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Discussion Starter · #1 · (Edited)
I recently completed a 6cyl conversion in my 79 Jeep J20 truck. Motor was out of a 92 Dodge 2wd. I put an NV4500 behind the motor. The truck drives good down the road engine seems to run fine, however it will only boost around 11 psi maybe 13 if i whined it out in 3rd or 4th gear. It appears as if my pump has not been tweaked at all. It will not put out any black smoke while driving. Just sitting there idling if I snap the throttle it will put out a small black puff. Saturday i turned the smoke screw about 2.5 turns the truck felt a little bit peppier but still not boosting any higher and no increase of smoke. I have checked for air leaks but havent found any yet, short of pulling the intercooler out.

just driving the truck around the power seems ok, but i put my TJ behind it on my trailer and it felt like a dog in 4th and 5th gear.

Any ideas? I will be changing the fuel filter out one day this week.

thanks joe
 

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There are a couple of things to look for:

Intake restriction
Boost loss(hole or loose clamp compressor side)
Lack of fuel

You may have a problem, or you may just have a lazy engine.....

My engine was a dog untill I made some pump mods, and it is now quite strong. I increased preboost fuel which made responce 150% better....little smokey now, but with the 19cm no gate turbine housing it is needed. I also did the governor spring mod and moved fuel plate full forward. After all of this it is a different engine. I realize you have a VE pump, but with some screw work you can do the same thing.

I would also be curious what turbine housing you had. I think some of those came with the 21cm no gate housing which is going to be really lazy in a light truck with stock fuel levels. Mine is a 19 and is a little lazy, but in a 7Klb truck it loads hard enough to spool pretty fast.
 

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The 92 engine would, in fact, have come from the factory with a 21cm exhaust housing. Changing to a 16, in conjunction with a slight increase in fuel and some tweaks in the AFC, will give that truck an entirely different personality. I would also strongly suggest verifying lift pump pressure and IP timing, as well as setting the valves. If any of those three are incorrect, nothing you do is going to make it run better.
 

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Discussion Starter · #4 ·
i've checked all my connections not evident signs of air leaks. Watching the boost guage it seems to spool up ok just not any thing higher than 11-13

how do i tell which turbo housing i have? is this the exhaust housing or the intake side housing?

I am running the late 90's air intake horn which is bigger than the factory 92.

thanks for your help.
 

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Is your turbo wastegated? If it is you could try pinching the line that goes to it. If it is this you would probably be better off getting a boost elbow that adjusts the pressure at which the WG operates at, this is just a little brass elbow with a allen headed grub screw. just a thought.

Gaza
 

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Discussion Starter · #6 ·
Is your turbo wastegated? If it is you could try pinching the line that goes to it. If it is this you would probably be better off getting a boost elbow that adjusts the pressure at which the WG operates at, this is just a little brass elbow with a allen headed grub screw. just a thought.

Gaza
there is not a WG
 

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i've checked all my connections not evident signs of air leaks. Watching the boost guage it seems to spool up ok just not any thing higher than 11-13

how do i tell which turbo housing i have? is this the exhaust housing or the intake side housing?

I am running the late 90's air intake horn which is bigger than the factory 92.

thanks for your help.
get the numbers off of the exhaust housing and you can look it up.
 

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It could be a problem with your afc diaphram, mine had cracks in it which caused the afc to be inoperative. I would also check lift pump pressure as flyin71h mentioned. To me your description sounds like your not getting fuel for some reason! Keep checking!
 

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What range is your exhaust gas temperature running while driving and towing?
 

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The 1st gen dodge trucks had a 21 housing non wastgate.They will only make up to 15 psi of boost with stock turbo and no pump mods. After a few turns of screw than you will get close to 20 psi of boost.

1.Those 1st gen in stock form are lazy to begain with ,what those have said Gov spring ,timing ,turn a few screws and that stock air box needs to be opened up to get more air .
2.The next thing to do is change the turbo housing to a 14 to 16 will make a big difference .


* note *
Please use a EGT gauge before you start doing any pump mods.

Scott

Scott
 

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The 1st gen dodge trucks had a 21 housing non wastgate.
Just to clarify, the 89 - 91 non intercooled Dodges had an 18cm housing. With the addition of intercooling in 91.5 came the 21cm housing, which was used thru the 92 model year. In 93, they went back to the 18 because of the poor performance and declining sales numbers. The 89 - 91 and 93 models ran noticeably better their 91.5 - 92 counterparts.
 

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Discussion Starter · #12 ·
in completely stock form, would this thing black smoke at all while driving.

What is the recommended line size for the lift pump?
 

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in completely stock form, would this thing black smoke at all while driving.

What is the recommended line size for the lift pump?
In stock form you might see a bit when taking off fast or lugging it (manual trans) ,so do and some don't .


Tank to pump 3/8 to 1/2 line is best.

Scott
 

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Discussion Starter · #14 ·
In stock form you might see a bit when taking off fast or lugging it (manual trans) ,so do and some don't .


Tank to pump 3/8 to 1/2 line is best.

Scott
on TNDONOR did ya'll change out his factor J-truck lines are reuse the factory stuff?

I am currently reusing the factory jeep tank and lines.
 

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We ran new lines so they would be no what ifs. I am using a new Jeep tank. You can just clean ours out and it will work fine
 

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Discussion Starter · #16 ·
We ran new lines so they would be no what ifs. I am using a new Jeep tank. You can just clean ours out and it will work fine
what size lines? rubber or metal? and did you do anything to the sending unit pickup tube and return tube?

I cleaned all my factory lines and take. everything was in really good shape.
 

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X2 on the boost and that era turbo. It is just like us with our stock esrky 90's 4BTs, 13psi is completely normal. X2 on what everyone else said. Make sure your lift pump is 100%, injection timing if you have the money is 100% correct. Then do the exhaust housing swap (less than $200 and night and day). Then appropriate fuel increases as necessary/preferred. Be forwarned it can be addictive (the power, etc). But the turbo housing alone with slightly turned up pump will be night and day... WE have a lot of 16cm2 housings as most of the Chevy-type 4BTs guys ran 16cm2 with their original turbos (that behaves like the 21cm2 on your 6BT) -- low boost, so a good mod to swap out the turbo possibly entirely for something cheap and used...
 
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