Erik do you sell just the catalyst? I have a friend who wants a high flow cat for his M3.

 

PM'd

 

Looking back at my data, I might have to change my opinion somewhat. The results are complicated by IATs being somewhat different in each run. Here's a rundown of the conditions:

- Tune was exactly the same for all the runs.
- 100 cell cat + RRE: IATs were about 57F for the entire run.
- Test pipe only, run1: IATs were 59F for the entire run.
- Test pipe only, run2: IATs were about 66F for the run.
- Test pipe + RRE, run1: IATs were about 71F for the run.
- Test pipe + RRE, run2: IATs were about 76F for the run.

So, there is a pretty decent spread of IATs among the dyno runs. If I overlay the data plots, here is what I find:

- Test pipe only: Both runs lay pretty much on top of each other for load, boost, and exhaust manifold pressure.
- Test pipe + RRE: Again, both runs lay pretty much on top of each other for load, boost, and exhaust manifold pressure.
- Boost and load during the test pipe + RRE runs are lower than with the test pipe only. Boost is about 1.5 psi lower at peak boost (4500 rpm), and about 1/2 psi lower at 7500 rpm. Load is about 20 lower. However, exhaust manifold pressure is the same for all the runs. So, do we attribute lower boost and load to the RRE or to the higher IATs affecting boost and load?
- 100 cell cat + RRE: Highest exhaust manifold pressure. Its consistently about 2-3 psi higher across the rpm range. However, load and boost match that of the test pipe only runs.
- For dyno numbers, running just the test pipe (without the RRE) yielded about 15 ft-lbs more torque at 4500 rpm but no clear peak whp gains. Test pipe + RRE were actually a few whp/ft-lbs lower than 100 cell cat + RRE. My guess is that's due to the 15-20 F higher IATs during testing of test pipe + RRE.

So what the hell does all that mean??? Comparing pieces seems to make some sense, but the whole picture doesn't seem to fit together well. What I feel safest saying is that at the boost levels I'm running:

1) Exhaust manifold pressure and peak whp are being limited more by the compressor side of the turbo running out of capacity than it is the efficiency of the exhaust side of the turbo.
2) A more free flowing exhaust perhaps provides some gains where the turbo is operating in its efficiency range.

A few more runs with the test pipe + RRE at the same IATs as the 100 cell cat + RRE might add some insight. I don't think that's going to happen any time soon though. I'll see if I can put the data plots together in a fashion that is reasonably easy to understand.

 

1 way for you to sort out your 100 cell cat+ rre data is to conduct a pull on a private road with 2 different ambient conditions....57f & 71f in order to note any boost or acceleration(power) differences.

actually, just run the car in what ever configuration ur in @ the 2 different temps.

or

P/RT pressure(kpa/ideal gas constant = 0.287 * temp "K") is your friend.

 

sweet! glad to know that there are several people pulling thats nice numbers out of the CBRD BBK full.
im new to the evo world, and thats the turbo im planning to run with about the same mods!! (minus the cardboard airbox)

 

Aby I need a cat

PM please!

cb

 

will do