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Altering Boost pressure on a 4JB1T

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Altering Boost pressure on a 4JB1T

Postby BalkaRoo » Sun Jun 12, 2011 6:58 pm

My 88 jackaroo is going to the doctors some time in the next week to get the injection looked over and I am getting a turbo place to have a look at the turbocharger as well so I don't have any trouble on a trip we are doing up in the North West in July / August. I have heard you can increase the boost pressure on the 4JB1 and then open up the fuel on the injection pump a bit, but have no idea what you do to set it up and was wondering if anyone can tell me how it is done ?

Graham
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Re: Altering Boost pressure on a 4JB1T

Postby geeves » Mon Jun 13, 2011 3:29 pm

turbo place should be able to do it for you. You can adjust the wastegate till the turbo gets 14psi or so. Standard should be 10. Then adjust fuel till it smokes under load then back off till it stops.
These modifications will not improve reliability although they should not hurt either. Unless you are doing a lot of hills you wont see a benefit in real terms as the engine already has adequate power even if a 10% gain is possible.
Personally I wouldnt make these adjustments without fitting a 2.5 inch exhaust and after market air filter first. Even just doing these gives a noticeable gain
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Altering Boost pressure on a 4JB1T

Postby BalkaRoo » Mon Jun 13, 2011 9:00 pm

Thanks Alan, the previous owner put a 2.5" exhaust on it already so I don't think thats an issue, although I think it still has the standard air cleaner ! My only problem is keeping up with some lead footed mates with 7.3 ltr "Navstar" powerd Ford F 250 and F350s ! Personly I would like to travel at about 90 KPH but they want to go at 105 - 110 Ks and then I have trouble keeping up.
What do they do to increase the boost pressure ? I see the turbo has an actuator that opens the wast gate and the injection pump looks like it has a unit on it that supplys either vacume or pressure to open and close the gate, do they alter the pump or the actuator to increase the pressure ? I am afraid this is all new to me, I havn't had a Diesel with a turbo before the jackaroo but I like the vehicle a lot, but just need a few extra horses on hills.
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Re: Altering Boost pressure on a 4JB1T

Postby Captcol » Tue Jun 14, 2011 9:41 am

it is the pressure from the intake after the turbo that opens the actuator and then the wastegate. The pipe to the injection pump is for boost compensation, higher boost more fuel is sent. A adjustable boost tap that goes between the turbo/intercooler and the waste gate to make it open later, but you need to keep an eye on boost levels and egt's mainly on hills or under periods of high load
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Re: Altering Boost pressure on a 4JB1T

Postby BalkaRoo » Tue Jun 14, 2011 10:48 am

Thanks blokes, wish me luck, I will get a handle on it eventualy ! I am going to put it in next Monday.
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Re: Altering Boost pressure on a 4JB1T

Postby rightnut » Tue Jun 21, 2011 3:56 am

Yeah I did mine, turned up my fuel and played with my boost, ran like a beast. Didn't do my intake and exhaust so resulted in a great hole in piston 3 :-( just done overhaul and back to standard for a while
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Re: Altering Boost pressure on a 4JB1T

Postby 4x4SWANNY » Tue Jun 21, 2011 10:43 am

how many winds on the screw did you do....Must have got hot aye ... A hole in 3 not really parr...lol
Ya must have been gutted though..Touch wood have never had a 2.8 or 3.1 blow up ......in 5 years of thrashing them...
Although im pretty carefull. about oil changes....
Oh well, can some one hook up the winch i cant open my door !!!!!!!!!
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Re: Altering Boost pressure on a 4JB1T

Postby BalkaRoo » Tue Jul 05, 2011 10:39 am

Well, have the jackaroo back from the doctors!
The injection blokes recon the tips were bad so had exchange injectors put in and had the timing slightly adjusted, they recon it wasn't retarded much but they altered it to standard. The turbo bloke checked out the turbocharger and said its the best condition turbo he has seen on a 4JB1T for quite a while. A bit like Allan he advised against altering the boost pressure because what I wanted was a vehicle to travel fast all day not to give a quick squirt and then drop back to a more sedate speed for a while letting it cool down. He did explain how he would alter it but advised me not to do it so I will try it this time and see how it goes. It may prove adaqate anyway, after the work was done its a different vehicle ! It will rev out to 4000 RPM with ease, before I was battling to get it past 3400 and anything after 3200 seemed to be breathless. It must be performing better because I got "zapped" by a speed camera on the way home from Bunbury yesterday :cry: ! I don't know if I will get a nasty in the mail because my speedo said 110k and it was a 110k speed limmit so it may not be high enough to get a ticket, the thing was that it was just efortlessly cruising not having its neck rung so all in all looks like a major improvement.
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Re: Altering Boost pressure on a 4JB1T

Postby geeves » Tue Jul 05, 2011 2:48 pm

What tyres are you running. If its 31s add 8% to speedo if 32s add 10 ie 32 inch tyres and 110 is really 121
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Altering Boost pressure on a 4JB1T

Postby BalkaRoo » Wed Jul 06, 2011 1:12 am

31s !
So it looks like I could be getting a bill in the mail !
I didn't think the difference would be as much as that. Oh well :|
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Re: Altering Boost pressure on a 4JB1T

Postby rightnut » Fri Sep 23, 2011 5:37 am

Done over 5k's on the motor now. Does run 10psi boost without me increasing it. Would like a little more power up after 3000rpm. She goes flat after that. Any ideas, don't wanna hole in another piston again lol
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Re: Altering Boost pressure on a 4JB1T

Postby geeves » Fri Sep 23, 2011 7:13 pm

what size exhaust are you running?
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Altering Boost pressure on a 4JB1T

Postby raquiuno » Wed Nov 02, 2011 7:19 pm

Hi!
After reading all your notes i was inspired to do some adjustments on my 2.8 turbo engine, i installed a manual turbo boost controller and boost gauge. Before it was just doing 7 psi max, now 20 psi 3000 rpm. very happy with the result but will it damage my engine with such a big jump on boost?

Thanks!
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Re: Altering Boost pressure on a 4JB1T

Postby geeves » Thu Nov 03, 2011 5:34 am

20 sounds a little high. Mine only went to 17 with the wastegate disconnected. Your overboost valve might also be playing up. Or removed. Unless you are using max boost all the time (driving like an 18 year old) you wont do harm but I would still not run it above 15
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Altering Boost pressure on a 4JB1T

Postby raquiuno » Thu Nov 03, 2011 2:18 pm

Thanks Geeves! will adjust it as per your recommendation. Better be safe than sorry.
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Re: Altering Boost pressure on a 4JB1T

Postby raquiuno » Sat Nov 05, 2011 3:31 pm

Hi Geeves! my mistake only 15 not 20, i read the gauge wrongly so i must say ive adjusted the boost correctly.
Thanks again!
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Re: Altering Boost pressure on a 4JB1T

Postby rightnut » Tue Nov 08, 2011 6:28 pm

Well she still got the standard pipe in and there no proper exhaust places here! I'd prefer to do it myself but don't have the time or equipment! What do you say to just pulling out the silencer? No rules or regulations here on that hahahaha! But wanna make my snorkel now and put either the pajero intercooler on or my big iveco one on lol, oh and this weekend I entered a flat track race and came in first! So impressed with how it power slides and kicked a ford ranger :o) wife says I must tell the boys she was so proud of me and bought dinner for me and 2 mates! Wish she took pics or vids for me to post but sadly there was none ....
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Pump and injectors changed to suit
235/85 R16 pirelli scorpins muds
Boost guage and adjuster made by plan. Bbm pin 231978AB

Re: Altering Boost pressure on a 4JB1T

Postby al1970 » Thu Aug 28, 2014 12:17 pm

15 psi is about a good place to start I use a boost controller about $30 on ebay and set it to what you like and do not have to play with turbo at all
Works better with an aftercooler/Intercooler

Im running 15 psi boost, advanced timing, Intercooled 2.25 inch exhaust with straight through muffler, Snorkel, electric transfer pump

running 115-120 kW and 340 Nm of torque @ 1600 rpm has clocked 355,000 klms 255,000 with intercooler
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Re: Altering Boost pressure on a 4JB1T

Postby geeves » Thu Aug 28, 2014 4:24 pm

two basic types of boost controller The simple type is just a bleed valve in the sense pipe between the turbo and waste gate It just lowers the pressure in that line so the waste gate opens later. Second type does the same thing but is controlled electronically so you can set it while driving. This is great in a Subaru wrx lowered to the ground etc but on a turbo diesel you might as well set once and forget.
Sanding your knuckles before starting work can help. That way you cant skin them
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