I know its been a while since I asked about this but my 1983? Silver 6v92 (flixable) has the 9T70 injectors , TV7101 1.39 turbo , and large radiator.
Before I reinstall it I would like to bring it up to 350hp
Am I correct that I need a TV7512 turbo with a A/R of 1.23 , and 9G90 injectors?
Do I need to check the cam?
Do I need to check the Blower? Am I looking for a bypass? How do i tell?
im guessing the turbo is this one >
Part Number 465369-5001S
Previous versions 465369-9001S, 465369-0001, 465369-1
OE number 23501978, R23501978
and injectors are > 5226410 INJECTOR ASSY., FUEL (9G90)
As always.. Thank you!
Bypass blower will bring you from 335hp to a full 350hp.
Quote from: TomC on August 18, 2017, 12:20:35 AM
Bypass blower will bring you from 335hp to a full 350hp.
Where am i looking for the bypass on the blower?
Yes that is the turbo and injectors I installed in my 6V92TA. It has the mini by pass. It is located on top of the blower at the back of it at the fly wheel end. It is a cylinder a little bigger than your thumb.
Your engine will put out more heat. Your cooling system better be in good shape. Is this for a Flx bus, or an MCI ? In my 5C, I have the smaller rad blower pulley, and the bigger squirrel cages. I have to watch and manage the temperature when the weather gets hot, like above 30C, 90F. But the power is great to have. It goes as fast and hard as a loaded late model 53000 lb Prevost.
JC
Bypass blower is a new rear plate. It involves removing and replacing the rear plate, attaching the feed hose to the pressure side of the intake. Bypass blower will bypass just enough air to equalize the pressure on either side of the blower to allow it to "freewheel" and not take power when you're pulling. I have one on my 8V-71. Good Luck, TomC
My radiator is a 7 pass with an 8 blade fan.
Its going in a PD4106
Anyone have a photo of the "Bypass" on the blower?
There is a bypass and a mini bypass?
Is it this?? ( not my engine )
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.wanderlodgeownersgroup.com%2Fforums%2Fpicture.php%3Falbumid%3D436%26amp%3Bpictureid%3D3431&hash=6f7466b5839dcd3297beebff9d51316b634900d5)
Yes it is a mini bypass.
JC
Ok i just went out and took a photo of my engine and there in no bypass...
Is this a problem??
Should I add a bypass??
You don't have to. It will run without it, as it does now. The bypass helps some, exactly how much I don't know.
JC
so im guessing the bypass acts as a check valve sensing positive pressure above the blower from the turbo.
keeping the blower from acting as a restriction.
So if turbo pressure > spring rate then bypass, or does it mechanically allow the blower to free wheel.
If this is true and there was an available port above and below the blower you could do an inline calibrated check valve - just a thought..
The by-pass releases the blower lobes so when the turbo boost is higher than the blower pressure the blower turns faster allowing the higher boost of air into the airbox. More power, less black smoke.
--Geoff
What is best case / worse case on the cams? I dont know what mine has... #6VF093525 8067-4423 1982?
My blower also does not have a bypass valve, stock from the factory, so I see no need to add one. As I see it, the blower is gear driven and it's speed is locked to the engine speed. It always takes whatever air pressure is presented to it and adds its mechanical boost to that pressure, it kind of has to. It's just a mechanical pump, after all. It always takes a certain amount of horsepower to create that boost, and the bypass simply stalls the blower so it doesn't add boost, and so requires less horsepower to spin. But the blower is still the gatekeeper to the engine, virtually all of the air needed to run the engine goes through the blower, and only a tiny amount bypasses through the valve. At the end of the day I see the bypass valve as a fuel economy device.
It also stands to reason that when the turbo pressure excedes the blower pressure, the blower is "unloaded" so it takes much less (if any) horsepower to operate.>>>Dan
Actually not so. I believe. The blower (on an 8v71, the only one I can remember the numbers for) moves around 440 cubic inches of air per revolution, or 880 CI per crank revolution since it's driven about 2:1. 880 is roughly 1.5 times the displacement of the engine, so it moves more air in than the engine can take out, and so creates a pressure in the air box. The engine manual lists the pressure developed, which varies by RPM and flow through efficiency of the exhaust, as being between 5 psi and 8.2 psi at 2100 rpm. That's above ambient at the intake of the blower. If the blower is seeing 15 psi from a turbo, then the air pressure inside the air box will be 15 psi plus 5 psi, less losses due to leakage and heat. Now why a bypass. The bypass takes some air from inside the airbox and passes it back out to the intake side of the blower to even out the pressure. If it can pass back all of the extra air that the blower moves in (around 300 CI per crank revolution) then it can completely unload the blower from having to move air into a restriction, and lower the load - it takes a lot of HP to spin the blower, and the load increases if you restrict the output so it has to create pressure. My research shows that the talk about the bypass when it was introduced was efficiency - if you design the system so the turbo is matched to the blower and the bypass, it should be quite a bit more efficient and produce better power as well. If you don't care about efficiency, a non bypass blower will produce more power, in theory, since it adds to whatever the turbo produces for that combination. There was a bit of talk about blower longevity - unloading the blower at speed relieves load on the blower bearings, and is one reason bearings were improved over time. Some smaller engines had been getting along with plain bushings in the aluminium end plates pre-turbo, and had to be upgraded when turbo's came along.
Is there such a thing as an electrically-controlled blower bypass valve that could be added to a non-bypass engine? Then one could choose whether to have maximum blower output but at the expense of efficiency and fuel burn, or reduced blower output but with reduced power needed to drive it. Does that sorta make sense? Surely it wouldn't be that difficult to rig up such a valve. Or is it a Rube Goldbergian exercise in futility?
My turbo boost gauge reads from the 1/4" port on the driver's side of the blower's airhorn, where my Quickstart ether injector used to be, and I see up to 26 PSI boost under full load. I assume the engine's air galleries are not also getting 26 PSI after the air has passed through the blower. What is the corresponding scavenge air pressure in the air galleries under full load?
John
I became fascinated by the subject of how much hp it takes to power the blower on our engines and how that affects efficiency. Google is obviously the front end to the greatest engineering library ever devised, and I quickly found a site with engineering equations for calculating all of the operational parameters of a roots blower in industrial applications (it's used a lot as an air pump in industrial air pressure and vacuum installations). It turns out that an 8V71 blower takes right around 7 bhp per blower rpm at 6psi pressure differential. My Detroit book says the pressure differential for an 8V71 is between 5 and 8 psi for most engines, so I used 6 psi. That is 32 bhp at 2200 rpm, so if you took a notional 8V71 T engine that was putting out 350 bhp, which my engine happens to do, add a few percent of driveline losses to turn the blower, you see that the engine is using in the ballpark of 10% of it's output power to turn the blower. You could therefore say that if the blower wasn't there, it would make 385 hp. Or you could say that if you changed the parameters of the turbo and the fueling you could get the same 350 hp with around 10% more efficiency. Now the question becomes how effective is the bypass feature of a bypass blower? The blower on our engine is running around 2:1 crank speed, more or less, and is moving around .5 Cubic Feet of air per crank RPM. The engine is 568 cubic inches, or .33 CF per rotation, so the blower creates an excess air volume of .17 CF per revolution. At 2200 rpm, that's 374 CFM of excess air creating around 6 psi of pressure differential that needs to be bypassed to the intake side of the blower to perfectly equalize pressure on both sides of the blower and reduce the BHP needed to spin it to zero (in theory). The engineering sites I found suggest that the size of the blower bypass can't pass that amount of air, so the bypass needs to be less than 100% efficient. If it could reduce the pressure differential by half, the power needed to spin the blower would reduce by half, and you could expect a 5% improvement in efficiency if the engine requirements were optimized to achieve that.
What happens at less than full power? Lets say that my engine in my bus needs 150 hp to cruise at 60 mph at 1800 rpm (I don't know that it does, I'm just doing a what-if). Blower power at 1800 rpm (at the same 6 psi pressure differential) is 25.8 BHP plus 5% for driveline loss make just under 30 bhp. That is 20% of the power output of the engine. If a bypass blower engine could reduce that loss by half, you'd gain 10% in real on the road efficiency, which is very close to what people report in real life.
Fun to think about this and try to work out an explanation. I doubt that I am dead on with this theory, but I think that I am on the right track. FWIW, a 6V71 blower (and maybe a 6V92 as well) is shorter than a 8V71 blower, moves about 10% less air per revolution, and requires about 10% less power to spin.
Brian
Detroit experimented with the centrifugal type blower on the 110 DD to take less HP it ran 9.8 times faster than engine rpm that didn't work to well in mobile applications.
There are 16 different blowers for the V DD engines,the best blower is the full bypass the mini bypass is ok it takes some pressure off to relieve the hp drain but not as effective as the full bypass for making power.
Those blowers have 5 different drive ratios and different lobes, some of the high HP 92 series in the marine world use a blower developed by Stewart and Stevenson design to pump more air with less hp
Do you happen to know the part number for a full bypass 6v92ta blower?
Can someone with a 350HP 6v92TA please give me the exact part number on their turbo....Thank you!
Before the Series 60 came out, Detroit experimented with many different blower configurations in an attempt to extract more efficiency from the 2 stroke design. The most efficient design was the 3 wheel turbocharger. Picture a normal turbocharger with an additional turbine housing in the middle of the turbo that was powered by the oil pressure of the engine. The theory was that when turbo pressure dropped below 5psi, the valve would open on the oil turbine and spin the turbo keeping the turbo producing at least 5psi. When the engine accelerated, then the turbo would take over and the oil valve would close on the 3rd turbine wheel. It worked well-but engine response was considerably slower causing black smoke coming out to the point that Detroit felt performance was sub par and the project was abandoned.
Another was to use a mechanically geared turbocharger with over run clutch-exactly what they use on the big locomotive engines. Same principal, except they used the rpm of the gear drive versus the turbo speed. Was like a bicycle in that the engine powered the turbo until the engine accelerated and the turbo over sped the gear drive. But this had good response time-but was too big and bulky. Hence the full bypass blower was as far as Detroit went as to making the 2 stroke more efficient.
Now if only they used air to air intercooling (like my 8V-71) along with common rail electronic fuel injection....
Quote from: Darkspeed on September 23, 2017, 07:29:33 PM
Can someone with a 350HP 6v92TA please give me the exact part number on their turbo....Thank you!
Call Tom @Turbo Resource 928-505-4610 tell him what you after and let him build you a turbo that will make more boost,more power and less smoke.Pull your inter cooler and see how many passes it is 1,2 or 3 you may be chasing rainbows if the after cooler is not large enough.Right now you have a 250 hp engine and a 100 hp is huge jump plus $$$
Great subject and thank you.