The Quest For Response
A Much Needed Update

Welcome back to Project GT-R! I’ve had so many people ask me about the car that I thought it was about time for an update… With work and life in general getting in the way, I haven’t been out in my BNR34 nearly as much as I would like, but that said, I’ve actually driven it more than last year, which is great I guess. The Skyline is currently running on its old 19-inch RAYS Volk Racing CE28Ns that I’ve had for over a decade now; they’re a set I like to refer to as my ‘street’ wheels. I fitted them late last year in an attempt to finish off the old Bridgestone RE-11s, which although date back to 2008 still have plenty of life left in them and remain ridiculously sticky. A few spirited touge drives have done nothing to wear them down, so I think I’ll have to just kill them off on a track day or something.

But aside from that, the car has been maintained in tip-top condition. The mountain of boxes for the much-awaited next round of mods has grown since the last time you saw the Nissan; the most exciting addition being an HKS V CAM kit which will be fitted once the turbos get replaced. Haltech will be sending me its new Elite engine management system and once that arrives I should be ready to go. I say ‘should’ because I’ve decided to control the HKS V CAM through the Haltech and therefore need to make sure that an additional cam sensor is thrown into the mix so that the ECU can take care of everything without the need for auxiliary modules. This is what all the delay has been about in case you were wondering. But don’t worry – with Ito-san at Do-Luck helping out and a solid technical backing from Haltech, I’m sure I’ll get there in the end.


In the meantime, I’ve been doing a lot of chatting with the guys over at Turbosmart, specifically about my overall goal with Project GT-R. That is, to create a very driveable car with a strong, torquey mid-range and minimal lag. Inevitably, we ended up on the subject of aftermarket blow-off valves (BOVs), an upgrade I’ve been pretty skeptical of, primarily because I couldn’t see any benefit in running them except for an increase in whooshing noises. If that’s the sort of thing you are after, great, but sensing there was no real performance benefit I dismissed it as something not for me. But then they told me about their new Turbosmart Smart Port BOVs and things began to get interesting. By design, these would actually allow the turbos to pressurize the intake tract quicker and therefore increase response. My interest was immediately piqued…


It seemed like there was a problem though – that being Smart Port BOVs are currently available only for the R35 GT-R’s VR38DETT. But once I expressed an interest, Turbosmart was happy to build a custom pair for the R34 by combining R35 valve portions mated to RB26-specific flanges. The prototypes were shipped to me from Australia in a couple of days, and once they arrived I took the car straight down to Do-Luck in Yokohama to have them fitted.


You can get to the stock blow-off valves without having to remove the front bumper, but due to the front diffuser there are still a ton of bolts to undo.


Once the main diffuser section and second cover behind it under the oil pan is removed, you’ve got access to the bolts that attach the inner fender liner. Then it’s just a matter of removing the right-front wheel to reveal the two factory recirculating blow-off valves that are fixed in position at the corner of the bumper.


Of course, having a lift (note the recess in the ceiling at the Do-Luck shop to ensure cars can be lifted sufficiently) is always a bonus, as is having an experienced mechanic do the work for your while you just stand around and shoot every step of the process.


This also gave me a chance to take a little gander under the car. This is always slightly depressing, and I noticed more stuff that has rusted and will eventually require some TLC.

In The Pursuit Of Response

But back to the job at hand… The two BOVs are bolted onto a cast section of aluminium piping which is secured in place via two brackets that ensure the whole ensemble doesn’t shake around. The recirculated air – which has been metered and therefore fuelled for – gets channeled back to the turbo side right after the AFMs. This is also the reason why, that when fitting an atmosphere-venting BOV to a GT-R the engine tends to stall, as it runs rich for a second.


Either that or you shoot big flames out of the exhaust! The Turbosmart Smart Port gets around this issue by design, but I’ll get to that shortly.


The first step was to undo all hose clamps and the bolts holding everything in place.


Voilà, the stock setup removed. As Turbosmart explains it, “Factory BOVs are very responsive to throttle changes as they do not require a high amount of vacuum/boost to open. Small throttle changes are enough to create a pressure differential between the top of the valve (vacuum) and the bottom of the valve (boost) to overcome the spring force and open the valve. Turbocharger response however is slightly diminished. This is due to the fact that the turbocharger is not able to pressurize the intake system because the valve is open. Air is travelling from the compressor, through the valve and back to the intake of the compressor. Boost can only be built when the valve closes. This causes a slight delay when the driver reopens the throttle as the valve needs to close to allow pressure to increase.”

Here’s what the setup sounded and responded like when I still had the stock BOVs in place. You can hear that the actual dump sound is very muted, and is actually flutter coming from the turbo side of the engine rather than where the valves are located.


On to the Turbosmart BOVs…


Each valve comes in its own box and is supplied with a gasket and a silicone vacuum hose as well as a CD-ROM with fitting instructions.


Of course, the quality is top-notch and there’s full aluminium construction for both the body as well as the flange section. The Smart Port has an aluminium piston which makes it lighter and therefore more responsive to pressure/vacuum changes. It’s also hard anodized for lower friction and increased hardness.


But what sets this BOV apart is that it’s both atmosphere venting as well as recirculating. Turbosmart initially developed it for drive-by-wire applications where even the smallest of pressure or vacuum differences would send the ECU into panic mode, therefore making vent-to-atmosphere setups impossible to use. Basically speaking, this twin-port design combines the benefits of both systems, recirculating some pressure back into the intake and dumping the excess through the secondary valve in the vent-to-atmosphere port. The tighter and quicker close then allows the intake tract to be pressurized quicker, resulting in better boost pick up between gears.

The Swap

In theory it sounds like a no brainer, but I was keen to get it all fitted and tested.


Here’s a look at the underside of the piston. Pushing it up by hand, the Smart Port has a firmer and tighter action.


Of course, its action is adjustable by simply turning the top (black) portion, hardening or softening up the spring. Check out the corrosion I found on one of the stock BOVs!


There was a bit of oily blow-by residue inside the piping, so that was quickly flushed out with the use of some brake cleaner.


The Smart Ports were shipped out with the R35 29mm flange for the recirculation side, so Turbosmart included the larger reverse-taper 38mm items to fit the R34. Incidentally, if you want to use the Smart Port as a purely atmosphere-venting BOV you can seal off the recirculating port completely with the included plate. Talk about getting the best of both worlds!


With the 38mm flange in place, it was ready to get everything plumbed back in position.


I was surprised how well the two silicone hoses of the stock setup had held up considering they’re 16 years old.

Better Boost Pick Up

And there you have it – all fitted in position and ready to go!


After clamping everything in place it was over to the vacuum side.


Since Turbosmart provided the small vacuum hoses, we got rid of the stock items which looked a little worse for wear after years of heat cycling.

After everything was fitted we spent some time adjusting the BOVs, first making sure they weren’t too soft at idle and then tightening them up further to ensure they stayed nice and tight until higher boost filled the intake tract. As you can hear through the clip above, the BOV sound is pretty evident now. It’s definitely something I’ll have to get used to, but the thing that surprised me the most was the perceptible difference in boost response during fast gear changes.


I’ve also noted a decrease in audible flutter, which you could previously hear when backing off the throttle slowly during in-gear acceleration. All in all, this turned out being an upgrade that added a noticeable improvement to the car’s performance and character, plus my son seems to really like the loud ‘whooshes’ the BOVs throw out when I back off the throttle. Smiles all round then!

Dino Dalle Carbonare
Instagram: speedhunters_dino



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Sweet-sweet wooshing noises! :D

Sandbagged and Tag

Haven't even read the article yet but always glad to see the old girl out!! XD


So funny how year ago, wanting an to atmosphere bov on my supercharger kit instead of the installed bosch 1" bypass valve led me down the path of intercoolers, turbochargers, and so many more products in the aftermarket world both as a consumer and as a manufacturer. Funny how it all started with this one little product and the desire to hear that Whoosh sound.


I like post like this that get a little technical on how a certain part works in a certain application. Especially since I'm building a custom turbo kit. And I get to see the products that other people use. I went with Tial btw but I know Turbosmart makes lots of great products


A Peugeot 207 in Japan! LOL


Becauseracetruck you are not building shit you are just another keyboard warrior, shut up kid.


Becauseracetruck Good luck with the build. Make sure you place your waste gates in the correct location so you don't have any problems controlling boost.


DonHoonigan And?


My turbo rotary 13b just got a new blowoff valve installed too. I think it's made by RE Amemiya. The problem is when I lift the throttle it doesn't make a loud whoosh noise...I am very disappointed. So I went back and rechecked and found that the timing belt is loose, could that have caused it?


@A00916171 Typically bov's need to be adjusted.  See if there is a way to reduce spring pressure it might be too tight.  As for the timing belt... you're on your own.  How old is it?


Perfect timing Dino.  I too value response but couldn't determine if a proper bov/bpv would help.  You just took care of that for me. Thanks!


@A00916171 Becauseracetruck  A00916171, what's wrong with what becauseracetruck said???? How bout you go adjust your 13B rotary's "timing belt".......?????? and stop trying to troll


@A00916171 timing belt on a 13b lol, it's prob your muffler bearings...


Nice addition to your Project GTR Dino! Skylines make me just smile, still my absolute Halo Car!


good read, by the way anybody noticed the number plates, super cool :)


DonHoonigan Looks like it has a huge front mount too


Weird when you look at your R34 and think that it's the same age as me!


Don't worry bro. I got this. Thanks


Hey man u seem to have had a bad day yesterday. Hope all is well. Just remember to stay HUMBLE. @speedhunters
Oh BTW here is a pics of just a few of the stuff I have collected over time for my build. [URL=]


Urgh, I want a BOV now. Always had that same internal argument about the noise. Good work man.


Great to read again about the R34! I look forward to the next upgrades. Enjoy it!


Sandbagged and Tag She got a right thrashing today :)


UltraChris2k DonHoonigan Well spotted. Sleeper!


@A00916171 troll


bluestreaksti I just took the car on a nice drive today and I can definitely say that on sprites driving the boost pick up between shifts is even more noticeable. Well happy!


Mahilal You mean the 34?


LukeEVOVIII Thanks for making me feel old!  haha


Speedhunters_Bryn Thanks Bryn! Long time my friend, hope all is well with you!


Nice Upgrade! I seriously want to visit Japan someday, if only there were R34's in Chicago!


Soo funny though.


Thanks. I've been doing lots of research with fitting the kit together. Kinda suck when you decide to boost a car/truck that isn't very popular and that not many people have modified. Got to build my downpipe and exhaust now. That's gonna be fun!


Becauseracetruck I've built lots of turbo kits. No one I know really cares about what it's going on--it can be a tractor for all I care, just make sure it's built well. My team has two trucks one which was the fastest lightning in the world (before it was totaled in a race) and the other is the fastest supercharged... Just remember to read before you build. I always recommend Corky Bell's "Maximum Boost." It's an old book, but it has a lot of great info on how to build a good turbo kit. It is very improtant to build a good kit because if you don't you can quickly ruin your motor or you'll be building it again.


Reminds me of the one brian drove in atbthe beginning of 2fast. It would make ta similar blowoff sound. It always makes me think of a moster trying to scare. Its cool


speedhunters_dino Mahilal what else :)


...pure envy from an American enthusiast. Just once in my life I have to take an R34 for a spin. Any other Americans on here have crazy plans like buying a Canadian snowboarding vacation home just to own the imports we don't have yet?


Good to finally hear an update on the GTR! Also good to see some Aussie shops helping out with the build :)


Speedhunters that's the kaido from fast & furious 4?


HKS BOV sounds still the best.


ToughDog  Got a vid?


Beautiful work Dino.


Love the vid of it in action through the bumper. Never seen one in operation before.


Speedhunters_Bryn Grab a fully recirculating DV. They aren't as noisy. :)


I have enjoyed reading this build of yours. This was a really interesting instalment.


Aaaaahhhh, that needed woshhhhh sound! thanks for sharing, now you have a happier R34


This is awesome! Thanks for keeping us updated on the R34, Dino!


Nice upgrade. You should also replace the cast aluminum piece w/ something custom fabbed. Its kind of like when your girl is wearing something awesome underneath her clothes that only you know about.


nice upgrade! hoping they'll offer this on subaru's EJ engines as well.


Surprisingly good mod!  I swapped out the stockers on my BNR32 with Synapse DV valves and flutter was eliminated and boost response improved greatly.


louis110 Yeah I'm pretty surprised too :) Is your R32 running stock motor/turbos?


butterballs Think they do?


jbfromsiliconvalley I thought the cast aluminium piece is really well made. It's the steel pipes on the other side that I thought looked pretty shite


reix2x And a blown right ear drum lol




BT180 Yeah neither had I till I watched the vid. I guess when you dump all the boost pressure the turbos can muster that valve is going to lift pretty high up. I could already feel the air blowing onto my hand while holding the  GoPro there


GregoryS Thanks!




speedhunters_dino Yup! Ran stock motor/turbos for the last 5 years, but finally taking the car to the next step this winter with Nismo LeMans turbos + HKS acutators, 260/254 9.15mm cams, metal head gasket/exhaust manifold gasket, ARP headstuds, ported manifold, Cusco twin turbo pipe, R35 MAF's, and a whole bunch of other supporting mods.


ToughDog Because it doesn't work. That "Super sequential" noise is just compressor surge, that BOVs are meant to stop.


I had an Apexi one in my 32GTR but i changed it for stock, Not a fan of the whooshing sound. Stock ones can handle enough power and im not aiming for huge horsepower anyway. I'd love to do a write up on my car but upgrades are very slow, need more money haha.


ScottJohnson5 Slow is good, I've been at it for 16 years... haha


louis110 speedhunters_dino Sounds good! Similar to what I'm doing.


Ezui butterballs There you go!


Ezui ToughDog I'll ask HKS next time as this makes no sense. Why would they make BOVs that are useless?


speedhunters_dino ScottJohnson5

Well that's alright then. The worst part is coming across small things you want to fix or work on haha. A few years back i used to have a MPII R34gtr but thats a sad story as it was stolen :( thank god i took many pics of it while i had it. since then ive had many cars but have come back to the gtr. Love your work mate (yep im aussie) and look forward to reading more.


I'm not totally sold on the logic. Yes, if a small pressure difference is all that is needed to open the factory compressor bypass valves, then it is possible they might be open for longer as it tries to build boost. By the same token surely that also means they will be more sensitive to throttle closure and will vent earlier, meaning reversion will slow the compressor less in the first place compared Turbosmart items. I could be totally wrong.


You never disappoint Dino. Good to see the Bae-Side make some progress, and the videos were just the cherry on top.


:) Good on ya


I did the old trick and fitted 1mm stainless orifice plates with 8mm holes to the discharge of the OEM BOVs. 
Works a treat.


Dino that's a nice piece of machinery with the Turbosmart dual BOV's!   Way to go!


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