Minor compressor surge. How to fix?

[RedDrifter]

I recently bought an ITS turbo for my R32 from UAS.

http://www.nismo.com.au/pricelists/General...skyitsturbo.jpg

Now its seems fine exept in 3rd gear as it starts comming on boost.

When it comes on boost I hear a flutter sound from the intake side of the car.

I believe this to be compressor surge?

The funny thing is that it stops after about 5000rpm as the motor gets into its power band.

I've tryed to get it to do it in 4th and 5th but it wont. 3rd gear is the only time it does this and only as it gets the rush of comming on boost.

Any ideas on how to fix the problem?

Will it hurt the turbo at all?

Does anyone know much about these turbos?

[N I B]

ITS Turbos are very good but you need a factory BOV plumbed back not an aftermarket one.

[Trust33]

factory bov???hi steve i thoughht an aftermarket one would work just as good if not better at fixing compressor surge...Why is this so?

[RedDrifter]

I have a greedy plumb back BOV.

Its not plumbed back atm due to intake mods I have to do soon. The surging I am talking about is not when I back off but when the RB20 comes on boost with wot.

How can a bov have anything to do with this?

As I mentioned before its only for a period of about 500rpm as I come on boost. From 4500 to 5000RPM.

[BHDave]

About the only thing you can do short of installing cams and will be to back the boost off, or if you have an ebc that references revs then bring the boost on a little softer at this point.

[Interloper]

I've got a bit of surge in my highflowed R34 GTT turbo but its always in 5th gear just as boost comes on strong. And like you, it goes away after about 4500rpm.

Can i ask what kind of power you are getting at the wheels with that turbo? as UAS reckon its "GOOD FOR APPROXIMATELY 260KW AT THE WHEELS" off their website. When in the RPM range does full boost come on?

[RedDrifter]

I'm not exactly sure but I'm guessing around 200rwkw's.This is at 14-15psi.

My injectors running at 97% duty cycle.

My SAFC is adding 4% more fuel after 3500rpm and on the old turbo (R33Turbo) the ratios were a little richer than 12:1.

I would think the turbo would be quite capable of getting 260rwkws as suggested by uas. Obviously if the car was tuned properly.

On an r34 RB25NEO motor I think this turbo would be nuts. The extra 1/2 litre would be ausome for spool up.

I've got a bit of surge in my highflowed R34 GTT turbo but its always in 5th gear just as boost comes on strong. And like you, it goes away after about 4500rpm.

Can i ask what kind of power you are getting at the wheels with that turbo? as UAS reckon its "GOOD FOR APPROXIMATELY 260KW AT THE WHEELS" off their website. When in the RPM range does full boost come on?

[RedDrifter]

So a set of cams would probly fix the problem?

Thanx for the info.

About the only thing you can do short of installing cams and will be to back the boost off, or if you have an ebc that references revs then bring the boost on a little softer at this point.

[Trust33]

I have a greedy plumb back BOV.

Its not plumbed back atm  due to intake mods I have to do soon. The surging I am talking about is not when I back off but when the RB20 comes on boost with wot.

How can a bov have anything to do with this?

As I mentioned before its only for a period of about 500rpm as I come on boost. From 4500 to 5000RPM.

Sorry.Your right.The cams to rid the chambers of a little bit extra gas.The bov to stop back pressure against the compressor when the butterfly is shut.

Does it wheelspin at full boost in first and second all of the time?What does third do?

[RedDrifter]

No it doesn't wheel spin at all.Grips quite well in first and I cant snap second due to crunchy syncros. Third will chirp.

I gues this will change when I put in the bigger injectors and get it tuned correctly for 20 odd psi.

I do have 235 tyres now so I suppose that will help traction alot.

In the wet however mmmmmmmmmnnnnnnnn lets just say its nut.

[Sydneykid]

I recently bought an ITS turbo for my R32 from UAS.

http://www.nismo.com.au/pricelists/General...skyitsturbo.jpg

Now its seems fine exept in 3rd gear as it starts comming on boost.

When it comes on boost I hear a flutter sound from the intake side of the car.

I believe this to be compressor surge?

The funny thing is that it stops after about 5000rpm as the motor gets into its power band.  

I've tryed to get it to do it in 4th and 5th but it wont. 3rd gear is the only time  it does this and only as it gets the rush of comming on boost.

Any ideas on how to fix the problem?

Will it hurt the turbo at all?

Does anyone know much about these turbos?

I have a few suggestions;

* If you have adj pulleys, where do you have the camshaft timing set?

* Will it handle more ignition timing at 4,500 rpm to 5,000 rpm?

* What is the dump, cat, exhaust like? If you are not running a split dump that would be a good place to start. A hi flow cat may also be worthwhile if you are still using the compliance cat. Exhauts needs to be 3.25" , you might just get away wiht 3".

[RedDrifter]

I have a few suggestions;

* If you have adj pulleys, where do you have the camshaft timing set?

* Will it handle more ignition timing at 4,500 rpm to 5,000 rpm?

* What is the dump, cat, exhaust like?  If you are not running a split dump that would be a good place to start.  A hi flow cat may also be worthwhile if you are still using the compliance cat.  Exhauts needs to be 3.25" , you might just get away wiht 3".

*I have stock cams and timing pulleys.

*My car is still running on stock ecu map so not sure about timing but guessing it will take more.(Not game to try just yet due to last motor going :Bang: just recently.)

* The exaust is a 3" turbo back kit thats looks to be mandrel bent and all.

And the cat is definately a large high flowing one. The system does have a primary muffler though.

* The intercooler is a Blitz kit that uses the stock piping in the engine bay. One end tank bends round and connects to a pipe that runs along the underside of the core.

mate.

[Sydneykid]

*I have stock cams and timing pulleys.

*My car is still running on stock ecu map so not sure about timing but guessing it will take more.(Not game to try just yet due to last motor going  :Bang: just recently.)

* The exaust is a 3" turbo back kit thats looks to be mandrel bent and all.

And the cat is definately a large high flowing one. The system does have a primary muffler though.

* The intercooler is a Blitz kit that uses the stock piping in the engine bay. One end tank bends round and connects to a pipe that runs along the underside of the core.

mate.

My suggestions; std cam timing is not the best, advance the inlet cam about 2 degrees and retard the exhaust about 4 degrees. That usually stops the compressor surge as the engine can absorb more airflow. The std ECU is a big limiter, time for a change. Not only will that fix the surge, you will also pick up a heap of power.

[N I B]

Factory BOV is an easy thing to try so have ago as i have seen it often.They are rescerculation(spelling) type valve and do help.

[RedDrifter]

Mic and I (good mate of mine) just finnished tuning the stock ecu (for the larger injectors) and now the compressor surge is not a problem.

We set the ratios to run at 11.6:1 (after 6psi)

and advanced the timing in the mid to high range a good 3-4 degrees.

Car is sounding alot better and the surge has not happened since.

SydneyKid was right in the fact a good tune would fix this problem and not to mention the big power gain it has now.

I am really impressed on how easy the stock ecu can be modified and how well it works.

[Bl4cK32]

I get this too on my rb31det. Its currently got the std rb20, but its been highflowed. Gets major surge problems in 5th right at 0 pressure....ie where it starts making positive pressure. It only happens at part throttle going up a slight hill in 5th, but its not too bad....just gotta have a little throttle or WOT to get rid of it

I always put it down to the turbo / exhaust being mismatched for the engine too....