Drive pressure on stock turbo 7.3

[Blown262]

So I've been slowly working on little things here and there for my 01. I've got a 4" turbo back MBRP and I have the EBPV unplugged and open (still physically there, though) and I have removed the intake heater and plugged it with a drain plug from a cummins. At idle, I show 15PSI back pressure on my scan tool, and my MAP is 11-12PSI. At full boost (24-26PSI) I am reading ~47PSI back pressure and ~40PSI MAP. I know turbo efficiency plays a roll in the difference in numbers, but is there any way to drop my drive pressures a couple more pounds and bring it closer to even with my MAP readings? I plan on deleting the EBPV in the near future, as well, as the only reason I left it in there was for engine braking with my old tuner. Thanks in Advance

 

[79jasper]

Those numbers actually aren't that bad.
Imo, best option is a better turbo.

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[Blown262]

Those numbers actually aren't that bad.
Imo, best option is a better turbo.

I didn't think they were terrible. I was just curious if there was a way to flow a little better, short of a new turbo. Even a couple pounds would make for more efficient power delivery, wouldn't it? I'm not the most in tune with the exact characteristics of these motors, but The physics make sense in my head. I know the EBPV blocks some air flow, but is there anything else causing a restriction I'm not aware of? And how much of a restriction is the stock intake manifold? Would a new manifold help drive pressures at all? I'm more or less content with the amount of power for the amount of time and money I've put into it for now. I'm on a PMR motor so I'm not looking to go crazy with power, as I do drive this truck every day and use it for work, so down time isn't really an option.

 

[79jasper]

Maybe a different turbo wheel or exhaust housing.

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[Blown262]

What wheel has the best characteristics for boosting down low, while not sacrificing too much up top. I don't mind giving up a few pounds of boost if I can boost sooner. I'm big on no smoke as well.

 

[uncool]

A 1.0 turbine housing, A 1.15 housing for the SD turbo (not a van housing) A true van turbo with the SD exhaust adaptor. A T4 style turbo and mount. That would be the order to go in to reduce back pressure.

Back pressure is all measured before the turbine wheel. Changing anything on the intake side will have very little effect on BP.

 

[Blown262]

What is the difference between a van and SD turbo?
The SD is a .84 housing, correct?

 

[uncool]

The van turbine wheel is larger. 67mm for SD vs. 69mm for the van turbine. Also the down pipe outlet on the van is smaller. Compressor side is identical.

Yes factory SD housing is .84.

 

[Magnum PD]

The van turbine wheel and shaft are the same as a OBS.

Those are high numbers. Is your wastegate working?

 

[Blown262]

Waste gate is working as it should as far as I know. I hear it start to open about 16psi. If I pull the red tube it will peak 30+ and defuel and I never hear it open.

 

[Blown262]

This is on the 50hp tune with the red tube pulled.

 

[jngreen]

So I've been slowly working on little things here and there for my 01. I've got a 4" turbo back MBRP and I have the EBPV unplugged and open (still physically there, though) and I have removed the intake heater and plugged it with a drain plug from a cummins. At idle, I show 15PSI back pressure on my scan tool, and my MAP is 11-12PSI. At full boost (24-26PSI) I am reading ~47PSI back pressure and ~40PSI MAP. I know turbo efficiency plays a roll in the difference in numbers, but is there any way to drop my drive pressures a couple more pounds and bring it closer to even with my MAP readings? I plan on deleting the EBPV in the near future, as well, as the only reason I left it in there was for engine braking with my old tuner. Thanks in Advance

I wouldn't worry about your drive pressure at all. The math says you are running 1.175:1 drive vs boost. That is nothing to be concerned about. There are some guys pushing closer to 2:1.

 

[Blown262]

I'm not overly worried. I'm just a big fan of efficiency. I am not going for the most power, moreso trying to utilize the power the engine is already capable of producing by freeing up everything I can. I like being able to haul 10k+ and not have any issues and not have any soot all over my trailer too.

 

[Magnum PD]

"That car was white when I loaded it"

 

[Blown262]

"That car was white when I loaded it"

"I'm taking $150 off the haul since it needs a full detail now"

 

[farmall99]

Keep in mind those numbers seem high due to atmospheric pressure not being accounted for. 14.7 psi at sea level IIRC. Take 14.7 away from that and your numbers are more normal sounding.


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[Blown262]

I turned the ICP pressure up just a touch and was able to drop a consistent 1psi on the back pressure while still maintaining ~25psi boost. So there's some efficiency to be gained yet. Im never satisfied so I'll keep plugging away until I either brake something or breakthrough with something awesome.