The bypass valve is the way to go for response and power. A blow off valve only makes sense if you want the noise.
Well exactly.... so really, WTF are we talking about here? Is the thread mis-titled? Has this thread been using the wrong terminology? Or is this just about the noise?
Most on this thread wanted the noise.
From https://www.turbosmart.com/news/five-facts-about-blow-off-valves-that-are-wrong/
No, the performance comes from the boost being "bypassed" back to the compressor inlet to help the turbo spool faster.
I'm new to turbos, but that's not how I understand it... I'm sure someone will correct me if I'm wrong.
Yes and no.
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for a high boost application, you want to blow off the high PSI. For a jeep, you don't want to lose boost everytime you let off the throttle, especially if you are on the rocks. You need to maintain pressure in the system so you have more predictable throttle response.
Somewhat related interesting article: https://www.roadandtrack.com/new-ca...70857/porsches-dynamic-boost-antilag-718-911/
The majority of the performance from the DV+ is the piston valve sealing back up before the solenoid releases the valve back to a closed state. It's basically a faster reaction and less blow off of boost pressure. When you go back on throttle the valve will already be closed and still maintaining some boost pressure so you don't have to wait to build boost. The re-circulation of the blow off has a minimal effect on the turbo spool. You go off throttle and it's basically a shot of air into the intake at less PSI than was in your charge pipe from being on boost and it's only like a second or two. The added PSI to the intake may ease tension on the turbo bearings but there would have to be back pressure from the air filter side of the intake system to give it a real boost to the turbo intake. The best analogy that I can think of is a water hose into a river. I'm by no means saying your wrong, but it's very minimal. I've ran with and without the re-circulation hose attached and couldn't tell any major performance differences. When I get time I'll make some log runs with my JB4 with and without the hose attached to see if there is any significant difference that I'm just not seeing or feeling.Yes and no.
Both types of valves are to prevent compressor stall. That's when the compressor is producing boost, the throttle body is closed quickly, and that compressed air in the intake has nowhere to go. This back pressure causes the compressor to stall. Not great for performance, and not great for it's longevity. Also remember a turbo is not directly mechanically coupled to the engine and run by exhaust, so the turbo will lag on both spool up and spin down somewhat just based on exhaust and it's mass alone. Preserving compressor speed is critical for response (as well as reducing compressor mass - but thats more expensive
The biggest gain is having the early-close function along with a proper bypass. As you come off the throttle the valve will open, boost will bypass and help keep compressor spinning faster than the exhaust flow can sustain on it's own. As the boost goes down the valve will early close and this faster spinning compressor will help build pressure in the intake again. Now if you get back on the throttle you already have some boost immediately, and a compressor that is already spinning faster then it would without the bypass which is where the performance bump comes from.
As you drive around on the street in stop and go the above cycle happens continually. You are typically not steady state on the throttle. You are always in and out of boost. Where the DV+ helps is to reduce the lag coming back into boost immediately after getting off the throttle; and this helps to improve the response drastically. It helps to hide the turbo lag in such a situation, and in a heavy JL this extra early boost/torque helps drive quality a lot.
I would expect that the plumb-back's performance improvements would mostly be from the correct metering of air. Vent-to-atmosphere should cause a (slight) rich condition when off throttle, which is probably why no performance difference is felt.
That's correct. That's why so many people that add BOV's get CEL's. However, in my case, which I should have mentioned, I'm running a Mishimoto CAI which has increased airflow. My theory is when the Diverter solenoid activates that the MAF sensor is looking for an increase of air flow based on the diverter blow off and the available air which is restricted by the factory intake. With a BOV that slight increase is not there causing a fuel rich condition because the computer is expecting extra air and then increases fuel. By running a less restrictive CAI the turbo and the engine get the air it's expecting and the computer adjustments are much smaller than running a BOV with the factory intake. The combination of a BOV and a restrictive air intake is enough to cause a fuel rich event that causes the computer to make adjustments that exceed thresholds and pop a CEL. Again... That's my theory based on everything that I've seen.
So is there a stiffer spring in the kit? Thanks in advance.
