My 2g w/ 1g bov and mbc has always behaved like this and I’m wondering if it’s typical:
boost will peak to 14.5 psi then quickly drop off to a sustained 12.5 psi
if all other engine stuff is stock aside from k&n filter, is that basically the most boost i can get on pump gas?
Thanks for clarifying!
Are you running the stock T25 turbo? If so it is typical for that turbo to hit a peak boost (in your case 14.5psi) then die town to 12.5. The T25 cannot hold a constant boost of anything higher than 12psi. When I ran my T25 with a HSK SSQ BOV and a Greddy Profect B boost controller, I hit 18psi on the T25, and then instantly it would die down to 12 and stay there. The solution to this problem is to get a bigger turbo. Since you are autocrossing alot I would reccomend the evo 16G. Minimal lag with lots of airflow.
If you are running a turbo bigger than the T25 then I would suspect you have a different problem. I would need more details before I could narrow it down to what it exactly could be.
I currently run 20psi on pump gas, so no the limit is definately not 14.5 psi. It is all dependant on injector size, pump gas can undergo a lot of boost pressure. With 450cc injectors you can run up to 15psi no problem, you can run more than this but you will detonate. Boost will not go down automatically if you detonate, so pump gas is definately not your problem.
