4CN Air

iTrader: (7)

I'm not able to control boost even to 16psi. The wastegate is a Turbonetics Racegate with a 9psi spring (which si functioning fine). I have a 3" exhaust leading to N1 duals. Also there is a straight through resonator welded into my midpipe. I've disconnected by profec BC and elt the wastegate see full boost, and I've even put the silencers in my N1 (large restriction) but nothing helped.

I'm thinking that maybe my ported engine is flowing so much that the .88 exhaust housing isn't large enough, that the turbo is spooling too quickly? I know this is also a function of the wastegate setup, but short of reworking the manifold I'm stuck with what I have. The wastegate itself should not be the bottleneck since it's 42mm.

So say I have inefficient wastegate piping, upgrading to a larger exhaust housing (say a .96 or bigger) should require less from the wastegate correct?

I'm getting full boost (16psi) very quickly. I'm out of first gear as pretty much as soon as you put the pedal down. If the problem is that my engine is simply outflowing my turbo setup, I guess it's a good thing, but am I totally off base with my assumptions?

Thanks for the help with a question I should know the answer to.

Regards,
Cody

bobybeach

id say run with it. whats wrong with 16psi?

im running very rare internaly wastegated .84ar t4 on full bridgeport with p trim turbine. A lot of people will say thats way to small and you will chock the power bla bla bla bla, but i think its perfect for street car even full bridge, I can hold 1.1bar all gears with the internal wastegate. power as early as 3000rpm on strong torque through to 8000. one day i will go bigger turbine housing with external, reluctantly though. not sure if the extra top end power is worth it on a street car now.

If you really confinced on running less boost Id recomend you go bigger on your wastegate. and regain your boost control that way. going larger housing wont help much it will probably still over boost but with more lag, so you'l just end up with a slower spooling spiking turbo.

Turblown

iTrader: (12)

Show us some pictures of your wastegate runners, and the w/g discharge.

4CN Air

iTrader: (7)

the discharge is to atmosphere

4CN Air

iTrader: (7)

yes 16psi is great, but I can't keep it stable. I'll be adding a 3 bar map and larger primary injectors and going to 18psi soon, but I'd like to make sure my current turbo/manifold/wastegate setup doesn't need replaced/modified.

Carl Byck

I run a street port with a .81 P trim PT67 450rwhp@ 15 psi (500@23), no problem keeping down to 12 psi w/ EBay WG 50mm. Carl ( 3.5"DP)

GUITARJUNKIE28

have you checked wastegate operation with compressed air? sounds like a busted diaphram

4CN Air

iTrader: (7)

yeah I've checked it, opens quickly and fully.

How does the mani look?

4CN Air

iTrader: (7)

the wastegate is fully opening when i give it compressed air. I backed the "preload screw" out the whole way so the spring pressure should be 9psi.

This is so annoying, I haven't been able to take my car to redline at all, and more importantly i have to watch my tach and my boost gauge, then shift whenever one of them gets close to red.

Is the wastegate not flowing enough? I'm thinking about taking off the w/g and running without one. If I build 16psi without a damn w/g then I KNOW my manifold design is the problem.

Can ANYONE offer some assistance?

Turblown

iTrader: (12)

Manifold looks fine, however can you post a picture of where the w/g runners are connected?

I doubt you would build any boost, if any probably a small amount with the w/g off; I've never done that but I've seen what very smal holes/cracks do..

If you move to a larger turbine housing the boost will build more gradually, instead of snap.

Its just how I like to do things, and everyone does things differently but I would move to atleast a 1.0 turbine a/r.

Its kinda hard to tell exactly what is wrong over the internet, however I've never had to use an extremely large w/g to control boost, and i've done rotaries up to 2 bar on the street...

Busted7

Im running the 62-1 on big port and had the same problem, i went to the 50 mm wastegate problem solved. Before that just on 10# spring it would go 20 plus,this hurt my foot!

DaleClark

iTrader: (55)

With a vacuum line running from just the lower nipple (the one closest to where it bolts onto the manifold) of the wastegate to the nipple on the compressor housing, NOTHING ELSE hooked up, preload on the spring backed ALL the way out, you get 16psi?

Are you CERTAIN you have the right spring in your wastegate?

Dale

BuckyFD3

I always thought that if you have a small A/R then you need a big wastegate to stop overboost and you can use a smaller WG for a big turbo.

GUITARJUNKIE28

generally, you're right about the small a/r, big wastegate.

but it's all relative and almost no 2 setups are identical.

4CN Air

iTrader: (7)

Yeah I could run 2 bar on the street with this setup with no problem also, the problem is keeping it down to 16-18psi. I'm positive the spring is the 9psi one. In fact it's the stiffest offered in the racegate (black spring). The preload spring is totally backed out. The shortest possible silicone vacuum hose is connecting the side w/g port to the nipple on the compressor housing. I still shoot past 16psi in a hurry.

The racegate has 42mm inlet outlet with a 47mm valve. I'm hoping going to a 1.00ar housing will fix the problem. It's actually a good problem to have I guess, means I'm flowing a lot of air!

I just won a 1.15a/r divided housing for very cheap, which is what I'd like to use, but this means going to a divided manifold which will be pricey.

Hey 1Revvin7, want to modify mine for divided use?

Turblown

iTrader: (12)

I've always labled w/g size, by the size of the valve. That w/g looks an awful lot like the turbosmart stuff. Anyhow...

Why don't you slap your new turbine housing on and call it a day? You don't have to run a divided manifold with a divided turbine housing.

However if you are set on a divided manifold we can talk about moding you manifold...

GUITARJUNKIE28

can you get a pic of the inside of the manifold where the wastegate runners meet up with the other pipes?

4CN Air

iTrader: (7)

I was told that a divided housing will crack on the divide if ran on an undivided manifold. If this isn't true I would have bought a divided housing long ago in anticipation of going to a divided manifold eventually.

no internal pics available since it's currently installed.

Turblown

iTrader: (12)

I've never seen a Garrett housing crack. However we've mainly ran that combo on the 4 cycl cars. I've only done one rotary that way and after 5k miles the housing wasn't cracked. I have seen non-garrett housings crack after prolonged use though.
If the housing cracks after 75k miles just replace it.
You could chamfer the edges on the center divide to help reducing the possiblity of cracking..

snowball

im runing a divided housing on the undivided HKS manifold with no problems.
its been about 6k miles and i have it apart right now i can take pics if you want.

4CN Air

iTrader: (7)

Well thanks for the reassurance guys because I've decided i'm goign to give it a try. It'll cost too much money and time sourcing parts for me to go with a divided setup.

I'll knife edge the center divide to try to prevent cracking and decrease turbulence.

I know I'll lose some efficency, but I've had a hard time finding any non-divided housings bigger than 1.00a/r.

Turblown

iTrader: (12)

I wouldn't knife edge it, just radius the edges...

Zero R

iTrader: (1)

Do not knife edge the centre cut it back in a C-shape about .5" then radius the edges it will crack if you knife edge it. I've seen it plenty of times.

-S-

4CN Air

iTrader: (7)

What about leaving it how it is for now? I mean as fast as I'm changing setups I'll probably have a divided manifold with dual w/g setup within a couple thousand miles.

Will it last a max of say 5k miles without cracking? Not askign for a guarantee, but has anyone seen one crack that fast?

Thanks again for the help guys.