Careful guys, with an atmosphere of 30kpa (= 4.4 psi) you'd all be boiling blood. I think that gauge is in inches of mercury (as are most US manifold pressure gauges), which would put your backpressure at an alarming 9.8 psi, assuming that picture is of a backpressure test. Please do clarify.

 

It is neither. The backpressure with our 70mm stage 2 sport exhaust on a stock 996 Turbo engine is 2.2 psi.
The same exhaust on a stock GT2 produces 2.2 psi as well and on a 996 Turbo K24 540 crank hp engine it is also 2.2 psi.
That's measured just before redline. On a build engine with 700 crank hp the maximum backpressure at 7800 rpm is 3.2 psi.
Nothing is so easy than a simple backpressure test.

 

That is easy: measure the backpressure on a stock engine

1) with stock exhaust
2) with the 200 cell Tubi
3) with the catless Tubi

That is an apples to apples comparisation.

If you feel that our 100 cell 3 inch exhaust with 1.75 psi backpressure on a stock engine is too restrictive for your 68mm VTG kit then I'll do my best to build a better exhaust. With all the R&D you've done on your Tubi exhausts you must have measured the backpressure of those exhausts on a stock engine. That's how we do it and that's how every other exhaust manufacturer does it. Please share your data.


With straight pipes torque and spool time is lost indeed. With short 20 inch straight pipes that is. Most of the loss is due to the short lenght of the straight pipes and not because of the low backpressure. With long straight pipes, the 60 inch version that runs from one side to the other, you won't have the same torque loss problem.

 

elite1,

Apologies for taking so long to comment in this thread.

The fact that you want to install a package yourself is very intriguing and I am glad to hear it. There is nothing better than a user purchasing and installing themselves then posting a positive review.

One of the first users of our 750 kit was 6speed user, eclou. He took the time to install the kit himself, in his garage, with just his basic metric hand tools. He also documented the whole process.

This post has helped me sell many turbo kit. I suggest checking it out when you have time. It is very detailed. Click HERE.

If you have an specific questions about our kit, please shoot me an email. I am glad to help.
Mike@AWE-Tuning.com

Finally, for those that want to read more about our what we offer, see below.
CLICK!

Thanks for reading and we hope to hear from you soon.

 

I hope can reach 800PS with my Europipe and the A3071's

 

Getting some clarification on this now....I'll as Louis to chime in or give me the info.

Stef...I think you misunderstood what I was saying. I have not tested the kit with your exhaust, so I'm not suggesting that it won't work. You can always run cats with our kit if you prefer it...but it will sacrifice some power. How much power....not sure unless we test it. We've only tested cat vs non-cat on our 68 kit with the Tubi exhausts and the difference is about 40whp. Your exhausts are great products, we've installed quite a few of them here. Our preference is just for no cats at all on our VTG kits...

 

Tom,

What's the performance difference between a Catless x-pipe like proto or 911 tuning makes compared to a tubi or cargraphic Catless? Do the x-pipes produce more power or same power just save on weight?

Thanks

 

Tom, very interesting observation as usual.

Is it the above because max back pressure is directly related to boost pressure (and different cars have different boost pressures)?

 

Stef, could it be that Tom and you are talking about 2 different measurements?

Tom's seems to be talking about a "maximum-hold" value in a dyno run. This max value could be at any RPM, wherever the boost is highest in that particular car's boost vs. rpm curve. Whereas yours seems to be a more steady-state number at red line?

If above is true, I would expect Tom's back pressure number to be higher than yours?

 

No

Let's move on: Power kits? What works and is not overrated?

 

Not for Stef obviously, but there is a reason for my curiosity of back pressure. I don't see it mentioned on any exhaust web site such as Tubi or Akrapovic or Cargraphic http://www.akrapovic.com/en/Automoti...s/default.aspx , NEVER even as part of advertisements.

I suspect this is because this number, as Tom mentioned, is car and system dependent; it is hard for me to think that it's not dependent upon for example how big the turbo is, and how much boost is being generated, the volume of air flow, etc. You could compare it within same car, but not across different cars, where it could/would become invalid. How to measure is another sticky point: peak hold vs. steady state at certain rpm. In other words, there is no industry standard - am I wrong? In this day and age of internet and google, if it's not posted anywhere, isn't that a sign that there is none?

 

Well the backpressure at 6500 rpm with 0.8 Bar turboboost is much higher than the backpressure at 4000 rpm with 1.2 Bar turboboost.
I can do some runs on my otherwise stock 997.1 Turbo and share the data if you're interested.

 

Tom, what have the GT2RS turbochargers in common with your 65mm turbochargers?

 

Yes I would love to see the data, especially if it's done at same RPM with different boost pressures, as in 2 different programs. Secondly, not related to our discussion, but for "academic" purpose it would be wonderful to have back pressure grafted against boost pressure and other log data on a curve: rpm on x-axis, back pressure/boost/timing/AFR/etc. on y axis. I am certain the big boys do this when they dyno their exhaust but I am not sure if it's possible with the current method?

My question has not been about whether your measurement is accurate, but whether it is a valid number that could be interpreted across different cars and manufacturers. In other words, for example, could we use your measurement against the measurement of say Akrapovic?

My reading so far, and what Tom has written, indicate that it cannot be and that is why no one publishes this number. The point of measurement (how far downstream you are from the cat), the boost, the engine, are all variations that make this measurement valid only in one particular car, not across cars or across manufacturers. Just theorizing of course, I don't mind being corrected by the experts on this field.

 

The point of measurement is between the turbocharger and the cat. All the 993 Turbo, 996 Turbo and the 997 Turbo stock exhausts have an extra bung to measure the backpressure. So the position of measurement is the same for everyone, the stock engine is the same too and I run my car with the sport chrono button activated. I've measured the backpressure during different weather conditions, while freezing and at 25°C and the results were identical. What other variations have I overlooked?