Boost pressure adjustment

[Dooda]

Hi
I have just fitted an intercooler to my Isuzu 2.8 td engine (1989 ish MK 1) and have noticed a marked drop in performance. I am told that the reason for this is that the boost pressure is now too low and that it will need adjusting to compensate for the intercooler. The turbo that is fitted does not have the adustable wastegate actuator rod that many turbos do so can anyone advise on how to adjust the boost and is it a DIY job? Removing the intercooler has brought the power back up.

[ISUZUROVER]

Where is the sensor located that is connected to the wastegate actuator?

If it is before the intercooler, you are getting a pressure drop across the intercooler which isn't being accounted for. Simply move the sensor/pipe to after the intercooler (preferably as close to the engine inlet as possible). Then you will get the right pressure going into the engine.

[Dooda]

Cheers Ben I take it by the sensor you mean the vacuum pipe? It runs from the turbo at present. I will give it a go thanks.

[ISUZUROVER]

Cheers Ben I take it by the sensor you mean the vacuum pipe? It runs from the turbo at present. I will give it a go thanks.

Yes, but it is actually a pressure pipe, not a vacuum pipe. Usually they are located in the cheapest location, just after the turbo outlet. The best place to move it to is somewhere near the inlet manifold.

Doing this should give you equivalent (or slightly better) boost than you had before. If you still want more, you can see if you can swap the wastegate actuator for an adjustable one.

Something else to consider - you sure all the connections were 100% airtight?

[HotFourOk]

Yeh spot on Ben, my wastegate actuator line goes from a T peice in the inlet manifold pretty much as close to the engine as possible.

Dooda, you could tap into the manifold to give good results, or even into the intake pipe just before it, might save some hassle, unless your handy with some tools.

If more boost is needed, a bleeder valve (Boost Controller) can be put in this line and allows pressure to escape so that the wastegate will actuate at a higher psi.

[Dooda]

Thanks Guys I am going to give this a go. It now seems that the second hand intercooler that I bought may be blocked with dirt so I am going to flush it out and see what happens.

[jeep97tj]

Just out of intrest what sort of pressure drop are we talking about, must be a bit if u can notice it?

[HotFourOk]

I cleaned my cooler last weekend.. put petrol in it..swished it around... drain it... Repeated this about 4 or 5 times.
Then i put metho in it and did the same... the metho then dries out and leaves no residue

So much muck and black junk came out of it

Do you have a boost gauge?? Maybe worthwhile if you fiddle around with boost

[Dooda]

I flushed out the intercooler with degreaser yesterday and you should have seen all the crap that came out of it! Re-fitted it to the Rangy and the mid range torque has really improved. I am going to try and relocate the wastegate pipe to the plennum chamber next. On the pump fitted to the landrover tdi engines an adjustment can be made to the smoke screw located in the cap on top of the pump. The Isuzu pump doesnt have this screw so I was wondering if anyone knew how to achieve the same tweaks. Does this adjustment lower the boost compensator into the cylinder and allow more travel on the fuel pin and can the same results be achieved by skimming off the nylon spacer to allow the compensator more travel?

[Bush65]

I flushed out the intercooler with degreaser yesterday and you should have seen all the crap that came out of it! Re-fitted it to the Rangy and the mid range torque has really improved. I am going to try and relocate the wastegate pipe to the plennum chamber next. On the pump fitted to the landrover tdi engines an adjustment can be made to the smoke screw located in the cap on top of the pump. The Isuzu pump doesnt have this screw so I was wondering if anyone knew how to achieve the same tweaks. Does this adjustment lower the boost compensator into the cylinder and allow more travel on the fuel pin and can the same results be achieved by skimming off the nylon spacer to allow the compensator more travel?

The smoke adjustment screw adjusts the amount of fuel at no/low boost.

If your pump doesn't have have a smoke adjustment screw, don't be concerned. Go to the next stage, which is to rotate the diaphram and reduce the spring force under the diaphram by adjusting the star wheel.

When you have the taper pin out to adjust the star wheel, look at the rub marks on the taper section to see if it has been travelling the full stroke . If it is, there is no point in changing the thickness of the "nylon spacer", which limits the down travel.

[Dooda]

John

The pin marks indicate that there is still a gap of about 4mm between the top of the wear mark and the shoulder of the taper pin. I've already adjusted the diaphragm and star wheel. Is it worth touching the spacer? I dont want to overdo things.

[red90]

I dont want to overdo things.

Do you have an EGT gauge? You should be checking all adjustments against max EGT at full power.

[tony cordell]

See http://forums.lr4x4.com/index.php?showforum=15 for lots of info on EGT gauges
and Thermocouple differences.

[dumbdunce]

http://cgi.ebay.com.au/Turbotech-manual ... dZViewItem


I have used thse controllers in about half a dozen turbo installations to date, they are cheap and give better boost control than a bleed valve. the downside is that they can not be plumbed back to the inlet like most bleed valves but that's only a problem if you make regular, deep water/mud crossings.

far easier than messing with the wastegate actuator or moving the signal port.

black gunk inside an intercooler is worrying; there should be noting in there but clean, compressed air.

[Dooda]

Valid points here guys, thanks for the input. I have only made some reletively minor adjustments at present and my intention is to maintain reliability of the engine before anything else. To date I have:

Installed an intercooler off a Range Rover 300 tdi as this fitted straight into my vehicle.

Turned the starwheel 180 degrees clockwise.

Turned the diaphragm 90 degrees clockwise to its optimum setting.

I am not after great high speed but pulling out of junctions can be a bit of a drama at times and so I would like to focus on bottom and mid-range power and more importantly, torque improvements.

I dont know much about turbos, boost and EGT except that you can quickly blow your motor if you get it wrong, hence the quest for advice. The suggestion to move the pressure pipe to the inlet manifold to maintain boost rather than increase it seems sensible and reletively risk free but the comments about EGT concerns me enough to wait until I find out more on the subject.

Has anything I have done up to now put the motor at greater risk than it was before. I do not get smoke once warmed up but at start I now get a bit of white smoke. Is this a concern? Very light dark haze when under full power. How does the Turbotech work please, it looks very simple in its design? How do you fit an EGT device and is it needed all the time or only for when setting up. Can I tee a boost guage into the system somewhere and what do they do? Bit of a newbie on this subject I know so any answers in Janet and John language please. Thanks Joe.

[dumbdunce]

How does the Turbotech work please, it looks very simple in its design?

it uses a spring loaded ball bearing as a valve to regulate when and how much boost the wastegate actuator "sees" - at low boost the ball remains closed so the actuator remains closed, that oost is built quickly (wastegate creep more or less elimiinated). as boost reaches the preset of the load spring (set by the screw) the ball opens, and the wastegate actuator sees boost, so operates the wastegate. I have found these little "homebrew" devices to be far more accurate at controlling boost - have built a few of my own but for convenience usually buy them.

How do you fit an EGT device and is it needed all the time or only for when setting up.

you need to drill and tap into the exhaust housing directly behind the turbine - the thread will be dependent on your choice of thermocouple. EGT gauges are a valuable tuning aid but it is also very good to have one permanently fitted - then you can set up your pump to slightly overfuel for maximum torque/power in short burst, and you can regulate the power with your foot as the exhaust temp gets towards your upper comfort limit.

Can I tee a boost guage into the system somewhere and what do they do?

yes, tee it into the wastegate actuator line (between the signal port and any boost controller) - all it tells you is the air pressure (above ambient) in your inlet. a useful tuning device but less useful once your initial setup is done. handy if you pop a hose off your wastegate actuator - it will suddenly start reading very high or low so you'll know something has popped off.


cheers

[Dooda]

See http://forums.lr4x4.com/index.php?showforum=15 for lots of info on EGT gauges
and Thermocouple differences.

I have had a look at the Lr4x4 site and it hs some good info. Can anyone recommend an aftermarket complete kit and supplier that will suit the Isuzu? I prefer a recommendation for a kit that has been tried and tested and is simple to install and reliable. Understandably there was quite a difference of opinion on the subject in terms of specification etc on the Lr4x4 site so an opinion based on experience would be appreciated.

I was under the impression that fitting an intercooler actually reduced the EGT, have I misunderstood that?

Cheers

[Bush65]

An intercooler can reduce EGT, but that is not their primary purpose.

When air is compessed it's temperature increase. An intercooler, cools the air before it enters the inlet manifold. As the intercooler reduces the temp of the air, it becomes denser, allowing more air to be stuffed into the cylinder, allowing more fuel to be burnt (if the injector pump is adjusted to suit).

White smoke is unburnt fuel. This is not unusual with a cold engine.

Black smoke from a warmed up engine in incompletely burnt fuel (some may be burnt in the exhaust system), which results when there is not enough air to burn the fuel injected. All modern diesel engines are turbo charged to increase the amount of air to the engine and cut down particulate emission (black smoke).

Excessive black smoke can be associated with high EGT. It is your best indicator if you don't have a pyrometer fitted.

Blue smoke indicates engine oil bypassing rings or valve stems.

The compressor housing is the best place to sense boost pressure for the waste gate or boost controller. I would look into an alternative way to adjust the waste gate, before moving the sense port to the inlet manifold.

Edit to correct stupid error in last paragraph.

[vn15]

The turbine housing is the best place to sense boost pressure for the waste gate or boost controller. I would look into an alternative way to adjust the waste gate, before moving the sense port to the inlet manifold.[/quote]

I am sure you mean compressor housing, turbine is exhaust side.

No probs to mount the actuator hose on the inlet manifold.

Not much work at all, drill a hole in the inlet manifold, mount a tee.

Then you get the actual boost the engine is getting, allways some pressure loss in the cooler.

[Dooda]

If you relocate the actuator hose, is there an optimum position for it to be placed for instance, reletive to the flow of air to obtain maximum benefits? Is the best all round 'package' to relocate the actuator and fit a Turbotech along with a boost guage? I also understand that some benefit can be had by removing a flap located in the exhaust manifold, anyone any experience of this? Many thanks for all the responses, some excellent info.

[HotFourOk]

Well if you situate it in the inlet manifold it will give you the actual boost the engine is recieving after pressure is lost through the intercooler, pipes, etc
All actuator lines that I have seen are at 90 degrees to the flow of air through the inlet manifold.. I think this gives good results.. and there is not many other ways of doing it i dont think

One of them turbotech things would give you good control of boost pressure.. and you can adjust it until you are back to your stock boost pressure in the inlet manifold before you put the intercooler on. Or more boost if you want the powahh!

I would get a boost gauge though mate.. its a definate.. then maybe an EGT.. although I dont have one I think they are very very important to monitor engine temps and combustion properties.

[Dooda]

Sounds good, I will give it a go and post the results. Thanks everyone for the input.

[Bush65]

The turbine housing is the best place to sense boost pressure for the waste gate or boost controller. I would look into an alternative way to adjust the waste gate, before moving the sense port to the inlet manifold.

I am sure you mean compressor housing...

Thanks, I did mean compressor housing.

[Dooda]

Well, I've ordered a Turbotech and boost gauge off Ebay so I will fit them and see what happens. Does the Turbotech come with setting up instructions? I understand that the Isuzu has a stock operating pressure of between 14 and 16 psi. Is this correct and is this what I should aim for? One more thing. If I fit the Turbotech then do I still need to relocate the actuator pipe to the inlet manifold or do I just plumb it in to the existing setup?

[HotFourOk]

14-16psi seems quite high.. My Rocky runs 11psi and I thought that was a fair bit for stock.

My bro-in-law has the same motor as you and I dont hear the turbo spooling up like mine does.. and I thought he ran less boost than me I dunno mate...

Tell us how the turbotech goes too!