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Post by Bruce on Aug 18, 2004 17:08:58 GMT 11
Can anyone tell me in simple terms how to adjust the boost? I was shown yesterday by a diesel mech friend, but as usual I did not take enough notice, he pointed to some thing on the front of the enjector pump. Going on the dyno tommorrow in Gladstone and want to know what goes on.
How is everyone dyno tune now going? all had a bit of time to see if economy has changed etc.
Cheers Bruce
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Post by mudgrip4 on Aug 18, 2004 20:42:23 GMT 11
Very pleased with performance of my 4JB1T after the tuning and dyno adjustment. VERY strong vehicle now with thumping 328NM torque. Can drive up v steep hills in 5th gear. Will accelerate up v steep hill in 4th from as low as 1500-1800rpm. Estimated horsepower 154 - 163hp according to dyno man. Fuel consumption better then I thought after 3-4 weeks of testing. Average about 50-51kms per gallon, or 31mpg - this in optimum 50-80k zones. Well worth it. Have not touched turbo though Bruce -advised against this. Mike.
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Post by Graham on Aug 18, 2004 23:07:21 GMT 11
As Mike said, it might not be a good idea to increase boost pressure. Or at least not too much  Std is roughly 12psi and I'm told that if running an intercooler, 14psi would be OK, but not heard of anything higher than this ever being 'recommended'. I would think that there are two simple ways to increase boost, and neither involve playing with an injector pump. 1) increase the spring tension on the wastegate. 2) bleed boost pressure off the boost hose going to the waste gate. I can't say I've looked closely at my turbo but this is 'standard procedure' for general turbo cars, I'm sure it's the same with the Isuzu diesels. Have a look at www.autospeed.com.auor use this Autospeed search link <click> and there's a bunch of articles on a "DIY Boost Valve". This will bleed off a certain amount of boost, tricking the wastegate into thinking that the turbo is producing less boost than it really is. I guess with something like this on a turbo diesel, you'll have to make sure that the fuel pump provides enough fuel for the boost level, and that it is told the correct boost level and not the 'fake' one, otherwise the engine may run too lean and overheat or just not run optimally. Make sure you do any playing like this with a boost gauge so that you can see what's happening with boost levels and not leave it all as guess work. Cheers! Graham. |
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wayne
Isuzu Baby
Love mods
Posts: 47
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Post by wayne on Aug 19, 2004 6:27:08 GMT 11
Running lean is only a problem with petrol engines.
Diesel engines like the 4JB1t don't use a buterfly valve thus they suck lots of air, at idle, and run very lean.
W.
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Post by James W on Aug 19, 2004 9:17:52 GMT 11
The turbo boost control is a simple feedback loop formed by the wastgate and the control diaphram.
The diaphram has a spring which opens the waste gate and the turbo boost air presure operates on the diaphram to close the waste gate. These forces balance out to regulate or limit the boost pressure.
Have a look on the turbo and you can see the diaphram with a short (a few inches) hose to the turbo outlet.
The adjustment on the injector pump you talk about must be fuel adjustment not boost adjustment.
See Grahams post above for how to alter this feedback loop and alter boost pressure.
The inlet on a diesel is always wide open as Wayne mentions, so rather than lean as such with incresed boost it may be just short of fuel for the increased mass of air with increased boost.
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Post by Harry on Aug 19, 2004 18:02:23 GMT 11
Would the boost pressure be the same at the turbo outlet as the inlet manifold?
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Post by geeves on Aug 19, 2004 18:06:52 GMT 11
In an ideal world yesBut you have 3 foot of pipe several right angle bends and maybe an intercooler in the way so you might loose a puond or 2
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Post by Harry on Aug 19, 2004 21:29:31 GMT 11
So moving the wastegate controller hose from the turbo outlet to the inlet manifold should produce a little more boost?
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Post by James W on Aug 20, 2004 6:57:22 GMT 11
Yes, shifting it may produce more boost. But lengthing the sense hose will probably produce delays in the feedback circuit. This may produce undershoot and overshoot of the the regulated boost pressure, or even oscillation.
It may however work fine, but delays in any feedback circuit are never good.
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Post by Bruce on Aug 20, 2004 7:32:52 GMT 11
Took the MU to a dyno guy yesterday and the only thing to adjust on the 3.1 is the screw on the back of the injector pump, (it has a cover over it ) this also increases the boost as well. This information he got from Brisbane Dyno Tunning, we are waiting on them to send him the read outs required to change the settings, to make sure we don't do any damange (temperatures and boost at certain revs etc) I would like to have a play with it myself but I better keep my greasy little hands off it and have the pros do it.
Cheers Bruce.
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Post by francesco on Aug 26, 2004 10:08:15 GMT 11
Brisbane Dyno Tuning is where I got my Dyno Done
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Post by Bruce on Aug 26, 2004 11:54:47 GMT 11
Hi Francesco, Its a bit far to travel to Brisse so am trying to get it done in Gladstone, still waiting for this guy to get back to me.
Anyway your MU is a 3.1, did you get the read out for it ? and if so what was the difference? and were you told what temperature, from there pyrometer it got up to at full boost. I think when I had mine checked, did not do any adjustments, was around 575 (c or F not sure).
Cheers Bruce
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Post by francesco on Aug 26, 2004 18:33:14 GMT 11
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Post by Bruce on Aug 26, 2004 19:12:16 GMT 11
Thanks mate, I'll have to look a bit though, the 2.8 is a direct injection motor and the 3.1 is in-direct injection so there would be some differences.
This guy Iam talking to said today that he needs to know what the temps are a intervals of 500rpm's. I may have to wait till I go to Brisse. We are off north in a couple of weeeks, see if we can find any wet weather.
Thanks again, Bruce.
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Post by dani4JB1T on Nov 24, 2004 3:47:32 GMT 11
Hello All...
I want to install a boost gauge ¿?....I think it`ll be a VDO clasical boost gauge....What about yours ¿?¿?...any opinions or recommendations ¿?¿?<br><br>thanksss
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RoeDao
Isuzu Junior
If you notice this notice, you will notice that this notice is not worth noticing
Posts: 52
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Post by RoeDao on Dec 9, 2004 19:27:37 GMT 11
I run about 11 psi of boost on my 4BJ1T 2.8...... i'm told factory boost is only about 8psi (low pressure turbo) I have totally blocked my wastegate and it never goes over 11 pounds of boost. The only way to increase boost is to increase the am ount of exhaust gasses....... that why they adjust your fuel mixture. A guy in Toowoomba told me he had his re-tuned to allow for the exhaust (2 1/2" like mine) and K&N filter...... he said the difference is massive!! i am yet to get mine done. The 4BJ1T runs fairly lean...... so i think i can afford a little more fuel  Mine rarely blows any black smoke...... but i will need to check the EGT as well. |
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Post by Graham on Dec 9, 2004 20:06:21 GMT 11
I put a boost gauge on my 3.1 MU and I just hunted for the cheapest one I could find. I ended up getting it from ebay for about $60 and I think it's an AVO brand from Japan. (there's an AVO in Melbourne but I don't think its related)
It does the job, I've found that my MU runs 0.9 bar, or 12psi. I've been intending to upgrade the exhaust for a long time now but just haven't done it.
RoeDao, may I ask how much did your exhaust cost and where did you get it done?
Cheers,
Graham.
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RoeDao
Isuzu Junior
If you notice this notice, you will notice that this notice is not worth noticing
Posts: 52
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Post by RoeDao on Dec 10, 2004 17:07:42 GMT 11
I put a boost gauge on my 3.1 MU and I just hunted for the cheapest one I could find. I ended up getting it from ebay for about $60 and I think it's an AVO brand from Japan. (there's an AVO in Melbourne but I don't think its related) It does the job, I've found that my MU runs 0.9 bar, or 12psi. I've been intending to upgrade the exhaust for a long time now but just haven't done it. RoeDao, may I ask how much did your exhaust cost and where did you get it done? Cheers, Graham. i payed $300 for mine...... i got it done at Carline in Muswellbrook. as for boost...... i'm also told that a minor adjustment will produce 13 to 14 psi...... but i'd have to get an intercooler |
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Post by fenlon on Feb 16, 2005 14:36:45 GMT 11
I was thinking of blocking my wastegate on my 3.1 like roedao said he did with his 2.8. Could this cause any internal damage. I'm looking to make up for the lost boost from the extra tube length I needed to install my intercooler. Thanks Jim
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RoeDao
Isuzu Junior
If you notice this notice, you will notice that this notice is not worth noticing
Posts: 52
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Post by RoeDao on Mar 13, 2005 16:43:47 GMT 11
i'm told it only becomes an issue at higher boost (16-16psi) I keep an eye on the I/C temp....... and i'm about to fit a regulator to adjust my boost so i don't over cook it on highway trips. I'm running about 16psi in cool weather, 15 in warmer weather.
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Mine rarely blows any black smoke...... but i will need to check the EGT as well.