Flattop
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Info below might be useful for anyone planning to change the WGA, it's data I wish I'd had a few years ago. A little background - I installed a JBA mid-pipe and exhaust (basically 3" all the way, starting from a few inches past the cat), on my otherwise stock eco. Turbo spooled up noticeably faster, but I got overboost codes when I floored it. Turbosmart made some interesting claims for their WGA, so I installed one with the "stock equivalent" 7 psi spring. Several sources said the stock spring was 5 psi, but additional preload made the wastegate cracking pressure higher. No more overboost codes, so I drove it that way for a few years.
Recently got the PCMTec software and started looking into tuning it. The stock value for wastegate preload is 9.3 psi, so I started wondering what I had actually done. I recently acquired a Mityvac pressure tester, perfect for this job.
First the stock WGA. Uninstalled, the actuator arm starts moving at 5 psi. Total available travel is 20mm. Installed, the preload is about 6.5mm, which results in a cracking pressure of slightly over 9 psi. Past that point, the actuator moves about 1cm for every 5 psi. Wastegate is fully open by 15 psi, which is a little over 1cm from the closed position.
On to the Turbosmart with 7 psi spring. Uninstalled, the actuator starts moving at 7 psi. Total available travel is about 16mm. Installed, with a 2mm preload (per the instructions), the cracking pressure was slightly over 7 psi. So my wastegate had been opening 2 psi early, which eliminated both the overboost codes and some of the top end power. I had to increase preload to 4mm before the crocking pressure got back to 9 psi. At that point, it would also fully open at 15 psi, with about 1cm of travel from closed.
So if I was to do it again, on an untuned engine with more restriction in the exhaust, I would preload the 7 psi TS WGA with 4mm, and probably test it to know exactly when it was opening.
And note that the stock WGA has more available travel and is larger diameter than the TS.
I'm planning to tune it with a bigger spring in the TS WGA, and will need to fix the overboost issue, but that's another story.
Recently got the PCMTec software and started looking into tuning it. The stock value for wastegate preload is 9.3 psi, so I started wondering what I had actually done. I recently acquired a Mityvac pressure tester, perfect for this job.
First the stock WGA. Uninstalled, the actuator arm starts moving at 5 psi. Total available travel is 20mm. Installed, the preload is about 6.5mm, which results in a cracking pressure of slightly over 9 psi. Past that point, the actuator moves about 1cm for every 5 psi. Wastegate is fully open by 15 psi, which is a little over 1cm from the closed position.
On to the Turbosmart with 7 psi spring. Uninstalled, the actuator starts moving at 7 psi. Total available travel is about 16mm. Installed, with a 2mm preload (per the instructions), the cracking pressure was slightly over 7 psi. So my wastegate had been opening 2 psi early, which eliminated both the overboost codes and some of the top end power. I had to increase preload to 4mm before the crocking pressure got back to 9 psi. At that point, it would also fully open at 15 psi, with about 1cm of travel from closed.
So if I was to do it again, on an untuned engine with more restriction in the exhaust, I would preload the 7 psi TS WGA with 4mm, and probably test it to know exactly when it was opening.
And note that the stock WGA has more available travel and is larger diameter than the TS.
I'm planning to tune it with a bigger spring in the TS WGA, and will need to fix the overboost issue, but that's another story.
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