air flow throught the engine


I'm not looking for high absolute HP numbers and would trade top end HP for more bottom end torque and better throttle response. My goal is for a 600hp (crank) setup.

So for quick spool up, I have to stick with either the stock K16's or a hybrid. I want to try the 16g hybrid and will run it with a 1.0 bar spring & external actuator.

For the ECU flash I figure I should use a tuner who can customise the flash to take advantage of the 16g as well as adjust the characteristics of the flash for low down torque and try to keep the torque peak as flat as possible.

Now its the improving the airflow through the engine that is the trickier bit, and I'm not sure of the relationship between better airflow and torque down low, especially for a turbo car. Its obvious that better airflow will improve the top end power, but in my research it seems that there is contradicting information about what improving the airflow does to the low end torque, and it seems that in some cases improving the airflow will take away some of the bottom end torque for the top end HP gains.


The airflow mods I'm looking at after much research for better driveability are:

- swap out the stock airfilter for a better flowing aftermarket one. At the 600hp level it seems that this will only have a marginal impact but a pretty easy/cheap mod to do

- Better exhaust. Drone with a tipronic is a potential problem for me, but the ability to have a better sounding exhaust note, lower weight in the back and better exhaust flow (eg. 70mm pipes) makes this a mod worth doing, and it does improve both the low end torque and the top end HP.

- Do the DIY header port (grind back the welds at the opening of the headers). A little like the airfilter mod, it may not gain any significant power, but it is easy to do while swapping the turbos. However I have had reports that this mod may actually reduce the low down torque, but I'm not sure why that would be because if anything it will help the exhaust turbine spin up earlier as the exhaust gases will flow faster?

- Add an extra cold air intake snorkel to the stock airbox (the "jimmer23" mod https://www.6speedonline.com/forums/...0&postcount=22). This won't improve power, but as I live in a subtropical climate, it will help get more cooler air into the engine for the 6 months of the year when it is hot. This is one mod that I know works well for turbo cars in hot climates.


How would the following mods improve the low down torque, throttle response and early turbo spool, even if they don't net any top end HP:

- Aftermarket airbox. Some gains are claimed, including improved driveability but just looking at the stock airbox & filter which is a good design and plenty of volume area for the filter will be hard to beat. A better filter and 2nd intake snorkel seem the best approach to me.

- Larger intercoolers. I can get some of the improvements a larger intercooler will bring with the 2nd air intake snorkel (more cool air). At 600hp crank the stock ICs should be sufficient.

- Better intake plenum. Would improve airflow but only marginal gains at this power level.

- Using an external wastegate. Not sure about this mod for increased torque/driveability. For the K16/16g with better wastegate springs I'm guessing an external wastegate may help with the exhaust flow?

- Using a higher boost, say 1.2 bar. Not sure, probably just benefits mid rev torque?


Is there anything else I should be considering to improve the driveability of the car around town (or am I on the wrong track with the mods above)?

Thanks for your input.

 

From the sounds of it I think you should contact Kevin at UMW for some of his "zero clearance" turbos. VERY fast spooling at no lag.

 

Buy a Honda Civic for around town and keep the TT for those "special moments"

tw

 

Pretty long post, sorry if its hard to digest.

The 996tt is still an awsome car, and is a great car for around town, but as I'm exploring mods I'd like to better understand which mods make the motor more dynamic around town versus mods that work well for track / high speed runs / drags. Sometimes on this site when mods are discussed (eg. airboxes), its not clear if these mods are aimed at just getting more top end HP or if they improve matters in normal (spirited!) driving conditions.

I suppose I am asking what mods should I look for that will improve torque low down, quicker spool up and better engine response in the low - mid rev range.

Thanks!

 

I think a LWFW is exactly what your looking for.

 

great for free revving but not for daily driveability around town

 

Gotta read the post - its a tip

^

 

Dean,

I will offer some advice based on my experience. When my car was stage 2 - K16's, flash and exhaust, I added the V-flow and felt much better throttle response and a stronger onset of boost. I used the V-flow for 3 years and I think it is a great mod, so I would consider the V-flow, if I were you. As a simple package, I would recommend a hybrid turbo of your choice, wastegate upgrade, tuning to match, V-flow, ported headers and exhaust. That said, I have a 6 speed where I am more apt to notice the throttle response, especially when blipping the throttle.

I subsequently went to a stage 4 with K16/24 hybrid's, wastegates, ported headers and V-flow and noticed a slight increase in lag (very slight), but much more power overall. The increased lag was not even noticed after a day or two, but the added power remained noticable and was enjoyed daily, during spirited driving. Finally, I went to the K24/18G's with fuel and realized less lag than the K16/24's with more top end (best set-up out of the three). All of these packages offered similar feeling low end torque (especially in 1st gear where any of them will light up the tires, so you can not really use all the torque), very quick turbo spool and excellent manners around town and on the highway.

The biggest difference appears to be that with each upgrade in turbo, the power is sustained longer - making the car ultimately faster and more fun in spirited situations. With the smaller turbos you have the quick spool, but it's over quickly and the car needs something more to keep it exciting. IMO, when you can combine that quick spool with a longer sustained thrust...that is when you really start to feel the "wow" factor. You mention your goals include throttle response during spirited driving - I have found the best throttle response I have had by far is with the K24/18G Protomotive 700 system (largest turbos of the three), but that is a fairly involved package. The K16/16G's you mentioned appear to be very interesting and based on Michaels dyno could be a sweet level, as they dynoed more power than my former K16/24 package (now Elliot's) that was/is pretty quick. And for the cost of the K16/16G conversion - I think you may be on the right track...

 

I would concentrate on the suspension before I modded the engine.

 

Go with Kevins UMW flash. Best thing in the world. Boost builds quickly at 2500rpm and Full boost at like 3200 rpms!

 

Kevin at UMW has a new K16/K24 turbo housing and turbine mixture that may suit you that are, perhaps, not well known to the board yet. He has the rep in the actual turbo's so to speak...he is the guy Porsche went to in a bind... His ECU tune is your first mod. Exhaust second. You may not need more than that.....

Anyway, lots of options. All good ones. Kevin my have clients in your town for you to talk to also.

Exhausts are personal.

If I had a tip, I would get a Carnewal ATIWE wheel with F1 paddle shifters....you have to really look. To me, that would be a lot of fun.

JB

 

John,

I get the higher sustained power that a larger turbo will deliver, but judging from driving the car stock even in spirited driving I'm not going to have many opportunities to "open it up" without getting to speeds that risk my license. I think the 16g or k24 hybrids will be about right for around town and for the price point pretty hard to beat.

It does seem a common consensus that a better intake does make the difference in throttle response, not necessarily absolute HP. But I wonder how a different airbox can be better, because the stock airbox has a lot of volume and the surface area of the stock filter is pretty large, especially compared to the aftermarket v-flow and agency power models. I'm thinking if I add a second cold air intake into the stock airbox and use a better filter (BMC), I'll get the same result of better throttle response.

JCB, Alex, I was not aware of a new package from UMW, I'll email Kevin. The 16g kit looks very attractive to me, although not as proven as the K24 hybrid and I do like how Kevin sets up his torque curve.

Duane, definitely, the suspension is next on the list after the upgrade and will be the subject of another post. The AWD "push" can be disconcerting, and the understeer triggers the PSM more times than I would like (especially for some reason around off-camber right hand bends).

Does anyone have any comments on porting the headers, would this reduce the low down torque?

 

Maybe, but from my experience (and I have heard the same from many others), the V-Flow delivers throttle response that you can unmistakable feel. I have not heard that about any of the other intakes...I am simply suggesting something that I know worked very well for me.

 

Yep, ultimately it is about unmistakeable feel. But looking at the physics of the v-flow setup, I can't see how it is better than the stock box and a BMC filter in the stock airbox.

I'll try the second snorkel mod DIY first to see if it makes a difference.

 

DEENDOB,

thats was one freaky long post- looks like you paraphrased just about every major development over the last few years LOL
IF you are so worried about what to get... spend a few hundred bucks and travel to see some boosted cars... maybe someone in ur part of the country has a k16/24s etc... with an exhaust, airfilter, etc.... that would make sense- to actually drive it before you get it. You see... to some LAG is anything above 2500 rpms... yet to me its anything above 5000 rpms... to you low end TQ may come on to late and to other too soon... etc... it's all relative...
I had, K16s, K24s, K16/26s, and now GT35Rs.... So I can say I speak from some experience...
One more thing.... be careful what you wish for... it is the TQ that spins your tires still driving around the city.... not HP... how often will you get on the car from 2000 rpms?
I personally think that is silly since I never kept my car that low in RPMS even when driving around Chicago... Except when leaving my neighborhood at 11 pm when the old folks are falling asleep...
A stage 2 UWM K16 hybrid, a k16/24 with whatever program will be fine, a 16G as well. Even the bigger turbos are fun when you appreciate 3rd thru 5th gear pulls ....
good luck,
markski