Question About My Skyline..

[KEN-R34]

cheers for a little more advice i guess i will go to a performance place for some advice to answer some of your questions it dosent have a stock ECU unit its had a new monza fitted one... i duno how good that brand is... and yeh i do get a bit of backfire sometimes and the car has stalled occasionally when ive been driving it but not really often just rarely. the boost is run really really high... on my boost gauge it usually is at 15 sometimes.. 20... i duno this is all just figures to me.. i think the fuel lines have been pressured to release maximum? this is just a few things coming from my home mechanic. duno if its right?

15psi sometimes and sometimes goes all the way to 20psi on stock turbo?? Also your car stalls when driving?

What is controlling your boost? Your turbo wont last long if what your saying is true....

My god you have opened a can of worms lol Your better of going to a performance workshop and getting someone with exp to have a look at your car in person.

[FEARNOV8]

lol hanaldo i actually meant to say how much boost can it handle because i wana get an aftermarket fmic and afc..no worries johnnyboi and it sounds like u having boost spike from wat u were saying with da psi jumping from 15 - 20 so yea ken-r34 is rite especially if ur turbo is stock

[Nic_A31]

His point was that stock BOVs can handle any amount of power, since power does not affect BOV operation, and BOVs do not affect power/performance.

If you did for whatever reason need a bigger one, you'd receive it with your turbo.

[Tony de Wonderful]

No, the idea of a blow off valve is to keep the vacuum in one direction. Surge occurs when the throttle body closes and high pressure air has nowhere to go.

Even if the blow off valve is small, it still keeps vacuum in one direction, and then once the air passes through the blow off valve, it goes through the turbo (again) which is no longer compressing (or compressing as much), so the pressure is released very quickly on both sides of the turbo.

With FMIC, high boost and you've got a responsive intake system, if you drop from full boost/redlining down to idle quick enough, you will get some surge for a split second, depending on where the blow off valve is located (the further away from the throttle body, the more likely) and how long the blow off valve takes to open.

How can the charge - between the throttle body and compressor - that is sent (by the bypass valve) to between the compressor and AFM, all get sucked back through the compressor if the throttle body is shut?

I understand the bypass valve equalises pressure either side of the compressor, but I don't see how in a situation going from WOT (and full boost) to closed throttle and idle, you don't end up (after bypass valve actuation) with pressure either side of the compressor which is equal but greater than atmospheric, and so you get atmospheric venting back through the AFM and POD/Filter. The volume of air downstream of the compressor (thanks to FMIC etc) is just too much to be equalised back to atmospheric by venting into the upstream side of the compresser?

[Tony de Wonderful]

cheers for a little more advice i guess i will go to a performance place for some advice to answer some of your questions it dosent have a stock ECU unit its had a new monza fitted one... i duno how good that brand is... and yeh i do get a bit of backfire sometimes and the car has stalled occasionally when ive been driving it but not really often just rarely. the boost is run really really high... on my boost gauge it usually is at 15 sometimes.. 20... i duno this is all just figures to me.. i think the fuel lines have been pressured to release maximum? this is just a few things coming from my home mechanic. duno if its right?

Sounds like your car is a time bomb.

[Nic_A31]

How can the charge - between the throttle body and compressor - that is sent (by the bypass valve) to between the compressor and AFM, all get sucked back through the compressor if the throttle body is shut?

I understand the bypass valve equalises pressure either side of the compressor, but I don't see how in a situation going from WOT (and full boost) to closed throttle and idle, you don't end up (after bypass valve actuation) with pressure either side of the compressor which is equal but greater than atmospheric, and so you get atmospheric venting back through the AFM and POD/Filter. The volume of air downstream of the compressor (thanks to FMIC etc) is just too much to be equalised back to atmospheric by venting into the upstream side of the compresser?

At 7000rpm, you're filling up 2.0 or 2.5 litres of air 7000 times a minute...so air is getting sucked through fast. No matter how quickly the throttle body shuts (which is never very quickly with a single body) the amount of air remaining between the compressor and the outside of the throttle body isnt much ... only enough to full the pipes from the turbo to the throttle body...it gets recycled back through the compressor to lower pressure and slowly that remaining air is still sucked into the throttle body via the idle control.

So yeah, just because you're at high rpm and full boost, it doesnt mean there is any MORE air (volume) before the intake plenum, it just means its flowing through faster.

And for air to be sucked back out the AFM / POD, the vacuum would need to be going the other direction - the only way that is possible is in the event your turbo does scream like a Flippy when air returns to it.

Edited January 18, 2010 by Nic_A31

[Kaido_RR]

His point was that stock BOVs can handle any amount of power, since power does not affect BOV operation, and BOVs do not affect power/performance.

If you did for whatever reason need a bigger one, you'd receive it with your turbo.

stock bov leaks.... therefore it can not handle any amount of power

[Nic_A31]

Generally nothing hand handle its job when it doesnt do what it's meant to

[FEARNOV8]

yea i think kaido is rite and think about it y would da japanese make atmo bov if they were useless? lol anyways do u guys go on much cruises? would be nice to meet fellow skyline owners

[Nic_A31]

LOL righto

[FEARNOV8]

mean does ur cef have a rb25det ?

[Nic_A31]

20DET... not enough RAW POWER to blow up my stock recirculating blow off valve.

[FEARNOV8]

lol all gud..in Nz there were heaps of them they mean cars..oh well im off got this stuipid 3 day induction for tafe im the only apprentice technician all the others are in da building industry haha but its all gud

[bubba]

It really doesn't matter how much power you are making. The point of a BOV is to compliment the turbo, they release the pressure so that the air doesn't get forced back through the turbo, slowing the rotational velocity of the compressor wheel which means the turbo will take longer to spool up (and also potentially causing damage to the turbo). A BOV is just a valve, with the only purpose being to release charged air. There is no performance gain from an aftermarket BOV compared to the factory one.

The only reason to change the BOV would be if you were running very high boost and the valve wasn't letting all of the charged air escape

I don't think it's much of a case of letting all the charged air escape as that is airflow and comes down to the size of the turbo involved, not necessarily the boost level.

The problems with running high boost is the spring pressure may not hold the bov closed when climbing high into the boost, forcing the bov open and effectively having a closed loop boost leak.

stock bov leaks.... therefore it can not handle any amount of power

Agreed, especially if it's run atmo.

Tony et al, I think something you guys are missing is that the stock bov is going to be held open ALL the time that the engine is in vacuum so any residual boost is going to be constantly recirculated while the throttle is closed till there is no positive pressure left.

P.S. I have just fitted twin GTR bov's to my 32 (along with full GTR piping/cooler/recirc pipe) so we'll see how they handle 25psi through a GT35R when the engine is finally put together

[Hanaldo]

yea i think kaido is rite and think about it y would da japanese make atmo bov if they were useless? lol anyways do u guys go on much cruises? would be nice to meet fellow skyline owners

Probably the same reason they made those hektik sik turbo fans that you stick in your intake pipe and totally give you AWSUM POWA while improving fuel consumption. Or maybe they are from the same makers as those fake turbo whistlers, they are pretty useful when trying to prove to everyone how big your manhood is...

Lol, believe it or not, most stuff is made to make money. Lucky for them, there is always someone out there that believes what they are buying either works, or is the coolest invention on the planet. Nuff said.

You should check out the events section for cruises, although there isn't much going on right now Still waiting for the season to kick off again

[johnnnnnyboi]

okay... this is promising... ok so performance place what we talkin like...? the car probs is better i just duno what im talkin about.. haha id prefer like one of you blokes to have a look id feel that performance blokes wud be trying to say its stuffed just to make me pay em money and crap like dat unlike u blokes u dont need anything... i duno i guess ill go see one just give me a good place nd ill go.

[Hanaldo]

No way man, you go to the right place and you won't have to worry about that. Check out the consolidated workshop thread, all the shops in that thread are highly recommended and very professional.

Autoworx is my recommendation, Alistar is a top bloke

[johnnnnnyboi]

No way man, you go to the right place and you won't have to worry about that. Check out the consolidated workshop thread, all the shops in that thread are highly recommended and very professional.

Autoworx is my recommendation, Alistar is a top bloke

ahh tru autoworx sounds good, their just round the corner from me! cheers hanaldo ill let you know how it go's and ill get back to you all about how fu#5ed up the car is haha

[Nic_A31]

I don't think it's much of a case of letting all the charged air escape as that is airflow and comes down to the size of the turbo involved, not necessarily the boost level.

The problems with running high boost is the spring pressure may not hold the bov closed when climbing high into the boost, forcing the bov open and effectively having a closed loop boost leak.

Agreed, especially if it's run atmo.

Tony et al, I think something you guys are missing is that the stock bov is going to be held open ALL the time that the engine is in vacuum so any residual boost is going to be constantly recirculated while the throttle is closed till there is no positive pressure left.

Correct

If anybody still doesnt understand BoVs, look at Wiki ... it has a colorful picture and shit.

You should check out the events section for cruises, although there isn't much going on right now Still waiting for the season to kick off again

What season ??

No way man, you go to the right place and you won't have to worry about that. Check out the consolidated workshop thread, all the shops in that thread are highly recommended and very professional.

Autoworx is my recommendation, Alistar is a top bloke

Erm...can't say I agree here. The reason I give soo many 'Liner guys shit on WA is that 99/100 take them into workshops and get shafted. Just because they have a shop or "skills" it doesnt mean theyre honest or the most effective way.

Besides, look what can happen if you give your Lambo to a mechanic.

The problem in mention isnt complex, it wouldnt hurt to do this in his own driveway and learn some basic shit about his car.

Edited January 19, 2010 by Nic_A31

[Hanaldo]

Correct

If anybody still doesnt understand BoVs, look at Wiki ... it has a colorful picture and shit.

I posted pretty pictures

What season ??

The cruising season. Duhhh Just means im waiting for some to get organised haha

Erm...can't say I agree here. The reason I give soo many 'Liner guys shit on WA is that 99/100 take them into workshops and get shafted. Just because they have a shop or "skills" it doesnt mean theyre honest or the most effective way.

Besides, look what can happen if you give your Lambo to a mechanic.

The problem in mention isnt complex, it wouldnt hurt to do this in his own driveway and learn some basic shit about his car.

Thats why there is the consolidated workshop thread, people have experience with these guys. There are actually mechanics out there that aren't just trying to make a quick buck. Some of them are interested in the car scene and a honest about their business. Its just about finding one you can trust.

I do agree 100% though, i would much rather do my own work to my car if i feel i am capable, but if he isn't confident of doing a good job then he would do better to take it to someone who knows what they are doing