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View Full Version : How much is too much boost?


DMAX Daddy
10-13-2003, 14:22
I put on a Banks Wastegate Actuator and the boost went up a lot. I followed their installation instructions to the T, even doing the adjustment 3 or 4 times just to make sure.

What is max boost?
mark45678
10-13-2003, 17:40
If I recall I think JK said that 32psi is about all the stock turbo likes? meaning to keep it in its range where more exhaust pressure will not make more power..... carefull hot air in higher egt out! you dont want a melt down or a head gasket leak!
DMAX Daddy
10-13-2003, 18:02
Im going to take 2 of the 9 adjustment turns out of it tomorrow and see what happens. Original installation took about 2 hours, from opening to closing hood this time should be 20 minutes! smile.gif
mtomac
10-13-2003, 18:13
don't go over 40psi
mackin
10-14-2003, 08:10
Originally posted by Micheal Tomac:
don't go over 40psi Forty HUH .....

You didn't hear about the guy at 32 PSI that spit chunks on the compressor side ?? Maybe it was a fluke keep us up to date Mike .... I'm thinking you'll know first before most of us .....

Mac ;) ;)
Kennedy
10-14-2003, 10:21
I've only ever seen 33ish at my post intercooler location. This will cross 40 psi pre IC quite easily in my experience. There have been theories as to overspeed peeling the tips off of the compressor wheel, and some say shaft breakage. Not sure, but it does leave the chicken or egg question...
DMAX Daddy
10-14-2003, 12:03
Well its getting dropped below 30 tonight if I dont have to work late.

I cant take a chance on grenading a turbo until a good aftermarket one hits the store shelves! smile.gif
CPMac632
10-15-2003, 06:43
Like I said before you won't break the turbo unless you plug off the wastegate. I don't think the wastegate adjustement does anything beneficial.
Oongawah
10-15-2003, 06:53
DMAX Daddy,

What boost pressure are you getting? Where did you tap in the intake? And do you notice any difference in seat of the pants performance? I'd ask more questions but it's still kinna early(hehe). -Chuck
DMAX Daddy
10-15-2003, 07:07
I took the boost signal off the cooler tube that runs from the top of the engine on the passenger side down towards the front, just a little to the left of this pic from JK's Duramax Tips section of his website.
http://www.kennedydiesel.com/images/Dmax-Boost-sensor-Location2.gif


Seat of the Pants Feel? A kick in the butt when it hits. I get boost A LOT faster on 55 to 70 MPH passes.
xwing
10-15-2003, 07:14
Question:
What good is more boost, IF there is NO black smoke?

If there is no black smoke, then all the fuel IS being burned efficiently, so adding more O2 is useless...even bad, since it makes the wastegate stay closed which makes more backpressure pre-turbo. The turbo ends up working harder for no benefit, and more backpressure preturbo is detrimental.

Seems to me increasing boost until no or little black smoke makes sense, then it's useless. On a gas car where more boost means more fuel put in by computer THAT makes sense, but on diesel where fuel amount IS the "throttle", once you burn all that fuel with air, any extra air is dumb...and sounds like it can overspeed/break the turbo anyway.

Has anybody with say a hot juice or whatever, kept stock wastegate (maybe 25-27psi max) and THEN back-to-back done 35-40psi or whatever to see if it actually helps quartermile mph or dyno hp??
DMAX Daddy
10-15-2003, 07:29
The wastegate, when I adjust it properly, WILL NOT ADD BOOST.

What its adds is how boost is applied. The factory wastegate starts bleeding boost off early, where the Banks Wastegate waits to the last minute to dump it.

Example, these numbers are made up but making an example.

Factory Wastegate opens completely at 24 psi, but starts opening at 18 psi.

Banks Wastegate opens completely at 24psi, but doesnt start opening to 22 psi.

This means that you have a little more pop when you floor it.

My problem is the settings supplied by Banks locked me in at about 36psi. I am going to adjust it in the factory setting range (24 to 26) once I get home early enough to have some light.

As I mentioned, on the 55 to 70 MPH passing move I have the boost in much quicker. This will stay true when I readjust it, it just wont be as much.
Oongawah
10-15-2003, 21:00
XWing,

These trucks have an air flow sensor just like a gasser. Just because you don't see smoke doesn't mean it's not getting more fuel. I've defeated the wastegate on mine, and have lowered my egt's 200 degrees, and have a very significant power increase at full boost(around 28psi @ 4500ft above sea level, and about 32psi @ sea level). I do have a lot of turbo lag now, but I'm toying around with it. Have fun, Chuck.
CPMac632
10-16-2003, 07:00
I have dyno'd my truck back to back with the wastegate turnbuckled shut and then open, the curves from 1100 up were identical other than the peak hp was down 3 with it buckled shut.
Kennedy
10-16-2003, 08:13
Originally posted by CPMac632:
I have dyno'd my truck back to back with the wastegate turnbuckled shut and then open, the curves from 1100 up were identical other than the peak hp was down 3 with it buckled shut. While my dyno curves were the Mustang "crayola" drawings w/o the ability to overlay, my results were quite similar when pinching the hose shut.

The Superflow software allows VERY easy, and detailed comparisons/overlays and I am anxious to get testing!!!
DMAX Daddy
10-16-2003, 08:20
Never ran on a dyno, is it slow acceleration to speed or WOT application?

I ask because I wouldnt think under steady acceleration any difference would be noted.

I think under full throttle wide open (say from stop to 65mph or a 55 to 75mph pass) acelerations it would make more of a difference.

Still learning, being in the generator business I run at one constant speed, just minor deviations on load hits. smile.gif