Blow off Valves?
- Thread starter NM
- Start date
i got a turbo xs bov and cut the spring down just so it was long enough to hold it shut at idle. works great now my box only comes off when the bolts break and im at full boost
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RidnHigh
Well-known member
Neil, what BOV are you running? Try running the pink spring in the Tial setup...thats what I'm running. I believe I am seeing somewhere in the neighbrohood of -3lbs of vacuum when i chop the throttle and i believe that spring is good to -4... what symptoms are you seeing that makes you feel like the motor doesnt like the pressure? I am with you i believe that all turbo kits should have a BOV, i wonder why none of the aftermarket guys do it on the pump gasser kits, just on the race gas stufff??
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NM
Well-known member
It is a Malpassi. It has an adjustable spring that I have set as soft as it will go. The sled does not run good when cruising, and I'm not sure it likes the small charge of warm air it is getting from the turbo. Not sure what the turbo builders are doing to get them to run clean pre boost, but this one runs terrible. Might need to ditch the intercooler, but I didn't think that it would matter when the sled is running in vac.
I am new to the 2 stroke thing. The good news is that our new fuel controller works great when the sled is on boost, I just need bigger injectors now because I under estimated how much power this sled makes. It pulled really hard at 9 lbs until it would go lean. I will change the injectors and try it again (should also check compression). I should also get a softer spring for the wastegate actuator so I can turn the boost down.
with the spring all the way soft is there still a preload on the spring? mine was that way so i cut it just to be long enough to hold it shut. i also had one that had 2 different springs and had no preload and set as soft as it would go was too stiff still so i just ditched it and went with the turbo xs
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Boyko
Well-known member
You did have to pick a hard 2-smoker boost, I do not know much about the 2011 pros, but the builder had problems getting them to clean up. How much have you dropped your fuel pressure? Having a BOV open will help a little but the problem is the exhaust pressure, and the way the ecu is set up, the factory fuel curve will be way fat until you get around 1.5psi of boost. Fuel ends up pooling in the bottom of the case so when you get the revs up or even lean the sled over it floods, I do not think just dropping fuel pressuure will do it on the pro,
Don’t worry you will get ripping Neil just keep at it.
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NM
Well-known member
I played with fuel pressure and it didn't seem to make much of a difference. I suppose playing with a prototype kit doesnt really help. We may build a water to air airbox and supply the turbo oil from the injection pump. I'm not a huge fan of ditching the oil injection, but we have to put race gas in it anyway, so no big deal.
Checked the compression and it is fine, so the knock sensor did it's job. The fueling on boost seems relatively easy, I just want to get rid of this bottom end boggy crap.
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NM
Well-known member
There is still some preload there. I am considering trying to fit a External wastegate so the stock pipe can evacuate the exhaust easier. I think that I am on the right path, just time and testing for now.
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NM
Well-known member
It is a prototype kit that Alpine built, and should work if I can get this bottom end cleaned up. I will look at a HKS. Thanks.
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