Lets talk about BOV's and boost controllers

BOV's are they needed? If so which one and how is it plumbed in?

Ditto with boost control... T-piece enough, or is there a cheaper electronic option?

I guess ditto again with afr meter? I love the idea of a wideband meter telling me what my engine is doing with fuel. Is there a cheap basic model out there?

You can run without a BOV as standard plenum has a pressure relief valve in it. If you want choo choo noises I find the turbosmart products good and GFB are also Australian and supposed to be very good.
they are connected to the pressure pipe between turbo and plenum closest to plenum as possible. Then then vacuum line connected to inlet manifold . Vented to atmosphere are illegal, plumb back to keep legal. (gases plumbed into air filter).

Electronic boost controllers are not cheap, but can improve boost response over manual boost tee valves. Also easy to set different levels with a press of a button.

Wideband AFR gauges and sensors again are not cheap, I would recomend PLX for an in car install.

if i can id like to sort of hijack this thread to keep things in one place?
im planning on/started to build mine up with the T3 exhaust housing flapper valve thing removed and a solid flange coveing the hole where of the old factory actuwater valve
ive also taken off the gonzo nose thing bit from my plenum n made a plate to blank off that hole as well from the factory over boost valve thingo this plate has a nice 1.75" feed pipe that fits my water to air IC setup nicely
anyway point is there is no where to dump/releve boost pressure apart from my right foot so my solution is to use one of thease! link is just for refrance
http://www.psituning.com/shopimages/products/normal/newforge008dv.jpg
thats not the brand im useing but its the right type ill have mine plumbed in so that the extra boost is sent right up to the carb befor its dumped back infront of the turbine that way its being passed throw my IC and not building heat being compressed over n over..
my qustion is do you think its possible to have the turbo itself over spin RMP wise due to all the exhaust gasses pushing the thing round no matter how much boost is dumped? clearly the more power my engine makes the more gasses it farts out for the turbo to get a whole bunch of rpms from
so im ondering if first off ill blow my turbo to bits from over RPM
or secondly if ill be above the efficancy iland due to rxcefice speed
if nether of the above happen i should have a nice setup as hopefully the turbo once spinning will keep momentum in gear changes and all so have almost instant boost apon clutch out gas down
if i need to add a hot side dump valve to reduce turbo rpm for safety and or efficiency it should be an easy task on my exhaust manifold design

I have had a little search as I had not heard of this setup myself.

From what I found it seems to have been used on massive high hp drag cars where turbo over spool would not be an issue due to only short bursts and massive turbo's.

For our daily needs and small turbo's im fairly certain it would be silly not to use a wastegate.

anyone know of a cheep but half decant hot side external waste gate that can be welded into the down pipe and manifold? ive seen a few but at like 200 bucks im not to keen
surely if you maintain the boost pressure cold side and maintain engine rpm than the exhaust gasses would have to be cheeped under control as only so much volume can flow at a WOT max rpm just like you need x amount of air to produce x hp and so surly the turbine would not just keep increasing speed as you would need more and more exhaust flow to keep pushing it faster?

sure you force more air in whitch makes more exhaust flow but once at max boost and max engine rpm there much be a maximum possible exhaust flow right?

i dono if it wasn't necessary no one would use them.. lol

what up with the internal wastegate?

External is definatly the go , they are more efficient and better control but are much more setup and plumbing.

I would be checking the quality of the diaphram and valve seal if you purchase a chinese copy , to make sure no leaks and is working at desired boost level.

if your set on one they are cheap enough >>

http://www.ebay.com.au/itm/Universal-JDM-38mm-Black-External-Wastegate-Adjustable-8-11Psi-Complete-Kit-/121209918733?pt=AU_Car_Parts_Accessories&hash=item1c38ac950d

Bit more compact >>>

http://www.ebay.com.au/itm/Vi-Blue-Car-Turbo-Charger-External-38MM-Wastegate-Dump-Valve-Universal-Fit-/181284720795?pt=AU_Car_Parts_Accessories&hash=item2a3569509b

Or tial copy with v-band flanges

http://www.ebay.com.au/itm/ROADSTAR-TURBO-WASTEGATE-EXTERNAL-38-MM-/251321467487?pt=AU_Car_Parts_Accessories&hash=item3a83ed425f

well ive spent the last few days thinking about this and have decided that after all the effort and cash put in to this project what the hell is say 200 bucks when you look at what has been spend over all?
so no alcohol for a few weeks to offset that extra bill haha

the fancy v band ones look like the go for ease of fitment/alignment
is there a rule of thumb for size of these things? 38mm seems ok to me as the down pipes are 52mm? and its not a 6L v8 its a 1.150L 4 banga

im not sure if there are any ways to work out, it would depend on turbo and boost levels though.

Lower the boost the more air the wastegate needs to bypass.

higher the boost the less aire the wastegate will bypass.


I would safely say a 38mm would happily work for any application on any mini engine. As a comparison my gt25 is around 20mm,

Also found this chart>>

Engine Capacity (cc) Turbo Specification Waste gate Size
1000-1999​ Stock 38-40mm
1000-1999 GT35 44-50mm
1000-1999 GT42 50-60mm
2000-2999 Stock 40-44mm
2000-2999 GT35 44-50mm
2000-2999 GT42 50-60mm
3000+ Stock 44-50mm
3000+ GT35 50-60mm
3000+ GT42 60mm