Stage 2 bypass question

[613B6]

Hey guys, I've tried to search for some stage 2 logs to view however have been unable too find any on pump gas. Can anyone tell me what they have seen in terms of bypass with a single pulley on pump gas, overall CF values, intake temps, etc? Right now my car is pretty stock with CTS intake/AWE exhaust and stage 2, I'm seeing bypass starting from 4k rpm at 1% up to approx 10% before knock correction, then bypass remains about the same until redline. If anyone could shed some light that would be great, Im also curious to see what the requested boost numbers look like in other people files.

[shoe3k]

The car is sensitive to intake temps, which why you would see the bypass open before knock correction. Don't forget to update your sig with your mods.

[613B6]

Thanks, yes I'm very used to Bosch MEx ecu's I need to educate myself further on the Simos stuff. There seems to be so many areas where bypass is effected for tq management strategies.

[bhvrdr]

Hi there,


There's 2 general reasons the bypass valve opens and bleeds boost: 1. Because the car is programmed to purposefully do so, 2. because the car senses a condition that triggers a safety measure in the programming that opens up the bypass valve.


Case 1: The stock program is obviously programmed to open it. This allows for a 333hp output in a variety of conditions, even at some alititudes. Aftermarket performance programs may also be programmed to open it, sometimes on purpose such as with Revo. Revo desensitizes the factory knock thresholds/safeguards to allow the car to run more timing that OEM strategies would allow but they also run reduced load targets and bleed boost a bit. This appears to be a purposefuly strategy. In this situation, sure you could run a CW on the Revo program but now you are running maximum boost on a car that has desensitized engine safeties for timing. I wouldnt do this. Other scenarios would be running a dual pulley on a stage 2 program. In this case, the car is bleeding boost because the program wad designed to hold full boost of a single SC pulley upgrade but not more than that. If you add the CW there, you can potentially get full possible boost and if your tuner retains all the factory safeguards, you'd retain them with the CW too.

Case 2: The second scenarios are when the car is triggering factory safeties because the car is not running optimally for any number of reasons. It could be california 91 octane causing knock, or a malfunctioning OEM cooling system causing high IATs.


You can log your car to see which scenario is happening. If you log your car and your actual manifold pressure is reaching your ECU requested boost/load targets you know it is because your programming is not allowing full boost for whatever reason the tuner had. If you log your car and your actual manifold pressure is below targets but you are seeing high IATs, EGTs, ECTs, Knock, and the bypass is opening, you know you have an issue with the car and safeties are bleeding boost.


IMO a properly tuned stage 2 car and one that is in a proper state of maintenance that is running quality 93 octane should have no issue keeping the bypass valve closed in most all situations. I've run my stock cooling car in south FL summers using top tier 93 octane and NEVER had an issue keeping the bypass valve closed even during torture testing of literally back to back to back runs with hot idles in between.

Mike

[613B6]

Thanks Mike for the info, would you happen to know what requested hpa numbers look like for a proper running stage 2 car? As well, what type of IATs are normal to see in a log at redline.

[Loe]

Thanks Mike for the info, would you happen to know what requested hpa numbers look like for a proper running stage 2 car? As well, what type of IATs are normal to see in a log at redline.

Are you needing a GIAC stage 2 requested boost file? Or just one in general?

[613B6]

In general, GIAC, REVO doesnt matter, Im more looking to compare a pump gas stage 2 log to mine for learning purposes.