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Post by geeves on Jun 19, 2005 14:01:48 GMT 11
I wondered about the acuracy as well but it is zero when off and shows a slight vacume at idle which is interesting as Ashes Terrano has about 2psi boost at idle. It certainly shows why this engine is so peaky
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Post by Graham on Jun 19, 2005 19:48:14 GMT 11
My gauge sits just above zero when engine is off or at idle. theoretically, a Diesel should never have vacuum, should it?
G.
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Post by geeves on Jun 20, 2005 14:33:55 GMT 11
By slight vacume I mean you can just see the needle move when switched off. essentialy this is zero vacume but not as zero as switched off
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andy
Isuzu Baby
Posts: 43
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Post by andy on Jun 22, 2005 15:16:42 GMT 11
i have a 1990 2.8 bighorn and it sits at around 1-2psi at idle and 0 when turned off. this was using the same autogauge boost gauge for $24 too!
my factory boost was 10.5 and now i'm running aprox 13psi also with my egr blocked off.
a hose came loose the other week and it boosted 14.8psi so this must be the max boost it'll run until the relief valve opens
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Post by geeves on Jun 22, 2005 16:23:59 GMT 11
Interesting. Maybe my turbo isnt as healthy as it seems It does have a very slight whine when cold
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Post by maletimaru on Jul 23, 2005 18:40:00 GMT 11
I have been told that the 2.8dt (4JB1-T) has weak conrods and not to move the boost at all but spend the money on an anti-lag system instead
Anyone else heard similar or have a theory on this (as it was recommended by a race development engine garage!!)
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Post by geeves on Jul 24, 2005 16:46:21 GMT 11
Considering it came from a race development garage maybe they are too weak for 7000 but thats never going to happen. The only failures Ive ever heard of on 4jb1 engines have been directly due to bearing failure due to poor maintanance by previous owners.
the earlier c223 engine definatly had an issue with thoughing rods but its a guess what milage this happens. A freind bought a 86 bighorn with the c223 engine that through a rod at 120000km but the previous NZ owner did only 6000k in 4 years which included comuting 30k each way to work 6 days a week for those 4 years and there were scratch marks on the speedo.
True milage was at least 200000
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Post by Jimmu on Jul 24, 2005 17:41:08 GMT 11
I fitted a boost gauge and an inline boost controller today.
Needle vibrates slightly at idle but stays at 0.
Stock boost was 10.5 PSI.
I set it to 12 with the controller.
Another point of interest was that it made full boost by 2100 rpm.
During testing I easily achieved 15+ PSI througout the rev range.
I reckon the turbo would push close to 20 if I let it.
Not that there is any point running more boost until more fuel is added.
That will come once the intercooler is fitted and I get it dyno tuned.
Jimmy.
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Post by draganlada on Jul 24, 2005 18:45:40 GMT 11
Hi guys
Can anyone post a picture where the boost gauge should be conected to
thanx
Dragan
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Post by wizbru on Jul 25, 2005 4:48:46 GMT 11
Hi guys
Just a quick question. I notice that you are all indicating the need to increase fuel after increasing boost which is fairly obvious. But isn't that what the boost compenstor thingy on top of the injector pump does??? Or will that only go so far and maxs out at standard max boost???
I'm probably not going to do much in the way of this sort of mod to my wizard but just curious.
Bruce
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Post by geeves on Jul 25, 2005 10:01:02 GMT 11
dragon there should be a rubber pipe connected somwhere between the turbo and manifold Most people just uese a tee piece on this. On mine it is on the side of the intercooler but yours might be differant
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Post by draganlada on Jul 25, 2005 22:07:48 GMT 11
Yes,Alan, there are two rubber vacuum pipes.One is operating butterfly inside air intake "thing" betveen turbo and manifold,but I don't know what is the point of having the butterfly coz it is open all the time and I never seen it closed up.Probabily it must be the other one (pipe) you've been tallking about .
Dragan
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Post by maletimaru on Jul 26, 2005 7:37:56 GMT 11
If anyone is in the know - should you fit blow off valve (quiet one not boy racer loud pshhhhht ones!!) to a diesel turbo engine?
I can get a turbo timer (similar to a blitz one), a racepro blow off valve and an autogauge boost gauge for $170 NZ - is that any good?
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Post by Graham on Jul 26, 2005 9:28:52 GMT 11
Hey there. By all accounts, you don't want a blow off valve. As there's no butterfly and the throttle never closes, the BOV would never actuate. Get the other stuff if you want though. I use my turbo timer when I'm getting milk at the servo (can remove keys and lock doors) but be careful if you have a manual as you'd be relying on the handbrake alone. A boost gauge is a good idea to give you some feedback as to what the engine is doing and comes in handy if you want to modify things down the track. If it's a package deal only, get it and resell the BOV!  $170NZ sounds good to me - my boost gauge alone was over $60... don't forget you'll have to install the turbo timer. That might be a few extra $$$ or a pain in the ####. Cheers! Graham. |
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Post by geeves on Jul 26, 2005 9:55:12 GMT 11
On mine the wireing was all there maybe it had one already. Repco are selling a cheap boost gauge for $30 Turbo timers start around $30 up to 200 There is actualy a blow off valve of sorts already on these engines It mounts on the inlet manifold and blows back though the breather pipe. Aparantly its set around 14.5 psi which is why a lot of people have problems getting higher boost. Its realy only to prevent over boost not any of the nastys that affect petrol turbos not diesel
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Post by maletimaru on Jul 26, 2005 21:28:04 GMT 11
Was told today by 2 diesel mechanics that factory boost on the 91 4jb1t was set at around 8 to 8.5 psi!!! and that the he4ads are VERY prone to going on them,if you wind the boost past 10psi - although he said by all means do it he will love the money i spend in future having to rebuild motor!!! lol
I was going to ask if anyone knows a way of getting ridof the lag time of the turbo?
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Post by James W on Jul 27, 2005 10:53:52 GMT 11
"Was told today by 2 diesel mechanics that factory boost on the 91 4jb1t was set at around 8 to 8.5 psi!!! and that the he4ads are VERY prone to going on them,if you wind the boost past 10psi"
Mine runs at 12.5 to 13 psi, always has in 100,000km I've had and abused it. Currently over 300,000 km on the one head |
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Post by geeves on Jul 27, 2005 13:12:44 GMT 11
Mine too runs 13.5 and regularly hits 4200 Also ran out of water when a heater hose developed a small (2 inch) ladder still no head probs. The 4jg2 definatly has head issues but Ive never heard of head probs on 4jb1 engines unless theve been severly mistreated. The local wrecker can sell every 4gj2 head he can get but never bothers with the 4jb1 heads if the engines tired. Still nowhere near as bad as toyota 2lt engines
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richie
Isuzu Junior
Posts: 112
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Post by richie on Jul 27, 2005 14:08:47 GMT 11
anyone here would know where in Sydney I can get my 2.8 MU dyno tuned?
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Post by Jimmu on Jul 27, 2005 18:42:59 GMT 11
maletimaru,
What sort of lag are you experiencing?
Jimmy
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$170NZ sounds good to me - my boost gauge alone was over $60...