Exsessive exhaust pressure February 14, 2009 01:03PM
I have a JD big block super farm and have a lot of pressure on the exhaust side of turbo.
I tried another turbo but had the same results . I have been told its cam timing.If so
which way and how much? Or any ideas would help. Thanks.
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Re: Exsessive exhaust pressure February 14, 2009 01:31PM
you need to open it up.
what is your temp?
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Re: Exsessive exhaust pressure February 14, 2009 02:01PM
How much pressure do you call alot of pressure in the exhaust? MACK
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Re: Exsessive exhaust pressure February 14, 2009 03:48PM
I dont know what the temp is. Head has been ported and polished and dont have any flow numbers in
front of me. And as far as pressure it runs 110 to120 lbs and 35 to 40 lbs of boost .
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Re: Exsessive exhaust pressure February 15, 2009 02:49AM
I'd say that you want to retard the cam (open the exhaust valve later). Possibly need a different cam with less exhaust duration.
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Re: Exsessive exhaust pressure February 15, 2009 01:16PM
No one can answer that question without knowing what turbo you have, and what you are measuring the pressure with. I suspect you have mechanical gauges with a check valve or a tell-tale pointer. You need a computer to get a reading at the same instance to know how much out of balance you are. Don't replace anything until you talk to someone and give them all the information. You will be wasting money to make changes blindly. Call Brent at GMS at 513-756-9900. Arlyn
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Re: Exsessive exhaust pressure February 16, 2009 05:36AM
True.

Also, where your pressure ports are relative to airflow direction can affect pressure readings. If airflow is pointed into the gauge port you can get an artifically high reading, especiually at an elbow. Ports should be perpendicular to airflow direction.
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Re: Exsessive exhaust pressure February 16, 2009 01:43PM
Yes we have tattle tale gauges on it .The way its hooked up I dont think is a problem .We put a GT42
box turbo on to finish up the season .It gave us a little more boost but didnt do much for the exhaust
pressure .We have talked about opening up the exhaust housing to see if that would help. I put a call
in to Brent at GMS but got the machine .I know there are a lot of variables that makes this work,and
that its something thats being over looked. Thank you for your input and any other thoughts you may have.
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Re: Exsessive exhaust pressure February 17, 2009 12:05PM
this may seen silly but did you make sure your gauge isn't faulty,try another gauge or at least check the calibration against a known good gauge, good luck!
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Re: Exsessive exhaust pressure February 17, 2009 03:57PM
from what I've heard the GT42's are restrictive on the exhaust side! try a bigger exhaust housing: at least 2 sizes
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