how to adj. turbo pressure??

[zzman]

Can anyone tell me how or even can the turbo pressure be adjusted on my stock truck?
If so, what is the limit or a good setting? Do not have gages yet.

thanks, Ron

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97 3500 dually, ext. cab p/u,5sp,2wd,3:54,245/75R16,
straight pipe,105k mi.
Ron

 

[Missouri Mule]

zzman,
I'll try and give you some general info and let the pros give you the detailed info.
Turbo boost pressure is determined by how large or small the tunnel this determines pressure. Also how much exhaust is spinning turbine wheel.
How ever you can adjust or add on a few things to get more boost when you need it. There is a star wheel on top of AFC,turning this I believe toward the pump will increase low rpm boost(it actually allows the turbo to spool up quicker) and give you quicker take off(don't turn it to much or you will get a large cloud of black smoke at take off).
The wastegate can be adjusted to allow for higher boost usually at higher RPM/speed. The wastegate opens a exhaust by-pass door so engine won't have to much boost(I believe to much boost will mess the engine up really bad). But by having wastegate the engine can use a turbo that gives it more boost at low RPM/speed. In the manual the adjustment looks pretty tricky but I'm sure there are several Bombers that will gladly give you instructions.
If you wish you can check the arcives, I know there is a bunch of post on these two adjustments and things that can be added or you can wait until one of the pros come along.
Other things to help turbo reach maximum boost potential is less air intake restriction, larger exhaust housing, less resticted exhaust system or different size turbo and of course getting more fuel to your cylinders.


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Bill Thomas
Missouri Mule - 96 Wht 4X4 ST CC,5 spd, 3. 54, 8 ft bed, 1 ft high cheater boards.
99 Freightliner bl/wht FL60 ISB-5. 9 24v,215 hp,520 tq,6 spd, 3. 59 nsr,16 ft box, 19. 5 tires,Wt/gvw 11,000/23000

 

[Kunze]

Gauges come first, that's the smart way anyway. As far as turning up the boost, well when you add more fuel you get more boost as the engine compensates for more fuel. I have my stock plate forward and I'm pulling almost 30 psi which is about where the wastegate opens up. Hope this helps. Keep the bugs of the glass and the Cops off your A$$ #ad


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'94, 2500, 4X4, SLT, 3. 54 gears, Prime Loc, Silencer ring in the tool box, DeeZee bright tread running boards, side box boards and mud flaps. Alpine CD player. I cleared 100K mi while the board was down. Jardine Performance 4" exhaust (sounds just like a Pete, it's great) Schied Diesel put timing to *15 (by timing light), put gauges in on the A pillar (trans temp, boost, and egt) They also set my stock plate up (40 hp 150 ft/lb gain) OH, what a difference a day makes

 

[Turbo]

Most of the guys around here turn up there boost by restricting air flow to the waste gate you can do that by restricting the hose going from your afc to turbo, BUT you would notice no improvement gains by doing this . You can add all the air you want to but unless you add fuel to go with it, it would produce no more power.

 

[zzman]

I have adjusted the star wheel quite a bit, really loose on the spring. It does produce some smoke when you first stomp on it, ok with me. Also it helped the lower end a little.
My thought here is to let my right foot become the govener, but I will need more boost or all that it will give me. I am trying to stay with the stock turbo, but am not sure if any more boost can be got from it. Not sure why a wastegate is needed either.
This experiment may cost me, but I am a hard headed fool at times too. It is about to dry up around here and then I can start this mess. I was trying to get all the tips I could before I start digging in it.
My days off come too far and few between. I like working on it myself, but this is a new critter to me. I gotta analyze everything it seems.
I appreciate your response guys, thanks Mule,Kunze and Turbo.

Now if I knew how much a stock turbo will produce. I thought I read where someone said they disconnected the wastegate from working. Can't find that now, but can you do this? If so why don't folks do this when they open the fuel up? Is this a bad thing for the turbo?
I'm just full of brain picking questions. Thanks guys, Ron




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97 3500 dually, ext. cab p/u,5sp,2wd,3:54,245/75R16,
straight pipe,105k mi.
Ron

 

[John Dimartino]

I think the wastegate is opened by boost pressure,so if you want to increase the boost you need to not restrict it,but put a tiny hole somewhere in line with the wastegate actuator,this will bleed off some of the boost pressure going to the actuatur,which will delay its opening and give a higher boost level before opening. Adjusting this calibrated leak,as i like to call it,is not as easy as it sounds,getting just the right size hole is difficult,but it can be done with trail and error. The best way to do this is with brass fittings,at the elbow on the turbo,buy some or get them from TST. The only time i would do this is if you move your stock plate full forward. It its stock,more boost wont help power,only increase cyl pressure and maybe knock 50 degrees off the egt if your lucky.

 

[JDinNY]

Boost is directly related to fuel, and of coarse your waste gate. The more fuel the engine gets, the more exhaust it produces, which will generate more boost pressure, if the waste gate will let it. The tst fuel plate comes with a little brass waste gate elbow to "fool" the waste gate.

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'95 xt cab,slt,4. 10,auto,285 BFG all terrain ko's on Centerline Extreme Billit Comet 3's,K&N,tst 230/605, silencer ring in top of toolbox, boost and pyro in full pillar mt. 167,650 mi and climbing... went to feed the cat and it was GONE !!!!!

 

[Turbo]

I made a mistake in my previous post it isnt the hose going from the AFC to the wastegate. It is the hose that goes from the intake to the wastegate it is telling the wastegate how much pressure you have. I would not punch a hole in this hose. That is not the correct way to increase pressure. As for what is your stock pressure I believe it is around 18-20psi. But I am not certain on that. What I am certain of is that if you add more air without doing something else it isnt going to do nothing. You will notice no power gains, the ones around here that are talking about running 30+ psi are not doing this to a stock truck they have put a plate or done something to the pump to alter the amount of fuel at a given RPM. More fuel + More Air = more power. Make gauges your first priority then get Something from TST to up your power you can buy a kit from them to up the power quite a bit and up pressure to around 30psi. You said in your post that you wanted to let your right foot become the governer, but remember the turbo is not governing your engine and really has nothing to do with it, it doesnt matter if you cranked 50psi in your engine it is still governed by the governer at a certain speed with a certain amount of fuel which can only be changed by what is mentioned above.

 

[zzman]

Thanks fellas, I plan to turn the fuel up, I realize the fuel drives the turbo. I just weren't sure how well the turbo will do with pumping more pressure. Is this stock turbo performing at its peak or can it take some more?
Hopefully I'll get a chance to start on the truck this weekend.
Thanks for the help, Ron


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97 3500 dually, ext. cab p/u,5sp,2wd,3:54,245/75R16,
straight pipe,105k mi.
Ron

 

[Turbo]

This turbo can produce more pressure than it is currently and it is the wastegate holding it back not the fuel.

 

[Missouri Mule]

zzman,
Wastegate = using a turbo(housing) with higher boost capability at lower RPM.
But because it has the capability to make more boost(compressed air) they add a wastegate one so you won't melt your pistons
down because to high of EGTs, two probably for emissions.
You can adjust the wastgate to allow for more boost at hight rpms.
Turbos without wastegates are usually mid range or high range boost only.
Boost gauge and EGT gauge a must if you start to play with boost.
By unresticting air intake you allow more air to be compressed more compresssed air meens more oxygen to burn fuel with(the fuel isn't going to burn with out it). It also depending how much you un-restrict it will help drop EGTs. Of course unrestricting exhaust at same time also helps a lot.
I think you can turn AFC star wheel until it takes off fast(with out a cloud of black smoke with out flooring it.