Gathering up some parts for a car I have sitting around. Heading in the direction of a 6.0L based / forged 408" / LS-3 headed motor. Nothing exotic, just good parts.
My thought was to go with a set of 69/73 Borgs with Bullseye V-band turbine housings. I know that VSR sells a copy for aprox. half the money. I know that ya get what ya pay for, and these are from the Orient. But I haven't really heard anything bad about them.
What do you guys think about a pair of these on a weekend ... stress reliever, street car ?

https://turbo4less.com/product/vsr-gen2-69-73-billet-86ar-dual-v-band-housing/

 

WOuldn't hesitate to run them.

 

I have one on a Duramax, and so far, so good. Plenty of love for VSR turbos out there. That said, I have seen a pretty substantial gain by going BW in a S400 frame when really pushed. Take it for what it's worth.

 

I wouldn't think that they would still be around, or at least considered "middle tier" if they had parts that wouldn't last but only a few months or a year before it was junk.

I don't think I would have room for a pair of S400 framed turbo's. And wouldn't a set of 475 or 80's be a bit much .. slow to build boost .. etc ???

I hung my helmet up around 10 years ago .. so this won't be a max effort race car.

I do thank you guys for your responses ...

 

The 369's should work quite well. The s400's are the only real comparison that i've witnessed, so I just threw that info in for comparison.

 

We need some kind of power goal to choose any turbo. Whether you have a 3L engine or a 6L Engine doesn't matter, a S364 would do 600rwhp on either of those engines and spool quite well using gasoline fuel and limited downpipe space, for example.

Twin S364 would be what- 1000rwhp capable? Ballparking. So anything larger than that and you must be wanting 1200 to 1500rwhp ??

For street cars, daily drivers, spotlight racers, you want to use the SMALLEST POSSIBLE TURBO combinations to minimize wheel mass and maximize spool character. Big ass turbos are for drag racing with nitrous and 2-steps and slicks and stuff where you can spool them sitting still and then actually hook all that. You won't have that stuff on the street (usually...)

 

Engine size doesn't matter, but na hp definitely does. Big turbos also work on traction limited street cars that make good na hp. No need to make a bunch of torque/hp under the curve if it's useless.

 

na hp is a very small component. For example if you want 800hp there is no way to get there using an na 3L or 6L engine that has street valvetrain components intended for longevity and a low rpm redline like 6000rpm. As we have discussed before its better to have a 2.5pressure ratio than a 1.5pressure ratio so the engine at 6L with the LOWER na hp is going to favor a turbocharger (any modern turbocharger) at some selected power range far above the na capability.

Next, the argument that low rpm torque is unwanted is kind of ridiculous to me. Torque is fun even if it spins the tires... Why use 6L engine then? why not 3L? 3L engine would provide the same power and reduced low rpm torque to reduce tire spin. Doesn't make sense to use a larger engine if its just going to produce tire-shredding torque?? Why bother?

Et Al; There are many more ways to reduce torque:
(boost control features such as boost per speed, gate functionality, CO2 effort, start boost function, small gate spring, reduced timing, etc... to reduce torque as low as desired)

than there are to increase turbo spool capability (nitrous, converter?)

Bottom lines:
1. Large engines that flow less (low na hp) make better use of modern turbochargers in street apps
2. Torque is easy to reduce, difficult to get back: use a smaller displacement if limiting torque is desired. Otherwise go all in on engine size for max torque. But if you do that then you can't speak from both sides of your mouth "we went with the largest possible engine to maximize low end torque but then we oversized the turbo to prevent having low end torque" What the $@#^%? Which one is it?
And for good measure
3. No advantage to oversizing a turbo when there is no racing involved where unloading the intercooler would be beneficial for long duration runs

 

I can fix this so it makes sense, if you don't mind

as long as power goal scales with na hp. For example a 300 na hp engine making 600 turbo equivilates to a 500na hp engine making 1000hp. In other words the effective doubling or more of an engine's na hp is necessary to get the most from a modern turbo (2.2+ Pressure ratio applied), taking a 500na hp engine and using a turbo to make 600 is a wild waste of parts & effort and ineffective use of a turbocharger, completely wrong combination in progress

This one is hard to generalize because some 2L engines out there can produce 150hp na and that is considered "good" but when they use a huge turbo to make 500hp it will absolutely destroy the tires ramping in that much boost as the rate comes on very late and powerful, like a sudden spool from a too-large-turbo causes massive tire spin. So it isn't fair to say 'good na hp works well with big turbos' they will just spike suddenly in boost on the end of the curve and spin like crazy.

I think the reason you said this however is because you are used to large engines with high na hp like 400 to 600na hp already. Those have very soft mid-section na torque though which is enhanced softly by boost due to all over overlap and inefficient mid-range of the setup... not really the fact the turbo is 'big'. A 'big' turbo is going to spool late and hard on most setups (any engine "big turbo'd") causing far more traction issues than one that spools gradually and well controlled- so we can't generalize about large turbos being better for traction at all really. It is kind of nonsense. The influence of rotating mass for large V8 engines with soft mid sections is playing a large role, more of a role than in a small lightweight engine (2L~) using light parts that have low torque losses, and those engines typically flow more in the mid-range using large cams (4-valve head with large cam superior to V8 head with large cam). It just cannot be general. The only way to really generalize this issue is to consider it a "CONTROL POINT" In other words, control theory application. The applied boost rate is a CONTROL feature, whether 2L 3L 5L 10L engine doesn't matter. Whether the turbo is "small" or "large" doesn't matter. It is merely a control application where the entire vehicle, weight of parts, and control over the boost ramp rate, using modern technology or other control strategy, is the deciding factor in whether the vehicle will be traction issues or not. For example pulling all the timing ALWAYS works to control torque and tire spin, any engine, any vehicle. There is no such thing as 'traction issues' there is only 'control issues'.

 

The OP has a 408 cid with a decent cylinder head in a street car, it makes plenty of torque out of boost for most street cars. Will a 364, or 366 work? Sure, but I don't see the slightly later spool hurting THIS combination. Just my opinion, and I think my comment fits the application..

 

slightly later? Hes talking about twins. And no power goal. Literally the slowest spooling combination possible on the planet is a huge twin turbo setup on an engine with no power goal in sight. Impossible to recommend a turbo with no goal in mind.

If the goal is 2000hp there is no way a 364 or 366 would work so you can't possible make that statement without knowing the goal, its like shooting in the dark. Its like taking a random amount of sugar in your coffee. Its like trying to hit three birds with one stone without there being any birds.

Turbo selection is based on power goal and usage, Not engine size.
Why guess ?? Why

 

F4k, im not going to argue this with you. Given the op's info I made an assumption as he seemed to have his turbo choice made already. This thread was about turbo quality if I'm not mistaken.

 

Fair enough, but if you came into the ER for a scrape and blood work turned up a bacterial infection I wouldn't just say "well hes only here for the scrape so lets just ignore the infection"

I call em like I see em ,

knowledge = not bliss > complacency = ignorance

 

I guess I'm just really good at being ignorant then... lol.

 

So long as OP doesn't ask about PCV we'll all be OK.

 

Did somebody say PCV? Oh my, we need pcv. Did I ever tell you guys about PCV? I don't think we ever talked about PCV yet. I'm glad somebody mentioned it, because I always forget to mention it.


Here a PCV measurement video, I Use 1-bar map sensor to determine crankcase pressure with and without the air filter pressure drop.


Future video I will discuss the roles of vacuum pump action on a crankcase (the engine is a vacuum pump), and how important the gas velocity component is, and partial pressure, gas kinetics & behavior, how oil droplets form under pressure, pressure influence on piston ring behavior, how pressure influences turbo oil drain, etc...
PCV is the most important aspect of combustion engine performance longevity.

See that wasn't too bad!!! But you don't hear me though

 

I am genuinely curious as to why on your setup you have the vent tube from the VC to turbo inlet angled 45* pointing towards the incoming air flow rather than 45* in the direction of flow. If you've explained that before, could you link to that post?

 

Excellent question. The simple answer is: convenience. It points towards the crankcase so the hose makes 'sense' and is short as possible. It's more important that the hose diameter and length be suitable (short and sweet and small diameter) than anything else when it comes to OEM style evacuation technique.

The majority of the pressure drop signal is a scalar- it has no direction. Pressure in a tire for example. I Write about conceptualization of gas molecules here recently
https://www.theturboforums.com/threads/turbo-size-confirmation-400sbc.388024/page-3#post-2052947

A true venturi will utilize a narrowing section- a 'choke' section where velocity increases and pressure drops, which is not the case in OEM style evacuation. It relies on Air filter pressure signal, not gas velocity or venturi.
There is probably some slight to negligible effect as air molecules traverse the opening- but it cannot be counted upon or utilized to great affect in this situation to my inspection, although I never tested the difference between straight, 90* away, 90* towards, etc... it isn't something I worry about because as you can see, the system works to provide the necessary 0.5" to 1.5" of pressure drop at WOT on the crankcase and thats all the matters to keep oil under control, keep it out of piston ring pack, keep it out of the valve covers, keep oil droplet diameter down, return oil the pan more quickly, reduce early ring switching, etc.... so many benefits to this technique provided by the OEM (it wasn't my design or theory- I merely copied the OEM turbocharger setup from all engines ever made from all factories and adjusted as necessary using the correct air filter by measuring directly as in the video).

 

I have learned that you have to be very careful when asking people what time it is ... some will spend the rest of your day trying their best to explain to us mere mortal's how the Swiss build watch's ...
Yes .. my main question was if "some" of the Chinese copy's were worth looking into.
I mentioned twin 69's as a target area for a 408 inch piece. No one said, they will never spool .. you'll hate em.
No one said .. there too small .. if you ever get a wild hair.
As I suspected, they will be easily controlled. Get past the torque peak without spitting the crank out on the street. And make ton's of power on top for this build and the next if it's a few inchs bigger.
I have the equipment to do O-rings. Fuel hoops would only require different cutters to be ground. I realize that I would need a fuel pump and injectors (maybe 16) to go to that range , but it's always better to think ahead.
I know better than to go here, but ...
I don't want to be building boost while driving in traffic .. LOL So yes, base torque does help. It also keeps a car with a tight converter from stalling when dropping it in gear.
If I said 600 hp would be fine .. there are those that would say .. thats way too much turbo. If I said, I expect to make every bit of 1500, there would be those who say , Ahh .. yea right .
So I steered clear of that .. mentioned cubic inch / cylinder head .. and would rather be pleasantly surprised.
Big tire car / 53% rear weight bias, I don't see it going sideways at the touch of the throttle. But ya never know, so thanks for the warning.
Crankcase ventilation ... I have always used an overdriven 4 -vane Moroso pump with a -12 hose to a large baffled puke tank. I put a poppet on the valve cover to limit vacuum to 12 inchs with great sucess. I monitored crankcase pressure with a Race-Pack . It let me know when I got greedy and started rattling the rings off their seats . Like I said, I hung up my helmet a decade ago. No more changing pistons in Wal-Mart's parking lot between races.
4K'ed .. if you want someone to believe anything you say .. that's been half way around the block .. please try something other than a kinked up filter adapter with a pitot tube facing in a direction that closes off ventilation .. right when it's needed the most. But then using a 3/8ths hose .. your not able to move much volume to begin with.
Sorry guys .. in 3 .. 2 ... 1 ... more

 

Hmm a 6-71 Roots doesn't seem to have any issue 1200rpm 800lbf-ft at 400 to 500". Maybe you are using too much timing? Or poor fuel quality to have those issues.

This is a 292" Blower engine has ~200,000 miles from a 2004 Silverado doesn't seem to have any issue, from Sloppy mechanics youtube (google sloppy mechanics for the dyno runs) always struck me as a great example of what you can do with low RPM boost.
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I guess you don't tune enough cars often enough to know what is possible even just using OEM headgaskets and OEM pistons?
500lbf-ft at 3000rpm is absolutely reliable with just 4.8L my friend, compare yours if you get a chance to see what you are missing.

Turbo selection is based on math. The engine itself makes a difference in terms of mathematics only, you can't just wing it. rofl
Yes we can blindly choose a much-too-large turbo and it will 'work fine', but you will never miss what you never had.

How much power can a 2L engine make with a 500hp turbo?
How much power can a 6L engine make with a 500hp turbo?

The answer might surprise you? (its the same thing!)

A larger diameter hose will kill vacuum signal, due to increased mass of fluid, so it is unwanted. Law of conservation of energy, momentum principle, flow work, etc... I guess you are not into much engineering applications. Luckily I have a fluid mechanics book handy and this is intuitive, I will post some fluid mech shortly

In OEM pcv applications (up to 1200hp using stock engines in my experience is fine) we want a short and small diameter hose to maintain gas velocity and low pressure which can utilize the smallest possible mass flow to get the job done. The larger the hose, the higher the pressure, the lower the velocity- It will work against evacuation efforts unless you have some kind of powerful external vacuum pump to supply the kinetic energy.

The size of the hole in an OEM valve cover sets the diameter which interfaces with the baffle located inside the valve cover. You can't open the hose diameter right off a valve cover with a 3/8" hole and expect anything other than complete and utter turbulence and failure, a massive zone of separation, disorganization, head loss.
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You would need to cut the valve cover open and re-weld some kind of extended volume edition baffle system... and the extra volume will kill the pressure signal so its not going to work that way in an OEM PCV application.

This 'small hose volume' is how all OEM turbo cars PCV works. For examples on OEM turbo engines using the same exact system:
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Its like you've never seen a factory turbo vehicle before, this is the OEM hose size they all use, nice and short and small diameter for OEM PCV systems. Calling BS On my setup is like saying all OEM manufacturers in the world are doing it wrong! Yeah sure

Next, Pitot tube does not establish any kinetic energy component from moving fluid. Lets use the book so we refrain from 'bs'
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Lets read carefully. " hence the height of the p/y line is called hydraulic grade line." We define p is pressure and y is specific weight of the fluid. Thus, our pitot tube does not rely on kinetic energy. Lets keep reading to make sure "The total Head (p/y +alpha*V^2/2g + z) is above the HGL by a distance of (alpha*V^2/2g)". It seems that the pressure divided by specific weight is the available energy for our pitot tube, as z is negligible with respect to compressible gas for intercooler plumbing, and the direction of the 'spout' tube is meaningless without some source for EGL supplied by the kinetic energy of moving fluids.

This is why I know that the direction does not matter and furthermore I've taken steps to show that it works in proof of concept- did you watch the video? 0.10volts of pressure drop on a typical 1-bar map sensor is approx .350psi or around 0.5 to 0.75" Hg of pressure drop which is IDEAL for a crankcase in my application. No need expensive vacuum pump with addl maintenance.

The book says I'm doing it right, and my data says I am doing it right, the only person saying "its wrong" is people without the math and science background and lmao its... kind of sad the hate that science and data generates sometimes. If real world data and mathematics won't convince those people- What will? Nothing! Nothing is what they get. They ignore it. They hide from it. Pretend it doesn't exist. "more BS INCOMING! ZOMG" Although their lack of mathematics when choosing a turbo sets the stage for an unfortunate mixture of parts which will not work well together, they will never know because they have nothing to compare it with. You can't know 'correct' until you experience it, and many never get to.