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Turbo Dose

skylinekid

By skylinekid,
in Engines & Forced Induction

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R34NRG Grand Master

R34NRG

Posted
Posted

everything to do with doseing is a myth......everything that says its bad for the turbo is all theoretical. theres no actual proof that doseing (exsessive compressor surge) will shortn ur turbo life, i know many vls dosing day in day out at 18+psi and still survive longer then many skylines.

bring on the flaming but i think dosing sounds awsome.....not the dolphin dosing though.

this kind.

ignore the title cuz americans dont know f*kn shit. they think any sound from the engine comes from a HKS SSQ LOL

jenkies Mentor

jenkies

Posted
Posted
everything to do with doseing is a myth......everything that says its bad for the turbo is all theoretical. theres no actual proof that doseing (exsessive compressor surge) will shortn ur turbo life, i know many vls dosing day in day out at 18+psi and still survive longer then many skylines.

bring on the flaming but i think dosing sounds awsome.....not the dolphin dosing though.

this kind.

ignore the title cuz americans dont know f*kn shit. they think any sound from the engine comes from a HKS SSQ LOL

its damn physics dude u spin something 100,000 rpm one way then reverse it in a second when its on bushings or bearings...... DUH its gonna do damage!

Simon-S14 Grand Master

Simon-S14

Posted
Posted

show us the proof then.

i have had many many engines over the years (non have blown up... i just have had a lot of cars) out of them only 1 had a BOV (my rb20) i do a lot of competition drift, and as yet have NEVER HAD A TURBO FAILURE from running no bov. I find that no bov makes for a much more responsive set up then having a bov.

the maths/physics says it bad, but wheres ther hard proof??

skylinekid Proficient

skylinekid

Posted
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Posted
show us the proof then.

i have had many many engines over the years (non have blown up... i just have had a lot of cars) out of them only 1 had a BOV (my rb20) i do a lot of competition drift, and as yet have NEVER HAD A TURBO FAILURE from running no bov. I find that no bov makes for a much more responsive set up then having a bov.

the maths/physics says it bad, but wheres ther hard proof??

i have a turbonetics turbo i have not had a blow off valve working and i was running 14p the bearings r noisy and the turbo has heaps of shaft play ive had it on the car for 20000kms i see this as proof for me

jenkies Mentor

jenkies

Posted
Posted
i have a turbonetics turbo i have not had a blow off valve working and i was running 14p the bearings r noisy and the turbo has heaps of shaft play ive had it on the car for 20000kms i see this as proof for me

many thanks and a very big thumbs up!

i have no hard proofe i just have common sence that all things wear eventually and turbos are one of those things... the principals behind a plumb back blow of valve help to keep forward momentum of the turbo and vent air to the intake to await throttle and spool up.....

no bov means backwards momentum (backspin) creating that dv tu tu tu tu noise because the air has on where else to go which means it would create more lag for the turbo to create forward momentum again.

this is my thoughts of common sence and theory anyway. tell me otherwise.

rev210 Grand Master

rev210

Posted
Posted

You are loading up the trust bearings on the turbo plenty. If other things fail before the turbo does that doesn't mean you aren't wearing it out faster or that there isn't instances of catestrophic failures in short periods. Turbo's that cop the abuse are doing so because they make them pretty well these days, not because there's no harm.

It's safe to assume turbo manufacturers know what they are talking about and we mere mortals don't.

From a Turbo Manufacturer (Garrett) website, one of a few refferences made on that site about the strain not having one introduces;

Blow-Off (Bypass) Valves

The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the

turbo’s compressor from going into surge. The BOV should be installed between the

compressor discharge and the throttle body, preferably downstream of the charge air

cooler (if equipped). When the throttle is closed rapidly, the airflow is quickly reduced,

causing flow instability and pressure fluctuations. These rapidly cycling pressure

fluctuations are the audible evidence of surge. Surge can eventually lead to thrust

bearing failure due to the high loads associated with it.

Blow-Off valves use a combination of manifold pressure signal and spring force to detect

when the throttle is closed. When the throttle is closed rapidly, the BOV vents boost in

the intake tract to atmosphere to relieve the pressure; helping to eliminate the

phenomenon of surge.

Here's an interesting one about compressor surge in general;

Surge is most commonly experienced when one of two situations exist. The first and most damaging is

surge under load. It can be an indication that your compressor is too large. Surge is also commonly

experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically

reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives

the operating point to the far left of the compressor map, right into surge.

Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point

back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass

valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly,

keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated

back to the compressor inlet.

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