BBK Full compressor surge at only 27 psi?
Mar 11, 2011, 09:45 AM
#76
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There are plenty of factors that make turbos die. I'm not trying to draw any conclusions. However, over spinning via boost leak is not plausible at all.
If the compressor wheel is contacting the compressor housing, it is thrust loading related, and can be anything from a nut coming loose, bad thrust bearing, or coming out of balance.
If the compressor wheel is contacting the compressor housing, it is thrust loading related, and can be anything from a nut coming loose, bad thrust bearing, or coming out of balance.
Mar 12, 2011, 10:29 AM
#77
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I don't see how a boost leak can induce detonation.
If u lose boost the effective compression ratio is reduced which reduces the chance of detonation, not so?
Now, if u had your mbc setup aggressively and there's a boost leak... and then u come along and fix the leak.....you increase boost and can induce detonation that way. This can be equated to having a leaky stock BOV, then upgrading it...eliminating the leak...which can either push the turbo into surge or cause a boost spike or both.
This is why it's a good idea to get a decent BOV before you up the turbo. The BOV may indirectly permit some extra boost depending on the state of your stocker BOV.
Mar 12, 2011, 11:49 AM
#78
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I use a HKS SSQ.
I don't see how a boost leak can induce detonation.
If u lose boost the effective compression ratio is reduced which reduces the chance of detonation, not so?
Now, if u had your mbc setup aggressively and there's a boost leak... and then u come along and fix the leak.....you increase boost and can induce detonation that way. This can be equated to having a leaky stock BOV, then upgrading it...eliminating the leak...which can either push the turbo into surge or cause a boost spike or both.
This is why it's a good idea to get a decent BOV before you up the turbo. The BOV may indirectly permit some extra boost depending on the state of your stocker BOV.
If u lose boost the effective compression ratio is reduced which reduces the chance of detonation, not so?
Now, if u had your mbc setup aggressively and there's a boost leak... and then u come along and fix the leak.....you increase boost and can induce detonation that way. This can be equated to having a leaky stock BOV, then upgrading it...eliminating the leak...which can either push the turbo into surge or cause a boost spike or both.
This is why it's a good idea to get a decent BOV before you up the turbo. The BOV may indirectly permit some extra boost depending on the state of your stocker BOV.
Mar 12, 2011, 03:22 PM
#79
My wife told me I shouldn't buy white underwear because it adds contrast to the skid markings. But that has nothing to do with bleach
Nevertheless, back on "surge" topic. One thing that precipitates this is not enough compressor inlet/outlet bypass at moderate load, and during transient throttle prior to WOT or wherever. Something that will bypass below fulll spool, or hold solid when loaded is good generally, but my impression is more, with the full.
A twin ported DV likely keeps mine from misbehaving. I just use a homemade contraption with a 3 port energized via TPS in ecuflash, 3.1 volts energized, 2.8 deenergized. _Just ensure it doesn't bypass at full boost on accident. That would spin the turbo into oblivion, especially on the FULL setup ( I assume the 10 blade wheel design might allow ridiculous shaft RPM if suddenly unloaded from a full load achieved at high boost near high eng RPM). This would also hold true as stated above for like a duct popping off at say, 6500rpm at like 28psi
Nevertheless, back on "surge" topic. One thing that precipitates this is not enough compressor inlet/outlet bypass at moderate load, and during transient throttle prior to WOT or wherever. Something that will bypass below fulll spool, or hold solid when loaded is good generally, but my impression is more, with the full.
A twin ported DV likely keeps mine from misbehaving. I just use a homemade contraption with a 3 port energized via TPS in ecuflash, 3.1 volts energized, 2.8 deenergized. _Just ensure it doesn't bypass at full boost on accident. That would spin the turbo into oblivion, especially on the FULL setup ( I assume the 10 blade wheel design might allow ridiculous shaft RPM if suddenly unloaded from a full load achieved at high boost near high eng RPM). This would also hold true as stated above for like a duct popping off at say, 6500rpm at like 28psi
Mar 12, 2011, 05:12 PM
#80
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My wife told me I shouldn't buy white underwear..... One thing that precipitates this is not enough compressor inlet/outlet bypass at moderate load, and during transient throttle prior to WOT or wherever. Something that will bypass below fulll spool....A twin ported DV likely keeps mine from misbehaving. I just use a homemade contraption with a 3 port energized via TPS in ecuflash, 3.1 volts energized, 2.8 deenergized. _Just ensure it doesn't bypass at full boost on accident. That would spin the turbo into oblivion.....
Mar 13, 2011, 09:24 AM
#81
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A twin ported DV likely keeps mine from misbehaving. I just use a homemade contraption with a 3 port energized via TPS in ecuflash, 3.1 volts energized, 2.8 deenergized. _Just ensure it doesn't bypass at full boost on accident. That would spin the turbo into oblivion, especially on the FULL setup ( I assume the 10 blade wheel design might allow ridiculous shaft RPM if suddenly unloaded from a full load achieved at high boost near high eng RPM). This would also hold true as stated above for like a duct popping off at say, 6500rpm at like 28psi
That's a useful proposition C6, something I have developed an actual standalone to do with a bit more user interface (one touch traffic or performance) & parameters (TPS,RPM,BOOST). Congratulations on your implementation.
I am currently working on a next gen device that will give you proportional DV control based on TPS,RPM & BOOST. Thus you will be able to 'Throttle" your DV/BOV based on a duty cycle much like an ebc now. Smoothly 'mapping' out any compressor surge at partial throttle etc, permitting more flexible high spool turbo to engine matchups across the volumetric eff. curve.
On note though, with the added BOOST parameter you can create a "pop off" protector for your motor. Even though you may "overspin" the turbo a bit at WOT...it's much better/safer than what high boost WOT detonation will do to your internals.
Mar 13, 2011, 11:29 AM
#82
Yah something about your parts combination. I am running 27 psi on E85 and get no surge at WOT. I get some part throttle drama, but that is largely due to my driving style (part throttle trying to maintain speed on the freeway). But WOT is always a clean pull all the way through. Once you get it sorted out I am positive you will be happy with it.
Mar 13, 2011, 12:28 PM
#83
Yah something about your parts combination. I am running 27 psi on E85 and get no surge at WOT. I get some part throttle drama, but that is largely due to my driving style (part throttle trying to maintain speed on the freeway). But WOT is always a clean pull all the way through. Once you get it sorted out I am positive you will be happy with it.
Mar 14, 2011, 07:07 AM
#85
Well,
seeing as even garrett will tell you that a boost leak will kill the turbo-
and on another note-
boost leaks can cause detonation-
If you have a turbo thats designed to run at 28psi.. peak efficiency- and you go over that- (because of say a 10 psi leak) you are now operating at 38psi at the compressor outlet- which moves the turbo out of it's efficiency range and causes hot air- which in turn warms the entire intake charge- and you now are causing detonation etc!
cb
seeing as even garrett will tell you that a boost leak will kill the turbo-
and on another note-
boost leaks can cause detonation-
If you have a turbo thats designed to run at 28psi.. peak efficiency- and you go over that- (because of say a 10 psi leak) you are now operating at 38psi at the compressor outlet- which moves the turbo out of it's efficiency range and causes hot air- which in turn warms the entire intake charge- and you now are causing detonation etc!
cb
Mar 14, 2011, 09:50 AM
#86
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I have a subaru with a GT35r on it 550whp... and that had boost hoses jumping of left front on the twist of the engine due to the FMIC piping.
Turbo has done 5000+mile... still running fine.
I am getting the BBK full converted to FP green... and I will test that and see how long it will last. I will check for leaks... same way I did it before.
thinking of even doing some testing to see if the turbo rpm runs away when boost pipes come off.
Turbo has done 5000+mile... still running fine.
I am getting the BBK full converted to FP green... and I will test that and see how long it will last. I will check for leaks... same way I did it before.
thinking of even doing some testing to see if the turbo rpm runs away when boost pipes come off.
Mar 14, 2011, 12:53 PM
#87
I have a subaru with a GT35r on it 550whp... and that had boost hoses jumping of left front on the twist of the engine due to the FMIC piping.
Turbo has done 5000+mile... still running fine.
I am getting the BBK full converted to FP green... and I will test that and see how long it will last. I will check for leaks... same way I did it before.
thinking of even doing some testing to see if the turbo rpm runs away when boost pipes come off.
Turbo has done 5000+mile... still running fine.
I am getting the BBK full converted to FP green... and I will test that and see how long it will last. I will check for leaks... same way I did it before.
thinking of even doing some testing to see if the turbo rpm runs away when boost pipes come off.
and the only proper way to test for leaks is a boost pressure tester!
simply tightening clamps is not appropriate- we've done posts on this!
cb
Mar 15, 2011, 10:02 AM
#89
typically bov's etc wont show leaks until 25 psi or so (what we find on ALMOST EVERY evo X valve here now).... you crack that threshold and have issues-
also- consider that when you are pressure testing- you arent pumping hot air through the system like the motor is under operation, nor are you testing with heatsoak overall..
be as thorough as you can.
cb
