Boost starting at high RPM
Boost starting at high RPM Im new with this whole FI world so bear with me please.
The motor is a ls1, it has a 76mm Turbo, hks bov, tial 44. It only has a mail order tune with a turbo base tune for now till i get it driveable. My tack is not hooked up yet but when its idleing it has around 20 vac when i give it gas it dosent go into boost until just right before the rev limiter. I know by not having the tach working i cant get a good reading of what rpm im at but basically i dont see boost till about 1k short of rev limiter. This is a DIY turbo kit so it may be an error that ive caused. Also i have my bov on a vac T thats connected to the line that goes from the side of the WG to the compressor housing and considering its a HKS it should be loud and it dosent make any sound but this is because the Bov should work when the motor comes from boost back to vac right? Does anyone know what my problems could be? THanks!
The motor is a ls1, it has a 76mm Turbo, hks bov, tial 44. It only has a mail order tune with a turbo base tune for now till i get it driveable. My tack is not hooked up yet but when its idleing it has around 20 vac when i give it gas it dosent go into boost until just right before the rev limiter. I know by not having the tach working i cant get a good reading of what rpm im at but basically i dont see boost till about 1k short of rev limiter. This is a DIY turbo kit so it may be an error that ive caused. Also i have my bov on a vac T thats connected to the line that goes from the side of the WG to the compressor housing and considering its a HKS it should be loud and it dosent make any sound but this is because the Bov should work when the motor comes from boost back to vac right? Does anyone know what my problems could be? THanks!
Your late boost could be exhaust leaks, incorrect wastegate reference, oversize turbine housing A/R, etc. However, the BOV reference definitely needs to come from the intake manifold in order to work properly.
Yea i figured i would start by checking for leaks, thats what im going to do in the morning. I think the WG is refrenced correctly strait from the turbo. The turbine housing is .81. I had the bov hooked up to a T in in the brake booster line and it did the same thing.
you wont see any boost in neutral. Turbo needs load from the motor/tranny/rear end and this isnt reachable in neutral...revving it, isnt proving anything....-20 vac. is 100% normal tho....thats what It should be. When cold and warming up, my car idles at -19...once warm, its at -21.
Also, dont run your BOV off any other vac. lines. Run it straight from a vac. line from you intake manifold. Same goes for the wastegate.
Also, dont run your BOV off any other vac. lines. Run it straight from a vac. line from you intake manifold. Same goes for the wastegate.
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On The Tree
Joined: Nov 2004
Posts: 199
Likes: 0
Turbo needs load from the motor/tranny/rear end and this isnt reachable in neutral...revving it, isnt proving anything
u could build boost in neutral . all u need is a 2 step rev limiter.
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really?? then explain to me why you cant build boost in neutral and it builds in gear?? Also, why does switching rrear end gears affect spool time?? The load you get from your gears and when your in gear affects your exhaust flow, hence putting a load on the turbo making it spool IN gear.
On The Tree
Joined: Nov 2004
Posts: 199
Likes: 0
really?? then explain to me why you cant build boost in neutral and it builds in gear?? Also, why does switching rrear end gears affect spool time?? The load you get from your gears and when your in gear affects your exhaust flow, hence putting a load on the turbo making it spool IN gear.
http://www.youtube.com/watch?v=2wMVfSrxfdM
most ppl switch rearend gears because they ran out of gear or lugged the motor at the finish line.Your turbo will begin to spool in wot at X rpm in any gear.It takes time for the turbo to spin up to the designated boost.for example say your turbo takes 3 seconds to go from 1 psi to 15 psi.IT will take 3 seconds in any gear. 3 seconds will eat more of the time in 1st gear than it would in 3rd gear.
Ask anyone with a manual transmission and a turbo how they spool the turbo at the starting line.check out the begining of this video.
http://www.youtube.com/watch?v=2wMVfSrxfdM
most ppl switch rearend gears because they ran out of gear or lugged the motor at the finish line.Your turbo will begin to spool in wot at X rpm in any gear.It takes time for the turbo to spin up to the designated boost.for example say your turbo takes 3 seconds to go from 1 psi to 15 psi.IT will take 3 seconds in any gear. 3 seconds will eat more of the time in 1st gear than it would in 3rd gear.
http://www.youtube.com/watch?v=2wMVfSrxfdM
most ppl switch rearend gears because they ran out of gear or lugged the motor at the finish line.Your turbo will begin to spool in wot at X rpm in any gear.It takes time for the turbo to spin up to the designated boost.for example say your turbo takes 3 seconds to go from 1 psi to 15 psi.IT will take 3 seconds in any gear. 3 seconds will eat more of the time in 1st gear than it would in 3rd gear.
Ask anyone with a manual transmission and a turbo how they spool the turbo at the starting line.check out the begining of this video.
http://www.youtube.com/watch?v=2wMVfSrxfdM
most ppl switch rearend gears because they ran out of gear or lugged the motor at the finish line.Your turbo will begin to spool in wot at X rpm in any gear.It takes time for the turbo to spin up to the designated boost.for example say your turbo takes 3 seconds to go from 1 psi to 15 psi.IT will take 3 seconds in any gear. 3 seconds will eat more of the time in 1st gear than it would in 3rd gear.
http://www.youtube.com/watch?v=2wMVfSrxfdM
most ppl switch rearend gears because they ran out of gear or lugged the motor at the finish line.Your turbo will begin to spool in wot at X rpm in any gear.It takes time for the turbo to spin up to the designated boost.for example say your turbo takes 3 seconds to go from 1 psi to 15 psi.IT will take 3 seconds in any gear. 3 seconds will eat more of the time in 1st gear than it would in 3rd gear.
Im not sure how many cars you have seen build boost in neutral revving...but I can only get 1psi If I bounce off the rev limiter in neutral....compared to when Im in gear, and power breaking....I can build boost but my tires start spinning before I see anything more then 3psi.
You ever been in a turbo car when the tires are spinning so much the boost starts to drop? Why is this? because spinning tires is taking away load from the motor....
you can argue with me all you want. Im right. Research it.
Last edited by kidcamaro98; Mar 10, 2008 at 11:59 PM.
the small turbo ar should have no problem spooling, that's why i bought it in the first place with my old M6 setup. i wanted turbo spool NOW. if you are just revving it in neutral, it might make a pound or so tops. try just driving the car down the street or something if it's driveable and i bet that turbo will come up really hard
Dam thanks for the input, i thought i had a bad boost leak or something, its my first turbo car and i built the whole turbo system my self so i thought it was an error in my work. So then when you hit about 1# in neutral does your bov go off?
On The Tree
Joined: Nov 2004
Posts: 199
Likes: 0
Ok then explain to me why a STandard car spools the turbo again and again during every shift and a auto spools it once...because during the shift on a standard your taking the LOAD away from the motor...with a auto, once you mat it, the load is always there KEEPING the turbo spooled.....your "theory" didnt prove a damn thing....
Im not sure how many cars you have seen build boost in neutral revving...but I can only get 1psi If I bounce off the rev limiter in neutral....compared to when Im in gear, and power breaking....I can build boost but my tires start spinning before I see anything more then 3psi.
http://www.youtube.com/watch?v=9IOpu...eature=related