@ESwift Here's my rig...although the truck has changed a bit.

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Same engine/trans as the red flatbed. I currently don't have gauges hooked up in the white truck (it's a money thing and since the SXE I don't worry about EGT). I like to be at or above 2k going down the road. Shift points hang longer, say at moderate throttle, the 3-4 shift is at 48-50 mph. I also have the towing tune defuel during the shifts....defuel, change gears, add fuel back...It's just easier on the trans. I don't need to be slammed horses against the dividers during the shifts.

 

We have very close shift points for towing, I need to talk to aa about maybe pulling some fuel out of the shift, as it does make for an uncomfortable ride with the heavy 5ver. For the most part between my 4.30 and tuning I rarely am below 1900, usually about 2100 which helps turbo to light quickly now. Still gotta get it dialed in. Hoping to have ouo bars and air bags on next weekend, that should improve the ride quite a bit when towing heavy. Truck still seems a tad low on power, but that may be because my other truck has 75 more horsepower at least, and a zf6.

 

Pretty much any company that makes a T4 kit would be worth talking too. The boys over at Hypermax have been at it the longest, CSD, Irate, Obsession, Bell Turbo. All worth talking too but Hypermax is the top dog IMO although they lean on the high performance side of things. KC turbos markets their 68mm turbines pretty heavily. Although I have yet to see any video/testimony of someone really leaning on it and keeping egts cool. I myself run their 68mm sxe turbine in a gtp38 and it performs well on a stock motor with no tuning. Have towed all over the country with it. Dont think I will ever run it on anything besides stock tuning though.

 

76/68 is stock GTP38 size turbine with BW desing.
I really want to resist the idea to downsize turbine in 7.3 liter diesel engine..

If person feels that 364.5 with 80/73 turbine is too big,heres what i would do:
Downsize turbine housing
Downsize compressor
Upgrade injectors

Jason WV

I suggest you to swap 363 63mm compressor wheel and housing,it has same exducer than 364.5 64.5mm compressor.
This will lower the compressor wheel trim resulting an:
More responsive turbo
Wider usable boost curve
BUT downsizing compressor inducer will lower the maximum turbo flow..

I have a 63.4/80 compressor in machined GTP38 housing.
Inducer is bigger when exducer remains the same resulting an bigger wheel trim.
Bigger trim compressor wheel flows more overall but boost comes like on/off switch..

So basicly i have a totally wrong setup for daily driver..
61.5/99 compressor size Holset HX50 with 86/72 turbine 16cm housing,OEM for 11 liter Scania, should fix that for me..
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My current turbine is KCs300 70mm machined to 1.0 non WG housing.
Just want to add my opinion about wastegates overall, get rid of them unless it is an external one..

 

I dont understand why people think the 76/68 bw turbine is too small, the 363 76/68 flows more air the a 38r at almost every rpm, no one says the 38r doesnt flow enough, it just is a turd at spooling.
when I bough my auto truck last fall I ran the kc balanced assembly for a while until I had time to do the t4. The oem turbo backing plate bolt had loosened up and eaten into the stock compressor wheel which I figured out as soon as I got the truck home from purchase. The kc assembly spools faster then the 364.5 80/73 ever will, even with the .83 housing,
I am debating on going down to a 363 76/68 even with my ac's and 4.30 gearing, I do not plan on doing it until my ouo bars are on and tunes are tweaked to perfection though.
In Jasons situation he can best match his spooling need by going smaller on the turbine, that will increase spool much more then any tiny trim made to the compressor side, also he can swap the entire turbo and exhaust housing and sell his current ones and about break even, no need to mess with wheels and modifying housings etc. Tossing in larger injectors and nozzles for 2 grand seems like an expensive way to solve a slightly oversized turbo, and even then they wont help the fact that he is not trying to run high rpms and tow heavy, he is keeping the truck efficient while driving around empty or lighter trailer at a lower rpms as there is no need to run high at the light weight levels.
I am in the same boat, when not towing I drive like an old man Sunday driving, but then I hook up and tow at heavy combined weight in the mountains, I believe the .83 housing helps split the difference of low spool and more air capacity for towing that I need, but still feel like I would enjoy the smaller turbo more in a lot of situations. The 363 76/68 with my 4.30s would keep the turbo spooled at its most efficient spot right about the best part of the torque curve, while being at the correct speed for my local roads, rpms would be right near 2000-2200 and with my ac's my pw would be low, which all combined should keep egts down much better then trying to push lots of air through at higher rpms and long pw well above peak engine torque area?
Or I could have done 30 or %80 nozzles for low pw at higher rpms
Sorry for rattling, still getting coffee
Hope it makes sense, not trying to be argumentative, just trying to say that some of us dont want to go bigger and faster and harder with everything just to use our current turbo.

 

What boost/EGT are you currently seeing at 2000-2200 RPM’s in various operating conditions? If I understand correctly you currently have a 364.5 and are not satisfied with the results in the 2000-2200 RPM range? Seems like it should be ready to rock at those RPM’s.

 

Finnish, Broke, Eswift I appreciate all your input. I feel like lately all I can concentrate on is turbo theories. I enjoy the discussion as we’re all throwing things out here and trying to figure this out together. I imagine some day a real turbo expert will read through all this and go then followed by a and then a full on
Not bashing anyone’s intelligence here but I just thought it was funny to picture.

Broke, you’re correct. I spoke to 3 places before ordering (well 4 if you count Obsession who never called me back lol). All 3 recommended the 73mm (but I want to ignore TCS here because he is mostly just a parts dealer and his opinion of the 363 vs 364.5 rpm difference has been discredited lately). So the 2 T4 kit folks I spoke to recommended the 73 turbine. But to be fair these weren’t turbo experts, they are more fabricators who also build 7.3’s. They are also into the truck pulling world and heavy modifications. I feel like maybe they don’t completely understand a normal light footed driver. For example CSD recommended a 366, we all know I wouldn’t have been happy with that lol. Irate recommended exactly what I’m running. I may have to look into calling Hypermax to hear their opinion.

So how much of a rpm shift do you feel happened by going to the .83?

You mentioned starting to spool at 1500 now with the 366/73/.83 setup
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My feeling is the 364.5/73/.91 barely begins at 1600, is kinda working at 1700, and real working range begins at 1800 (and goes forever from there). I know this seems different than Sous’s experience.

Maybe we need to get a poll going and throw this data on a spreadsheet.

Finnish, when I spoke to the turbo folks they said a 364.5 vs 363 was only about a 50rpm shift in operating range. Now pair that with the .83 housing and maybe I would be happy. But both of these companies said dropping turbine size was the “best” change for me. Like Broke said, these are not 7.3L specific folks though.

Eswift, I think you told me the .83 dropped the operating range down by about 150rpm.
Would you mind sharing your opinion on the same line of thought I listed above? Barely starting, just beginning to work, and actual working range.

Guys I’m sorry to beat this to death.

Another thought that’s crossed my mind is this.
We’re talking about using a modified lower A/R housing to make the turbo work better. At this point we are outside of the normal BW design range of the turbo. Wouldn’t it make more sense to move to another factory designed BW combo? For example if we are needing the modded .83 housing then maybe it’s an indicator that we need to drop turbine size. I’m not discrediting the effectiveness of the modded housing, but just wonder if there’s a better way...... Or it could be that the 73 turbine is solely what makes this turbo work at lower EGTs.

I’ll also throw this out here. Andrew at AA was originally against the 68 but the more we talked he began to be open to the idea. I asked if he knew anyone who used it. He does but the guy has bigger injectors, the 68 turbine, AND a .83 housing. He said the guy loves it BUT this guy also really likes to light up his tires. So this fella was basically after a tip in throttle in your face boom.

 

@RacinJasonWV

I'd maybe use 1500 on the low end....but I think your statement is pretty darn close.

 

Everything is great empty at those rpms, egts get a bit higher and tip in smoke output at moderate+ throttle input goes up with a heavy 5ver on (especially if it dips to 1800). The turbo is lit before 2000 and climbing, but the smaller unit may help as it would be more in its sweet spot already at 2000.
I am still getting bugs worked out, right now I cannot run the tune I want to be in with my 5ver because of axle wrap and some driveline vibration when truck gets squatted that much. As soon as my ouo bars and air bags are on I can run those tunes more and dial it all in, right now I cant really get a baseline to tell if a turbo switch is needed at the power levels I want to run.
Another issue is that we have at maximum 1 more short camping trip this year, baby#3 is due mid October and I cant see us going on camping trips after that until spring. May have to just pull camper around for no reason ;-) to dial it in.
Things I am working on right now:
- #3&8 injectors show out of rotation/balance on cct or live data meter, believe because of the crappy gray cps, I have good oem black ones and am going to try put one in, expect it to go away.

- when towing heavy, cruising at very light throttle on flat areas or just keeping it where I want it on slight down hill I get a bucking and jerking and have to either let off throttle or wot it.

- Egts seem about 100° higher then should be, boost seems 5psi lower then it should be. Can't find any leaks either side of turbo

- Total power towing the 12k 5ver seems lower then it should, but maybe I am expecting too much as I am used to my other 7.3 with slightly larger injectors hotter tuning and a zf6, that truck has service body so I cant tow the 5ver to compare:-(

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Jason, right now things fighting me as far as gettin data are, empty driving I have tuning set to not let the converter stay locked basically below 1900, my truck is almost always above that rpm so initial boost rpm start is hard to tell, it drives fantastic empty fast boost low smoke etc, light trailers are great, then with the big 5ver it kinda falls on its face, but as said before I cant run the tune I want yet.
the. 83 seemed to increase spool time about 100-150 on the 364.5 80/73

One odd thing on my zf6 truck the 364.5 has a very distinct light point at about 1800 rpms, by 2000 it is pulling hard and egts hit a wall at 1150 max and usually start dropping as boost levels out (180/30 in truck) 35-40 max

On auto truck I have zero distinct light point where it is full on hard pulling, it is just smooth boost all the way, boost climbs to about 30-32 max, egts never hit a wall will climb 1300+ (160/0)

With the .83 my ebp went up about 7 psi more then the .91, it also "spikes" ebp higher and faster

 

If the TC unlocks below 1900rpm that will definitely kill off performance. At 1900rpm my truck is buzzing along at ~17psi. It will stay locked if I want it down to 1500rpm, which is great because it starts building boost around 1500rpm. Another thing to consider is I am running an 11+0 billet compressor wheel that tends to have a better low end.

 

At 1500 if I have any kind of load driving sucks, I never want to be that low in any circumstance unless it is totally flat and I am empty. I specifically told aa that I dont want to be under 1800 rpm for any reason
Shouldnt the 11+0 be better for upper rpms and spool slower?
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I'm still saving for my setup. Guess I'll wait and see how Jason's setup peforms if he goes to the 68 turbine SXE.

 

I'm a complete novice when it comes to this turbo stuff. Like mentioned, there seems to be no perfect turbo to suit everyone's needs. I don't know what the perfect turbo is for me. I'm looking for the turbo that will have the power to climb the grades with heavy 5th wheel in tow and maintain speed, and allow me to ignore EGT's because they won't be a problem. So what turbo setup that is, I don't know.

 

Guess I dont understand not wanting to be under 1800rpm. If your making boost, why not? Just got done towing the stock trailer I posted earlier 225miles. Most of which was 55mph @ ~1750rpm. The truck flat out gets it done and egts are low when doing so



Generally speaking single length blades (9+0, 10+0, 11+0) have better low end response (reason why they tend to surge more) and staggered blades (5+5, 6+6, 7+7) are more top end oriented. The claim is that the 7+7 is the middle ground. It does have 14 blades total so it is likely to be the heaviest of the group.

AA may be a great tuner, I just have a hard time taking someone serious whose only business website is Fakebook.