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My son's gtv6 recently popped off the plenum while I was doing some work on the power windows, starting and turning off the engine from time to time. I wasn't even in the driver's seat, turned the key to start it and POW!
After some choice adjectives in Spanish as is my custom, I decided to get serious about this phenomenon.
No it doesn't happen often at all, but when it does happen it's always a PITA to loosen the clamps getting access to them with a slender screwdriver, resetting the plenum and then getting access into that tight space again to tighten the clamps. I don't like living with problems, if I can resolve them.
So I began to think about it, which is usually kind of dangerous.
I researched low pressure relief discs, conventional pressure relief valves, and the spring loaded disc that is sold for the 911 flat 6 engine which addresses the backfiring habit and prevent cracking of the airbox. I looked at back fire protection for propane-fired engines like forklifts. Unfortunately we are restricted by space limitations and the ribbed design of that cast aluminum plenum anyway. Realizing that any of several methods might work, I finally decided on a pop off cap fitted to a large-diameter hose barb. Like an oversize vacuum port cap. Will this be large enough in cross-sectional area to reduce the explosive pressure enough to keep the plenum in place? Heck, I don't know! I didn't do any calculations. I didn't have enough data for that. But I just decided to go with as large a fitting as I could and relocate the check valve and hose for the power brake booster.
So please just refer to the photos and you'll see that I bored out that port to 18 mm from the stock 16 mm and installed a large hose barb fitting with as large an ID as possible. And I relocated the power brake hose over to the other side using a 1/4 inch pipe thread fitting and 3/8 diameter hose. I also used a plastic check valve in place of the original steel threaded check valve that was installed into the plenum.
After some choice adjectives in Spanish as is my custom, I decided to get serious about this phenomenon.
No it doesn't happen often at all, but when it does happen it's always a PITA to loosen the clamps getting access to them with a slender screwdriver, resetting the plenum and then getting access into that tight space again to tighten the clamps. I don't like living with problems, if I can resolve them.
So I began to think about it, which is usually kind of dangerous.
I researched low pressure relief discs, conventional pressure relief valves, and the spring loaded disc that is sold for the 911 flat 6 engine which addresses the backfiring habit and prevent cracking of the airbox. I looked at back fire protection for propane-fired engines like forklifts. Unfortunately we are restricted by space limitations and the ribbed design of that cast aluminum plenum anyway. Realizing that any of several methods might work, I finally decided on a pop off cap fitted to a large-diameter hose barb. Like an oversize vacuum port cap. Will this be large enough in cross-sectional area to reduce the explosive pressure enough to keep the plenum in place? Heck, I don't know! I didn't do any calculations. I didn't have enough data for that. But I just decided to go with as large a fitting as I could and relocate the check valve and hose for the power brake booster.
So please just refer to the photos and you'll see that I bored out that port to 18 mm from the stock 16 mm and installed a large hose barb fitting with as large an ID as possible. And I relocated the power brake hose over to the other side using a 1/4 inch pipe thread fitting and 3/8 diameter hose. I also used a plastic check valve in place of the original steel threaded check valve that was installed into the plenum.




