turbo spools but no boost
08-14-2013, 10:05 PM
#41
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i was having a simular issue and its coupled with actual exhaust leaks however, i did notice when i had a small 4lbs wastegate spring and ultimatly, it couldnt hold even the initial boost in vac that it created i wound up putting a small 10lbs and a large 8bs spring and with a MBC, was getting 9psi finally! and thats with a exhaust leak still lol and referenced from the coompressor housing. im gonna move it to the intake manifold soon.
08-15-2013, 02:40 AM
#42
@joshuagrooms83 Ok im going to order a 10 psi spring just to try it. That would be my low boost setting anyway. I will also test all the piping for a leak. Did it sound like your turbo was making boost? I can hear my spool pretty good
08-16-2013, 01:37 AM
#43
Ok so tonight with tons of lag I made 13.5psi I did 2 things before I made a test past. The first was the one way check valve going from the manifold to the optispark was bad. The second was I put a huge stack of washers on top of the wastegate spring to hold it close. I'm pretty sure it wash the wastegate.
08-16-2013, 08:28 AM
#44
Ok so tonight with tons of lag I made 13.5psi I did 2 things before I made a test past. The first was the one way check valve going from the manifold to the optispark was bad. The second was I put a huge stack of washers on top of the wastegate spring to hold it close. I'm pretty sure it wash the wastegate.
08-17-2013, 01:47 AM
#47
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I read through this and here are two theories of mine.
In the video you seem to explain that the hotside coming to the turbo is 3inch? and if i understood that correctly then that answers a big question. That is the reason you are then seeing 6psi at your rev limit,cause typically the hotside to the turbo in 2.5 inch possibly smaller. With 3 inch the exhaust coming from the motor is only starting to really get the turbo going once there is enough exhaust being produced to propel the turbine at your rev limit.
Second theory, is the bov could possibly be leaking, sounds wierd but my bro's car did that and we had to get a new BOV cause for some reason she wasnt sealing up all the way during throttle.
I hope this help and when you said a t70 .96a/r i do not think that is to small, for 650hp? that should get you there.
In the video you seem to explain that the hotside coming to the turbo is 3inch? and if i understood that correctly then that answers a big question. That is the reason you are then seeing 6psi at your rev limit,cause typically the hotside to the turbo in 2.5 inch possibly smaller. With 3 inch the exhaust coming from the motor is only starting to really get the turbo going once there is enough exhaust being produced to propel the turbine at your rev limit.
Second theory, is the bov could possibly be leaking, sounds wierd but my bro's car did that and we had to get a new BOV cause for some reason she wasnt sealing up all the way during throttle.
I hope this help and when you said a t70 .96a/r i do not think that is to small, for 650hp? that should get you there.
08-17-2013, 01:06 PM
#48
Ok thank you. I have a wastegate issue. It seems it was pushin open because I have a 4lbs spring. I put a stack of washers in there to hold the wastegate closed and it made 13.5 psi but there was a ton of lag. It took like 5 sec to build boost. I also break boosted it and made 2psi before I left and it slowly built up to about 6psi then the boost hit hard and jumped to 13.5 but I was getting too sideways so I had to let off. I was only at about 5k rpm so I know it will make more. I need to get a stronger spring asap and that should fix it
08-17-2013, 02:14 PM
#49
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Ok thank you. I have a wastegate issue. It seems it was pushin open because I have a 4lbs spring. I put a stack of washers in there to hold the wastegate closed and it made 13.5 psi but there was a ton of lag. It took like 5 sec to build boost. I also break boosted it and made 2psi before I left and it slowly built up to about 6psi then the boost hit hard and jumped to 13.5 but I was getting too sideways so I had to let off. I was only at about 5k rpm so I know it will make more. I need to get a stronger spring asap and that should fix it
08-17-2013, 07:27 PM
#50
As far as spooling a remote mount goes. The biggest problem you have to overcome is the loss of heat, which reduces volumetric flowrate past the turbine. Volumetric flow rate is what spools the turbo. The higher the temperature of the exhaust gas the more it will expand.
Your goal is to retain heat, and increase the velocity of the exhaust gas through the system.
If the LT1 has headers ditch them, or at a minimum wrap them.
Cast manifolds hold in heat better due to there thickness.
Wrap the exhaust all the way to the turbo to retain heat, this gets expensive.
2.5" would be better for two reasons first is its smaller diameter so there is less pipe wall for heat to be transferred to the environment on its way to the turbo. Second due to its smaller diameter and the fact that the motor has to flow the same amount of exhaust gas the velocity of the gas going through the pipe has to increase, which pushes on the turbine harder spooling the turbo.
Increase the size of the downpipe, it will produce a larger pressure difference across the turbine making it extract more energy from the exhaust gas.
Noticed you are from California so weld in some header flanges and make a test pipe to delete the Catalytic converter save it, weld some flanges on the converter and bolt it back up when its smog time.
Check for exhaust leaks have a buddy block off the exhaust pipe to a few seconds to pressurize it and listen for the sound of rushing air then fix it.
Your goal is to retain heat, and increase the velocity of the exhaust gas through the system.
If the LT1 has headers ditch them, or at a minimum wrap them.
Cast manifolds hold in heat better due to there thickness.
Wrap the exhaust all the way to the turbo to retain heat, this gets expensive.
2.5" would be better for two reasons first is its smaller diameter so there is less pipe wall for heat to be transferred to the environment on its way to the turbo. Second due to its smaller diameter and the fact that the motor has to flow the same amount of exhaust gas the velocity of the gas going through the pipe has to increase, which pushes on the turbine harder spooling the turbo.
Increase the size of the downpipe, it will produce a larger pressure difference across the turbine making it extract more energy from the exhaust gas.
Noticed you are from California so weld in some header flanges and make a test pipe to delete the Catalytic converter save it, weld some flanges on the converter and bolt it back up when its smog time.
Check for exhaust leaks have a buddy block off the exhaust pipe to a few seconds to pressurize it and listen for the sound of rushing air then fix it.
08-18-2013, 10:33 PM
#53
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nice glad we could help. I don't get how in these rear mounts that the wastegate cant even hold the low amount as advirtise. im guessing that with the exhaust building up in the exhaust, the initial exhaust back pressure is high and forces the gate open, even at low/ no boost levels with light springs. I only noticed this when I happen to put my hand on the driver side exhaust and felt warm air coming out. I was like "WTF" lol so that led me to put larger springs in there until ultimately I put a 10lbs and then I actually cut half a coil out of a larger 10lbs spring that fit in my wastegate and im assuming its about 8lbs now but could be a touch higher. either way, its weird that even with a manual boost controller set at low setting that I only getting 9psi and I got damn near 18lbs spring sitting on top of that damn thing. ive read around and this seems to be pretty common anomaly with custom rear mounts where we are using larger or more effient items compared to a base sts system. Zombie mentioned it once on his thread and a few others have. I even had to discover it on my own lol
