At moderate flows (ie midrange, high boost) the 16G big compressor map has a nice big hump of decent efficiency that extends to a PR of about 3.3 IIRC, allowing for at least about 2 bar (29 PSI) once you account for losses between the compressor and the inlet manifold. The exhaust manifold pressure certainly isn't sufficient to push open a weak wastegate in the midrange at this level. Agree with you at the top end, and agree it is probably too much in the midrange for safety on modest octane on the stock internals, but not because of the efficiency of the stock turbo in the midrange.

 

22psi is deff not the limit of making power without knocking on the stock 05 turbo, but without a tune it is like Russian Roulette.

 

True. My car runs 24psi peak on 93 octane with a 10.5 hotside (making my '04 turbo a '05 basically). That is where Chris at AMS set it because it was safe and knock free to that. Of course with the 272s it tapers off.

28psi without meth though is just crazy. And one thing I will add that I didnt see anyone mention (while I was just skimming) is when he gets tune/meth/pump, get head studs as well for that much boost!!!

 

lifting the head never hurt nobody?

 

this coming from the kid with a 21psi tune.

 

He is asking a question here.

So to answer I guess I would say that yes lifting the head enough will cause a blown head gasket and there are many idiots who ran way too much boost and had this happen and that does "hurt".

 

Yes, he is asking a rhetorical question, and i was just messing with him. I <3 teh dextors.

 

No..... all I asked was its OK to run 28PSI? its SAFE? I never said I want to run that high.

 

use common sense. stock parts are designed for stock boost. when u go above & beyond, u best start a collection jar to replace broken pieces. i run 30psi on stock turbo/motor but its not a daily & i'm tuned for racegas only...

 

never a bad thing

he is still faster than you at the track

you just love his hair

you can run the 28psi, on pump (93oct)? might be a little high, (91oct) NO!!
But,why not run that high? the car is more fun at high boost just tune it accordingly with the proper setup (meth, race gas, etc)

on a good condition stock motor, you can run high boost (27-30) on a stock turbo with no ill effects for a while as long as the ecu is tuned properly. I ran 30+psi on a VIII turbo, then IX turbo and finally a 3065 all on a stock block for well over 3 years and 30k miles.

 

:-) Over 400 AWHP, with tune.

 

Am I the only one seeing he is running 28lbs on only pump gas. Not Meth like everybody is saying they do. He also lists no tune. If anybody thinks you can run 28lbs on stock tune on strait pump is nuts...especially on VIII's. Considering you are in WA you probably run 92octane like the rest of us.

 

so you're only asking if it was safe... but you did it anyway?

 

thats what I did on 100oct on stock turbo at 32lbs

you're not the only one

a little late

 

get some headstuds, a bigger fuel pump and injectors, E85 and a tune, you can run 28psi all day!