6.2 compound turbos

[Black dawg]

advanced timing will give
more black smoke everywhere
less boost
slower boost


slower timing will give
less black smoke
more boost
quicker boost


The one hotrod 6.2 I had would peg my 15 psi gauge with a stock banks kit.

I would make a mark on the pump and start playing with the timing. you will know when it is too retarded because it will miss and run crappy when you first start it.

Does the cold advance work?

 

[otisd85]

i dont know what the cold advance is, is that the cold idle sensor towcat mentioned in post #10? if it is then no i havnt replaced that sensor yet.

on the passenger side of my ip there is a plastic deal with 2 what looks to be vacuum ports that had nothing running to them when i bought the truck and i put rubber caps on the ports but i dont know what thats for either

 

[Black dawg]

that deal is for th400. the cold advance would be the small (green?) wire to the top of the injection pump. try un hooking it when you first start it in the morning you will hear if it works or not.

 

[towcat]

um??? what do you mean when you say "dead"? it has no side to side play that i can feel, very little in/out play, the turbo spins freely with your finger, and there are no scuff marks inside the housing or on the blades.

what is it that makes you think something is wrong with my truck? it starts good with a little white smoke out the exhaust when its cold, it holds good oil pressure about 30-35psi at warm idle and 45psi when driving, it has a little blow by when i remove the oil fill cap but not much and i have seen a lot worse.

when i rev the engine in netural it makes very black smoke but at the tail of the black smoke there is a small **** of white. i dont know what that means. if it means anything.

from your original comments, it is an indicator of a bad turbo. now that you've checked it out, you have an indicator of overfueling. i can't begin to tell you of the number of MBZ turbos that I have found locked up dead over the years. generally the symptoms are like you described.

 

[otisd85]

that deal is for th400. the cold advance would be the small (green?) wire to the top of the injection pump. try un hooking it when you first start it in the morning you will hear if it works or not.

what should i hear if it works or if it doesnt work? i dont think i heard anything change. am i listening for a click like a solenoid makes when turning on and off, is the engine supposed to idle up or down like the choke on a gas burner, or is it supposed to die when the wire is unhooked?

there is 5 wires going to my pump. i am color blind so im not going to try and say what colors they are. two of them are going to the deal with the vacuum ports and do nothing when unhooked. one goes to the top rear of the pump and has a jumper going to a round black plastic deal tilted at a forward angle on the drivers side of the pump with a long screw sticking out, with no effect if they are unhooked. there is also a heavier gauge wire that when unhooked kills the engine and it will not start until its reconnected.

i am guessing that the cold idle advance is the plastic deal with the long screw and the screw is for adjusting the idle when cold. is that correct? if it is then i would have to say, no it does not work. where do i start to try and fix it?

 

[turbonator]

The sending unit on back passenger side of head, is a thermal switch to control both the cold advance and the high idle. The two wires to the vacuum control is for an automatic transmission (THM 400), an indication of either the motor, tranny or injection pump were changed in the past.

On your IP, there is the large "pink" wire to control the shut-off solenoid. The two green wires (smaller) go to the back passenger side of the IP for the cold advance and the other goes to the front drivers side to the high idle solenoid. These are important when starting until the motor reaches operating temp (130'F IIRC), then the thermal switch (back of passenger head) opens.

The smoke that you are describing is over fueling, more boost would give more air to burn this cleaner. Not every turbo with "no-play" is still good, as the exhaust turbine will wear from the hot air and carbon from exhaust gasses. This actually burns the blades off the turbine wheel. This in turn causes more lag and less boost from a given turbo.

A couple things you can also try, is to replace the Banks intake hat,for something smaller with better direct flow. The Banks air-box is also restrictive. If these are modded or changed, you should get another 3-5 psi boost.

 

[otisd85]

the tranny has been replaced, i replaced it with a nv4500. i have removed the vac control and wires running to it.

the cold idle was not working so i wired it to a toggle switch, so i can tell if its working with the flip of a switch, and i can use high idle when doing things like jump starting another vehicle.

it has the banks air box and intake hat. im thinking of replacing my banks turbo with a wh1c off a 96 5.9 cummins out of a ford bus. im just not sure about the amount of boost it will make. i know you can buy or build adjustable boost elbows for the waste gated turbo, i dont know how low you can turn the boost down? most people do that to make more boost, not less.

 

[towcat]

the tranny has been replaced, i replaced it with a nv4500. i have removed the vac control and wires running to it.

the cold idle was not working so i wired it to a toggle switch, so i can tell if its working with the flip of a switch, and i can use high idle when doing things like jump starting another vehicle.

it has the banks air box and intake hat. im thinking of replacing my banks turbo with a wh1c off a 96 5.9 cummins out of a ford bus. im just not sure about the amount of boost it will make. i know you can buy or build adjustable boost elbows for the waste gated turbo, i dont know how low you can turn the boost down? most people do that to make more boost, not less.

before you go through the grief of putting on the WH1C turbo, try ditching the Banks intake box. I did that on my '85 burb and it woke up the turbo. If you do go with the WH1C, you might want to regulate it downstream on the intake box. I'd be careful though, it might be a lazy spooler. With my WG banks in the earlier post, I'm hitting 10psi at 1200rpm. the one in the below pic is 5-8psi at 1500rpm.

 

[otisd85]

i will have to try and loose that intake box, and see what it does for me.

10psi would be great, but i was hoping to use the wh1c just because i already have it, maby not if its going to be too laggy. 5-8 psi at 1500 would be a big improvement to what im getting now.

with my 5 speed i rarely use 1st, 2nd raps out so fast its time to shift before the boost climbs, if i run it up to 3200 rpm ill see about 8 psi in third, in 4th it gets to 7 psi when i shift about 2800 rpm, and then i can hold 4 psi in 5th if im still trying to accelerate. all that is at WOT, cruseing in 5th i make no boost unless im running about 70 mph at 2100 rpm then i see 1 or 2 psi. if im coming to a hill in 5th at 70 mph and hold it to the floor i can get to about 4 psi at the bottom of the hill, but it looses rpm and boost, and the egts raise to the point i have to down shift.

i can make plenty of black smoke on demand, and my egts would climb out of the safe range if i let them, so that tells me i am getting plenty of fuel and not enough air. thats why i was leaning to a bigger turbo, and i already have the holset so i figured id try it.

typing it all out, and seeing it on the screen is a bit depressing, and makes me realize how gutless my truck really is

 

[otisd85]

the plastic line running from my intake hat to the boost gauge, i can see oil in it. will this affect my boost readings, give me inaccurate reading, or is this not something to worry about at all?

 

[Black dawg]

with a maxed 6.2 pump you should not have smoke or egt problems. do you know what pump number you have?

 

[towcat]

with a maxed 6.2 pump you should not have smoke or egt problems. do you know what pump number you have?

imho he's got problems with enough air going in.

 

[Black dawg]

I always get rid of the stock airbox and wrap the crossover and downpipe. I have had several of these, and any timing over 5 degrees will make the turbo lazy and less total boost.

 

[otisd85]

with a maxed 6.2 pump you should not have smoke or egt problems. do you know what pump number you have?

no i do not how do i find out?

imho he's got problems with enough air going in.

this is why you suggested removing the air box? that is next on the list, when i get a chance to play with it.

I always get rid of the stock airbox and wrap the crossover and downpipe. I have had several of these, and any timing over 5 degrees will make the turbo lazy and less total boost.

wraping the crossover will help get more heat to the turbo, increasing drive pressure, and making more boost, correct?

what will wraping the dp do besides cool the under hood temps?

maybe i dont quite understand timing. correct me if i am wrong, the injectors pop before tdc on the comp stroke? advancing makes them pop closer to tdc, retarding they pop sooner, with the piston farther down before it reaches tdc?

i dont think i will mess with timing, from what i have come to understand making the injectors pop sooner will raise cylinder pressure putting more stress on the hg and increasing the chance of a blown gasket. does that sound correct?

 

[Black dawg]

wrapping the down pipe is also supposed to help with velocity.

there is a silver tag on the side of the pump with a bunch of numbers.

advancing pops the injector sooner before tdc(piston traveling towards tdc)
retarding pops the injector later before tdc (piston closer to tdc)

How does it start cold, any rough running or white smoke?
if you are playing with the throttle in neutral, when you floor it quickly, what does the rattle sound like compared to holding the throttle steady.

the rattle should stay pretty much the same when you floor it quickly. If it really growls, you have too much timing.