Manually Controlling the Exhaust Bypass Valves

Hi Russel,

You are right. You didn't say anything about engines. I got fixated on engines and didn't even consider you may have been referring to the silencer / cats.

I cannot speak with high authority on whether running a silencer that is designed with bypass valves could be damaged by running the same silencer with the bypass fully closed. In thinking on it, I guess that would depend on the silencer in question. My initial thought is that there is very low risk.

On the F355 there is a real danger of running fully open valve as the bypass valve is ahead of the silencer and the gases that are bypassed go thru some mini-cats, which could cause overheating at the entry point to the silencer. There is thermocouple there that if it overheats, it throws the infamous SLOW DOWN light. That is not generally a problem on subsequent model Ferrari's as the bypass valves on downstream of the silencer. Your point, though, is what might happen if you run the car with valves fully closed and all the gases are now passing through the silencer. As I stated above, I think very low risk that anything is going to happen of any significance.

I envision the typical user will use the always closed option in two environments:

1. Low RPM cruising where he/she wants low noise. E.g., highway speeds at 70 to 80 mph and RPM around 3500 to 4000.
2. Track days to meet noise restriction. In these situation the engine speed as high as 8000, but for short periods. With total track duration of less than 30 minutes.

Bottom line, this is a user requested function and just like using the fully open function, to be used with discretion. My intent is to offer the option for fully closed operation as I have been requested to provide this function. Specifically from European owners who want to track their car and meet sound requirements. But, I also intend to provide the caveat that the system is not designed to operate in this fashion and operation is at owner's discretion. Similar to my existing caveat that the system is not designed to operate with valves always open either. To answer your question ... no, I am not making any guarantees.

Although it may not seem like it ... I really do appreciate your comments as it forces me to think through consequences. It is because of FChat community and users like you, I hope to be able to offer the choices that users want.

Regards,

Steve

 

Hello All,

I have a new model of the Exhaust Bypass Valve Controller. Incorporates the Always Closed option ... but this option is only recommended for use for specific times when having the valves open might make the car too loud ... for example, at some tracks in UK, on novice days, there might be noise restrictions that might not be met when the vehicle's ECU opens the valves at high engine RPM.

My controller will keep the valves always closed, but will also increase exhaust system back pressure and this will reduce peak horsepower and engine efficiency. For this reason, I do not recommend the Always Closed option for casual use.

The other operational modes are still there ... Always Open and ECU Control of valves.

Other improvements include full integration of electronic components on a printed circuit board and using a high-gain antenna to improve RF reception of the remote control.

Thanks and kind regards,

Steve
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I have been given more info about running a Ferrari with the exhaust system bypass valves always closed.

Basically, there should be absolutely no harm in normal driving. Keeping the valves always closed will limit the peak horsepower, but not by much. Engine peak horsepower typically is achieved at fairly high RPM.

It is very difficult to connect how the exhaust system itself could be damaged because of prolonged closure of the exhaust bypass valves. It will not have to dissipate any more or less heat due to bypass valves position. However, one could possibly see that in situations where the engine revs are very high for prolonged periods (e.g., racing), and the exhaust bypass valves were closed, the increase back pressure could possibly raise the temperature of the engine's exhaust valves. If they were to become too hot, they could be damaged.

Bottom line ... for the vast majority of us, under normal driving conditions where engine revs are likely to be less than 4000 RPM except for short spurts, having the exhaust bypass valves closed will not present a problem. People who truly race their cars, will have purpose built exhaust system that do not have bypass valves ... so the topic is moot. People who occasionally track their cars where there are noise limitations, should use discretion keeping the valves closed when tracking. IMO, the risk of overheating the engine exhaust valves is low as typical track times are 20 minutes or less and engine revs are not likely to be so elevated during that time as to cause any damage. And, for most people, tracking their cars is only an occasional thing.

Regards,

Steve