Mazda Rotary Club

General => General Technical => Topic started by: m1tch on December 28, 2009, 04:31:43 PM

Title: Bov on high flow turbo?
Post by: m1tch on December 28, 2009, 04:31:43 PM
Hi guys,

I will be taking delivery of a nice shiny T88 for my FC, I know that it needs quite a large wastegate which is why I am also nabbing a 55mm wastegate to get rid of all the exhaust gasses to control the boost.

I need to ask about the other end of the turbo, the BOV, what size/sort should I get for the turbo as it will be flowing much more air than the current one!

I currently have a Blitz dual drive BOV, 1 port for low boost, 1 for high boost, so it can handle some good airflow, but I know that there will be much more air flow with the new turbo, so do I need to upgrade?

The T88 doesn\'t have a ported shroud like the GT4088 I was going to go for, and I have already had to get my OEM one rebuilt due to the last owner wrecking the bearings due to turbo chatter :(

I just need to ask as when I let off I need the air to actually escape rather than smash back into the turbo lol

Also, are there any high flowing recirc valves around? I might change back to a recirc to reduce the wastage of all that nice boost I just created lol
Title: Bov on high flow turbo?
Post by: Prof on December 28, 2009, 05:00:21 PM
recirc valves don\'t preserve the boost - since they vent back to the low pressure side of the turbo.
 
Jury seems to still be out about whether not to have a BOV, to have one and vent to atmosphere or to have one and recirc back.
 
Bear in mind that if you recirc the warmed up compressed air back into the intake pre turbo - it will go around again for more heating ;)
Title: Bov on high flow turbo?
Post by: m1tch on December 28, 2009, 05:06:21 PM
Quote from: Prof;661858recirc valves don\'t preserve the boost - since they vent back to the low pressure side of the turbo.
 
Jury seems to still be out about whether not to have a BOV, to have one and vent to atmosphere or to have one and recirc back.
 
Bear in mind that if you recirc the warmed up compressed air back into the intake pre turbo - it will go around again for more heating ;)

Recirc > mini intercooler = win? :D
Title: Bov on high flow turbo?
Post by: L18M on December 29, 2009, 12:21:34 AM
what about twin bov? one either side of the ic?
Title: Bov on high flow turbo?
Post by: neil_jdmr on December 31, 2009, 08:15:50 PM
Quoteand I have already had to get my OEM one rebuilt due to the last owner wrecking the bearings due to turbo chatter :(

 
Any proof of that Mitch, only ask as im interested to know as afaik chatter has never really been proved to cause any damage and is more likely oil stavation.
 
Im really not having a go or anything, seriously, but just interested in this topic as i ran without a bov on stock fd twins for ages without issue (still boosting up well on the same set admittedly with a bov now tho).
 
Please dont take this the wrong way:guinness
Title: Bov on high flow turbo?
Post by: m1tch on December 31, 2009, 08:18:54 PM
Quote from: neil_jdmr;662431Any proof of that Mitch, only ask as im interested to know as afaik chatter has never really been proved to cause any damage and is more likely oil stavation.
 
Im really not having a go or anything, seriously, but just interested in this topic as i ran without a bov on stock fd twins for ages without issue (still boosting up well on the same set admittedly with a bov now tho).
 
Please dont take this the wrong way:guinness

I went to get my OEM turbo ported due to the new exhaust, universal turbo had to completly rebuild my turbo as everything was shot lol the previous owner had basically left some vac lines venting to air, meaning that the BOV didn\'t fire fully if at all, which caused the bearings to fail lol it still boosted, just wasn\'t smooth lol