4BT Boost pressure
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    Default 4BT Boost pressure

    Does anyone know what the boost pressure should be at wide open throttle when reving the engine on an air-charged intercooled 4bt? Most specs I see show more than 10 pounds of pressure. I am just curious because I believe I might have a turbo that is failing since all im getting at the discharge side of turbo is 3-5 pounds of boost. Is that normal? Thankls for any help.

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    Is that free reving or with a load what turbo
    1989 ford ranger 4bt... standby for further details

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    I have a stock 4bt with the H1C turbo I can see up to 15psi loaded with 3/4 throttle.
    1987 GMC step van Utilimaster body with a 4bt, 4spd and Ranger III splitter OD. 100k miles
    KDP killed 10k lbs loaded

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    Just revving a turbo'd motor won't produce much boost. You must "work" the motor, accelerate hard, or full throttle uphill, in order to see maximum boost.
    On my 6bta I will see about 35psi. My 4 isn't on the road yet.
    If yours is wastegated, that will set the boost level. W/g diaphrams can fail, causing boost problems.
    In memory of JimmieD,
    "Please, READ STICKIES at top of forum sections!"

    '81 Dodge Ram 2wd shortbed, 4BTA, nicknamed "Old'sCool." 164hp/488tq!
    '96 Ram 2500 4X4 Cummins. "slightly modded"

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    my hx30 on my 4bt is doing 20 psi.... i did put an adjustible boost elbow inline on the wastgate boost line though and also turned up the fuel on the pump... But like others have said you wont see much boost unless your under a load and on the fuel hard.
    1989 K5 blazer... ppump 4bt swap, nv4500, np241. swap in proggress.....

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    This is just reving the engine at full throttle sitting still, so that makes since that it would not produce much boost, just thought it would produce more than what i saw. The turbo that is on the engine is a holset WH1C, which I am not familar with. I guess working on other turbo diesels they seem to whine more than what mine does in noise by just reving the engine, mine seems really quiet, but like you all said it may be just beacuse its sitting still. It is wastegated, so I am just trying to see if I have something wrong there before I put my fenders back on (it would be eaiser now to work on it now).I am still building the truck and have not yet dren it yet. Is the appropiate test to drive it, load it on a hill and see what it then produces before I think I have a problem with the turbo? Thanks for all the help.

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    Default boost

    The way i tell if a turbo is good before i run it i dissasemble it to insepect it. Look for chipped turbine fins, excesive bearing play(thrust and axial) and finally the turbo seals themselves.... if all that is good your good to go. if you want to see if your turbo is fine without dissasembling it i would take a good light to see in the compressor opening and wiggle the turbine shaft, see if you can touch the comp. housing anywhere with it. up and down movment should be minimal and no in and out play..... if your turbine spins free by hand and you canot touch the comp. housing by physicly tring to make it touch you should be fine.
    1989 K5 blazer... ppump 4bt swap, nv4500, np241. swap in proggress.....

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    Search worked.. I'm not on the road yet and have maybe 1 psi on boost with no load.. I'll have to hook up some drive lines first.
    One thing I might ad is that it is important to not just take apart a turbo- many are balanced as an assembly and need to be indexed and marked- each part of the assembly according to holset instructions I found on-line..

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    Be sure and read up on the importance of a Pyrometer to protect your diesel engine from damage and/or destruction caused by high EGT's.
    Please, READ STICKIES at top of forum sections!

    1967 Dodge Town Wagon now D-200+ - CPL 858 - HTT Stage II/H1C 16cm2 Ex/58mm Comp wheel, no W/G, turned fuel pin, twisted screws, 3,200 spring, milled head, '92-'93 CTD intercooler [THANKS BILL!!!] Dodge NV4500, 4.10 DANA 60HD rear, '72 Dodge D-200 front axle, 1 ton+ springs, Air-Lift front airbags, front/rear swaybars, Tom Wood's driveshaft, Hercules All Trac A/T in LT 245/75-16.

  11. The Following User Says Thank You to JimmieD For This Useful Post:

    Elbonk (12-22-2013)

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    Gotcha.. its on my very long list.. which should be getting shorter but for some reason I keep finding things to put on it..

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    Quote Originally Posted by Elbonk View Post
    Gotcha.. its on my very long list.. which should be getting shorter but for some reason I keep finding things to put on it..
    Yeah, now ain't that a funny thing? Did my build about 7 years ago, still fiddling with it and 'just one more thing'...

    I think you'll be okay on the boost, mine doesn't show squat just sitting there, even if I nail it hard, but on the road it's right up there and can hit about 23-25 lbs boost. You should be okay if the gauge even moves when parked.
    Please, READ STICKIES at top of forum sections!

    1967 Dodge Town Wagon now D-200+ - CPL 858 - HTT Stage II/H1C 16cm2 Ex/58mm Comp wheel, no W/G, turned fuel pin, twisted screws, 3,200 spring, milled head, '92-'93 CTD intercooler [THANKS BILL!!!] Dodge NV4500, 4.10 DANA 60HD rear, '72 Dodge D-200 front axle, 1 ton+ springs, Air-Lift front airbags, front/rear swaybars, Tom Wood's driveshaft, Hercules All Trac A/T in LT 245/75-16.

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    I turned my "stock" rebuilt pump up 1/4 turn and achieved 3-4 psi boost at the top of 3rd, 4th and didn't get to 5th on the test strip. After another 1/4 turn I achieved 7-8 psi, I also put on a Larger H1C (not shown), It has the same exhaust housing as my "baby". I received my pyrometer and will try to get that installed. You will see in this video that I made a little adapter (behind the oil line) to accomodate a big or small compressor housing but I didn't continue the dual chamber division on the adapter. I was curious if you folks think it would be worth it to maintain the pulse sequence. I need to pull the adapter anyways to put in the pyro which I was also planning on putting in right before the turbo in the adapter vs. the exhaust manifold.. Good idea?
    The manifold has a lot more provision for flow and timing on the pulses vs. a stock 6bt, it is the rear dump type but flipped. Once again, your input is much appreciated. I am looking more for fuel economy and moderate performance but even as it is I am impressed at how torquey it is. My main problem is the early GM NV4500 that I put behind it definitely favors a wide band of rpm but I am OK with that as the 1st gear low is nice and slow.

    http://youtu.be/XujGBTTjxh4

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    I'll do a build thread one of these days but I have been fiddling with the turbo and adapter. I 15 psi if I throttled up just right in the right gear so I pulled my adapter and put in a divider to maintain the divided manifold and turbo and I noticed much better throttle response, quicker spool up and regularly get 10 to 15 psi. I think I pulled 18 psi in 5th gear with 33's and 4.10 gears. I still need to put my Pyro on but have been trying to get my caster correct so I don't crash while testing.. My temporary gauge is in bars, my psi gauge I picked up only goes to 15 psi.. the bar one goes higher!
    Thanks Jimmie D for posting on my comments.. You'll be missed.

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