boost within the system, SC.
Thread Starter
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
boost within the system, SC. Ive recently changed to an ecu with better logging functions.
This has allowed me to monitor pressure in the inlet end tank of my IC, outlet end tank, and also MAP, all using suitable pressure sensors. I will also be adding a sensor to monitor cooland system pressure soon too.
Given I am spinning the YSi pretty fast, I had thought my IC was posing a restriction, as relatively speaking, my boost isnt that high.
Intercooler is approx 3" thick around 13" in height/rows, with 2 cores around 11" tube length, welded together, at a slight angle for ease of installation..Tube and fin design. I simply re-used old cares from a twin setup to save on cost when fiting the LS1..
Outlet end tank is slightly improved over pics shown. All plumbing is 3", to an 85mm TB and elbow/Edelbrock
Im spinning the blower via 8.5" crank, 3.0" blower, which at 7000rpm is about 68K at the blower, 12 rib, and I see nothing to indicate slip is a problem.
At 7000rpm I am only making 19psi logged via 3 bar map sensor on intake elbow ? ( 225kpa )
Mine isnt a big motor, 382, 215cc Edelbrock heads with a 224/230 on 115 LSA cam.
As it stands, I dont seem to have any measurable restrictions worth talking about ???
Its interesting to see how boost within the system changes at different throttle openings, closed throttle until BOV's open etc
But in general, max pressure drop across my IC seems to be 2psi, but most of the time its less than that, usually around 1psi.
I doubt my air filter is a restriction, as its fairly big, with a decent 4-6"bellmouth
Does my boost seem low ? I know boost isnt everything, but when I see other guys making more, or similar boost, spinning the blower slower, and with bigger motors, I just find it odd ?
Graphs here may not show much, but posting a pic anyway. It tends to get crap quality when I snap the screenshot.
Map being 3 bar also reads vacuum.
Pressure sensors are 0-30psi only ( numbers are voltages, but the trends displayed are fine. )
Log is taken from a 4th gear run, with approx 4 secs displayed on current screenshot. I did have to modulate throttle a bit due to wheelspin, roughly 100-136mph, 4800rpm to 6300rpm or thereabouts.
Blue line is MAP in kpa
Red line is boost in the inlet end tank.
Green line is boost in the outlet end tank. Biggest variation is about 1psi ( 0.150volts ) on the graph.
Bottom graph red line is engine rpm, blue line is undriven wheelspeed. The rise in rpm, and dip in MAP is me backing off the throttle due to wheelspin. IC pressure can be seen to rise here too due to the closing of the throttle, as map drops to vacuum on same, then both backm up again on re-openeing throttle
Boost in the end tanks can be seen to rise on closing throttle, until the BOV's open ( one mounted before and after the IC ). Even at normal cruise, Im seeing as much as 5psi in the IC depending on engine rpm. At idle there is no noticeable boost in the IC.
This has allowed me to monitor pressure in the inlet end tank of my IC, outlet end tank, and also MAP, all using suitable pressure sensors. I will also be adding a sensor to monitor cooland system pressure soon too.
Given I am spinning the YSi pretty fast, I had thought my IC was posing a restriction, as relatively speaking, my boost isnt that high.
Intercooler is approx 3" thick around 13" in height/rows, with 2 cores around 11" tube length, welded together, at a slight angle for ease of installation..Tube and fin design. I simply re-used old cares from a twin setup to save on cost when fiting the LS1..
Outlet end tank is slightly improved over pics shown. All plumbing is 3", to an 85mm TB and elbow/Edelbrock
Im spinning the blower via 8.5" crank, 3.0" blower, which at 7000rpm is about 68K at the blower, 12 rib, and I see nothing to indicate slip is a problem.
At 7000rpm I am only making 19psi logged via 3 bar map sensor on intake elbow ? ( 225kpa )
Mine isnt a big motor, 382, 215cc Edelbrock heads with a 224/230 on 115 LSA cam.
As it stands, I dont seem to have any measurable restrictions worth talking about ???
Its interesting to see how boost within the system changes at different throttle openings, closed throttle until BOV's open etc
But in general, max pressure drop across my IC seems to be 2psi, but most of the time its less than that, usually around 1psi.
I doubt my air filter is a restriction, as its fairly big, with a decent 4-6"bellmouth
Does my boost seem low ? I know boost isnt everything, but when I see other guys making more, or similar boost, spinning the blower slower, and with bigger motors, I just find it odd ?
Graphs here may not show much, but posting a pic anyway. It tends to get crap quality when I snap the screenshot.
Map being 3 bar also reads vacuum.
Pressure sensors are 0-30psi only ( numbers are voltages, but the trends displayed are fine. )
Log is taken from a 4th gear run, with approx 4 secs displayed on current screenshot. I did have to modulate throttle a bit due to wheelspin, roughly 100-136mph, 4800rpm to 6300rpm or thereabouts.
Blue line is MAP in kpa
Red line is boost in the inlet end tank.
Green line is boost in the outlet end tank. Biggest variation is about 1psi ( 0.150volts ) on the graph.
Bottom graph red line is engine rpm, blue line is undriven wheelspeed. The rise in rpm, and dip in MAP is me backing off the throttle due to wheelspin. IC pressure can be seen to rise here too due to the closing of the throttle, as map drops to vacuum on same, then both backm up again on re-openeing throttle
Boost in the end tanks can be seen to rise on closing throttle, until the BOV's open ( one mounted before and after the IC ). Even at normal cruise, Im seeing as much as 5psi in the IC depending on engine rpm. At idle there is no noticeable boost in the IC.
Thread Starter
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
Its just an imageshack link ?
I left the pic big, which is why I linked it...
direct link
http://img511.imageshack.us/img511/5536/boostloggd6.jpg
I left the pic big, which is why I linked it...
direct link
http://img511.imageshack.us/img511/5536/boostloggd6.jpg
10 Second Club
Joined: Apr 2002
Posts: 1,755
Likes: 2
From: Cincinnati, Ohio
So far I have seen 14 lbs. I am having a high RPM issue so that is at about 5800 rpm. I was expecting 14-16 with this blower. I do have more cubes so a little less is expected. I have no slip either. So 19 sounds good to me.
TECH Addict
Joined: Jul 2005
Posts: 2,153
Likes: 3
According the Gerhardt at Bell Intercoolers, the rule of thumb is that you don't want more than 10% pressure drop from the compressor outlet to the intake plenum. So, that would be a total of 2 psi through all the piping, the intercooler, and the throttle body.
Mike
Mike
