- Joined
- Mar 2, 2013
- Messages
- 176
- Location
- Brisbane, QLD Australia
OK, time to finally post on this thread:
First off, I have the Termi full system and I'm not a fan of AR's system, though I appreciate Rich for developing it and bringing it to market. Competition is the only thing keeping Termi and Akrapovic in check. Lets face it, if Termi was the only system available, a lot of us would pay an extra $k or two just to have it.
Rich's main fault in this is publishing his comparison numbers, both in peak power and noise. As we said nearly a year ago, that's just bad form. Publish your own graphs showing your curves, AFR and an expected average gains. By not doing so, Rich as left himself open for this discontent.
Any turner worth their salt will admit that Peak Power result from a given dyno are worthless if compared to other Peak Power result from another given dyno. You will find that results from different Dynos and taken under different conditions even on the same dyno will differ. Even though CF attempts to correct for temperature and pressure, the environment will vary your results by +/- ~2% or more.
As well as factors in the DYNO machine and environment, the selected Correction Factor (CF) can play a part in the numbers game -
DIN uses 1013mBar and 20 degrees Celsius as the nominal conditions, whereas the SAE uses 990mBar and 25 degrees Celsius as the nominal conditions. DIN also uses absolute air pressure SAE uses dry. Difference being that dry doesn't account for relative humidity.
The formula for CF is too difficult to type in the text area, but the important thing to remember is that CF DIN is usually ~1.16% higher than SAE.
In short, unless every run is under the exact same conditions, the peak numbers mean little. The only true thing to take from a dyno run is the shape of the torque and power curves and the Air/Fuel Ratio.
Gavin D - Subtraction of back pressure without remapping will decrease the fuel to air mixture ratio (Lean out). Running lean will give you more top end power and higher engine running temperature. In tuning term, lean is mean, but you don't want to go too lean least bad things will happen. But that will never be the case for the Termi slip-on our race exhaust mapping.. they'll always be on the safe side. (usually richer than the Stock map)
Addition of Back Pressure without remapping will increase the fuel to air mixture ratio (richen). In moderation, this can add more torque and response down but less top end power. The engine will also run slightly "cooler" due to unburnt fuel. Going too rich will bog down the engine and make it feel sluggish.
Most manufactures tune a little lean to help pass emissions - Lean = a cleaner burn and less work for the catalytic converter.
Picture this if you will - you have a Stock system which is trying to meet noise regulations so is creating back pressure which will in turn richen the fuel mixture. Now Ducati has to back off the fuel to lean out the mixture to to meet EPA and EU3 emission standards. Now you take away the Stock system back pressure by installing an open system ie Termi Slips or full system, the Up Map will have to enrich the mixture.
From the results thus far, I would speculate the RB unit is setup for the Stock map and not the Termi slip/full system upmap. This would cause the extra rich running with the addition of the RB unit and the AR system.
DRSapp
Thanks for the response and I can't agree more with what you have said.
That does contradict a lot of what has been written by self appointed forum experts on here with a number of them claiming making the fuel mix richer would give you more power etc. please read from the start if you have missed them.
Please note I don't believe what I wrote about the exhaust function was totally incorrect just that I was not aware of the effect it could have on the richness/leanness of the fuel. Thanks for making that clear.