newschool72

iTrader: (12)

Ok, I have another thread started here , "boost in first gear" and the answers have been very helpful, but since this can be a whole other topic and the other title doesnt get to this threads point, here goes.
I found that my HKS SQ4 BOV was leaking during a homemade leak down check/procedure . I have installed a "test" pipe in place of the pipe that holds the BOV and plugged the vac line . So...how bad is it on my turbo to just run without a BOV ? My turbo has the anti-surge compressor cover if that makes a difference.

newschool72

iTrader: (12)

Come on people, no one has an opinion on BOVs ? No bad experiences running without one ? No cool research on the ins and outs of the pluses and minuses ? No , my buddy blew his comp wheel off by not running one ? Speak up LS turbo magnates !

yenkomike

iTrader: (2)

I don't run one and have no plans to add one. have ran this turbo for 3 years with no issues. some say compressor surge is bad without a bov and some say a turbo can over spin when one opens hurting the turbo. all 6 of my buick gn's and 2 turbos on my nova and never had an issue

parts left out that are not needed cause no issues. jmho.

newschool72

iTrader: (12)

See? Thats the stuff I needed to hear ! I dont give a rats a$$ about some whistle or hissing Fast and Furry noise, I just stuck one on my set up cause thats what a turbo set up is suppose to have about everywhere you read.Thanks Yenkomike, for the wisdom.

a05c

It's a cheap piece of mind to keep unnecessary wear on the turbo. When you're talking turbos that are $3500+, what's 300 bucks to keep unnecessary abuse on it?

kingtal0n

iTrader: (1)

It is absolutely necessary if you plan to get high mileage from the turbo. Many turbo manufacturers are now including the bypass directly to the compressor cover. The same goes for filtration- you must use a high quality paper style filter if you wish for high mileage. Many here do not drive their cars daily/hundred thousand miles, so in terms of "years" sure they have the turbo for 3 or 10 years, but only put 5k miles on it.

pdxmotorhead

So am I missing something,, isnt it a blow-off if it blows to atmosphere, and a Bypass if it blows back in to the inlet side of the turbo after the MAF, so that off the line before boost its N/A until the turbo spins up, as well as keeping the actual air flow measurement? IIRC some cars have both? (Sorry senior moment... )

truckdoug

iTrader: (25)

I run a BOV. I like the whoosh and I DGAF that it sounds ricey

Blacksix

A BOV is not a bad idea when using a manual trans because of the constant WOT lifts when shifting. With an auto trans, not so much. Had turbo Buicks for years and once you're aware of it you just naturally let off the throttle gently after WOT instead of just letting go of the pedal. Never used a BOV. When speed-shifting a manual you just don't have time for that kind of finesse.

V8's with big pipes and long runs to a giant-mount intercooler have a lot of air running around in the system to cushion the shockwave if the throttle blades snap shut. So maybe not a big deal there either. But imagine if you had a turbo with no intercooler and a short pipe to the throttle plate, I would think it would be absolutely essential.

In a perfect world you should use one, but most adults don't like the racket. Unless you're expecting it to last 100,000 miles, I wouldn't worry about it.

newschool72

iTrader: (12)

I had a chance to test the car without the BOV today to see if it made a difference on my boost issue. It didnt......so I put it back on. My ECU seemed to get a little confused with all the extra air pushing against the throttle blades on decel. I guess the system (self learning) is use to the BOV and if its not affecting the boost , I will keep on using it .
My 18 yr old son has been pissed every since I took it off anyway. It seems that for his generation , the sound is as important as the power.

stevieturbo

2.5 hours after posting and you're whinging about no answer ?


Run with or without, really no big deal either way, but there is no generic answer for every setup.

stevieturbo

What people call them is irrelevant, they all do the same thing.

They vent air. Where the air goes...who really cares ?

newschool72

iTrader: (12)

What, are you the timeline police, Stevie ? I was looking for a quick answer because I wanted to take the car out for a test and since EVERYONE on this forum has an opinion on BOVs, I was hoping for a quick response. Thats one of the reasons LS1 Tech is such a great site......There is always someone with an opinion, ready to respond. Some sites I have been on take days to get to the truth. You can usually get honest opinions in minutes or hours here.

kingtal0n

iTrader: (1)

Nearly every car that comes factory from Japan with a turbo has a bypass, and a paper air filter.

stevieturbo

Almost all cars use a paper air filter for the engine.....nothing new there.

Cant say I've ever seen a Japanese car with a filter on the BOV if that's what you're referring to. They would never need to as they all recirculate.

pantera_efi

iTrader: (1)

Hi, OK you have a Surge Modification on the Cover, good AND this lowers air temperature.

AS YOU STATED many "opinions" with LITTLE FACT have been provided.

Thus some facts :
Compressor surge RAISES IAT, NOT GOOD
The BOV valve, when open, will discharge air cooling the compressor.
The BOV valve protects the compressor wheel by stopping the air flow out the compressor inlet that CAN PUSH the wheel into the cover.
The BOV, when open, will SLOW down the turbine.

NOW good advice would be to view the Compressor Map in the operational area.
WOULD you state the compressor part number/operational range ?

My method, FOURTY years ago, was to "throttle" both the turbo AND engine which results in higher turbine speed.

Lance

newschool72

iTrader: (12)

Its a CXracing chinese turbo that clones the compressor wheel off a garret 4508, 108/80mm. Going off the garret map, its a very good match for my engines air flow and stays in the 72+% range all the way through my RPM range, 3500 to 6500.

pantera_efi

iTrader: (1)

Hi, OK this is a START.

POST the MAP here I will show all here how to read the "surge line".

Lance

newschool72

iTrader: (12)

Here is the compressor map, Pantera. Thanks

newschool72

iTrader: (12)

Compressor map is up and im ready for knowledge on surge lines