Just a thought, I know about the stock wheel(got one), and have read about the Wicked Wheel. Now from my old days in the boat buisness, we would re-prop a boat with a higher pitch to move more water, thus making the boat go faster.
Pitch on a prop is defined as the amount of distance the propellor will move forward in a revolution. more pitch = higher velocity of medium moved.

I also have read about how over 25psi boost we are just super heating the charge air, and our turbos lose efficiency. Why? is it because of the pitch on the exhaust side wheel, or is it just heat soak from the higher EGT's that it takes to move the compressor side fast enough to produce more boost.

I guess my ? is are the stock blades designed for optimum efficiency, or is there a higher pitched wheel on the market that can acheive greater boost from our stock turbo's. Does the pitch on the exhaust side need to be more to turn the compressor side faster?

The WW by design cannot acheive more boost than that of a standard wheel because of the less surface area of blade faces.

Yes, I know I can go buy a new drop in TN, BB, H2E, etc..., but is there a less expensive alternative by just replacing the stock wheel with a wheel that is designed to move more air.

If a wheel was available that fit our turbos, and moved more air, how much lowend would we be giving up? Do we need an low pitch exhaust side wheel that is moved faster by lower volumes of exhaust, and a higher pitched wheel on the comp. side that is moving more air because it is turned faster by the lower pitched (drive) wheel?

this ought to give Gene something to think about.

Everyone else, what are your thoughts?

 

The biggest problem with going over 25lbs of boost on the stock turbo isn't the compressor side so much as it is the turbine side. Drive pressures on the turbine side begin to spike way higher, causing a huge imbalance of pressures across the turbo. This is what kills the turbo and the thrust bearings.

Put a larger turbine housing (1.0 or 1.15) on the stock turbo, and now you can hit 30+ lbs of boost and still keep the turbo in good health, all with the same stock compressor wheel.

 

Curtis...if he raises the A/R ratio to 1.15 won't it begin to kill off low end boost (slow to spool)? I'm just wondering out loud, trying to get my mind around turbocharger basics.

 

Yes, that is the downside of a larger tubine housing.

The smaller the housing, the quicker the spoolup, but you sacrifice the top end performance because the smaller turbine housing becomes a bottleneck. That's why our trucks have a wastegated turbo to help bleed off some of that drive pressure and protect the turbo.

With a larger turbine housing, boost pressures drop on the low end and the turbo can become laggy. However, at higher boost levels you get a reduction in drive pressure as well as EGT's.

The .84 housing that comes on the Superduties is about as small as you can go without creating serious EGT issues. Once you start adding more fuel, the .84 housing becomes way too small and a turbo upgrade is often needed.

BTW, vans with the PSD come with a 1.15 A/R turbine housing.

 

Yep, I am with you Curtis and understand those basics of the Turbo, but to my original question, would a lower pitch drive wheel alleviate the the stresses because it would provide more torque to the comp. wheel with a higher pitch to flow more air. If you flow more air then you are creating more drive pressure due to the exhaust flowing faster. It is an endless loop cycle, but, what is terminal velocity before you start melting and over stressing the bearings?

 

If You Get A Van Tubo What Are Some Of The Things You Need To Change If Any? Does The Exhaust Bolt Up, What Affect Does It Have On Towing Etc.

 

EBPV delete adapter, a non-EBPV turbo pedestal, a new set of pedestal o-rings, blue lock-tite, small torque wrench. The up-pipes bolt right up and the adapter mounts to your stock down-pipe. If used in conjunction with the ATS ported intake housing it will not surge and will drop your EGTs.

 

Does anyone know the A/r ratio for an early-1999 7.3?

 

I'm not sure if changing the pitch of the compressor wheel will give you that much more air. At least it won't be enough to balance out the drive pressures on the turbine side in a high boost situation. I guess if someone had time and could fabricate some wheels they could play around with it, but I imagine the turbo manufactures have already done that and found the best balance with the current wheels. In my opinion, I think the current pitch of the compressor wheels allow for maximum air at higher velocities (over 100K RPM's). If you changed it, I'm thinking the turbo might spool a bit quicker, but your MAP would drop considerably and you'd loose top end boost.

But I do know what you are talking about with the boating analogy. Change the pitch of the props and you get a boat that responds differently at low and high speeds. What kind of change it would make with a turbo???? Who knows . But, I think I might have another analogy.....

Rev the boat motor too high, and you blow the engine. Doesn't matter which prop you have, one prop might allow you to have a bit faster top speed, but in the end the engine has the ultimate limitation. Same for a turbo. The limiting factor is the exhaust drive pressures. Change the compressor wheel, but that turbine side can only flow so much exhaust gas before something goes boom. If you want a faster boat, put in a bigger engine. If you want more boost, put on a bigger turbine housing and add some fuel.

I guess that's my 2 cents...... for what it's worth Hope I made sense.

 

COOL SO ALL i NEED IS A VAN TURBO AND AN ATS HOUSING

 

Turbine: .84 A/R
Compressor 1.0 A/R

 

AND some good tunes or injectors to get it to spool. It takes a LOT of fuel to get a 1.15 to spin at low engine RPM.

 

Since you mentioned my name, I figure I'd better post something so that you don't think I'm ignoring you! One of these days I'm going to start a thread, and post a bunch of info I've been accumulating on turbos, including compressor maps, etc... First, as far as I can tell the WW was designed specifically for an early 99 turbo only, but will physically fit on the late 99.5+ turbo, and vice versa for the 99.5+ wheel.

The following quote from Banks about the differences between the turbos is why I think each wheel has some unique design features that are tailored for their respective turbos. I can tell you with absolute certainty that the 99.5 wheel IS NOT designed for and will not work well with an early 99 turbo, even though somebody decided to start rebuilding the old turbo using the new wheel. A 99.5 wheel just doesn't work worth a darn on an early 99 turbo, and I had mine removed at my earliest opportunity which was 300 miles. When you read these quotes from Gale Banks regarding the WW and surge, remember that his Banks wheel = WW=OEM Early 99 wheel, they're all just a stock wheel from an early 99 turbo.

Ford-Diesel.com: What did Ford change in the turbo on the 1999.5-up Power Strokes? What is “compressor surge,” and how can it be fixed on these trucks?

Gale Banks: There are a few notable differences between the turbo design of the ‘99 (early) and the ‘99.5-up (late) trucks. To begin with, the compressor housing size (A/R ratio) changes from a 1.10 on the early turbo to a 1.00 on the late turbo. The diffuser face inside the compressor housing increases from a diameter of about 5.5" to about 6.0". The compressor outlet diameter increases by about 0.400". These changes account for the difference in physical appearance between the two. In addition to these changes, the compressor wheel itself is of a different design. Unfortunately, under full power operation, the late-style compressor occasionally goes into a condition known as compressor surge. Surge is an instantaneous reversal of airflow that occurs as boost increases at a fixed airflow. This can even occur on a stock vehicle under heavy load. Every compressor has a point at which it will go into surge. When viewed on a compressor map, the limitation of the compressor is called a surge line. Higher levels of boost will require a compressor wheel and housing combination that has a higher flow range before hitting the surge line. Figure 1 demonstrates the difference in the surge line of the factory wheel and the Banks wheel. When a compressor goes into surge, the only remedy is to reduce boost or change the compressor wheel. Our Git-Kit and Stinger levels moderately increase airflow (moving right along the X-axis) and stay below the surge line as boost is increased, so a replacement of the wheel is not necessary. Stinger-Plus and PowerPack® require the wheel because the turbine housing allows for an increase in boost that oversteps the stock surge line.

Your boat propeller analogy is better suited for the turbine, because there the exhaust gas flows straight through. My quote below is from the so called "vortex of doom" thread, and in it I see your boat prop as being more like the jet turbine fan ot the radiator cooling fan analogy I used. There's a bunch of technical names for the way the compressor blades are shaped to grab the air molecules, and sling them to the perimeter of the wheel where they're forced through a narrow slit into the compressor housing, kind of like the operation of a "one way valve", but I'll have to save that for another time as the wife is saying I've got to go now! Anyway, it's not at all like the operation of a boat or airplane propeller that pulls the air through the blades, and out the back side of the fan.

 

So go to the 1.5 housing and add some spray to get the rig moving out of the hole and you are good

 

I have what might be a dum question but I know very little about turbo set ups wether it is a gas or a deisel but I know this guy that has a trubo 6 grand national and he is injecting methonal to help cool intake temps which in turn cools exhaust temps??? which produces more dense air charge creating more power can this be done with a deisel engine? If so wouldn't this help your EGT's