Yes of course sea level and cool, low water content are always the best air to run in. Just pointing out my experience from 23 years ago at 10,000 plus feel turned a M5 into a car that felt like a VW bug In passing I will note that in those days Mexico was a lot safer and many car lunatics would go there for super high speed driving. (Not so smart today sadly - you are likely to loose your car or more)

On that note. In recent years using borrowed cars I have found South America has some great places to drive at full speed.. of course much harder to get your own car there and back

 

 

Just a little update to this thread - almost done the fine tuning. The boost curve is pretty much there. Car is running consistent 2.7-2.8s 60-100mph in 3rd gear on pumpgas even in warm weather with nearly full tank. I had a good run that did 2.6s on the same pumpgas but the boost in the midrange was just a smidge out of the sensor range so I pulled it back. Lots left in these turbos but with stock rods I'm not gonna push it too much...unless Sam says it's okay, lol. j/k I know that we are pretty much "there" as far as stock rods and pumpgas go.

 

After you peg the sensor is when the fun begins

Enjoy it bud and appreciate all the info on your thread

 

Your set up is moving and on pump!! I am still confident you would be 5.8-6.0sec 60-130mph conservatively.


LOL!

 

It's true...someone had posted that these turbos "come alive" after 1.5bar. After a taste of 1.5ish bar I agree! Wish I had stronger rods!

My pleasure and I appreciate your willingness to share your knowledge.

 

I'll try to find out.

 

I wish that too I'm not sure why you all call that "safe". 22 to 23 psi is not safe. I have seen bent rods at that level. It sure all depends on your driving style, but pegging the sensor on a stock motor is too much in my book. Good luck.

 

As you are most likely well aware there is a lot more then just boost pressure that causes bents rods. It is cylinder pressure especially at peak torque that bends rods. If you bring in the boost down low slow, but equally important timing (there are a lot more factors) you should be fine. Heck he can run 30psi’s on stock motor if he runs 10degrees of timing, but he would make less power then someone that ran proper timing and 18psi’s. The key is cylinder pressure especially at peak tq with stock rods.


I know you know this stuff and just want to keep a fellow member safe, but also keep in mind Asher is not tuning his own car. Sam that has built many of these cars on stock motor, has built a solid reputation by making fast and safe machines, not by blowing them up.

Asher, I say ask Sam for the “more” tune he alluded to!


Thanks

Bobby Ali

 

Hi,

of course you are right, but I very much doubt that they have reduced OEM timing for more boost. OEM timing and this amount of boost blows stock cars here and we have better pump fuel (I guess even compared to Canada, but I am not sure).

Maybe it works because of the usually short blasts on your speed limited streets and statistics hence are working in your favor - which only means it takes more time. His 60-130 time is way too quick for the mild tune argument thru midrange.

But as you say: Sam will cover it

My guess is this car has at least 900 Nm of torque and this amount of torque is too much for my taste.

I have seen bent OEM rods at 900 Nm and snapped OEM rods at a little over 1000 Nm. A stock engine can't take that forever and 800 Nm cars never run these times.

Anyways: I hope all stays together and safe.

 

Hi Sam,
I am still working in my job

Tuning is just a hobby, but I admit, it got out of hand and I feel very comfortable in the 996/997 arena. Let me put it that way: I have enough experience to backup what I say with real world data and I left the area of educated guesses long time ago.

I know you are very dedicated and know your stuff. I was just expressing my opinion - no offense intended.

Andreas

 

I've never posted a 60-130 time for this car so I'm not sure which car you are referring to...maybe Bobby's car?

There are lots of cars here that bring in the boost gently around 4k rpm and gradually ramp it up to redline. My previous 68s were over 22.5psi at less than 4k rpm all the way to redline. The car was repeatedly run hard and went to the track a few times. When the 68s were changed I had a leakdown test done. All cylinders were equal and excellent results which I assume implies no bent rods.

You are right that the runs done here are typically shorter and not long 5th gear runs like in Europe which are more stressful to the car...

 

I have scoured the forums trying to determine what is considered "safe" as far as boost or power levels etc.. Great thread by Tom from Champion, and another from K24f after his engine had to be built. There was no universally accepted value for hp or tq or boost that was felt to be the unanimous limit on a stock engine. Most people indicated that "it was all in the tune" meaning the way that boost and timing are ramped up relative to peak torque. I realize that going aftermarket involves a certain amount of risk. I will post up my boost vs rpm graph and "load" vs rpm graph shortly and compare it to my old Champion 68s. My car will see full throttle 3rd gear runs and a few 4th gear runs as well as some time at the track. I personally think my car has an easy life for a 997 turbo and is more likely to fail from being babied than overdriven, lol.

 

So what you are saying Bogg is you aren't boosting high enough Just kidding bud. Enjoy the car

I think if we were pulling mile long races or road race tracks obviously we would need to be more conservative on stock internals. We can get away with squeezing a little more because of the duty cycle the engine sees.

 

I think that is right, Maestro. I'm really enjoying the car. It's fast and smooth with a power band similar to the 68s. These xonas at 20psi matched the 68s at 22.5psi on pumpgas for repeatable pbox numbers (60-100 and 75-110). With a gently upward tapering boost curve the performance is noticeably better with the Xonas…