Currently I have stock K16's with a 1bar flash. They have served me well for 3 years and while I have been dialing in my upgraded suspension. Only drawback is they lose punch at higher rpm's. I'm not looking for a 700/800HP kit but something mid-range with dependability. I'm not into drag racing, just road racing at the track. I have been thinking 16/26's but now wonder if a K24 hybrid would be better. I know I will need IC's, re-worked intake tubing and a clutch. What turbos do you think will fit my needs the best?

 

Define track... how many days a year does your car see the track? What is your experience level, ect.

 

I run Laguna Seca, Sears Point/Infineon and Thunderhill.. The K24's are a REALLY nice fit for those tracks.. Because the boost lives between 4000 and 7000 rpm, you are almost never out of the boost (if you are in the right gear for wherever you are on the track).. The top end is amazing and the Car is very controllable (in my opinion) out of the corners...

I am running an EPL tune, 100 cell cats and the X-Cellerator 2 1/2" system, 1.1 Bar boost and the Car FLIES!! My next and final step is the billet compressor wheels for the K24's, injectors and intercoolers, with the appropriate EPL tune and then I am done.. At that point I should be at 600+ RWHP on race gas and that will be more than adequate for the track, otherwise I will not be able to put enough tire on the Car to get the power down.

Another benefit of K24's is the vast array of knowledge about them.. Lots of tuners have a solid track record with tuning them, including Tony at EPL, Todd at Protomotive and Markski to name the three best.

Cheers...

 

Hmmm I'd be careful of going too big on the exhaust side. I honestly think anything more than 600rwhp in these cars can be "fun" but more of a handful than necessarily fast Even with the good suspension you have... You want something consistent and with a good curve down low as well

 

The billet wheel I will be going with is just an updated 18G sized wheel with a more modern design and better flow and spool characteristics.. The boost will come on sooner than with my stock K24's, because of the more efficient compressor wheel design AND the lighter billet wheel.. Perfect for the GT2...

 

White solo run group, about 12-15 track days per year.

Alex, what is your opinion on my question?

 

Go with the K24/18g setup and have Tony tune it. I love mine and I track my car as well. Nasty power and good for overall street manners. Plus Tony and crew can datalog now as well. I am looking forward to that since I just had injectors installed on my ride.

 

Landjet, look no further:

http://switzer-spi.blogspot.com/2010...or-996-tt.html

If you have any questions contact me to discuss.

 

When I looked into this, I talked to a bunch of folks - users and tuners. For the most part, people are happy with what they have, even if their setups are all different. You've had a few of those in this thread already, and I am sure that you will see some more. That's good, because it means there are a lot of reasonable choices, and it's bad too because eventually you have to choose one. Just to add to the noise, I'm very happy with my UMW ZC hybrid K16/997GT2 turbos.

I think that the downside of the K24's is that they make their power too high in the rpm curve for road courses, especially ones with slow corners. Some other hybrid K16 setups also have this characteristic. Let's take the curve that Neil Switzer posted above, even though it's a hybrid K16. He's adding the last 50 hp between 6500 and 7500, and he's making just half of the max at 3600, 2/3 at 4000. I am not saying that this is a bad package, or that any other package is bad, you just have to look at your application.

Now think about how you drive your car. Almost all of your events are at Summit Point, which has some pretty slow twisty sections, as well as the front straight, where you can already get to the top of fifth gear. I think that what you really want for that application is throttle response, and lower end power. To me, that argues for K16 hybrids, which several builders can make reach up into the 600 whp with appropriate fueling and other mods. I've attached below data from my Durametric runs after installing the UMW Stage 2A package. Kevin tells me that the engine load max corresponds to about 520-530 ahp on the dyno. I am not claiming that, because I haven't dynoed the car. The most striking thing to me on my very first laps was how easy it was to drive the car with the new turbos. The throttle response is outstanding. That comes from the shape of the curve in the range 3500+. I should note that my car has stock injectors and fuel pump, just a 5 bar FPR. The tune is limited by the fueling at this point - Kevin tweaked it down a little based on injector duty cycles. With better fueling, he has shown this turbo producing over 600 whp in another thread.

A word of caution, too - if my experience is any example, you get up to 600 whp, you *will* be buying some more driveline parts. It's not a coincidence that I've had wheel bearings and CV joints fail since my upgrade, and I am probably pushing "only" 520-530 awhp.

Hope that helps.

Jon

 

What is the dip at ~6200RPM that is consistent with *almost* all dyno graphs? I did some searching and some suggested in the intake manifold, but with no before/after concrete results. Have you found that to be the case as well?

 

Hey Larry... the cars that I've liked driving the most have usually had a gt28alpha or some equivalent. Anything with a K24 based hot-side had a bit too much lag for my liking and tight/twisty tracks and more "explosive" power. That's fun on the street but not for me on a track.... Back in 04 when we did JWGT2's 996GT2 for the shoot out it had less HP than most but was a second quicker than any of the others around the track with Darren Law/Johannes Van B. driving It had 540rwhp which I think is a perfect level for a 315/18 pilot sport cup or 335 toyo r-compound tire. It was really manageable power too. A lot of different shops/tuners sell what they call they're mid-600 kits for the TT and I think that's usually a good level for extensive track work. My 3.8L with over 700 to the wheels was honestly not all that fun at the track

 

For the slower corners, its just a matter of downshifting to get into the power band. The only time I'd say it becomes a real issue is if there are any 1st gear corners after a straight on shorter courses. Some may argue this makes the car harder to drive, as it requires more shifting, and doing downshifts always has the chance of upsetting the balance of the car if you have to do it mid corner and you aren't experienced in doing so. Personally I'd prefer a car with a wide powerband in RPM ranges that doesn't require much shifting, but just pointing out you *can* drive around the fact that the powerband is moved up if you are ok with more shifting and higher revs.

There's also the issue that you'd need to rev higher (7500 in the above example) in order to take advantage of the power, so another question that remains is what is the longevity of the motor with the higher RPMs? Is it safe to do for extended periods?

And brakes ... and tires!

 

Some tuners also slam dunk the boost and let it hit as hard as possible, so when you roll onto WOT you lose traction. Great for a drag car, not so good for a road course.

 

I agree with you. My comments were aimed at making the car easier to drive.

I was already buying those consumables on a fairly regular basis. It's the hard part failures I'm not so fond of.

Jon

 

It is caused by a lot of things, mainly intake harmonics.