Jump to content
SAU Community

Bov Ughhhh.... Please I Am Not A Wanker.....

CEF11E

By CEF11E,
in Engines & Forced Induction

 Share

Recommended Posts

CEF11E Veteran

CEF11E

Posted
Posted

OK.

First of all my need just so coensides with 1000 new forum posts about BOV's and I would like to add I am not after any sound or cool looking shiny metal thing to bolt to my intake. I need a solution...

I have a VG20DET Auto nissan and have recently put an RB25 turbo, 3" exhaust, highflow cat, Retuned ECU, Water/Methanol Injection kit, transmission cooler ect ect...

The car came WITHOUT a BOV from the factory and was fine without one untill I added my list of goodies...

Since adding the bigger turbo it seems to make a huge Whoosh coming off the accelerator as all the air goes through the custom airbox/pod. It also feels slower coming onto boost between gears.. The car is putting out 204RWKW and the tune is almost perfect so it has nothing to do with leaning out or anything silly like that. Sounds like a need to recirc some of that air...

I know what I am doing with mechanical/electrical stuff most of the time and I reprogrammed my EPROM myself, Fitted the turbo and all other bits myself and built my water meth kit myself so I am not a silly teenage dirtbag...

So... my questions are

Will a R32 or R33 standard BOV handle 14PSI? or should I get another aftermarket Recirc BOV.

My space is limited as there is about 12" inches between the turbo and the throttle body. Also I have a water/meth kit installed and I don't want the BOV to Recirc Methanol and Water thru my turbo so it will have to plumb in before the mist nozzle giving me a total of about 6" to work with.

Any advice would be greatly appreciated...

Link to comment
https://www.sau.com.au/forums/topic/112184-bov-ughhhh-please-i-am-not-a-wanker/
Share on other sites
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

It shouldnt be slower on boost after a gear change.

Its an auto. There should be little difference.

IMO the BOV has less of an effect as you are on the loud pedal the whole time, so no real loss of load. If you put an ATMO BOV on there you wouldnt even hear it go off between gear changes...

Hrm...

CruiseLiner Mentor

CruiseLiner

Posted
Posted
It shouldnt be slower on boost after a gear change.

Its an auto. There should be little difference.

IMO the BOV has less of an effect as you are on the loud pedal the whole time, so no real loss of load. If you put an ATMO BOV on there you wouldnt even hear it go off between gear changes...

Hrm...

very true, only goes off when backing off the throttle. worth protecting the turbo though considering the pressure on it when the air suddenly comes back out the air filter.

TTT Grand Master

TTT

Posted
Posted
so I am not a silly teenage dirtbag...

it's true.. he's decent..

hahahaha

my under standing is that you are saying it feels slow to come on boost when you've come off the gas, not between gears.

yes the stock skyline bovs will handle 14 psi of boost.

but you might have problem mounting it.

You might want to consider a BOSCH bov.

they are plastic, good for about 15 psi and are sold from repco type places for about $45.

the reason I say this is because it is a universal fitting bov.. as in it doesn't have to be bolted in to place like the skyline ones do.

just reading through what you've done, you're a handy bugger aren't ya?

hahahaha

well done.

see what I mean by mounting..

skyline/vr4 bov

t_366.jpg

bosch bov

bosch-bov.jpg

CEF11E Veteran

CEF11E

Posted
  • Author
Posted

thanks guys,,,

much appreciated.

What happens is that I floor it from take off and it gets to 8000rpm and changes into second, the turbo goes WHOOSH and then starts spooling again.

What it seems like is the shaft speed is really high before the change and between 1st and 2nd it slows down as there is nowhere for the pressure to go. Once 2nd is engaged it lags and 1/2 a second later it builds boost again.

On the boost guage it never reads below 9~10 psi between changes.

BOV is a cheap bit on insurance anyway so i will get a standard rb25 BOV seeming as it is a rb25 turb,

Cheers guys.

paulr33 Grand Master

paulr33

Posted
Posted

what you are seeing and experiencing is the fundamental reasons why the BOV was designed and setup to correct;

turbine shaft being flung back to a lower speed on gearchange

to reduce the stress placed on the compressor wheel during geachange

so yes fit a BOV and all should be well

BezerkR32 Veteran

BezerkR32

Posted
Posted

I agree with Nismoid, should not see any boost drop on gearshift in a automatic. BOV will help in back off situation, but somethings not right there., if anything you might see a spike on shift.

It shouldnt be slower on boost after a gear change.

Its an auto. There should be little difference.

IMO the BOV has less of an effect as you are on the loud pedal the whole time, so no real loss of load. If you put an ATMO BOV on there you wouldnt even hear it go off between gear changes...

Hrm...

JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted

From what you have described, yes a BOV will help. Although it is not quite what I expected on an auto.

Interesting problem you've got there, I started writing a technical response but found there were too many things I don't know about your situation. I'd need to talk to you to work out what is happening.

someonestolecc Grand Master

someonestolecc

Posted
Posted

You wanker...

Just kidding. Just use any nissan bov? silvia, skyline, whatever. I know exactly what you mean about the shitty feeling, happened first time I put my atmo on and had it screwed real tight (no bov effect).

You can do a pretty good setup with the right sized radiator hose for plumbing back. I'd just rip out the pipe and have welded on it a flange thingy, then measure of the distance and run down to repco/whatever to buy a radiator hose that fits the bill. Plumbacks galore!

Also isn't the methanol sprayed right before the intake plenum? if so you shouldn't get too much blow off coming back through the bov into the intake, just put some sort of filter on it!

PS great work on the figure - you're the man!!! When ya comin back to sydneY!?!

TTT Grand Master

TTT

Posted
Posted

so foot is flat on floor, gear changes, foot still on floor.

I don't see how a bov will help this at all.

it doesn't go in to VACUUM at all (you said stays around 9psi) so how will the bov even open to circulate this?

although, maybe the stock skyline (R32 or R33 is same.. by part number even) which has that little bleed hole under it next to the bov piston will allow circulation during AUTO gearshift.

If you want to TEST, I can help you out on the weekend with stock bov on my car.

TT

CEF11E Veteran

CEF11E

Posted
  • Author
Posted

Thanks TT and CC :P

but i am in Canberra now :P

I will be buying a stock BOV as it should really have one anyway.

If that dosen't fix the problem i will cross that bridge when I come to it.

I just increased my timing by +3 deg from 4000 to 4900 (change point into second when flooring it) and it has helped the situation but it dosen't hit like a hammer when going into 2nd.

As this may be useful information to others I will keep this updated when I have added the BOV.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

The turbo should not be "whosing" when the car is upshifting... is your foot FLAT to the floor when this happens?

If so you have other problems as the TB should be wide open and not causing anything.

Installing a BOV wont fix the problem you are having unfortunately.

Time to visit a workshop or someone that knows a bit more

cheers

Abo Bob Grand Master

Abo Bob

Posted
Posted

Maybe what you have is something like reversion (I think it's called) or surging.

What I'm trying to say is perhaps the engine when it drops revs down on the change of gear is suddenly unable to ingest the large amount of air being shoved down it's throat creating a temporary partial blockage which forces some of the air backwards through the turbo.

Pure speculation based on incomplete knowledge.

Hey cef11e - are you going to/have you done a write up on the water methanol injection and subsequent tuning? Is that what you used my old fuel pump for? I'd love to hear the full in depth story.

CEF11E Veteran

CEF11E

Posted
  • Author
Posted
Maybe what you have is something like reversion (I think it's called) or surging.

What I'm trying to say is perhaps the engine when it drops revs down on the change of gear is suddenly unable to ingest the large amount of air being shoved down it's throat creating a temporary partial blockage which forces some of the air backwards through the turbo.

Pure speculation based on incomplete knowledge.

Hey cef11e - are you going to/have you done a write up on the water methanol injection and subsequent tuning? Is that what you used my old fuel pump for? I'd love to hear the full in depth story.

I used your old fuel pump as a pickup pump in my tank Abo bob. It's working a treat :). I will do a writeup on the meth kit as soon as I get some concrete results and I have been running it for a few weeks.

I had to rewrite an eprom to suit after the meth kit was fitted as the AFR's were to rich running a mix of 50/50. Before fitting the meth kit I was making 154RWKW with 10psi and bugger all timing(as i had no intercooler and i didn't want to risk pinging) and after fitting it I am running 14psi with 10+ deg more timing and making 204RWKW. I am really supprised at the power level as it's a stock rb25 turbo. But the dyno operator said it was to do with the massively increased timing and higher octane.

BTW there is no sign of knock at all.

I am really pushing the envelope and may drop the timing back and reduce the boost a little in the colder weather as my AFM is reading 4.0V at WOT over 7000RPM... injector duty cycle is also getting into the mid 80's.

I am injecting using a 2.75US gallon hago oil burner nozzle @ 110psi. I am in the process of setting up an intake temp probe and some other bits. But I am really happy with the performance...

CEF11E Veteran

CEF11E

Posted
  • Author
Posted
nismoid.. was that last statement supposed to say WON'T fix the problem?

CEFFIE - you moved to Canberra? why on earth would you do that?

what.. sydneys daily shootings is not good enough for ya?

hahaha

yep the only real thing canberra has going for it is 0deg winter nights and my cushy new job. + saving for a house :)

You got yourself a new ride i see :) nice one dude... looks really nice.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...