Leaking Blow Off Valve

[Blackkers]

Hey guys,

I've got a bit of an issue with my set up:

r33 rb25det,

hypergear 21U highflow, 20Psi E85. Made 306kw on the dyno with wheelspin.

I run a single GTR blow off valve recirculating

anyway Toshi said during tuning that it feels like there is a small boost leak and it does feel a bit laggy in lower gears. I pressure tested the system and it holds very well, I used soapy water and the only leaks i found were above 10psi and that was from the oil catch can. I pressurised from the intake pipe to the crossover pipe so both sides of the BOV were pressurised.

I'm wondering if when I'm coming on boost maybe the bov is leaking into the recirc pipe? Has anyone had issues with this before? my GTR valve is in pretty average condition visually.

I want to make a plate to block it off and hopefully that will improve response. This shouldn't affect the tune right? seeing as it recirculates after the AFM (I have a wideband I will be checking anyway). I don't plan to run this set up as I don't like the idea of hectic flutterz and stalling etc. I'll replace the valve if I have to but I won't get ahead of myself just yet.

Also, I've read about people using beer cans to make a block off plate. This sounds easy but I'm not sure how well a thin piece of aluminium will hold up against 20psi and I certainly don't want that finding it's way into the engine. What do you guys think?

sorry about the essay, thanks in advance

-Tim

[scotty nm35]

It will affect the tune if the turbo is more responsive obviously, but blocking off the bov with a bit of coke can is a good test to see if it's leaking. Anything is fine, 2mm alloy would be even better but it's only for a test.

[Dose Pipe Sutututu]

Hey Tim,

Perfectly fine, no way the can will enter the pipe if you make it the same size as the stock gasket with the 2x holes for the bolt..

Tune wise no change, except on decel, you might get the occasional pop or near-stall as it will richen up the mixture

[Blackkers]

okay wicked but it won't affect my AFRs by much I'd hope. Ill keep an eye out anyway and keep you posted.

If I'm up for a new BOV I would prefer to spend the money on a brand newy. Are those Turbosmart Kompact plumbback valves any good? I'll find a link:

here http://www.turbosmart.com.au/product/kompact-plumb-back-nissan apparently these bolt straight up.

[scotty nm35]

I use one, you may need to stuff around with spring tension but they work very well. Mine has been on for 4+ years and it was s/h. No issues so far...

[Dose Pipe Sutututu]

nothing wrong with the stock one man, I ran 1.3 bar into the factory GTS-t one for years.. however it was squished in a vice (to preload the spring more) haha

[Blackkers]

mad okay thanks for the input lads I might have to 'modify' a GTST valve with a socket and a hammer haha.

How do you change the spring tension in the TS model scotty? Glad to hear it has lasted so long, makes me feel better about buying one seeing as they are $160ish compared to $15 for a 2nd hand GTST valve

Edited February 7, 2014 by Blackkers

[scotty nm35]

nothing wrong with the stock one man, I ran 1.3 bar into the factory GTS-t one for years.. however it was squished in a vice (to preload the spring more) haha

You could have picked up 2psi for free with a Kompact.

[scotty nm35]

How do you change the spring tension in the TS model scotty?

You need to buy another (softer) spring from TS, and the top screws off. Most guys don't like the little flutter they make and want the softer spring.

[Blackkers]

alright kompact it is. I'm going to go murder a beer can and I'll get back to you

[scotty nm35]

Don't pick some panzy euro beer, it will make the flutterz sound gaids.

[Blackkers]

haha VB it was, slight gain in response. Slight but definite. Only noticeable in 1st,2nd,3rd. It feels like its spooling much quicker. I guess the spool wouldn't change but more air is entering the motor. anyway I'd call it maybe 400rpm difference in 1st gear

AFR's didn't change as far as I can tell and no weird noises. Well other than the sututu which sounds pretty loud with a pod filter and your metal intake pipe.

I'll remove the plate and add a new bov to the list of things to do before getting a touch up tune.

touch up tune was on the to-do list anyway due to the 255 pump being maxed out and having to increase the injector duty to maintain good AFR's in the top end. The pump can't keep up and fuel rail pressure must be dropping I guess; I trust toshi's judgement but I don't like the idea of 100% duty on the pump, what happens if my alternator shits itself and suddenly the voltage across the pump drops to 11.5

thanks for your input

Edited February 7, 2014 by Blackkers