Fluttering...?

[Locum51]

Okay so here is another thread up for discussion:

The Problem/Question:

Seeing as I may be owning a :banana:Supra:banana: soon *crosses fingers*
As shown on the thread name; i somewhat understand the difference:think: between compressor surge and fluttering in regards to a turbo...
Can someone elaborate more on the differences and when and when not to use a external bov?

[SXRguyinMA]

you always want a bov. bad things can happen if you don't have one. the bov goes between the intercooler and intake manifold. When you're on the throttle and making boost, then suddenly close the throttle, that boost has to go somewhere, hence the need for the bov, otherwise you can blow your pipe couplers or even your intercooler.

I think you're thinking of the wastegate. this is mounted directly to the turbo itself and controls how much boost the turbo produces. usually these are tuned with springs. Some vehicles (like big rigs and performance light duty diesels) don't use wastegates at all.

with regards to fluttering or surging I can't comment more. surging may be a fueling issue in regards to fuel/boost ratio. too much or too little fuel will cause engine surging. Also, too big/too small of a turbo for your engine may cause fluttering or surging as well

[BuzzKillington]

There's a lot of bicker between BOV/no BOV.

Some believe a blow off valve saves the life of the turbo by eliminating flutter and others think the flutter saves the life of the turbo by slowing it down faster. There are 250mph drag cars that don't use BOVs for this reason... otherwise the turbo'd still be spinning an hour later, shortening the life of the turbo. Personally, I just don't like the sound of flutter/surge and I LOVE the sound of external BOV's. I'm sure there's tons of info on this in tuner forums and stuff. Maybe give garret turbos a call and ask them personally.

[SXRguyinMA]

good input buzz. I too love the "pshhhh" of a bov :D

[Locum51]

Yea, i was just confused on which is better in the long run for a turbo...Some say that they run with no bov and their turbo is fine...I've heard other people say that their turbo didn't last that long because of not running a bov.

[SXRguyinMA]

well like BK said it does slow it down faster, but at the same time what slows it down is a LOT of excess pressure. If you're going to be doing hi-rpm hi-boost drag runs, then sure. but for regular street use, I'd put it in. your turbo will never see the kind of loads and rpms that a drag car turbo will see, so there's no worry of it spinning for any length of time w/o proper oiling. plus install a turbo timer if you're worried about the turbo's oiling and cooling. basically when you shut off the car it keeps the engine running for a preset time at idle to let the turbo de-spool and keep oil flow to it

[Locum51]

Yea, i just wanted some clarification on compressor surge/fluttering.
Say a bov was installed but i still got fluttering (<10psi), would the bov springs need to be tightened or loosened?

[Oneslowz28]

Every Turbo car I owned had an BOV installed and a turbo timer (sans my trucks). Turbos do wear out and that's why they make upgrade kits. The turbos on the supra are pretty stout and will be fine. When they do wear out, upgrade to ceramic ball bearings and forgettaboutit! IMO its shutting the engine down while the turbo is still glowing hot that causes premature failure. A turbo timer will fix that. But what do I know? I just ran 20 PSI daily for 4 years and every weekend turned it up to 25 for racing. I only ran low 11's in the 1/4.

If you still get fluttering at 10PSI then you would need to tighten the spring IIRC. Its been almost 10 years since I had my GSX.

[SXRguyinMA]

I would say loosened so it'd let more pressure out and not close to early

[NightrainSrt4]

I don't know about supra's, so this is coming from my turbo'd SRT.

It's been a while since anything interesting was in my SRT, but IIRC you'd want stiffer/tighter springs in the bov. <10psi is pretty low boost. The piston in the bov is moving back and forth, causing the fluttering sound, but isn't fully opening or closing.

As long as you get full blow off at high boost / peak boost levels you should be fine. You're boosting at low levels and the piston is just moving around as it isn't enough pressure/vac to keep it in one place. Fluttering at low boost is pretty normal. You can check the spring, especially if it is an older bov, if it is a concern though.

If it isn't blowing off at high boost then you've got a problem be it vacuum lines, boost leak, etc.

[Twigsoffury]

I've got a stage III BOV after eating a bowl of my GF's homemade chilli.

[slaveofconvention]

Damned US/English translations. This had me utterly baffled until I had a lightbulb moment lol. Here in the UK we call these Dump Valves heh.... You definitely need one. Nothing about performance or longevity - you just need that Buh-D-Phssssh noise baby!!!

[Oneslowz28]

I went through a few BOV's on my eclipse back in the day. My favorite one I think was made by greddy or maybe turbo XS. Its name was RFL and stood for Really F**Kin Loud. When we went on cruises you could hear me in the front of the line and I would be 40 or so cars back. I had 1 custom one machined by a friend, 2 turbokenetics and 2 ebay "JDM" models. One of the ebay models was modified to fit a duck call on and tape it on. It was pretty funny blowing off with that on. It would wake people up at red lights and eventually got me pulled over by the cops, who wanted to know WTH that sound my car was making was.

[SXRguyinMA]

lmao nice

[Oneslowz28]

I remember one time at a show one of our cc members had just picked his 240sx up from the shop that morning. He had trailered it to the show because he did not have INS or a tag on it yet. The shop had just swapped in an RB26DETT from a skyline. He had spent about $10k on the swap, ordering some aftermarket parts from Japan and having some parts polished to a high shine.

Well at the show he rolled it off the trailer and we pushed it 10 feet to his spot on the line. The first part of the show had all the entries ride around a 4 block loop at idle speeds. They called this a "remembrance cruise" and it honored the old timers who had passed away in the previous year, so no one was allowed to hot rod it or show off. Anything above an idle got you kicked out of the show.

So we get back to the line and everyone is setting up their car for the show off. I have my hood open, hatch open, and the screens glowing. I am wiping things in the engine bay off with a rag when I hear him take his 240 to red-line. He holds it there for a few seconds letting it bounce off the peg and when he lets it release we hear 2 loud pops. They sound much louder than gun shots and we hear his car go silent. I am shaking my head thinking this guy just gave his brand new swap a new breathing hole. He is white as a ghost and everyone around is looking in his direction. So he opens the hood and is cursing. There is not a drop of oil on anything, no smoke, no smell, nothing. So we are on the ground, looking under the car, feeling in areas we can not see and both of us are wondering what the noise was.

After looking for about 5 minutes he notices a piece of red rubber wedged behind some wires. What evidently had happened was that the BOVs he ordered from Japan came with horn shaped stacks on the end. Those stacks were polished to a bright shine and then covered with a thick form fitting rubber cap to protect them during transport. The shop had forgot to take them off when they put them on. When he idled around the 4 blocks they were thick enough to stay on if the BOVs even opened at all. But when he was bouncing it off the rev limiter the turbo must have spooled up to 15-20k rpm and when he let off the throttle all of that air had to go somewhere and it literally inflated those 1/8" thick red rubber caps like balloons until they popped.

[SXRguyinMA]

lol that's hillarious

[BuzzKillington]

Almost forgot... LUUUUUUUUUUCKY!!!!!! :P

[billygoat333]

hahaha funny story cj.

[Locum51]

Yea, i just heard someone's SRT4 flutter and i kinda cringed. Compressor surge and fluttering sound almost the same, IMO there is a small difference in sound. I'd rather be on the safe side and have something like this:

http://www.youtube.com/watch?v=HblCEQXQ8Q4&feature=related

or

http://www.youtube.com/watch?v=DpSW8FoTh1g&feature=related

WARNING: Prepare to whip cream your pants after hearing this. Haha.

[Locum51]

Disregard the fluttering but i'd love for the supra to accelerate like this after the fuel cut:
http://www.youtube.com/watch?v=-cEvqGSZGnY&feature=related