pole position

LOL, professional internet debater..................hit the nail on there head right there.


On a related subject, apparently PAG knows a thing or two when it comes to intercoolers. Various highly touted aftermarket 993tt IC's showed a LOSS in comparison to stock on a engine dyno . When Weissach got serious with their GT2 racing efforts they farmed the IC development out to Secan and those things are currently 20 - 30 G's used.........maybe they should have just surfed the net for some advice in regards to big ,baaaaaad, polished import tooner scene IC's and saved themselfes a bundle.

95ONE

I did the same thing a while ago. (Stock vs. My own intercooler set up) I posted the Dyno sheets. Did anyone do a search on here? Stck K26/6 @18psi. WHen it actually was hitting 18psi... I made 18 more horspower than with the stock intercooler. As boost dropped, so did the gain. 13 hp. 255peak vs. 268RWHP after intercooler mod. I don't think this was so much efficiency (Still better) as it was better Flow. I DID have 4 of those big red turbo looking fans on the intercooler. Apples to Apples though, because I did this for the stock intercooler also during the Dyno Run.

I Proved to myself. Have Empiracle data. And will argue when it suits me.... An updated intercooler makes more power. 18 hp is a large gain.

Porschefile

Lol. That's not even an argument. You are talking about a relatively new $190k+ car (when new). Technology has advanced a hell of a lot in the past 20 years. For nearly $200k it better damn well have a good intercooler. I think you and quite a few others are completely missing my point. It doesn't matter how nice and efficient the stock IC is. It is relatively small in volume and has a relatively small surface area, and that is the point. For a stock car, it's a very nice IC, and hell out of most of the stock turbocharged cars I've ever seen (except some crazy high dollar stuff), it is about the nicest production IC out there for a STOCK car. When you drastically increase the volume of airflow you are forcing through the motor, it becomes more important to use certain components of larger volume. What's the reason you want to increase the size of so many of these components? By increasing the volume of many of these components you are reducing surface friction among other things. A specific volume of air being forced through an object has a specific mass. A specific mass of air being forced through a small object is going to result in increased pressure, increased airflow velocity (to a degree, things like stagnation could actually decrease velocity under the right circumstances), increased air temps, etc. Some of those things are contrary to trying to push an even larger volume of airflow through an object, let alone a motor. By doing so, you are forcing the turbocharger to work harder to try and move the same amount of air, which ultimately leads to increased air temps. Then to top that off increase the size of the turbo as well as the amount of boost pressure and you are now compounding the restriction. Does that make sense to everyone? It's fairly simple physics. Does the correlation between airflow volume and associated component volume make sense? Let me simplify that. The stock IC was designed around a setup running ~20-26lb/min mass flow. Now increase the mass flow rate to roughly ~36-44lb/min (say around the 400hp mark) and you have substantially increased the mass of air being forced through the motor. It's unrealistic to expect that the stock IC is still perfectly efficient at that point as you are nearly doubling the mass flow rate.

It's been my experience that IC's the size of our stock ones are a bit too restrictive with the volume or airflow required for say ~350+whp. That's not speaking from what I've read on the internet, that's speaking from what I've seen with my own 2 eyes on various cars between 2.0-3.5l displacements such as 240sx's, 300zx's, 350z, etc. If you don't believe, then just consider this. For the sake of argument, take a look at the stock IC on a 993tt and 993 Gt2. I don't know if anyone here has seen a stock IC from either of those cars but, they are a bit more than twice the size of a 951 IC, and probably closer to ~3 times the size. All that for a 400-430whp car? I wonder why Porsche would have used an IC 2-3 times larger than a 951's for a power level around 400hp if they could have saved 2-3 times the space as well as weight going with a smaller IC. That's right Porsche knows what they're doing; no argument there. Expecting that a stock component from a 20 year old car is still going to be efficient when you are nearly doubling the power level is however not too realistic.

The only reason I "whine" so much on this forum is because some of you guys drive me absolutely nuts! I mean, just keep an open mind and give some serious consideration to what I'm saying.

TurboTommy

Porschefile;
it's obvious that as the hp goes up, eventually certain stock components aren't goint to cut it.

But you insinuated, in your post, that volume and mass flow are the same (read it again).
In reality, you can increase mass flow without necessarily increasing volume.. This way, heat exchange will be negatively effected only very slighty. Not to mention that the placement and ducting of the stock location is probably one of the best I've seen on any car ( read: good cooling, despite apparent small ambient air exposure ).
Now, squeezing more volume through it, is more of a problem.

billindenver

Ok, 10 bonus points for the first person to tell Porschefile why a 993tt needs a larger intercooler than a 951. There are actually two, VERY basic and somewhat obvious reasons for the 993 needing a vastly larger intercooler than a 951 and neither of them have squat to do with HP or air flow.

No, it's not for bling
No, it's not because Nissan designed the 993 motor
No, it's not because bigger is better

Hint...basic thermodynamics for reason #1 and basic aerodynamics for reason #2.

Back to the drawing board File.

TRP951

What about 70 some lb/min

billindenver

Oh, I can't stand it. The 993 is AIR COOLED for gods sake. Of course it needs a larger intercooler...the thing is inside the engine compartment acting as a huge heat sink with two turbochargers below it throwing heat (which rises) straight on the intercooler. On top of that, there is no way the intercooler in the rear of the car gets near the air flow that ours gets. I mean seriously man, that is the best example you can come up with?

How about showing us how the larger intercooler on your car reduced your lap times? Increased your dyno numbers? Dropped your IAT? Oh...not a track guy, never been on the dyno and oh yeah...stock 951.

Yup, you're an expert.

Porschefile

Bill sorry but, you're an idiot. There are plenty of other stock cars using much larger IC's, like Evo's, STI's, Skyline GTR's, Numerous Audis, BMW 335i, and there are plenty more where that came from. If you can't understand simple physics, you're not worth me wasting my time. We're done here.

333pg333

It actually seems to me that most of you are making good points. If we remove the emotions we may all be pulling in the same basic direction. I admit I'm out of my depth here in view of thermodynamics, mass air flow, lb per min, etc, but isn't the sum of the product limited by it's weakest link? Or if we increase flow through a bigger turbo plus do some headwork, change the intake, then turn up the boost to say eg 22psi that has been bills benchmark, aren't we going to be compromised by the size of both the i/c and the i/c pipes?
Now back to the gist of this post (I think), if you're not going to be after major hp gains then there would be better things to spend your $$ on before a aftermarket i/c. Obviously it's also very much dependant on what your goals and intentions for the car are. If you want to drag from one traffic light to the next and post it on Youtube then you probably don't need a bigger i/c. If you want to go and do some DE's, then you probably don't need a bigger i/c. If you want to build a motor up to over 450hp and wind the boost up over sustained periods, then it's time to consider a bigger i/c with all the other mods you'll be doing it will make a difference. Oh and even if you're just after big numbers for the dyno and do the increase of i/c and pipes you actually should get a better spoolup. Just ask ST, he did.

95ONE

Here is a link to a short write up with Dyno Data about a year ago.

Stock vs. (Custom) intercooler Set up

333pg333

Interesting write up and one that sort of concurs with both camps here, but ultimately it would show that the higher your hp goals are the more necessary a larger i/c becomes. Did you wind up doing more mods and measuring the gains?

billindenver

Again, all emotion and no real data. The question was will an intercooler show gains early on in the mod process. Ehall stated that until mods got into the upper end, money should be spent elsewhere....which is when you went off on him. He didn't deserve that, and you have zero experience proving your point, you have never even driven a modified 951. When you give examples that are completely out of line and are called on it, again you get emotional and start name calling. Exactly what people expect from you...entertaining but not really useful. I would encourage you to be involved in the discussion, but you really need an emotional check. You are beyond your experience/educational level.

95ONE

Being that I have my own shop is a god and bad thing. I Started to do the clutch and Flywheel, then, I decided while the rear is out, I'd upgrade the rear bushings, then while I was there I decided to Replace the whole front suspension. then do a refresh on the engine with the belt and tensioners / O-rings, seals, hoses, gasketsetc.etc.etc. Might as well take the engine out for the oil Pan gasket and weld in Lindy's baffle..... Oh god what have I done!!!! It's a pile of parts! Well, I've pretty much replaced everything. I have a 60-1 turbo on there now. I'm welding up the Down pipe for it. I'm waiting for a few more parts to come in and then I'll get to start putting it together. Which will be next week some time. But I probably wont run it until I've decided on what sort o management I'm going to go with. Oh man. I'd say I'll have a good comparison of the old turbo charger VS. new. (Truly the only upgrade I did engine performance wise) in about 2 months. THen I'll work on an Intake manifold. Stock vs custom apples to apples.

special tool

Porschefile - I don't know what you are saying here, and once in a while you do come up with a good point (hell, even a blind chicken catches some scratch once in a while ) but I believe the stock ic is more than adequate to cool ALL RANGES of any k26 family turbocharger.
If you leave the k26 family (front or back!!!), probably you will see gains with a bigger ic.
Much bigger turbo, and definitely gains.

Porschefile

One more comment and then that's all I'll post on the subject. It's comments exactly like this that have me so festered up on this forum. I've tried to provide input to people from my real life experiences. Unfortunately it's tough for me to get straight to the point in a simple manner and usually my emotions show through. I've messed with plenty of cars in the 300-400whp level (and a few over that), and a wide enough variety to establish my own beliefs. Several of you berate me like I'm some newbie that has absolutely no experience with turbochargers. Have any of you actually even ever used a larger than stock IC on any car before? I have. If you haven't, maybe you should simply give my comments some consideration before attacking me. I may not have done much with 951's, however these cars are not so different that no comparsion can be made to any other car. If anyone thinks otherwise, they are only fooling themselves.