trying to decide if the 38mm is sufficient for the precision sc34 .63ar, compressor wheel 69. i will be running this at about 7-9 psi.

thanks,
albert

 

10-fo. Just make sure your mani. is flanged for a tial also.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TIal &raquo;</TD></TR><TR><TD CLASS="quote">Which wastegate do I need?


Selection of the correct size/model wastegate is dependent upon several variables.

Bolt in compatibility. The 38mm and 46mm gates are made to be direct bolt in replacements for existing wastegates as well as custom setups. The 38mm gate is dimensional equivalent to the Turbonetics delta gate with many features not found in the delta gate. The 46mm gate is a drop in for the 930 Porsche turbo cars.
Flow capacity. Contrary to popular belief, larger higher HP applications do not necessarily require the largest wastegate available. The lower the boost pressure you are gunning for the larger your wastegate needs to be. An engine/turbo combination that is set to 25+psi has a smaller wastegate flow requirement than the same application set to 7 psi. This is because the wastegate is used to lower the boost not raise it, the lower the boost pressure is set the more flow the wastegate must allow.
The spring. TiAL wastegates are not adjustable. To change the boost pressure at which the valve opens requires changing the spring within the wastegate. Springs range from .3 Bar to over 1 Bar are available. The most common way to select your spring size is to pick a pressure rating that is a couple tenths or a bar or a few psi lower than the boost pressure you intend to operate the turbo/engine combo at. This way a boost controller can be used to adjust the opening point of the wastegate and help you fine tune to the exact pressure that is desired. This also allows adjustments to compensate for changes in atm pressure, altitude and temperature, which will all effect the way your wastegate does it's job.
Mounting the wastegate. this is one of the most overlooked areas of boost control. In a perfect world you would select a mounting location for our wastegate that allows the gate equal access to all cylinders or rotors. This promotes equal exhaust port pressures between cylinders/rotors and avoids mysterious tuning problems resulting from uneven exhaust port back pressures. Another aspect to keep in mind is the high velocity of the exhaust gas inside the exhaust manifold, sometimes exceeding 800ft sec. Gas that is traveling at such high velocities will not easily make 90 degree turns of zero radius into the wastegate inlet. Remember Newton's second law, "bodies in motion tend to stay on motion". That particle of air is not particularly inclined to make a 90 degree turn and 800ft/sec. It must be persuaded to do so by giving it a gentle radius and easy access to the exhaust flow. Simply welding the gate to the side of a tube may work in some cases where the manifold back pressure is thru the roof, but in modern high efficiency turbochargers the pressure inside the manifold can be quite low and special through should go into wastegate runner geometry. The penalty for poor gate placement and poor gate runner design is having to use a larger gate.

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thanks, for the info from tials website, but i read that already. i would just like to know if it is sufficient enough. with all factors taken into consideration, would 38 mm be big enough in the worst situtation?

eh, im not even sure if im making sense in how i explain it. ever get that feeling where u make sense in ur head, but when u try to explain it, no one understands wut the **** ur saying? thats how i feel now. oh man im confused. i think i will just go with a 40mm just to be safe. thanks for ur help guys

 

(The lower the boost pressure you are gunning for the larger your wastegate needs to be. An engine/turbo combination that is set to 25+psi has a smaller wastegate flow requirement than the same application set to 7 psi. This is because the wastegate is used to lower the boost not raise it, the lower the boost pressure is set the more flow the wastegate must allow.)

So basicly what its saying is if you are running lower boost then a higher mm wastegate would be better?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Integspeed21 &raquo;</TD></TR><TR><TD CLASS="quote">(The lower the boost pressure you are gunning for the larger your wastegate needs to be. An engine/turbo combination that is set to 25+psi has a smaller wastegate flow requirement than the same application set to 7 psi. This is because the wastegate is used to lower the boost not raise it, the lower the boost pressure is set the more flow the wastegate must allow.)

So basicly what its saying is if you are running lower boost then a higher mm wastegate would be better?
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i already know this, that is y i am asking if 38mm is sufficient enough for the sc34 at 7-9psi of boost. i know there is going to be a lot of pressure due to low boost. but i wanted to know if the 38mm can release enough of the pressure so there isnt any boost creep.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ATF Kuk &raquo;</TD></TR><TR><TD CLASS="quote">

i already know this, that is y i am asking if 38mm is sufficient enough for the sc34 at 7-9psi of boost. i know there is going to be a lot of pressure due to low boost. but i wanted to know if the 38mm can release enough of the pressure so there isnt any boost creep.</TD></TR></TABLE>

I would say no then.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ptran13 &raquo;</TD></TR><TR><TD CLASS="quote">

I would say no then.</TD></TR></TABLE>

that maybe a bit premature...

what manifold is going to be used in the setup?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by twkdCD595 &raquo;</TD></TR><TR><TD CLASS="quote">

that maybe a bit premature...

what manifold is going to be used in the setup?</TD></TR></TABLE>

My fault, I did jump to conclusions, if it's anything less than a tubular equal length with optimal wastegate placement, then I'm going to say no. The wastegate isn't going to be evacuate the exhaust gas effectively.

 

its no thing, I just curious what manifold its on... some of the higher end mani's should be ok cause their ideal wastegate placement... for most anything else I do agree with you.

 

It will work fine for your setup in DIRECT answer to your question. It's been done tons of times.