Vacuum lines and gauge install Help to Newbs
any source before the Throttlebody,otherwise sometimes its possible that when the car isnt in boost and is in vacuum the FPR will actually drop the fuel pressure according the vacuum.
TECH Regular
Joined: Dec 2006
Posts: 417
Likes: 1
From: Canada
all great info. ill be looking at this as i install my goodies. i have a question tho
you said that if you have an intercooler and ref. the waste gate off the turbo *say it has a 8psi spring in it* you would be getting less PSI to the motor, like say 6-7psi correct? and as long as i hook my boost gauge up AFTER the TB. i would be a correct motor boost reading?
im asking this becuse i have a stock lt1 and my w/g came with a .6 bar*8.7psi at sea level* and i was thinking if i reff it off the turbo i could get some boost drop threw the piping and intercooler and say run 6-7psi at the motor with out changing much...could this work or am i just being a silly teen?
you said that if you have an intercooler and ref. the waste gate off the turbo *say it has a 8psi spring in it* you would be getting less PSI to the motor, like say 6-7psi correct? and as long as i hook my boost gauge up AFTER the TB. i would be a correct motor boost reading?
im asking this becuse i have a stock lt1 and my w/g came with a .6 bar*8.7psi at sea level* and i was thinking if i reff it off the turbo i could get some boost drop threw the piping and intercooler and say run 6-7psi at the motor with out changing much...could this work or am i just being a silly teen?
all great info. ill be looking at this as i install my goodies. i have a question tho
you said that if you have an intercooler and ref. the waste gate off the turbo *say it has a 8psi spring in it* you would be getting less PSI to the motor, like say 6-7psi correct? and as long as i hook my boost gauge up AFTER the TB. i would be a correct motor boost reading?
im asking this becuse i have a stock lt1 and my w/g came with a .6 bar*8.7psi at sea level* and i was thinking if i reff it off the turbo i could get some boost drop threw the piping and intercooler and say run 6-7psi at the motor with out changing much...could this work or am i just being a silly teen?
you said that if you have an intercooler and ref. the waste gate off the turbo *say it has a 8psi spring in it* you would be getting less PSI to the motor, like say 6-7psi correct? and as long as i hook my boost gauge up AFTER the TB. i would be a correct motor boost reading?
im asking this becuse i have a stock lt1 and my w/g came with a .6 bar*8.7psi at sea level* and i was thinking if i reff it off the turbo i could get some boost drop threw the piping and intercooler and say run 6-7psi at the motor with out changing much...could this work or am i just being a silly teen?
TECH Regular
Joined: Dec 2006
Posts: 417
Likes: 1
From: Canada
well. its my DD and id rather be safe then sorry *higher mile stock lt1*. PLUSS its always easier to turn the boost up from a lower point then it is to turn it down from a higher point so if its to low i can always up it..if its to high im kinda SOL becuse id rather not change the spring
Hey man, this is how I just finished hooking it up for the same exact reason. I say it will work too, I am waiting on parts at the moment so can't tell you for sure. One good thing about it is though I did read in a post from Jose at Forced Inductions and he said that is a good place to use as a reference.
ddnspider, is there anyway to keep the boost gauge from bouncing around between shifts. Or is that normal, never had a boost gauge so I am not sure. I have it referenced just before the TB, if that helps.
EDIT...saw ur sig.you are a stick.and i see you have centrifugal blower.boost is based on RPM with those.so when u shift your RPM drops causing boost to drop with it and as rpm rises so will your boost gauge.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo the purpose of a boost gauge is to read positive pressure(whether it be in psi,kpa's,or bar) and if so equipped it can also read vacuum in inches i believe.im assuming youre a manual car and dont powershift,so when you shift the throttle shuts closed for a split second which drops the boost pressure.Then when you hit the gas again in the next gear it will take a short moment for you to reach full boost again(lag). thats why it fluctuates in between shifts.
EDIT...saw ur sig.you are a stick.and i see you have centrifugal blower.boost is based on RPM with those.so when u shift your RPM drops causing boost to drop with it and as rpm rises so will your boost gauge.
EDIT...saw ur sig.you are a stick.and i see you have centrifugal blower.boost is based on RPM with those.so when u shift your RPM drops causing boost to drop with it and as rpm rises so will your boost gauge.
for a turbo setup if u wanna see the boost level of the spring or whatever you reference it after the TB.for a centrifugal blower its rpm dependent.when youre between shifts the throttle plate slams closed so no air goes in,ie no boost.
Thanks for your response
Teching In
Joined: Nov 2007
Posts: 16
Likes: 0
From: Aurora CO
not to be a jerk but that is actualy wrong what ever the pressure is in the intake manifold is what the engine is recieving and at idle when you are in vac. fuel pres. is supose to go down. If hooked up before tb when you boost your car and then let off your fuel pressure would go up when it doesnt actualy need the fuel so go real rich. if no cat u will belch flames which i cool but plugs burn up fast
not to be a jerk but that is actualy wrong what ever the pressure is in the intake manifold is what the engine is recieving and at idle when you are in vac. fuel pres. is supose to go down. If hooked up before tb when you boost your car and then let off your fuel pressure would go up when it doesnt actualy need the fuel so go real rich. if no cat u will belch flames which i cool but plugs burn up fast
Teching In
Joined: Nov 2007
Posts: 16
Likes: 0
From: Aurora CO
well if it is a fully custom set up with flat longterm fuel maps only for race kinda car but if its a moded up street car thats how you want it. because thats how it is factory and it is simple tunning is much more of a pain a factory fuel system has a 1:1 fuel press. regulator that lowers pressure at idle because its after tb. now you hook it up before and when you let of throttle you get adverse effect a spike in pressure meaning you get more fuel and you just let off the throttle so the need for more fuel... minimal when you test for bypass accuracy on a dyno you hook a boost gauge up before tb and you wound be amazed when you are in boost at say 4,500 and let off thottle that tb slaps shut that air piles up so fast a 8 psi system can comanly spike to 18 before tb and with a 1:1 fuel pressure regulator it is not a big deal but if you have a higher ratio or a fmu after regultr say a 12:1 thats 216psi at 18 psi of boost pop you just blew a fuel line ask anybody who runs a shop that commanly supercharges or turbos f-body cars they will say all pressure refrence fuel componants need to go off after tb pressure because thats thats what pressure the engine gets
you pick a source BEFORE the throttlebody for a reference for a FPR so that it will only see boost.you will not see vacuum BEFORE the throttlebody.AFTER the throttlebody the intake manifold will see vacuum,therefore it can possibly drop your fuel pressure below the intended base fuel pressure causing you to go lean.Ive had the car on a dyno and have watched my fuel pressure gauge on the FPR when in boost vs no boost.having it before the throttlebody makes for less fluctuation in the fuel pressure so why complicate it more by having to tune for a larger range of fuel pressues.
