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I don't think I've seen this discussed here, maybe it's too ricer.
At times, like at the track I'd like the option to hear the 964 in full song. I don't have the skills to do a GT3 exhaust install so am thinking of adding a Y pipe and cutoff to the cup pipe. Effectively this would give me the option of bypassing the secondary. Has anyone already done this?
Surely I can't be a pioneer here, as this seems that it will work. Someone else must have done it.
The good news is that the until will fit in the space around a primary bypass pipe and be largely hidden. The bad news is that it won't work with the supplied motor as it can only fit in a downward orientation, which is too low for normal road use. I will have to work on a cable option to operate the butterfly valve. Total invested so far is USD 115 for the unit shipped from China.
There's a bit of info out there about noise reducing valves for 911s but they tend to be the inline valves - I've not seen the Y-pipe used before.
The part that would bother me about the Y-pipe is the disruption to the flow when the valve is closed (so in reality most of the time). The Y-valve would be a lot better if the butterfly was right up at the join. It may or may not be an issue but doesn't look 'right' to me.
Have you ever heard your car with this little noise reduction? For me the it's good for the novelty factor but would get pretty tiring pretty soon.
Sorry if that sounds a bit negative, I guess it's all personal preference really and it could be a fun project.
The Raceland exhaust cutout may be a better physical fit. A bit pricier than your setup and doesn't come with the remote.
I'm not sure if there's room, but if you could rotate it so the actuator is not hanging down, and then have the pipe pointed straight towards the pavement. Just a thought.
There's a bit of info out there about noise reducing valves for 911s but they tend to be the inline valves - I've not seen the Y-pipe used before. The part that would bother me about the Y-pipe is the disruption to the flow when the valve is closed (so in reality most of the time). The Y-valve would be a lot better if the butterfly was right up at the join. It may or may not be an issue but doesn't look 'right' to me. Have you ever heard your car with this little noise reduction? For me the it's good for the novelty factor but would get pretty tiring pretty soon. Sorry if that sounds a bit negative, I guess it's all personal preference really and it could be a fun project.
I can help tinkering so this is a 'suck it and see' type project. I'm not sure if the valve will survive constant pressure when closed, or it will introduce back pressure. We shall find out soon. As for the noise, I expect it to be unbearable for all but the track. If it all fails I will put it back to as is.
I can help tinkering so this is a 'suck it and see' type project. I'm not sure if the valve will survive constant pressure when closed, or it will introduce back pressure. We shall find out soon. As for the noise, I expect it to be unbearable for all but the track. If it all fails I will put it back to as is.
Haha, fair enough. Post a sound clip when it's done.
Funny how different it is over here - we are constantly having to try to quieten out cars down to be allowed onto the track. Loud days are 105db!!!
I've sourced a cheap primary bypass so am resurrecting the project. It's a RUF bypass modified with a resonance chamber (never seen that before). I'll fit the pipe as is first just to see what difference it makes. If it's nothing special it's getting the cut.
Originally Posted by Steve Weiner-Rennsport Systems
How do you plan on changing the fuel mixture when you actuate the exhaust bypass since these engine do go lean when such changes are made?
Steve, I wasn't aware of that. I know SW chips can take account of the exhaust configuration but there must be a fair few unmodified chips on cars with various configurations of cat, primary and secondary bypasses. Is it a significant change? I have an after market ECU and wide band O2 sensor to measure this. Thanks for the heads up.
Steve, I wasn't aware of that. I know SW chips can take account of the exhaust configuration but there must be a fair few unmodified chips on cars with various configurations of cat, primary and secondary bypasses. Is it a significant change? I have an after market ECU and wide band O2 sensor to measure this. Thanks for the heads up.
Yessir,...its a significant change in a car that already runs close to Stoich (closed loop).
I don't know about other ECU's, but Motec can be setup to compensate when an exhaust bypass is opened, however one needs to do the mapping for both configurations.
Originally Posted by Steve Weiner-Rennsport Systems
Yessir,...its a significant change in a car that already runs close to Stoich (closed loop).
I don't know about other ECU's, but Motec can be setup to compensate when an exhaust bypass is opened, however one needs to do the mapping for both configurations.
so are you saying I need to send my Steve Wong chip back to have it re-configured if I just add a primary bypass? I've been meaning to get around to installing it this winter
06-11-2015, 06:17 AM
Exhaust cut off on a 964?
