Compressor surge and bad BOV?

spainobain1234 · 11-22-2012, 12:55 AM

Quote:

Originally Posted by bigal0043

Now say i did a piggy back system... down the road when i go to put in 550cc injectors would i still need a lexus afm??

and how much are one of those "apexi avc-r or s-afc"

where can i find one at?

edit i found this one on mvp

http://www.mvpmotorsports.com/Templates/fr...1200&SearchYN=N

i also just found one over on alamosports

http://www.alamomotorsports.com/apexi/safc.html

SAFC is a bitch to wire because once you mess up, there is no going back.

Plus my ebay Blow offvalve somehow blew the turbo! The blow off valve blew my turbo! LAME!!!!

cre · 11-22-2012, 08:19 PM

The SAFC is the easiest fuel controller there is when it comes to the wiring. Fewer wires than even the stereo has. Now if you're clueless when it comes to the tuning then you're always better off having a shop do it.

A bad BOV or even deleting it isn't going to kill a healthy turbo any time soon. Many race circuit vehicles which run obscenely high boost are built to run without them. There are a number of factory vehicles which never had them and ran/run just fine. It's a longevity device and on a daily driven vehicle I recommend them, they extend the life of the turbo and ease stress on the drive train between shifts. A bad wastegate on the overhand... well, that'll kill a whole lot of stuff.

spainobain1234 · 11-23-2012, 09:51 AM

Quote:

Originally Posted by cre

The SAFC is the easiest fuel controller there is when it comes to the wiring. Fewer wires than even the stereo has. Now if you're clueless when it comes to the tuning then you're always better off having a shop do it.

A bad BOV or even deleting it isn't going to kill a healthy turbo any time soon. Many race circuit vehicles which run obscenely high boost are built to run without them. There are a number of factory vehicles which never had them and ran/run just fine. It's a longevity device and on a daily driven vehicle I recommend them, they extend the life of the turbo and ease stress on the drive train between shifts. A bad wastegate on the overhand... well, that'll kill a whole lot of stuff.

What will make an external Wastegate go bad? mine connects below the bottom of my header underneath the flange, and the car backfires and Compressor Surges like none other! Then my brand new gt35 blew.
http://www.youtube.com/watch?v=HJlkVdJAyvo
http://www.youtube.com/watch?v=hye-XKFhKeo

cre · 11-23-2012, 07:16 PM

This needs to be moved to a new thread. We don't need to keep bumping a 5 year old thread which is barely related (as it'll keep sending email to people who haven't been here in ages). Look in the MKIII section for the new thread. I'm moving these posts to a new thread in there.

cre · 11-23-2012, 07:58 PM

Off throttle surge isn't an instant turbo killer. You'll find plenty of tuners who intentionally tune adjustable BOVs to not open at lower vacuum levels (so it doesn't open when shifting after a low boost level) in order to improve throttle response. Surge like you hear when you're actually on the throttle is HORRIBLE and usually very damaging as both the compressor and exducer are both under a serious load and then start getting pummeled with severe oscillations axially and radially, thrust washers decay as the oil film is compromised and the same with the bearings. On the other hand a BOV which isn't closing all the way can over work the turbo and cause excessive wear if it's not caught but it's usually not an overnight kind of thing.

The back firing doesn't tell me much other than your fueling may need adjusted, you're air metering system isn't setup properly or there's a significant timing problem.

It is possible for a bad BOV to cause damage but it's unlikely unless there were other critical issues with the setup. Plenty of cars came without them ever installed, manufacturers still make some without them and a lot of race vehicles don't use them. I haven't run a BOV on my MR-2 in years, pushing 16psi on the stock turbo... It's still not showing much more wear than when I bought it. I don't recommend everyone start running out and removing theirs but doing so is seldom a car killer.

A defective wastegate or inadequate discharge aperture will often be evident as your boost creeps beyond the set boost level while you're on the throttle. That's if the system isn't able to expel the excess exhaust charge. This isn't necessarily going to kill the turbo unless it really gets up there but may cause significant engine damage if your system isn't setup for the kind of load and fueling requirements of said boost. Of course if you don't notice as your boost climbs up to and beyond 25psi then the problem is even more with the driver than the car.

If the compressor is working too hard because of a poorly matched compressor and exducer you'll get the really nasty kind of compressor surge and are very likely to cause significant damage throughout the system. There are a couple other causes for this problem but I'm not going to get into all of it. The quickest fix is to turn the boost down, in all but the most extreme cases this will alleviate the problem. In really bad cases you may even see the intake charge meeting or exceeding the ambient air pressure (ie. it's making boost) at low RPMs or even at idle...

The BOV has nothing to do with this situation. Sure the BOV may be responsible for an off throttle flutter but the WOT surging isn't related and that's the one that's a real killer.

Without seeing the turbo and dismantling it I can't offer more than ignorant guesses as to what your problem was.

11-22-2012, 08:19 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The SAFC is the easiest fuel controller there is when it comes to the wiring. Fewer wires than even the stereo has. Now if you're clueless when it comes to the tuning then you're always better off having a shop do it. A bad BOV or even deleting it isn't going to kill a healthy turbo any time soon. Many race circuit vehicles which run obscenely high boost are built to run without them. There are a number of factory vehicles which never had them and ran/run just fine. It's a longevity device and on a daily driven vehicle I recommend them, they extend the life of the turbo and ease stress on the drive train between shifts. A bad wastegate on the overhand... well, that'll kill a whole lot of stuff. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

11-23-2012, 07:16 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	This needs to be moved to a new thread. We don't need to keep bumping a 5 year old thread which is barely related (as it'll keep sending email to people who haven't been here in ages). Look in the MKIII section for the new thread. I'm moving these posts to a new thread in there. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

11-23-2012, 07:58 PM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Off throttle surge isn't an instant turbo killer. You'll find plenty of tuners who intentionally tune adjustable BOVs to not open at lower vacuum levels (so it doesn't open when shifting after a low boost level) in order to improve throttle response. Surge like you hear when you're actually on the throttle is HORRIBLE and usually very damaging as both the compressor and exducer are both under a serious load and then start getting pummeled with severe oscillations axially and radially, thrust washers decay as the oil film is compromised and the same with the bearings. On the other hand a BOV which isn't closing all the way can over work the turbo and cause excessive wear if it's not caught but it's usually not an overnight kind of thing. The back firing doesn't tell me much other than your fueling may need adjusted, you're air metering system isn't setup properly or there's a significant timing problem. It is possible for a bad BOV to cause damage but it's unlikely unless there were other critical issues with the setup. Plenty of cars came without them ever installed, manufacturers still make some without them and a lot of race vehicles don't use them. I haven't run a BOV on my MR-2 in years, pushing 16psi on the stock turbo... It's still not showing much more wear than when I bought it. I don't recommend everyone start running out and removing theirs but doing so is seldom a car killer. A defective wastegate or inadequate discharge aperture will often be evident as your boost creeps beyond the set boost level while you're on the throttle. That's if the system isn't able to expel the excess exhaust charge. This isn't necessarily going to kill the turbo unless it really gets up there but may cause significant engine damage if your system isn't setup for the kind of load and fueling requirements of said boost. Of course if you don't notice as your boost climbs up to and beyond 25psi then the problem is even more with the driver than the car. If the compressor is working too hard because of a poorly matched compressor and exducer you'll get the really nasty kind of compressor surge and are very likely to cause significant damage throughout the system. There are a couple other causes for this problem but I'm not going to get into all of it. The quickest fix is to turn the boost down, in all but the most extreme cases this will alleviate the problem. In really bad cases you may even see the intake charge meeting or exceeding the ambient air pressure (ie. it's making boost) at low RPMs or even at idle... The BOV has nothing to do with this situation. Sure the BOV may be responsible for an off throttle flutter but the WOT surging isn't related and that's the one that's a real killer. Without seeing the turbo and dismantling it I can't offer more than ignorant guesses as to what your problem was. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->