Redleg

If you have the smoke screw turned in much, your just dumping fuel on the launch. I still have the stock turbo, but most guys turn the screw back when they upgrade the turbo. It's makeing up for the lag the smoke screw is compensating for. Just thinking it might be one more thing to help your mileage. Might even experiment turning the star wheel back a bit. I agree,settings shouldn't really affect cruising mileage, just thought maybe your haveing some fuel wasted when you get going. Have you played with the timeing?

Bob Beauchaine

I set my wastegate to be fully open at 34psi which equates to 32psi on my gauge and mine will flat haul ---- when I put my foot in it. Look at my sig for #s. Peirs likes to see the HX35 run at 30 to 34 psi max. In spite of what you hear RWHP does not necessarily equal a factor of 10 times boost number - look at me 32 psi 378 RWHP. What numbers do you see on the dyno and how does it feel to you. A larger exhaust will lower boost and EGT's because it's breathing better.

Bob

hertz

Bob, you have the products and HP/ TQ numbers I want. My truck runs really good now but I know it has more potential. Bob did you change the governor spring.

wannadiesel

While you're in the pump to do the governor spring there's a little lever that you can grind on to add some more fuel for free. Link to the TDR thread

http://www.turbodieselregister.com/f...ad.php?t=90284

Don't get sucked into the idea that more boost is better. You only want the minimum amount of boost needed to burn the fuel cleanly and keep EGT under control. More boost is just backpressure, it hurts power and economy. If 26 psi is keeping you cool, that's great! That PDR 35 is a good turbo.

Speaking of economy, the reason the mileage sucks is that you're using the power. You have to burn fuel to make power, the more power you use the more fuel you use. Remember that you're pushing a house down the highway at 70 mph, it takes a bunch of HP just to move the air out of the way. I know it's painful to contemplate, but running at 60 would really pick up the mileage.

Backing out the smoke screw will reduce the smoke right off idle. This will help the mileage somewhat if you're running local, but it's not any help out on the highway. I have mine set flush with the inside of the cover so there's no preload. With big injectors the smoke screw is really unnecessary.

Dan Brooks

That's strange - I picked up two or three PSI when I installed the 4" system.

hertz - Did you change anything else at the same time you installed the injectors?

FWIW, I'm getting 25 PSI at WOT with stock injectors, mild pump tweaks, and a 16cm non-wastegated housing.

wannadiesel

Stock turbos and hybrids are different animals. Switching to a hybrid will typically lower the boost level because it's better (cooler/denser) boost. Better boost lowers the EGT. Lowering the EGT will lower the boost level - keep in mind that the turbo runs on heat, less heat = less boost. I don't think there's anything wrong, you just have room for more fuel before you outgrow the PDR 35. And that's a good thing.

Bob Beauchaine

My pump was built and installed by Wentland Deisel and after warranty, tweaked some more by me so I don't know for sure about the gov. springs. I know that when I dyno I usually see about 3200 rpms but that can come from the high RPM limiter. I've also got a Banks intercooler which breaths about 50% better than stock.

Bob

hertz

MPG is what I've thought it would do. Pretty much all the time I'm running 15-20lbs of boost. I just know with this setup now that there is more room for inprovement and I'll get it. It's amazing with these motors you really don't have to sink alot of money in them and they become powerhouses. Cummins seen alot of potential in these motors to be able to double the HP without spending a whole lot of money. All I did was add the Bully +50hp and what a inprovement, I though I would see at least 30psi when switching to these injectors though.

hertz

I just ordered another piece to the puzzle. Old Smokey fuel pin. Can't wait more HP

frostie

I definately agree, you need more fuel. If you are only at 700 on your pyro then you are way underfueled.
There has been lots of discussion on turbos. I believe you are low on boost and more fuel will increase your boost.
The smoke screw on top, dont bother with it, keep it backed out. The smoke screw just makes smoke and does nothing for performance.
Im not sure where your fuel screw is set but I think you need to turn it in some more Im getting 24 PSI with stock nozzles and a 16 houding and the fuel screw turned in. With POD nozzles I bot about 35 PSI boost.

Den

Just as a comparision I have a stock turbo, injectors and a 21 housing and I get 24 PSI. Only pump mods were 2 turns on the high idle and 2 turns on the full power on the back of the pump. Takes till top of second to get up there though


Den

hertz

Well here's what I don't understand. I looked in search for Bullydog +50hp. A member bought them and already had a HX35 he said he was hitting 30psi +. I have the same thing and I'm only hitting 26psi. I'm trying to figure out if it just because it's a bigger truck or what (bigger intercoller)? When I hit 26psi I may be half throttle and then it doesn't go anymore (boost) just the EGTs start to creep up. I'm getting this fuel pin and I guess I'll see If I'll get anymore. Something doesn't seem right though. I should be getting 30psi +. I am thinking the wastegate is open a crack (I have the line pinched with visegrips). From the turbo to the intercoller, to the motor has no leaks pressure checked it. The head has been rebuilt last year and all new intake gaskets have been put on my brother did the work (he's really careful on putting things back together). i think this setup on a pickup would hit 40psi +. I know boost doesn't make HP but it helps push the air out and keep things cooler. I really just want a efficent running motor. My sign tells everthing I have and have done. The pyro gauge is post turbo it was already there when we bought the truck.

Alec

What do you mean by "half throttle"? The governor is a modified constant speed governor, so if you are pulling a hill at 1800 rpm, say, the engine is getting the same fuel whether the pedal is on the floor, or the pedal is just far enough down for full power at 1800 rpm. I'm having trouble making that clear -- I hope it's somewhat understandable.

Basically, for a given engine rpm and a given EGT, you will see a specific manifold pressure. If the EGT's go up at a specific rpm, then you should see boost go up too -- at least until you get to the point where your turbine housing is "choking" the exhaust flow. So if you are hitting 26psi at "half throttle" and then not seeing any more climb in manifold pressure, it could mean that by the time you get to that accelerator position the governor is already delivering full fuel (in which case the EGT's would continue to creep up over time) or it could mean that the waste gate is opening at 26 psi, and even though the energy (in the form of air flow and temperature) available to drive the turbo is increasing, it is being dumped instead of converted into more compressed air for the engine intake (which would be accompanied by a more rapid increase in EGT's).

If you can go from 700 degrees and 26psi of boost up to say 900 degrees without seeing an increase in your manifold pressure, then your gauge isn't working, or your waste gate is opening, or some air (hot or cold) is going somehwere it shouldn't.

wannadiesel

Part of it is that you have a hybrid turbo with a much better compressor section than a stock HX-35. See my previous post on that.

To check whether or not the wastegate is being held open, unbolt the actuator. There should be spring tension holding the wastegate shut. If there's no tension the actuator is misadjusted.

hertz

I don't get more then 26psi at WOT the EGT will just start to creep up. It acts like the wastegate is working but the line is pinched. It just seems kind of odd to me that someone else see's 30psi+ with the same thing. Dave I understand what you are writing. I was thinking if this is all the boost that I'm seeing I could switch over to a 16cm non gated housing and really keep the EGTs down. I guess with trying to find a air leak it trail and error. I'm sorry about being a Pain In The A$$. I was wondering if there are problems with the waste gate actuator sticking open a little. Thanks for your time.