Do you have pictures of the porting that you did? Typically you shouldn't lose 2psi from porting a blower... It should either be a wash or you should increase boost.
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02-08-2012
Do you have pictures of the porting that you did? Typically you shouldn't lose 2psi from porting a blower... It should either be a wash or you should increase boost.
02-08-2012
i dont think i have any pics but i thought that by openning the lim would decrease the boost but i didnt go nuts on ghe blower outleti kinda copied the pics of everyone else and opend the triangle
02-08-2012
Porting a LIM/blower shouldn't reduce boost pressure. It should reduce output temps.
Flow mods, cam, rockers, heads, headers are what lowers boost pressure because you are flowing more air through the cylinders and not leaving it backed up in the LIM.
02-08-2012
thats true i guess its possible it was a colder day when i was making about 13psi i think i still have the datalog i think it was btewwen 12.5 and 13, and now its at like 11.3, so its really no more than a 1.5psi difference, i know when i had ny 3.4" pulley on it was around 8psi
02-08-2012
You probably destroyed your blowers Volumetric Efficiency by doing that. Any porting on the outlet should be minimal as in smoothing it out, not opening things up. The notable drop in boost proves it. Sorry dude,Originally Posted by nyls1346
02-08-2012
i dont think i destroyed it, like i said i dont open up the triangle really in size, i smoothed the bottom corners to remove that hump and then revoved the bridge that goes from side to side above the triangle, but i didnt really make the triangle bigger in physical size, i also smoothed the edges around the triange to help flow..
i did quite s bit of research before i went ahead and did this, im gonna get a datalog tonight and see how much boost i make because its nice cold weather tonight
02-08-2012
You probably destroyed your blowers Volumetric Efficiency by doing that. Any porting on the outlet should be minimal as in smoothing it out, not opening things up. The notable drop in boost proves it. Sorry dude,
02-08-2012
I said probably
Lower boost levels tonight on his datalog will prove it.
Seriously though, there's a high percentage of people who ruin their blowers by porting them.
02-08-2012
Theres a thread for this topic, and its not here, but over there: http://www.grandprixforums.net/m90-porting-56101.html
02-08-2012
Just a thought/question. Just because you loose a little boost doesn't necessarily mean you loose power. Does it? Increase flow will lower Boost. So if you can get the same amount of fuel/air into the combustion chamber with less pressure, you're better off right? Same power less heat = better volumetric efficiency doesn't it? That's why all the big shops use flow benches to port heads.
02-08-2012
^^^^ youre half right... while a properly ported blower will essentially make less heat making less pressure... too much drop can mean all the air isn being pushed into the LIM but around/in the blower casing causing it to loose efficiency...
02-09-2012
Increased flow in/out of the combustion chamber will lower manifold pressure.
But touching the blower won't change the efficiency of the process mentioned in the previous sentence.
Flow is one thing, but so is velocity and efficiency of the intake and exhaust runners.
02-10-2012
boost pressure changes due to air density are not really able to be measured by any type of boost gauge... dropping 2lbs of air by 100 degrees may reduce the pressure created by that air by .1 or .2psi... Its not really measurable.
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