Boosted Falcon

I was watching something on youtube and they were saying that compressor surge, known as a flutter? is bad for your turbo as it turbine spins backwards and forwards..giving you the 'Suuuu tutu tutu' noise
Is this true?
What is exactly compressor surge?
I"ve heard of Flutterdump where the BOV opens a little late producing the "fluttter and the Tshh"
Any info on this?
Cheers
- Ash

Compressor surge certainly is bad for your turbo. It won't happen over night but it will eventually destroy the turbo.

I've got a bit of flutterdump going on, more dump than flutter though. I'll adjust the preload on the BOV and see if that helps. In the end who cares?

Moving the BOV to the TB side cooler piping would probably solve it too, there's no room though.

The wheels CAN'T turn backwards, the excess air that's in the pipes from the cooler when the TB shuts will cause the wheel to slow down as it chops through the air, which is what makes the "flutter"noise. Yes it is bad, but not as bad as people make it out to be, VL's came out stock with no BOV, but then again that was over 20 years ago From what i've seen it will take years for the turbo to stuff up from lack of BOV.

The original AIT setup had about a 15mm BOV, it dosed before I upgraded it. It was attached to that breather barb on the TB housing just in front of the TB plate.

Doesnt spin the turbo backwards it just stalls the turbo shuddering it which makes the du du du noise.

Definately bad thats why Im in the process of putting a bov in I dont wanna spend more money rebuilding another turbo!!

turbo rebuilds (for bush bearings) = $90
well the kit, rebuilding a turbo is easy, just mark up the parts, so it remains balanced when you put it back together

and if you BOV hole isnt big enough, you will "PSCCCHT" on lower boost, but once it reaches a higher boost, it will flutter

i <3 my flutter
http://www.youtube.com/watch?v=pMNKx3p0mr8

http://forums.nizpro.com.au/showthread.php?t=24

Think you gotta sign up for it.

Cliff notes...
Nizpro say no BOV, no worries.
Stage 2 and up kits don't come with a BOV.
BOV = rice.

Good enough for me, and carries more weight then anything else in this thread.

Yep a properly engineered system doesn't need one. Hence why most of us need one.

Steady wrote:BOV = rice.

That is easily the most ridiculous thing I've ever seen you post Steady.

I'm just cliffnoting Simon @ Nizpro.
He didn't say that exactly, but I think it's pretty safe to say that was his conclusion.

89AIT wrote:Yep a properly engineered system doesn't need one. Hence why most of us need one.

I hardly think a nizpro kit with a plenum is that much better designed than what the rest of us have. Its just a motor with a crappy cast manifold, plenum and piping.

The same principles apply. Throttle shut = no exhaust gasses = no forces pushing the turbo forwards so it doesnt really matter that much when the air goes back through it.

I would fit one. Not because they save turbos but because fluttering has had its time like riding on black stockies.

I love it how people who don't like BOV's always bring up rally cars
How can our cars and budgets be compared to rally cars, EVER?!

BI6TIM wrote:I love it how people who don't like BOV's always bring up rally cars
How can our cars and budgets be compared to rally cars, EVER?!

Rally cars are on and off the throttle constantly.
They also can't afford, timewise, to be replacing turbos at the end of every stage.
Why would they choose to make something unreliable in a racing discipline where reliabilty is probably the most important thing?

we compare our cars to VL's.... how can we do that


fact is, over time yes... its bad
but meh!

Its good to see the important things being debated... like whether flutter is in style or not... haha

Flutter is so last year but meh still turns heads!

Here's my opinion-

Fluttering/dosing is only bad for turbo's that run heaps of boost and have a relatively small thrust area. Thrust area being the surface that stops the shaft moving along its axis in the core.

Eg, a VLT turbo is pretty small, has small wheels compared to its thrust area- you will never kill it with no BOV.

Same goes for something like a GT42 that has a massive thrust area being a large frame turbo.

Things like the larger T04's, which can be similar to a GT42 in wheel size, but with a much smaller frame can take a beating without a BOV.

Add low oil pressure into the mix- which turbo's rely on to maintain a cushion between the thrust collar and the thrust bearing, and things are going to go to sht pretty quickly.

Steady wrote:

BI6TIM wrote:I love it how people who don't like BOV's always bring up rally cars
How can our cars and budgets be compared to rally cars, EVER?!

Rally cars are on and off the throttle constantly.
They also can't afford, timewise, to be replacing turbos at the end of every stage.
Why would they choose to make something unreliable in a racing discipline where reliabilty is probably the most important thing?

Don't rally cars have quick release turbo's

http://www.turbobygarrett.com/turbobyga ... ch101.html

Garrett say use one. Use one.

Also, if your thrust bearing shits itself the wheels can touch the turbine and exhaust housings, which fucks them immediately. In severe cases, it can stop the front wheel while the back still spins, which undoes the nut on the compressor wheel and the shaft eats shit, game over turbo in both cases. I know this first hand.