n249 bypass chatter

[james walker]

can anyone confirm the size of the nipple under inlet manny to the left of the fpr one... larger than the frp nipple, im now going to run vac source direct to dv top, which iirc is 4mm then put the fpr vac source back where it was.

also can i get reducers for silicone hose? woul prefer not to tbh, ive seen robdon is using some sourt of connector on the top of his dv, id like to do the reduction there if possibl, so run 8mm or whatever size it is to the dv then reduce with a l shaped connector to the dv size... if that makes sense?

 

[dan.seat.cupra]

ive got a seat ibiza cupra r 2001 how do i go about bypassin the n249 an will it sound alot better ive got a baileys dump valve on my car?

 

[TubbyTwo]

do a search mate, been covered loads of times.

 

[DannyC87]

can anyone confirm the size of the nipple under inlet manny to the left of the fpr one... larger than the frp nipple, im now going to run vac source direct to dv top, which iirc is 4mm then put the fpr vac source back where it was.

also can i get reducers for silicone hose? woul prefer not to tbh, ive seen robdon is using some sourt of connector on the top of his dv, id like to do the reduction there if possibl, so run 8mm or whatever size it is to the dv then reduce with a l shaped connector to the dv size... if that makes sense?

which one James? There is 1x8mm and 2x4-5mm nipples.

 

[james walker]

yeah, got the 8mm nipple danny thanks

ordered some 7mm vac tubing and a reducer to 4mm for the dv inlet.

gonna go strait from the 8mm nipple on inlet manny and have the reducer close to the dv for that inlet, then go fpr to the 5mm nipple.

see how that goes

 

[ChrisGTL]

yeah, got the 8mm nipple danny thanks

ordered some 7mm vac tubing and a reducer to 4mm for the dv inlet.

gonna go strait from the 8mm nipple on inlet manny and have the reducer close to the dv for that inlet, then go fpr to the 5mm nipple.

see how that goes

Did you get any further with this James? I did my 249 bypass this weekend and my turbo sounds like its stalling too.

I used 4mm VAC tube, with a 4mm connection, made the mani to DV pipe as short as possible.

Did you leave the other two connections unblocked or did you blank them off somehow?

 

[james walker]

i rerouted using spare nipple so no t, its the same.

i blocked the 2 connections. not sure what would happen if unblocked

 

[LEE69]

Didn't think it would change as vacuum is vacuum.
If left unblocked you'd be adding extra air to the inlet.

 

[james walker]

just removed a potential restriction there lee, one less join to fail

not sure now why its chattering then, seeing as someone else had it now.

just tends to do it low revs tbh

 

[Cupra Ross]

Are you sure its not just dump echo through your induction kit, James? If its proper chatter, its pretty obvious even on a standard 1.8T with standard airbox and it sounds as if its coming from low down in the engine bay (which it is).

Contrary to popular belief, its nothing to do with the wastgate on the 1.8T, its actually pressurised boost air trying to flow the wrong way over the spinning turbine blades after the throttle butterfly closes and in the absence of air being allowed to escape from the charge pipe via the dump valve.

Its a very very bad thing because it puts a lot of stress on the turbine shaft. Bye bye turbo if its left uncorrected.

I'd bet, its just dump echo, I get plenty of it through my Carbonio, although with the 007P fitted in reverse you can't hear much over the chirp.

 

[DannyC87]

Because not enough boost deviation is built up at low revs to open the DV fully? With the n249 plugged in the vacuum tank can be used to assist the opening of the DV to ensure a clean dump everytime.

 

[james walker]

so its normal then.... and fine for it to do it?

 

[DannyC87]

so its normal then.... and fine for it to do it?

If it is only doing it at low boost then I would say it is fairly normal (mine does it). Do you have the yellow spring in your 007p btw? If so that will amplify the effect.
Since it is fairly common in low boost applications not to use a dump valve at all, I can't see it causing excessive wear. If 20 odd psi of boost was being forced the wrong way through the turbo that'd be a different matter!

I need to come to Retford soon to buy some methanol so I could potentially come for a listen and offer a second opinion if that helps?

 

[LEE69]

Mine echos through my HKS mushroom, as you say, only on low throttle.

 

[james walker]

If it is only doing it at low boost then I would say it is fairly normal (mine does it). Do you have the yellow spring in your 007p btw? If so that will amplify the effect.
Since it is fairly common in low boost applications not to use a dump valve at all, I can't see it causing excessive wear. If 20 odd psi of boost was being forced the wrong way through the turbo that'd be a different matter!

I need to come to Retford soon to buy some methanol so I could potentially come for a listen and offer a second opinion if that helps?

retford, methanol..... where be that round these parts then?

well tbh matey, sounds like that what it is.

 

[ChrisGTL]

Mine only does it on low boost too. Thats using the green 007p and a BMC CDA.

TBh, I can't feel any difference from when the 249 wasn't bypassed......so prolly just put it back to how it was. The noise it makes is like a echo, but does sound like the turbo is stalling.........don't think i'll risk my turbo dying.

 

[DannyC87]

retford, methanol..... where be that round these parts then?

well tbh matey, sounds like that what it is.

Not sure where abouts, a fleabay seller lists it there. It is my closest source!

 

[JamJay]

So what do people recommend, plugging up the N249 nipples or leaving then open to the atmosphere?

 

[DannyC87]

So what do people recommend, plugging up the N249 nipples or leaving then open to the atmosphere?

I removed the whole vacuum tank and associated gubbins - just got the n249 plugged in electrically with nothing else attached, cabled tied out of the way.

 

[JamJay]

Well mine is open to the atmosphere and I've had no issues (touch wood) so I guess it's ok to leave it this way?