Triple_T

Searched threads here, got lots of info and figured out that the P.O. has a bleeder valve setup in my car! This explains why the bleeder valve is vented to the atmos.
According to what I have read, this is an archaic setup and that I should install the MBC according to Lindsey Racing.
http://www.lindseyracing.com/LR/Parts/VACDIA.html

Lindsey Dual Port Wastegate,
Hallman MBC
Lindsey Racing Super 61 Turbo P Trim

btw, What exactly is "P" trim?

Thanks

Zeff

I looked up the Hallman MBC... see if this is like yours http://www.hallmanboostcontroller.co...structions.pdf

If so you see what your in and out is on you mbc.

Look at this diagram too for the lindsey stuff for routing it is much simpler to understand for the mbc section




The P trim if I'm thinking correctly is the turbine wheel on your turbo, from what I understand the stage 2 is like a stock k26 turbo turbine, stage 3 is the best for a 2.5l, the stage V and P trims are more for top end flow.

Someone else chime in if I'm wrong on the turbine stuff.

Triple_T

Nice and easy to follow diagram! thanks!

I actually have the Hallman Pro MBC. sorry

So, why was it in vogue at one time to vent a dual port Wastegate?
Was there any performance gains/losses compared to non-vented?

Paulyy

pretty much you're running in single port more on the wastegate. you can leave it (nothing wrong with that) or just do it like the diagram.

with your MBC the bottom is input and the side is the output if that makes sense.

TurboTommy

Yeah, that's a big turbo you have there.
The P trim is pretty much the biggest turbine wheel you can get without more significant fitment issues.
Usually reserved for 3.0L engines; otherwise very laggy.

Paulyy

that must be quite laggy.

Triple_T

Yah, laggy... boost kicks in at 3200 and then you get sucked back into the seat until your front end lifts OR the back end breaks loose
Is there any literature on what exactly a "P" trim is?
Also, hooking up the DPWG as per Lindsey instructions, will that decrease lag? My reasoning is: the vacuum lines are no longer open to the atmos via the bleed off valve. And, will this even be noticeable?

Paulyy

the P trim is a different type of exhaust wheel on the turbo. compared to a stage 3 or stage 5, it allows more exhaust flow through the turbo so less x-over pressure but more lag and topend power.

in dual port move it keeps the wastegate closed until desired pressure, compared to single port mode it'll open slowly increasing lag until desired pressure.

How much boost are you running, and are you saying you get (full boost) at 3200 rpm?

TRACKIN951

So tell me all you MBC guys out there...Do all you experience the same variance in boost levels in different gears? For example, if I were to set 15psi in 2nd gear I would overboost in 3,4,5th as there is more load in these gear. So I set 15psi in 4th but only get about 12psi in 2nd. Not ideal...

Obvious solution is an EBC but I wanted to know if everyone experiences this the same. Black **** MBC and Tial 38mm.

Paulyy

same thing will happend with a EBC, it all depends on the turbo. my k26/6 got 15 psi in 2nd (set to 15psi max boost)

TRACKIN951

Well I can get 15 psi in 2nd gear if I set the MBC correctly but then I will over boost in all the other gears. My understanding is that an EBC will actively adjust to not allow the car to overboost. Is this not correct?

Paulyy

A MBC and an EBC are pretty much the same, Except the EBC is just digital and can allow for more adjustments. the better EBCs can compensate for boost drop at upper rpms. an EBC can make the wastegate open at the boost pressure of your choice say 10 psi or 13 psi for an example so it'll change the way the car respons either soft or sharp onto boost. there is overboost settings but it varies depending on the controller.

my eBoost2 has a lot of settings. i've got an overboost protection and an overboost alarm. i can set the alarm at 18psi and the overboost at 19psi if i want.

blown 944

A p-trim is 2.92 or close to that on the inducer. It's a pretty big wheel for a 2.5 unless you are planning on pushing it beyond 400 hp. IMO it should only be used in a large t3 or a smaller t4 housing. Using them in the replica hotsides is counter productive IMO. The one thing I do like about a large turbine wheel like that is that it hits like a shotgun when it spools and makes good top end. Unless you like lag or use a bigger engine I wouldn't use it.

TurboTommy

Why is that, you think?
Using them in a number 10 would probably be good, I'd think.
Also, if you machined a replica hot-housing to fit a larger wheel (like a P-trim), wouldn't it indirectly give you even a slightly bigger hot-housing? (Because, to fit a bigger wheel, the machining would have to expose an ever larger area of the entry snail) Or, am I not visualizing it right.

blown 944

It still has to go through the volute. You don't machine that to fit the bigger wheel. No matter how you look at it you are still blowing through a small set of straws. The only way I would even try it is to use a large waste gate. The 10 cm may work but with the size of the wheel the spool would be slower than std size turbine wheels. The turbine housing can only flow so much air effectively. The 10cm would be maxxed well before the turbine wheel so I just don't see the point.

IMO a stg 5 size wheel would be about as big as I'd go in a replica.