or so we think, this board is a very very small fraction of 996TT's out on the road

 

Oh you caught me! The reason I have never posted ACTUAL performance numbers is because I really don't own a turbo. I am a 10 year old boy in Cedar Rapids, Iowa who just wanted you all to think I was a real Player!

Sorry, I will just go back to my video games now!

 

Couple of facts:

Car will run hotter on a dyno. Proven.

Fans will create a big difference in Dyno numbers. Proven

Fans cant exactly duplicate real world wind.

I too do not like dynos, it can be useful for mods though. Im all for real world testing also.

1999Porsche911 did you ever dyno your car? I would hope so, with that kind of a modification a dyno should be one thing looked at.

 

I expected you to find a way out. Par for the course I guess.

 

You're off base. Using fans will (at best) will bring the temperatures closer to ambient. The worlds most powerful fan will not make it any cooler than ambient temperature. Dynoing without fans is basically equivalent to blocking air to the intercooler on the road and that isn't accurate data. A cheat would be to spray nitrous oxide gas on the intercooler to fudge the numbers. But fan cooling is acceptable and is what is used by manufacturers and race team engineers.

 

Guys - read the rules before you use these usernames related to companies with your advertising signatures!


# 1

Erik@RPM

# 2

Shiv@Vishnu


READ the first post on the forum guys!
https://www.6speedonline.com/forums/...p?s=&forumid=2

 

Maybe you misunderstood what I was trying to say. I'm not very articulate at times. A car on the dyno with fans on it will run hotter then a car just driving down the highway. Considering it is the same ambient temperature. How do I know this? I have a stand alone, and it measures my intake temps. I use to log these to compare the dyno to the drag strip. My intake temps after the intercooler were on average 10*-15* cooler after a pass at the strip when compared to a run on the dyno.

So if you are stating a car will run cooler on a dyno with fans then it does on the road, you are incorrect. I have over 200 passes at the drag strip, and over 50 dyno's worth of experience. And this wasn't some weak 300whp car either, it was making 530whp.

Sorry, but my car going 130mph down the strip gets a hell of a lot more cooling in it then it does sitting on the dyno with a fan blowing a 25mph wind at it with the hood up.

In conclusion, I drive my car around and I wouldn't compare it at idle in a still wind situation, to that of being on the dyno idling with fans on it. Do 5 passes in a row, with those fans on it, and 5 passes on the street, measure the intake temps, and I guarantee the intake temps on the street will be lower. I know, because I have measured them. Sorry bud, but you are incorrect. My intercooler also gets heat soaked a lot easier on the dyno, hence the cool down times and fans. Because no matter what you say, those winds do not create the same effect on the car as you driving down the road at 60+mph.

 

Who ever said that the fans will bring the temperature below ambient temperature? No one on this thread. Have you ever even measured what the coolant temperature is that is running through your intercoolers? Do you even realize that there is as much as a 40F difference in coolant temperature when air is passing over the coolers versus no air moement, even at moderate engine speeds? A fan blowing over your radiators can reduce engine temperatures by as much as 15F?

Before we continue, we need to make sure that you agree with the laws of physics:

Do You agree that the temperature for the engine coolant is higher with the car running without air passing over the radiator?
Do you agree that the coolant for the intercoolers is hotter with the engine running without air passing over the intercoolers?
Do you agree that your engine bay is cooler when you have the trunk lid open and blowing air into it?

If you don't agree with these three things, there is no point in reading further, cuz, you won't get it

It is also a fact that cooler air is more dense and when mixed with an increased amount of fuel, it will produce more power, pound for pound.

It is also a fact that the timing of the engine is partially dependant on the engine temperature. The hotter the engine, the less advanced the timing will be. Reducing the timing reduces the power of the engine.

So now, can you tell me which will provide you with cooler intake and coolant temperatures;

a) A car sitting on a Dyno with large fans blowing over the front radiators, over the intercoolers and into the engine compartment,

or

b) You car, on a beautifull, sunny 75F day driving around town?


The fact is, this dyno setup will keep the intake and coolant temperatures artificially cooler than you can possibly maintain on the street. Therefore, the HP numbers you get on the dyno using such a setup is artificial and overstated. Just as, running a car on a dyno WITHOUT fans will understate your car's power.

There is nothing new or brilliant about the above. Anyone who has any experience in turing cars knows that these dyno charts are, at best, a guestamate and seldom can the reported power be transfered to the street. For tuning, dyno's are fine, but if your loking for an absolute number for the power your car is producing, they are not much more than a method of driving your car fast without going anywhere. Just like having a drivetrain loss between the engine and wheels, there is a "calibration" loss between the dyno and the street.

 

First of all, my 30+ years of testing concludes otherwise. I would expect you to begin seeing lower intake temps at the end of your run. Why, because, if you have any power in your car, your doing over 120 mph. Ever test what the intercooler temps are when the car is moving up to 120 mph? They are about 40F higher than they are at the same speed on the dyno when using the above described fan setup.

How many gallons a minute does your pump move the coolant through the intercoolers. Now, calculate how much time it will take the coolant that is cooled by air movement to completely pass through the system and back to where it will have any benefit on intake temperatures. Before your run on a 75F sunny day, your intercooler temps are at least 40F higher than at the same time on the Dyno with the fans. This is not conjecture, but a result of many years of testing. So now, how long (based on the capacity of your pump) can you remove that hotter coolant out of the system? I think you'll see it takes just about as longs as your run took and that is why you seeing drop at the end of the run. You get absolutley no benefit of the cooler air passing over the intercoolers until at least one complete cycle of the coolant. On the dyno, because the fans are not providing you the CFM's of air as does a 120 car moving down the street, your intake temps may be high at the end of the run.

However, because the results of the dyno are determined by, among other things, how long the run takes, because you have artificially cooler intakle temps during the early part of the run, the time to complete the run is less than it should be.

 

What did your SC C2 make on a dyno? Sounds like you really hate dynos for a reason...

 

I don't hate dynos at all. They are a good tool to use when you are tuning a car, but only for comparative increases (or decreases) in power, not for HP ratings. In other words, whether a dyno gives you accurate power figures or it is off by 30%, doesn't matter. What matters is that it is consistant in either being right or being wrong by the same amount everytime. So, if you dyno your car and it shows 100 hp and then do some mods and another test on the same dyno shows you have 150 hp, you gained 50% power. That 50% is accurate (if all conditions are equal) so it doesn't matter what the real hp numbers are. You still improved your cars horsepower 50% whether it was from 100 - 150 or 300 - 450.

As far as dynoing my car....I have had it done numerous times, along with some of my other cars over the year. Earlier this year, I dynoed it 4 times in the same day on four different dynos just to prove someone I know wrong. I got 4 different results. 356 to 434 at the wheels. I wonder which one is right? LOL!

Someday they will come up with a better dyno that will more accurately measure the true power a car has on the street. I think when this happens, many people will be upset to see their numbers drop drastically.

I prefer to gauge the power of my cars by how they perform on the street. I will use a dyno to measure percentage change in power. I run against a guy I have been friends with for years who has a dyno chart showing his blown 70 Cuda has 585 rwhp. It's always a laugh when my, somewhere between 356 and 434 rwhp 996 gets to 100 mph only 2/10 of a second slower that he does. A piece of paper does not always translate into performance.

 

Why are you talking about coolant running through the intercooler? I run an air to air intercooler, and if I was running liquid to air it wouldn't be coolant, it would be ice water. The only place coolant runs through is the radiator (engine, water cooled turbo's, etc), and that doesn't effect my intake temps.

I guess you need to dumb it down for me doc', because I don't really understand what you are trying to say.

 

I am familiar with turbocharging, the power gains seen from timing advance and intake temp reduction. I have monitored pre and post intercooler temps in my other turbocharged vehicles. I don't care how big the fan is, the throttle body temperature of an RX-7 on a dyno is significantly higher than on the open road. It is very prone to heat soak and a fan can't cool the car the way the air does at speed. I can't speak for the 911 as I haven't dyno'd it.

From my experience it is hotter inside the shop than outside. So the answer is "b." Maybe your shop is airconditioned? As I mentioned before (and my point was missed), large or small, fans aren't going to make the temps any cooler than ambient. At best they maximize the use of the intercoolers and also keep the engine from overheating. They aren't going to cool enough to allow major advances in timing thus increasing HP/torque, certainly not more than what you could see on the street.

To dyno without fans is idiotic. Do they perfectly reproduce the effects seen when driving? Of course not. From our experiences, we disagree on how much they actually cool, but I think we all agree that dynometer testing is an imperfect tool but useful nonetheless.

 

I tell you what the first time I run it at the quarter mile I will be sure to post the slip to make you happy!

If you really want to know how fast it is why don't we meet halfway between West Michigan and Chicago and you can see first hand how slow it is!

 

Why so much hedging Buddy? Take a few seconds to clock some runs, which I am sure you have already done. Why not let us know. It would be fun to see if a "beast" is really so much faster at certain speeds than a much lower powered car. You could do a 0 -100 time on your way to work. You have been bragging that your car is sooooooo fast for months now. I am not arguing whether it is or not, but, give us some numbers and let's see.

Could it be that your car is all show and the numbers really don't transfer to the pavement? Only you can show us which it is. A few months ago you were chopping at the bit to take your car out and clock it at different speeds. What happened? Results not what you expected? If you're going to talk the talk...well, you get my point.

Please post another excuse as to why you can't.

I won't hold my breath.