Turbo experts... where's the boost?

Black dawg

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If you have no leaks, more fuel will push the turbo harder and make more boost with the similar egt.

Every factory style kit (with the better downpipe and exhaust) I have been around has been able to run with a maxxed pump without egt troubles. Smoke is usually only if you jump on the throttle at lower rpms but clears up quickly.
 

Black dawg

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I have also found that advanced timing will cause more smoke and higher egt.
 

DrCharles

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ANY leak will effect your boost.
A turbo effects the boost, a leak will affect the boost :D

Yes, I am aware of that! My point is that the smaller the leak, the less effect it will have...

I would like to hear, from someone who actually had a small leak and fixed it, how much difference it made...

I too have read that excessive advance causes smoke and high EGT. Seems somewhat counter-intuitive since retarded timing would cause "afterburning" in the exhaust, so higher EGT? But then again, more heat in the exhaust spools the turbo quicker and brings in fresh air. My brain hurts :rolleyes:

As mentioned, my IP and injectors are old, and I don't know how old. Worn pumps cause the timing to not advance with increasing rpm as much as it should. No one around here (except maybe the John Deere dealer which my mechanic borrowed it from several years ago) has a timing adapter. Not even the International truck place, where they told me, "that engine's too old for us"!

So until I get a dial-back light, I'll just experiment with small changes in timing.
 

DrCharles

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Also - I don't have the original air intake ducting (which was restrictive at the front opening anyway). The 4" snout on the factory airbox is just open under the hood. I also plan to build a cold-air intake with a piece of dryer duct, which should also help lower the temps a tad.
 

jrollf

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Also - I don't have the original air intake ducting (which was restrictive at the front opening anyway). The 4" snout on the factory airbox is just open under the hood. I also plan to build a cold-air intake with a piece of dryer duct, which should also help lower the temps a tad.
My 93 was missing the cold air intake, sucking in hot air from the engine compartment.

Summers in the desert southwest, I noticed about a 100 degree drop in EGTs when I setup/replaced the missing cold air intake.
 

gnathv

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I had a small leak in my intercooler piping. I put 15lbs of shop air and used soap suds to find small bubbles at silicon connectors, it was small. It greatly improved response and added 4 lbs of boost. I’ll also beat the dead horse, when your moving down the road the under hood air temperature is the same as ambient outdoor temp. Put a probe under your hood and see for yourself. When stopped the under hood temp does rise.
 

DrCharles

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when your moving down the road the under hood air temperature is the same as ambient outdoor temp. Put a probe under your hood and see for yourself. When stopped the under hood temp does rise.
Thanks for the data. I also found a large intake-side leak (snail to intake gasket) by the blowby under pressure that sprayed onto the firewall padding! I'm sure that accounted for some of the improvement when I put the new CHRA in, but I'll never know how much, now...

I'm still looking for experiences with hot-side leaks if anyone cares to post them :)

If I had a temp probe (other than my IR "pistol" thermometer) I would certainly experiment.
I am not 100% convinced that all the compartment air assumes the ambient temp while in motion - especially where the airbox inlet is, directly over the exhaust manifold and beneath the hood padding...
Given Jrollf's post a few minutes before yours, it did make a 100F EGT difference to his rig :)

My truck feels more powerful and responsive with each incremental improvement. The turbo cartridge is the best $209 I've spent on it. But the next one is expensive (IP and injectors)...
 

gnathv

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Until you can get the money together for that step, find all your hot side and cold side leaks. Play with your timing (you can always set it back as long as you scribe where it was) after all of that turn your fuel up or down. It’s always amazing how these engines run when everything is in the sweet spot. Google cowl induction and read about some of those air intakes as well.
 

Big Bart

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Another interesting observation: the oil pressure (sending unit at turbo oil inlet) is higher! It used to drop off the bottom of the gauge at idle when hot, which is 4 psi or less with that sending unit. (I have a variable sender with the resistor in the cluster jumpered, not the "idiot light without the light that Ford so thoughtfully provided). Now the pressure is well up on the gauge even at a hot idle. That means more oil to the rods and mains :)

I also noted that with 10 psi boost available (and still no smoke at full boost and wide-open, so I may be able to turn it up another 1/2 - 1 flat), the Facet 40285 pump can no longer keep up with the demand (Fuel Filter warning comes on) during a long pull, flat on the floor :(

I am planning to reinstall a new mechanical lift pump, and leave the Facet in series, after the mechanical pump. You can suck through the lift pump with no resistance, I checked ;) I like having the Facet for easy priming and elimination of air after repairs, without cranking the batteries/starter to death. But it is marginal for stock boost/fuel and is overmatched with greater-than-stock boost.

If it still can't keep up with the mechanical pushing, out it comes!

Ditto on what TNBrett shared.

But a question of worn turbo, larger inlet/outlet on old turbo, or perhaps a leak.

Likely it is due to wear. But perhaps your Chinese replacement has smaller passages, tighter tolerances, or smaller bearings thus restricting flow and builds more pressure on the inlet side.

To both of your points, some increase in block psi likely since less oil can bleed off and out the oil pressure/turbo oiler port.
 

The_Josh_Bear

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Thanks. I actually did wire it shut and it made only a small difference, not enough to risk running that way with no protection at all. My spring feels very strong too. I could apply variable air pressure to the actuator and watch the gate arm for movement, but that doesn't tell me how effective each increment of opening is...

I do have an adapter box to measure timing - but I don't own a dial-back timing light ;) Could always calibrate the damper, I suppose. Or I might just experiment with a dime's width one way or the other from the current, allegedly correct, setting.

About the up-pipe joint - that pipe is at least 2" ID. Does a small (say 1/32") leak really affect boost that much? Even if it went all the way around, the total area of that gap would be a tiny fraction of the 3+ square inches of opening. :oops:
Sounds like the WG is not the culprit.

Dial timing lights are pretty cheap via harbor freight or garage sales...that's how I got 2 of them lol. Found an ancient Snap-on unit next door for $10 mostly to verify if my HF unit was working right.

As for the hot side leak, YES a 1/32" gap will bleed off more pressure than you think!

The reasoning is that it's air(compressible) and under pressure. So it will escape a relatively small gap much much faster than a liquid. Plus the hot side it pushing more PSI, up to double the cold side, and more pressure=faster and more drastic losses from a leak.

In my experience I lost 3 psi max with my up-pipe fitment not all that good and mine was tight enough that I could barely remove one half with the other side still bolted on.
I had a small leak in my intercooler piping. I put 15lbs of shop air and used soap suds to find small bubbles at silicon connectors, it was small. It greatly improved response and added 4 lbs of boost. I’ll also beat the dead horse, when your moving down the road the under hood air temperature is the same as ambient outdoor temp. Put a probe under your hood and see for yourself. When stopped the under hood temp does rise.
This is really interesting, I know everything got better when I got my intake hat seal leak-free.

I'd be very interested on the temp-probe under the hood. I have always heard the opposite and am currently sucking under-hood air with my BHAF.
 
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DrCharles

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That's a neat instrument display... is it wireless too?

The reasoning is that it's air(compressible) and under pressure. So it will escape a relatively small gap much much faster than a liquid. Plus the hot side it pushing more PSI, up to double the cold side, and more pressure=faster and more drastic losses from a leak.
No kidding, I know how an air leak works. My point was that the turbo passes most of the gas, a lot more than a 1/32" gap. What I'm interested in is the *percentage* losses.
The compressor makes boost approximately proportional to the square of the shaft speed. If the shaft speed is also proportional to the square of the turbine (exhaust) flow, the boost loss would be a fourth-power function of the leak. Which would multiply fast from even a small leak, as you note:
In my experience I lost 3 psi max with my up-pipe fitment not all that good and mine was tight enough that I could barely remove one half with the other side still bolted on.
Now that is actually useful data. Mine is not as tight as that. I've got the wye shoved up as far as I can before tightening it down, and with a coating of Ultra Copper RTV.

I will look for soot, and may need to try and seal it better (maybe a piece of shim stock would help make a tighter fit?)
 

sjwelds

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Just gonna add my experience. My truck is a 92 with the ats 093, F350 4x4 long box with flatbed, zf5.

I have adjusted the wg arm to where I can get ~ 12 psi wot empty. Stock IP turned up a ways. My timing is around 6 degrees.

Said all that to say I don't think your setup is too far off. I would probably dial your timing back and see what happens.
 

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