EGT too high, too much smoke & bark

R

Reddog1

New member
Joined
Sep 27, 2010
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17
EGT’s climb quick , a lot of smoke on initial acceleration, spools very quick. (about 27 to 28 PSI), quickly let off pedal (10 pounds boost or more) and turbo will bark.

I have had the mods listed below for three to eight years, with the turbo being the latest. I have modified and adjusted the AFC several times. I usually haul a 4200 pound slide-in truck camper, truck is 6200 pounds. MPG empty is typically 17 to 17.5, with camper 12 to 12.5. I am very happy with the power, probably more than I really need.

PDR HX35/40 w/12 cm exh.
boost Elbow
#10 plate (stock position)
370 injectors
Timing 16*
3KGV
60-lb valve springs
Marine Head Gasket (0.020)
4" muffler & back, (3” turbo through 3-inch US Gear Ex. Brake to 3” resonator)
BHAF
Auto (DTT)
1996, 2500HD, 2WD ‘96
US Gear aux. tran. (underdrive - 4:10?)
3.54 gears
19.5 tires/wheels (32-inch diameter)


1 What can I change to lower EGT? Will injectors make a big difference?

2 Why would the PDR HX35/40 w/12 cm exh. bark so easly, and how can I reduce the barking other than the go pedal?

3 What can I change to lower smoke?

After hours of searching and reading past Posts (this Forum and others), I think I need to change the injectors and maybe the exhaust housing, but would be interested in other thoughts.


Wayne
 
get some correct 5x.012 145 degree spray angle injectors, that will help with smoke and extra heat.

you can tighten up your star wheel to control smoke when boost is coming on, and bacl the pre boost screw out for initial smoke

all turbos bark on an instant shut off of fuel, just let up easy, or dont try and load the turbo so hard at lower rpm's
 
i'd have to say that the hybrids turbo your running is NOT much of an upgrade at all.... going with a 14cm turbine housing would have helped a bit, but a better choice would have been one of the S300 variants...

X3 for getting a good set of injectors.... cheap isn't always the best, especially when it comes to the fuel and turbo side of things.
 
Unless you have had material taken off your head or block, the oversized gasket isn't helping either.
 
OrangeNV – I have been thinking the 5x.012 145 degree spray angle injectors would be the first positive change.

For clarification, when you say “tighten up your star wheel”, are you saying move the star wheel toward the radiator, or firewall?

I am aware of the pre boost screw. I think I pretty much have a grip on adjusting it.

The turbo barks with very little effort. I am not sure the PDR HX35/40 w/12 cm exh. was a good choice.


WUnderwood – I think dumping the 370s would be the best and first positive change for my application.


Kronic_187 – I think you are correct on the PDR HX35/40 w/12 cm exh. Not being an upgrade. I wonder if a 14cm turbine housing will help with my issues? Is there a S300 variant charger that will perform well with a stock down pipe?

Cheap was the best, at the time I got the 370s. I was running the truck without a load at the time, got them on sale for about $350 when comparable injectors were over $600 at the time. Add to that, a poor man has poor ways. I do not regret having went with the 370s at the time, but I do think my current needs would be better served with more efficient injectors.


TheBigNasty – After a gasket leak at the #1 cylinder, I had the valves done and 60# springs. It was necessary to machine the head by 0.010. I used a marine head gasket.


Please post, if you think of something else, or if I have given responses to promote more options or thoughts.


Wayne
 
You want to put more compression on the spring in the AFC, move the star wheel towards the fire wall. There are a bunch of threads on here about AFC tuning. If you have some time do a search and get to reading. They are very informative.
 
Thanks bna5017. I have read back about two years on this and a couple of other Forums an any post relating to the AFC modifications and adjustments. I have done the adjustments and modifications to the AFC in years past. It is amazing how much I forgot after several years. I removed my AFC this week, and re-adjusted and/or confirmed the various adjustments. I found nothing out of adjustment.

I have read so much, I am concerned that maybe I have mis-read something. This is why I ask about the star wheel adjustment. The primary purpose of the question was to confirm that I understood what I read and remembered.


Wayne
 
Reddog1 said:
TheBigNasty – After a gasket leak at the #1 cylinder, I had the valves done and 60# springs. It was necessary to machine the head by 0.010. I used a marine head gasket.


Please post, if you think of something else, or if I have given responses to promote more options or thoughts.


Wayne
Click to expand...

Machining the head does not require a thicker head gasket. You just gave up some compression.
The block, different story.
 
Yes it does. Machining the head drops the valves and injectors closer to the piston. You need a thicker headgasket to bring them back in to stock locations. And it wouldn't drop the compression. If anything it would raise it.
 
BgBlDodge said:
Yes it does. Machining the head drops the valves and injectors closer to the piston. You need a thicker headgasket to bring them back in to stock locations. And it wouldn't drop the compression. If anything it would raise it.
Click to expand...

It's a flat head. The valves don't get any closer, the are in the same place. Read-up grasshopper.

As for the injectors, you get thicker copper washers for those.

It's amazing that you have 11K+ posts, and you think that shaving a FLAT head would raise the compression. Adding the .010 extra to the head gasket DROPPED the compression by whatever marginal amount.
 
haha ya, back to topic, I would be much more worried about sprayin out the bowl than the compression ratio. especially with timing and 370's
 
If the head is shaved and the valves are not reworked, you will gain a marginal amount of compression. Think about it this way, if you grind on the head and unshroud the valves, you lose compression. In stock form, the valves have a minor amount of taper/unshrouding so milling a few thousandths off the head will marginally raise compression.

Also, running thinner injector washers will marginally raise compression as the injector nozzle will protrude into the cylinder bore just a few thousandths more.

And you're right, running a thicker gasket will lower compression, quite a bit more than milling the head and running thinner injector washers will raise it.

Just saying, technically speaking, BgBlDodge posted a true statement.
 
Ridemywideglide said:
It's a flat head. The valves don't get any closer, the are in the same place. Read-up grasshopper.

WAT?

As for the injectors, you get thicker copper washers for those.

please elaborate

It's amazing that you have 11K+ posts, and you think that shaving a FLAT head would raise the compression. Adding the .010 extra to the head gasket DROPPED the compression by whatever marginal amount.
Click to expand...

its amazing that you have 300+ post and talk like a profesional
 
I will have to say the drop in compression must be marginal. I went with the .010 gasket thinking that with higher timing it would be a bit better.

As for performance, I have noticed no decline at all. Still tows great. I am considering going back to some 145* injectors though. I am probably a bit out of the "bowl"?
 
Ridemywideglide said:
It's a flat head. The valves don't get any closer, the are in the same place. Read-up grasshopper.

As for the injectors, you get thicker copper washers for those.

It's amazing that you have 11K+ posts, and you think that shaving a FLAT head would raise the compression. Adding the .010 extra to the head gasket DROPPED the compression by whatever marginal amount.
Click to expand...

Explain that to me please. I'm dying to know your logic on that. I know the head is flat, but like big blue24 said, the valves are shrouded some by extra material on the head. You mill that extra material away and you now just dropped the valves and the entire plane of the head however much you milled off of it that much closer to the piston. Try milling .020 off a head and running a stock head gasket with stock valve lash specs. See how that works out for you.
 
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