SI valves

[danomite02]

Has anyone, actually had an SI valve fail before? Not " oh i heard about them failing" Actually seen with their own eyes, a failure in our platform of these valves?

[GMR Badass]

People will always have mixed reviews about them. Back when it was the ZZP and Intense were going at it you always saw Intense exploiting every SI (sold by ZZP) failure. On the flip side ZZP never had negative response to the Manley valves that everyone recommends running.

In 2007 I saw a 3800 Turbo in a Firebird drop a couple valves on the dyno....AFR was dead on and boost wasn't cranked up.

Personally I'd say pay up......pay a little now, or pay way more later. You're talking about a custom turbo kit, SC, and intercooler setup....not to mention dropping in a 1" chain....so why skimp out on what valves you plan on running. Extra cost is totally worth me not having to deal with the aftermath of a valve failure.

[danomite02]

I agree. Was just curious. ZZP wont give me a straight answer, The guys at SI state the valves only pop heads off from the valves bouncing from too weak of springs.

[GMR Badass]

Even on their website it says not recommended for turbo applications.

The way I look at it is that if people running SI valves weren't running enough spring pressure, then you'd have to assume that just as many people that were running Manley valves also weren't running enough spring either. Over the course of the platform spring pressure was always determined by what cam (valve lift) and rpm target...it's never been about what valve you were running to choose the corresponding spring pressure...... Yet you don't hear about Manley valves having the valve head pop off, or stock valves for that matter......shows me which valve is inferior.