Compressor Surge

[wortho32]

hay guys still got the flutter proble with my 32 gts-t was watching youtube, there was a car doing the same thing as mine it is called compressor surge dose anyone know how to fix this proble? is it because my turbo is boosting 2 hard 4 my car?

my mods are power fc,z32, fuel pump, adjustable cam gears, gtr injectors, and a vg30 turbo witch has been complete rebuilt duno the specs.

[R31Nismoid]

put a plum-back/recirc BOV on it.

Simple.

[wortho32]

noise isn't the proble it blows off while i am on the gas watch thie link

[R31Nismoid]

is this the first time running that turbo?

If so, likely a shit hi-flow

[wortho32]

is this the first time running that turbo?

If so, likely a shit hi-flow

it was on a mates car and went well..

could the air flow meter have this affect?

[(OO)SKYLINE(OO)]

put a plum-back/recirc BOV on it.

Simple.

Thats pretty much your answer.

Reason you are getting the 'Dose' noise is because the air is being pushed back into the turbo = Compressor Surge.

The whole point of the standard plum-back / recirculate BOV is to prevent Compressor Surge. Air gets pushed into the intake not the turbo.

You DON"T want Compressor Surge or say good buy to your turbo.

[R31Nismoid]

How can it be airflow meter... when there isnt one on the youtube vid?

Was it off the same motor? (same spec etc) ?

[daxter]

wortho32, Can you post up a pic of your turbo. It could be a combination of things. Is it a high flowed turbo with a larger compressor wheel?

[SirRacer]

quite a number of the big named japanese intercooler kits dont come with blow off valve mounts.

quite a few race cars also dont run blow off valves so im sure they arent THAT bad for the turbo system. that said i do run one myself.

[H@ME]

yeah i am currently not running one on my turbo set up, however i thought that with bigger turbo's it wasn't an issue as much.

[MBS206]

You DON"T want Compressor Surge or say good buy to your turbo.

Please explain how "flutterz" does fuly sik damagez to the turbo?

Turbos are designed to flow uni directionally, IE, no matter how much air you force backwards through a turbo, it won't move, it'll sit still. Force air the other way, and it'll spin. So really, flutterz can't even slow the turbo down... What does slow it down is the fact the waste gate stays open the whole gear shift IF you don't run the pressure source off the manifold...

I run a T04R on my R33, and have ZERO lag or anything between gearshifts, and I have NO BOV, purely because I run my pressure source off my manifold.

[H@ME]

When you say you run the pressure sourse off the manifold you mean via wastegate?

[Bumblebee]

Geez, compressor surge while loaded up.. havent seen many of those on the dyno..

but its generally when the compressor wheel supplies more air than the engine can actually swallow which does happen...

Bov wont fix it... ive read alot of articles on this sorta stuff, but havent ever put any into practice... i reckon try with lower boost settings, or change the turbo...

Its generally because the inlet wont allow more air in, so it reverts back the other way n causes the flutter on load..

[H@ME]

So on bigger turbo set ups is running no b.o.v a problem? can the compressor surge damage the turbo/or engine?

[blind_elk]

This is from gofastbits.com

Compressor surge: You can think or surge as the point at which the compressor blades begin to “slip” in the air, losing their pumping ability, much like an aircraft wing loses its lift when it stalls. In a turbo, this happens in a series of bursts, as the blades slip, then bite, slip then bite. This sets up a pulsing wave in the turbo piping and explains why the sound has that characteristic “flutter”.

The interesting thing about compressor surge is that it occurs much more readily at low turbo shaft speeds. At these low shaft speeds, on road cars this is generally between 2000 and 3000 RPM, compressor surge is not much of a problem, as the loads generated by the surge are miniscule compared to what the turbo encounters at high boost. However, if surge occurs at high RPM and boost, it is possible to reduce the turbo life and/or damage the compressor.

[H@ME]

" However, if surge occurs at high RPM and boost, it is possible to reduce the turbo life and/or damage the compressor." okay well question answered i guess however i still hear of many people doing this with larger set-ups with no worries.

[PM-R33]

You DON"T want Compressor Surge or say good buy to your turbo.

Pffft as if you want to get rid of compressor surge.

Soft.

[RB30-POWER]

bigger cams, ported heads, bigger turbine a/r, smaller compresor a/r are all things you can do to try and get the turbo away from the surge line.

if that doesn't work, you need to select a more apporpriate compressor for the engine airflow characteristics.

my car does this on part throttle around 0-5psi boost, boost just jumps up down constantly, you either have to gun it or downchange to get the load of the engine, really anoying.

if it does it on full throttle, you can cause big trouble and should tend to it immediately.

i'm guessing the turbo you have has some old school t4 compressor wheel on it, designed for low shaft speed, high airflow, when it's mated to a high speed small a/r t3 turbine you can get bad results.

[paulr33]

hi

when we speak of compressor surge there are two that come to mind

#1

when you come off the throttle without a BOV the pressure must go somewhere

so it collides midflight and causes a massive pressure spike on the compressor side of the turbocharger

the massive spike in pressure causes the compressor wheel to surge in speed

this is usually seen by the "vl turbo tutu tu tut tutu" noise on gearchange or backing off on the throttle

#2

this is less common but does occur, the compressor wheel goes past its efficency zone

and the speed of the wheel flies past the compressor's fastest's speed

the end result is that pressure past the compressor wheel is higher

than what the compressor can actually supply.

ie the compressor wheel is XYZ variant and can supply 45lbs of airflow at XYZ turbine speed

but it surges as pressure past the compressor wheel is actually 51lbs of airflow, thus the compressor wheel surges

if you have #2 i would check the turbo specs, check your boost control systems

check your intercooler pipework and intercooler core

something is making the pressure spike past what the compressor can supply

if possible measure pressure at plenum and pressure at turbine outlet

[W0rp3D]

The turbo i now have was having this problem, was coming onto boost way to quick, my turbo was back cut so the boost would come on later and stop this happening, here is a link the thread which has all the r&d in it and some usefull info for you http://www.skylinesaustralia.com/forums/35...-9b-t22706.html easiest way to fix it is to either back cut your exhaust wheel or get a good boost controller that you can set up so boost is limited at certain rpm's, mine hits 14psi at about 4300rpm.

Edited November 11, 2008 by W0rp3D