Dump valve question - 'pigeon' noise

I currently have a Blitz dump valve fitted but am thinking off removing it and blocking off the pipes if htis is possible. My mate has this done on his S14 and it makes a 'pigeon' noise as its something to do with the wastegate.

Is it ok to do this with the sequential system or could this cause problems?

The noise you're referring to is nothing to do with the wastegate, it's compressor stall as the turbo tries to push back the other way, chopping through the air. This is what a blow off valve tries to prevent.

Isnt the pigeon noise reserved for single turbo conversions with external wastgates.

Didn't think it was something that happens with a stock TT system

the noise is as Gaz says, compressor stall.

Many people say its bad for the turbo, but then knowledgable people such as Chris Wilson say running without a BOV is fine, so im still on the fence so far!

Some people with UK spec soops have done this i think. I don't think this is safe on a J-Spec due to the ceramic turbos.

Here we go LOL! stall or surge (waits for the jet technician's to chime in:p)

But anyway its down to the turbine being stooped by the non moving air in the pipework when the throttle is closed quickly, some say it shortens the life of the turbo and prevents quick re spool.

Me i like a bit of both, dump and stall/surge;)

Oh! and it doesn't matter which turbo setup you have.

P.s, i think the noise it ridiculous and if aviodable then all the better. Nothing wrong with a nice Pssssssst

I currently have a Blitz dump valve fitted but am thinking off removing it and blocking off the pipes if htis is possible. My mate has this done on his S14 and it makes a 'pigeon' noise as its something to do with the wastegate.

 

Is it ok to do this with the sequential system or could this cause problems?

Plenty of stock BOV's for sale on the forum if you want to get rid of the Psssssst noise without any detrimental effects.

A danish magasine tested a turbo nissan with BOV venting to atmosphere a stock bypass BOV and without. It was ½ a second quicker to 62 without a BOV or with a bypass one compared to the BOV venting out.

Just thought I would mention. Kind of interesting.

I would go back to a stock BOV to be safe, toyota put enough into R&D on the 2jz without putting the stock BOV for in no reason

While we are talking about noises, you can get Compressor Stall on a stock TT but do you guys get a high pitched siren when spooling (Mine is BPU TT, havent actuall took off the turbo heat shield but they appear to be stock)

A danish magasine tested a turbo nissan with BOV venting to atmosphere a stock bypass BOV and without. It was ½ a second quicker to 62 without a BOV or with a bypass one compared to the BOV venting out.

Just thought I would mention. Kind of interesting.

I think it depends on the engine management as well, I know the 1.8T VAG engines are generally not compatible with BOV's because it sees a leak in the system due to the MAF sensor (similar to UK Spec's?) so doesn't quite run properly, something like that anyway. Not sure what the Nissan you mention uses for air measurement but I thought it's worth a mention.

I can usually get the 'pigeon noise' gently accelerating in 5th at about 80 and letting off with my TT with stock recirc valve.

I think it depends on the engine management as well, I know the 1.8T VAG engines are generally not compatible with BOV's because it sees a leak in the system due to the MAF sensor (similar to UK Spec's?) so doesn't quite run properly, something like that anyway. Not sure what the Nissan you mention uses for air measurement but I thought it's worth a mention.

 

I can usually get the 'pigeon noise' gently accelerating in 5th at about 80 and letting off with my TT with stock recirc valve.

There are two different types of non recirc BOV, a two stage version for cars with MAF;) however not all makes have the MAF version.

I think it depends on the engine management as well, I know the 1.8T VAG engines are generally not compatible with BOV's because it sees a leak in the system due to the MAF sensor (similar to UK Spec's?) so doesn't quite run properly, something like that anyway. Not sure what the Nissan you mention uses for air measurement but I thought it's worth a mention.

 

I can usually get the 'pigeon noise' gently accelerating in 5th at about 80 and letting off with my TT with stock recirc valve.

I can also get a pigeon noise if I gently accelerate and lift off

I think it depends on the engine management as well, I know the 1.8T VAG engines are generally not compatible with BOV's because it sees a leak in the system due to the MAF sensor (similar to UK Spec's?) so doesn't quite run properly, something like that anyway. Not sure what the Nissan you mention uses for air measurement but I thought it's worth a mention.

 

I can usually get the 'pigeon noise' gently accelerating in 5th at about 80 and letting off with my TT with stock recirc valve.

You are correct regarding cars running MAF. They meter in the air intake and therefore if you later in the system vent that already metered air to atmosphere, the car will not have the correct info on how much air is in the system.

The Nissan (some small little hatchback thingey) was running MAP IIRC.

It's also typical for the stock recirc to result in a bit of stall. I think its due to some membrane stiffening over time. That happened with my MK3.

Its as said compressor stall and not a good thing its air trying to forcing itself forward so figure out for yourself if its a good thing or not, risk of being yelled out but in a jet engine is the same they fit surge bleed valves some engines call them diffrent thing 2.5 bleeds diverter valves etc but basically it discharges air to prevent this as it can destroy a engine quickly, of course a turbo you can get away with it but on say j spec ceramics i would not wanna chance it