OK, let's just get this out of the way up front. Now that I'm doing real research about adding power to my own 996TT you guys are going to see a lot of stupid questions from me. Please try to keep the laughter to a minimum and realize that I'm serious about gathering knowledge.



Anyway, I've owned my 996TT for about 3.5 years and enjoyed it very much just the way it sits. It has a Gemballa re-flash and I added an OEM based catless exhaust (still have the catted one too). My clutch is stock and I'm not even sure if I have aftermarket diverter valves at this time. The overall performance is no longer impressive to me and it's time to add horsepower, I'd say at least 100. I made the incredibly foolish mistake of driving my buddies modified Nissan R35 GTR and now that is going to cost me big-time.

So, I'd like to hear about pros and cons of the K16s (modified to at least 16G level) and the K24s, both in stock and modified (18G trim). I have never driven a K24 equipped 996TT so do have a bit of wondering about their powerband, but my K16 car practically drives like a low compression V8 with super quick spool-up, mediocre mid-range, and fairly flat top-end power. It just doesn't pull up top like I want it to, and obviously there is some work to be done to achieve that.

I suspect I'd lament a bit of low end response, but might be happy with the overall mid-range and top-end power improvements. I would like to hear from others who have faced the same challenges and overcome them. I can definitely embrace that turbocharged motors will never really overcome high compression NA ones, so do prize that turbocharged rush. That being said, I don't want a lag monster either, so am a bit gun-shy to rush into something I might regret (I suspect that no variant of a K24 is going to feel like that though?).

Another somewhat limiting observation I've made with K16s appears to be that unless I'm willing to eat the core charge, that rebuilding mine is the only real game in town. I cannot magically turn mine into K24s to pursue the K24/18G upgrade path, so that's a slight bummer but something I need to contend with. I definitely have some horsepower envy right now, and could use some counsel surrounding if the K24 trade-off is worth it and I just just focus on being in the right gear at the right time.

Thanks all, and happy boosting!

 

HI Steve,,Dont get me wrong here But you have been on here long enough and I believe you know your answer..lol..
You know theres been alot of questions with back and forth answers on this over the years >>> SEARCH and compile because as all of us doing mods we want reassurance one day and the next we go another direction..LOL..
Good Luck..

 

I've actually read about it a fair amount...but want to get some more recent feedback. I feel like there are more options than there used to be for the 996TT platform (certainly since I bought my car) and was hoping to spur on a fresh discussion. What are K16/20s? K16/26s? I have no idea what that stuff means. Are all the secondary numbers compressor wheel sizes? How do their powerbands compare? Are some just bad matches for a nearly stock car?

Perhaps it was wrong of me to limit the discussion to K16 versus K24, but a bolt-on comparison is largely what interests me. Thanks!

 

Most all of us get bored after a while and then power hungry in which we look for more ways,,thats why we are on here .
We look for the cheapest way first and say thats enough we are done but Then.............................................. ..................................................
Most of us go through those COSTLY stages of upgrading again,,as you know also..lol.

 

As prodigymb would put it... If there's lag, you're in the wrong gear!

 

heres an example you might be able to use.
i have k24 basically a x50 package with a tune , headers and exhaust 93 oct file. dynod 490 rwhp /502 ft/lbs.
layinback met with me same day same shop with similar mods to mine(actually a few more mods) billet k16 103 oct file and dynod at 1.4 bar on gbc. he got 553 rwhp /600ft/lbs
so with his car maxed out basically on k16 he saw approx 60 rwhp and 100 ft/lbs torque more than me.
on a couple 60 to 130 runs (in mexico!) i could start to walk away then he would run me down. car is very fast but imo he is at the limits of the k16 . if i modd up to his level (and i am!) i think its going to be a much different outcome

 

k24's lag until they hit their stride at wot. regardless of the gear you're in but hang on when they do hit. 16's run out of juice. so for me ( not knowing how all the other setups compare ) hybrid 16/24's are the best combo of the two for a street car.

instant on boost ( really ) and the top end of a 24. supporting mods are a good idea also. for comparison i've driven stock k16 cars, owned an x50, and currently have the hybrid turbo car. just my experience.

 

OK, good discussion points...thank you guys.

Regarding something like a hybrid K16/24, could someone define what that is to me? Which part remains K16 and which part is from a 24? I actually reached out to Blouch with these kinds of questions but they never sent me back an answer as I was determining to find out what my options where with K16s as my starting point, and it looks like there are a few flavors to choose from.

I'm a bit surprised that 550 whp could be attainable on a K16 hybrid, but obviously that is going to be with really good fueling and fuel quality. I hope that isn't just what I've seen referred on here as a 'tuner horsepower' special, since I'm looking to avoid that. Ideally I'd be running an E85 tune since I have local availability for it, but know that means serious fuel upgrades and a tune to match.

Thanks all.

 

HI,If you are going to stick with your 16s,,then Billets would be the way to go in my opinion.
Would it be worth it to buy some K24s and turn them into 18gs? I think not because now that you are into it that much ,I would spend the extra and get some ball bearing turbos after market turbos and then be done with it..
Unless you find a set already done for a good price..
I say the above because I said I was happy with my K24/18gs and can not beat the bang for the buck But I am use to the power ,bored, so I now want to go bigger to another turbo thats going to cost more which if I did that at the beginning I wouldnt have gone through the whole K24/18g tuning route,twice..lol..

 

This is actually one of the key issues I'm trying to avoid, meaning re-work to attain future goals. I know it's hard with any modified cars since you can say "hey, I want 550 whp" then go out and achieve it yet change your mind 2 weeks later and want 700 whp. So, that is factoring into this for me as I hate to do stuff over and over. For instance, when it comes to the clutch, which I'll obviously need for just about any aftermarket turbo combination, I plan to just buy a multi-plate clutch the first time and be done with the whole thing.

Since there are so many supporting mods I'll have to do overall to my stockish car, I'm looking to come up with a staggered way to do the upgrades to preserve my bank account from total annihilation. The problem there is that most of the mods I need are pretty substantial so costs cannot be avoided. Assuming I wanted to go with K24/18Gs, which sound tempting based on my power goals alone (700 crank horsepower is what I'd like at this time), this could be done semi-incrementally, but I'll have to pull the turbos off and have them upgraded, then have the car re-tuned later.

Obviously this level of indecision comes normally from owning a modified car, so at least I know I'm in good company here.

 

hot side ( exhaust ) turbine/ cold side ( compressor ) intake. so on a hybrid 16/24 the cold is the k16 part allowing for quicker spool, while the hot side is the k24 all stuffed in a k16 housing. i'll probably f*ck this up since i'm hardly versed in turbospeak but i certainly know what "works". i think i've got the hold/cold side thing figured out lol. correct me if i'm wrong.

my tune and setup are an "advertised" 550hp, but i think i'm closer to 475 whp MAYBE a bit higher is about right. this with larger i/c's and dv's 5bar fpr etc etc. but numbers are numbers. who knows, i could kill myself daily at will with this setup on the street. ymmv but not by much

hybrids are probably the least expensive turbo upgrade ( far as i know ) and WELL worth it ( over stock, that is ).


here's a quick turbo tutorial for ya. not that ya need it...


http://www.hotrod.com/techarticles/e...o/viewall.html

 

Thank you my friend. I'll happily read up on the tutorial as well.

 

no prob. btw. there are 16/24's to be had very inexpensively so if you did got that route. check on ebay, or i know a 6'er here that could hook you up w info as well as answer questions "professionally" lol. it's truly bolt on and go ( depending on tune and other little stuff ) to make it all flow together. but do it you'll never look back.. and contrary to what some might tell you. you *can* stop power modding at that level, and be *mostly* happy 99% of the time. street or canyons/highway driving. lastly, i have found there are more times i have "too much" ( lol ) power on the street.. vs too little.

 

my advice is to pick up the phone and call one (or all) of the highly regarded tuners on this site (The Kevins, Markski, etc.) They can answer all of your questions and give you excellent options and advice.

 

Steve,

I had a flash and tune for a few years, then went to the K16/24 zero clearance turbos as an upgrade. They were OK, but left me wanting more within a month. Upgraded to K24/18G later that year and that was what I had in mind...I did the intake plenum upgrade and injectors with the 18G's and did not notice any additional lag compared to the K16/24 - just more power everywhere, especially the top end where the 16's lack. IMO, K16/24 is not enough to warrant the expense of a tune and labor to upgrade. Based on my experience, I would go straight to a 24/18G, I think you will be extremely satisfied. Don't be afraid of "lag" with 24/18G's - it will not be an issue.