igo4bmx

I'm actually running my greddy profec b spec 2 to the side port on my 38 mm wg...
it holds boost perfectly at 11 psi....

if a mbc works through the side... why does the ebc have to attach to the top?

i'm just curious what the reasoning is behind this

adseguy

the nice thing about an EBC is that it hold the valve TOTALLY shut until whatever PSI is reached. An MBC just "tricks" the wastegate into thinking it hasn't reached the wastegate spring PSI. With an MBC the valve will open before full boost is reached and cause slightly less spool time. It's also put at the top because if the device fails you won't overboost since the spring will regulate boost then

Muckman

iTrader: (2)

What if you connected both top and side ports to a vac source IF no boost controller was used? Would it not open because pressure would equalize on both sides of the diaphram?

DaveF

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Muckman &raquo;</TD></TR><TR><TD CLASS="quote">What if you connected both top and side ports to a vac source IF no boost controller was used? Would it not open because pressure would equalize on both sides of the diaphram?</TD></TR></TABLE>

yes. or open very slightly..

Muckman

iTrader: (2)

What if it was reversed? IM connected to the top wg and the turbo compressor to the side wg? The IM vac source should be less considering the pressure drop. Wondering if it would hold the wg shut longer like an EBC does.

DaveF

but there would still be pressure on the top of it. so it wouldnt open like it was supposed to and overboost would occur. im sure it would hold it shut like you are saying, but up top it would overboost like nuts.

Synapse

Hey Muck, this discussion you are having about pressures to the gate is how I came around to the geometry of the Synchronic WG I'm working on. Synchronic Actuator geometry has unequal actuator areas, so that you can apply pressure to one piston area at the top of the WG, and get higher boost pressure by pneumatically changing the preload on the spring. The combination of 3 different piston areas is how you can come up with 7 different boost pressures at the actuator level.

One of the other things I've been playing with as well, is applying vacuum to one of the smaller piston areas on top of the actuator, so that between gears, the WG valve opens and the vacuum of the engine bypasses the turbine. Like a built-in anti-lag between gears.

http://www.synchronicactuator.com -Click on the pdf to see how the geometry is different from a traditional actuator. Not a car parts page, just FYI.

Muckman

iTrader: (2)

I admire your out of the box approach to designing new products to address old problems. That is very good idea as is your FPR design.

tony1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Synapse &raquo;</TD></TR><TR><TD CLASS="quote">One of the other things I've been playing with as well, is applying vacuum to one of the smaller piston areas on top of the actuator, so that between gears, the WG valve opens and the vacuum of the engine bypasses the turbine. Like a built-in anti-lag between gears.

http://www.synchronicactuator.com -Click on the pdf to see how the geometry is different from a traditional actuator. Not a car parts page, just FYI.</TD></TR></TABLE>

If you open the wastegate between gears then you're going to loose any exhaust energy that you would have to drive the turbine. How would this work like anti lag? Anti lag is keeping the throttle open so as to keep air coming into the motor and moving across the turbine.

Synapse

There are many different anti-lag strategies out there besides just drag racing, depending on formula.

This doesn't really apply to drag racing, since you hold the throttle open between gears.

But one of the other strategies that exist for road racing is dump raw fuel into the exhaust between gears via controlled misfire and light it off with air from the blow-off dumped into the exhaust manifold.

This is still just conjecture at this point, but the hypothesis is that between gears, both exhaust and intake manifold go into vacuum with the throttle closed, that vacuum slows down the turbine between gears. Opening the WG bypasses vacuum away from the turbine and straight to the DP, essentially not allowing vacuum to decelerate the turbine.

This is a similar approach to a BOV helping spool between gears by not allowing excess pressure between the closed throttle and compressor wheel to slow down the moment of the compressor wheel.

Preliminary testing is yielding good results, but mostly annecdotal, no sensors yet to compare shaft speed or anything.

tony1

Anti lag on a road race or rallye car works by introducing the air from the blow off valve to maintain "exhaust" energy to the turbine (with fuel and ign changes), with the throttle closed.

Bypassing "vacuum" at the inlet of the turbine would be better than not, but i still don't see how it would maintain shaft speed and/or boost. Seems like the best you could hope for is the turbine wheel keeping some inertia, which doesn't seem like it would do very much.

Synapse

I guess we're saying the same thing again here, about anti-lag as the external combustion via ignition cut and the bypass charge auto igniting the fuel in the exhaust? I hope you aren't saying that discharge from the bypass valve keeps the turbine going with the throttle closed.

Anyway, like I said, it is a theory right now.

tony1

You have to keep air moving across the turbine, that's what the bov bypass does. If you have the throttle closed and no air introduced into the manifold, then it won't keep the shaft speed up. There will be backpressure at the outlet of the compressor because the throttle is closed. Bypassing the air back into the exhaust manifold keeps air moving across the turbine, which is then ignited with the fuel added from the computer along with extremely retarded timing. This keeps the shaft speed up because you are still moving air across the turbine, and you have relieved the pressure from the outlet of the compressor, by giving the air somewhere to go.

DaveF

tony, do you have any pictures that would help show what you are talking about? i can sort of understand what is going on but a picture would help me understand more about it.

80884

It sounds simple. Let me see if I have this right...
1. shift
2. bov opens
3. air coming out of bov goes to exhaust manifold
4. ecu takes care of adding fuel and retarding timing, giving your exhaust manifold fuel and spark
5. air from the bov is mixed with the fuel, also flowing passed the turbine wheel keeping it going in the right direction boom it ignites and keeps moving.
Presurized air goes from compressor side to take the place of the not existant (or severly reduced) exhaust gasses, alowing the turbo to maintain a decent amount of airflow accross it to keep moving at high speed.

If I have any of that wrong let me know.
Dave I can draw you up something in paint if I have it right lol

tony1

That pretty much sums it up, though that style is generally used for rallye racing and such. It's used so on decel, when the driver is off the throttle coming into a turn or something, it keeps the turbo up so the boost response when he gets back on the throttle is almost instant. If the throttle is open then there is no need to bypass the air from the bov to the turbine.

DaveF

sounds crazy.


hook it up with that paint drawiing hahahahaa

Synapse

External combustion engine.

This is why you typically will see flame out the exhaust of rally cars under hard decel on corner entry. Be forwarned that this is pretty tough on the turbine.

80884

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dturbocivic &raquo;</TD></TR><TR><TD CLASS="quote">hook it up with that paint drawiing hahahahaa</TD></TR></TABLE>
You asked fot it, but you know what, why do just one!?

Bypass valve closed, throttle open, turbo having fun...


Bypass valve open, throttle closed, turbo still having fun...


Don't try to copy my design, the parts are definatly custom made...and yes i do work on the side if you need somethign done, lol

AbitAvenger

I thought the initial testing ppl did with this way back in the day yielded high rates of turbo failure? What has changed w/ turbo design to allow this to happen now?

Synapse

The rally guys that use this method typically use the turbo for only one race.

But, the advancement in materials, such as high nickel superalloy steels that could take the temp, and even more exotic materials like ceramic and Ti turbine wheels have made this possible.

_Endless_

i'm curious, is there any advantage/disadvantage of runing a MBC to the side port only of a wastegate compare to this setup http://www.tialsport.com/docum...l.pdf ? does one setup offer better spool time than the other?

igo4bmx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 80884 &raquo;</TD></TR><TR><TD CLASS="quote">
Don't try to copy my design, the parts are definatly custom made...and yes i do work on the side if you need somethign done, lol </TD></TR></TABLE>

I swear i just ssautochrome selling mspaint pictures that look just like yours on ebay.

DaveF

so is the fuel being added through an extra injector into that bypass port or is it going through the regular set of injectors. what about all the backpressure in the turbo ? or is this irrelevent because you are "off the throttle"??????

tony1

Fuel comes through the injectors. I don't think this will build alot of boost so much as keep the turbine speed up and air moving. When you open the throttle and close the bov, the turbine speed is up and boost will build almost instantly.