What the SRT engineers say
Here's the post I was referring to in my last post.
http://forums.viperclub.org/grail-trail/625903-why-venom-control-runing-10-4-afr.html
Quote:
Originally Posted by Schulmann
We had a dyno session day in our club last Saturday. One of the thing that stunned us was the really rich AFR on the GEN4 Vipers above 4000rpm. For some unknown reason the AFR drops from 13 to 10.4 suddenly at 4000rpm causing the engine to loose 50hp. We were expecting 540rwhp and got 490 rwhp.
It makes me remember my old 2000 when the AFR suddenly dropped due to ignition issues above 5000rpm.
We had two Vipers with this problem. On the third one the dyno master has stopped the session because the engine was hesitating too much at 4000rpm.
What is going on in the GEN4 VENON control at 4000rpm ?
How Venom control protects the engine against knocking ?
FROM THE SRT ENGINEERS:
We'll help Herb out with this one - We don't want to get into the habit of responding to any and all issues on this Forum but we will make a few comments on this issue.
First, the addition of an aftermarket air filter element can and generally does adversely effect the operation of the MAF sensors. Any change to how the air enters the clean air duct upstream of the MAF sensors can change the airflow measurement. A change in the construction of the filter element will change its characteristics. In any of our testing, the production air filter element has almost no restriction at production airflow (we worked ******* this!) so save your money and prevent other issues by not changing the filter element.
There is a WOT timer in the Venom that protects the exhaust valves and pistons from over temperature. The timer is set to enable at 4000 rpm and after 12 seconds of uninterrupted WOT the timer matures and the fuel is enriched by 6%. This is not something most owners will ever experience while driving the car but it is something that can happen on a dyno. Any time the driver tips out of WOT, the timer is re-set.
The knock system will add fuel as it reduces spark in order to protect against over temperatures. When running on dynos in some cases we have seen noise induced by the dyno that can be interpreted by the system as knock. This will greatly reduce the performance.
Make sure you are running good fuel on the dyno and keep air and fluid temperatures under control - not something many shops handle very well. The Venom will retard spark and again add fuel for inlet air and coolant temperatures that are above normal. This is done to prevent knock and protect parts.
In summary, it's not quite a simple as it may seem to get a "proper" run on a dyno. Chrysler spends many millions of dollars on equipment to properly test cars and engines. If we could do it for the price of a $50,000 or $100,000 dyno and get good and consistent results we would! If simply changing the air filter element would get us 5 or 10 HP, we would have done it!
) my ass cheeks are far more sweet than sensitive.
