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Modified 6.5 Build

6.2 turbo

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Heads are on, ARP studs torqued to 130 ft lbs with moly lube. Used high temp silicone on the block threads.
 

6.2 turbo

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Had it runing on the stand. Engine seems good,but inj pump leaks at the advance plug. Have the injectors set at 3500 psi. Ip is not putting out as much fuel as it should either. I think the advance is not working, prob because of the leak.
 

Jaryd

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I’m asking because I don’t know and I want to understand.

What does the high pop pressure do for it.

Does the IP have to be built differently to be able to handle the injectors popping so high.
 

Will L.

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Pop pressure of the injectors is it’s own world of experimentation. You need to spend probably 100 hours reading to get an ok grasp on it.

The basic thing is - lower pop pressure allows more fuel at each event. But higher pop pressure creates better misting of the fuel. Finding the perfect mix of the two is the key.
More fuel gives more power, but if not misted perfectly, then more goes unburned and that is smoke. So better misted burns higher percentage and can give more power with less fuel.
See how quickly they both seem “best”?

Other contributors are:
harder starts with high pressure.
Faster wear of ip high pressure.
Delayed time of high pressure.
IP built for higher pressure.

Many pump builders get “rated” or people decide on person X over Y because their pump can push say 10cc more in volume. But they build the pump to push more volume at a lower pressure. Remember its like the two are on a teeter totter. Volume up= pressure down.
So the builder of the pump has to know what pressure you want. Almost every builder out there now I have heard of only wants to deal with lower pop pressures. The guy that used to be the premier builder in my area knew how to keep the pressure up high and increase the volume so it could do both. It kinda is unfair to say X can build a pump to do 110cc3 without including what the resistance pressure is.

The fuel system on these engines can be tinkered with as much or more than the engine itself for dialing in what exactly you want.
 

Will L.

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Dude, you are just dragging me into this build innan addictive way. Every 3rd post from you feels like a plot twist cliff hanger somehow! Ok, so..

Heads are on, ARP studs torqued to 130 ft lbs with moly lube. Used high temp silicone on the block threads.
Not arguing here- seriously wondering and trying to learn what you have done before-
90 is normal from ARP doing the load cell testing on the block and heads. The studs strength maxes out at 135 iirc. Bending the metal being held down or ripping the studs out is the danger of torquing too high. Are you just now going to 130, or have you been using 130 and maybe that is part of how the heads have been warping on you?

Next: HI I AM A GREEN ENGINE!! That color is perfect for this build - very much non stock! Love it.

Wow that turbo sits high! (And is green too!:happy:). That’s gonna clear a hood? Before I saw the bracket I thought it was hanging off something overhead where you painted it.

Did you make the turbo flange or have a link where you bought it please? That looks like one I am in need of.

Great price on the ip goodies, but yeah that just seems way too small. I want a built 33 but think at least a 31. 29?? I had an amazing pump builder before he died. My pump knowledge is greatly lacking, but enough fuel to push that high of pressure injectors? Mind you I am a fan of high pop pressures, at least I was back when diesel was real diesel. But high pops mean the pump needs to be up high, and to have high volume AND high pressure is difficult- but then out of a 29? Again not gonna argue, just feels like another plot twist to how are you Gonna make this happen. It feels like you have done all these puzzle pieces before and it’s old hat to ya.

Oh yeah small precups too? As in triple squares?

I am with you on the turbo, compression ratio. 400 hp- what torque?p Then pop pressure- what injectors & nozzles? What torque?
Anything I missed inside the green block? Balanced, blueprinted? Chain or gears? Rocker arms?

You know, i was about to fall asleep and said, I’ll Just see if anybody posted anything then rack put. Had to go back and reread the thread, then type this book response because you have my interest peaked. THANKS! Haha

Cant wait to hear how This turns out.
 

6.2 turbo

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The turbo is a bit high,but the truck has a 2 inch cowl hood. I have torqued head studs at 130 or 135 ft lbs before. At 150 ft lbs the deck starts pulling up around each stud. We used a new timing chain ,that was probably made in the 90's ,and it fit very tight. The nozzles are china 311's which I couldn't be happier with. Oil pump is the high volume one, 80 psi at idle,and 100 psi with rpms. I blocked the by pass,and deleted the cooler. This is with 30 wt breakin oil.
 

6.2 turbo

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As far as the pump,the .290 should be fine. It usually takes me a couple tries on on each pump I build. Plunger size is not near as important as all the other mods and adjustments. Basically what I'm saying is , a stock pump with only big plungers ,will not be as good as a fully built smaller pump.
 

Rockabillyrat

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The DB2 has a operating pressure close to 10,000psi. It has no problem handling the higher pop pressures. The only real issue is higher pop pressure means more leak down at the plungers, and H&R assembly. That can lead to hot start issues. But with tolerances in the ten thousandths of an inch there's not much your going to do to change that. They are a machined pair and stanadyne already tightened up the tolerances years ago for hot start issues.

Higher pop pressure also has less duration thus less volume. I agree a properly set up pump will give a stock larger pump a run for its money. But the biggest issue with a rotary pump is high rpm fueling. With the combination of small plungers and high pop pressure the output volume at higher rpms will be lower vs a .330H&R. The .330 has obviously more plunger volume, a more aggressive cam ring, and if I remember correctly bigger charge ports. So it's a better option over a .290 or .310. The price on a new H&R and cam ring though makes it a big investment. I've also bought a few NOS .290 H&R for my big plungers pumps. I feel alot better about risking a $200 part over possibly locking up a new $900 one from the fuel shop.

This has been a fun build to watch. Looking forward to seeing how it turns out.
 

6.2 turbo

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Precups are triple square,and the head are stock 6.2 . They don't even have valve seals. It will be fine,plus the valve stems will get lubed better.
 

Will L.

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So the van/hummer exh manifolds have a 1.75” outlet. You’re going up to 2.5” then back down into the T4. I’ve been wondering about the same, or maybe only going to 2” then into the T4. Because the twin scroll t4 and turbo never hit larger size. A t4 opening is 2.04 x 3. So one side being 2x1.5= 3sq” -a touch under by space lost to divider, but so tiny, call it 3”. Then a 2” pipe has 3.14sq” so it is already slightly larger. 2.5” pipe is 4.90sq”.

So here is what I was thinking: expansion from 1.75 to 2.5 will dump heat before turbo, but also by expanding then restricting after would mess up the laminar flow.

So am I wrong - my turbo and exhaust knowledge is SO lacking...

Also, are you keeping the 2 bellows? Guess I can wait and see for that. flow sucks and they tend to crack at the band clamp. I Nickel anti seize helps during install of those to get in place better because the bind really bad being so thin. Otherwise its the pricier wire mesh type, but they flow better.

Also- is that a 14 or 16 hx40 housing? Looks like bigger, but maybe it is that mega-green standing out.

Have you done the triple squares with the bigger turbo and fueling before without a 2’ diameter smoke cloud when hammering full throttle take off? Everyone here has heard WarWagon talk about it, but he beats the drum loud enough I never bother. Back when I tried an s400 on a 6.2- that was my experience too. I just had a stock db2831 pump with screw spun maybe 1 turn and I always got 24-30” cloud. Ended up going 1/3 throttle till about 15 mph. This was in my 92 k2500.
 

6.2 turbo

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The turbo housing is .82 ar. I think it's to small. But I did install a big 10 blade turbine with 64 mm exducer. Yea I'm not real impressed with the stock bellows either. They are so thin ! I have run big and small precups ,and for me, smoke the same.
 
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