Originally Posted by drwrx
I'm not certain I agree. The extra 3 to 5 lbs of boost and the set of headers could be all the difference. And while his post says 15psi was "all it could hold at redline" I'm not certain what that means. Every person I've ever known with a vf22 has never had any problem running 20+psi all the way to redline. The problem has always been "not enough fuel", and too much boost. It's no suprise where the "more topend" is coming from, the extra 5psi of boost. 5 lbs is a huge difference!
I'm not dissing the 18G, it's a great turbo and should perform better than a vf22. But what is stated above is not what I would call a fair comparison.
You are absolutely correct IMHO. And the reason the VF22 couldn't hold more than 15psi to redline WITH the stock wastegated spring (~7psi) is just one of the many reasons it's so much fun to live at high altitude
. Over the winter I added a helper spring to the VF22 so it could hold 20psi to redline and it felt quite a bit better... for about 8,000 miles that is until I my car turned into the spy hunter smoke screen car under boost [heh]. After that I went with the 18G with a 18psi wastegate to hold 20psi to redline (lost about 3-4psi to redline with the headers with the weaker 15psi can I had on the 18G originally).
But I then ran the 18G at 20psi daily for about 10,000-15,000 miles which btw up here worked out to be in the 3.0-3.2PR range = VERY high turbine rpms. I then sold it to another owner who ran it just as hard for about the same amount of miles maybe more. Then the 3rd owner opted to have it rebuilt just as a precaution and precursor to installing it.
So IMHO, totally can't verify this, the VF22 with the helper spring to hold 20psi to redline would have probably made about the same hp/trap speeds in the 1/4 mile but it only lived about 8,000 miles at the 3.x+ PRs that come from running 20psi at 6000ft asl. So the 18G is a much more durable and cheaper turbo to maintain in the long run.