paralleled 2 he351ve for testing purposes no issues.
I figured you can parallel them. I was thinking of making a Y in the manifold and mounting one upside down reclock it, then half the turbo sizes I use!
I think you need a he561ve and do a compound ;D
Wanted to do something no one else thinks of, if a he351ve can do at least 400hp on a 5.9 then that's probably at least 600-700 on twins
It's pretty complicated to get the flow rates correct...
If you run the two turbos NON SEQUENTIAL (not compounded), you're essentially halving the airflow through each compressor, pushing you over closer to the surge line at a given pressure ratio...
If you're running them sequentially, you probably will also run the hot sides sequentially, which would probably require different openings.. Also, it'll require different compressor characteristics. With the hot sides sequential, you want minimal backpressure from the second turbo so that you maximize the pressure drop across the first, causing it to spool fast, and only once you get a certain shaft speed/ pressure ratio going you'd close the second one to get it going. With sequential cold sides, the bigger (first) turbo doesn't need to be able to make huge pressure (a 3:1 ratio is lots), as the second one (smaller) will easily compound that to a 10:1 total PR, but needs to be able to get a decent pressure ratio with no help from the first in order to allow the heavy fueling to spin the first one up...
It's easy to get something that half-works and looks cool, but really hard to design something that excels.
I think to get a working twin VGT setup you'd be forced into being able to control each one individually
what rx7man said perfect. I don't have diesel so one of you guy's should test this lol.
Did you guy's know a guy in the 30's was running over 100 psi boost.
If i can get my hands on a m2 holset for under 1k i'll put it on my 65 mustang. ;D
I don't see how the compressors inlet will be halved as twins, only the exhaust side will.
Literally need to cut the mouth off a manifold and just make a Y for testing. I'm sure the manifold will love a gillion pounds on it lolol.
I'm sure they can be paralleled, would it be better than a large single.. MAYBE. Pressure isn't the only thing happening to drive turbos, going to loose half the heat, etc etc. I would be more than willing to try it if someone would fab up a manifold for me :D
I wonder if there's any way to re-address the turbo... the other option would be to scrap the entire circuitry on it and have the lilbb control a BLDC motor driver, or have a second CAN controller.. neither of which are very pretty solutions.
The engine takes in so much air.. if you have two parallel turbos feeding it, each has half the air flow, but must still operate at full pressure, thus you're moving closer to the surge line... If you were to do this with either smaller turbos or bigger engines, it would work, but that's usually not as good a solution as a bigger (usually more efficient) turbo.
If they're sequential you have the problem of controlling pressure ratios and shaft speeds, and the primary (bigger) turbo needs to flow a greater volume of air than the secondary.
Note: I'm rewording my definition of primary and secondary to match what seems to be industry standards... Primary is the bigger, and usually first in the flow of the cold air, secondary (smaller, first to spool) is the one first in the line of the exhaust flow... it's pretty confusing.
If you had VGT turbos for both, I think you could effectively run both off the exhaust manifold and not run the hot sides in series.. at low boost ratios you keep the big one closed, open it up enough to get 80-100RPM, then start opening the bigger turbo's hot side, which will make it come on, though more slowly than in a series connection, the plumbing would be easier. It could be done, but I don't think it would be better.
sometimes theres a reason things are done the way they are, and compounded turbos are a good example.. I would LOVE to try it with a pair of VGT's though.. I think you could have some wicked results... I would look into a different compressor wheel for the 351 though.. one designed with less inertia to spool quicker, though with less pressure capability.. you wouldn't need to get 4:1 ratios anymore, 3:1 would probably be about right so you could throw the fuel at it quickly, but once the big one fires up that PR would drop to 2:1 or less...
Someone get me a bigger VGT that's CAN bus controlled and I'll do it!... Anyone got some 12V injectors that can throw the fuel at it?
Again twin turbo you combine the cfm of the turbo outlet, it doesn't get halfed otherwise there's no point in putting 2 on ;)
Which is why in a lot of twin turbo setups, you'll see 2 turbos smaller than a single, that flow more than a single combined, better bottom end, less top end.
ie:
2 200cfm turbos vs 1 350cfm turbo, even thou the 350 will make more peak
Yes, you combine the CFM of the two turbos.. each one is flowing half..
Now if you're doing this with a 351, that puts it closer to the surge line.. if you were to take a pair of hx30's you could probably do it just fine
This is only for parallel turbos of course
The 351 flow doesn't change, it isn't closer or further away from surging. They combine output in the IC piping.
If each turbo is running 60k @ 300cfm, you get 600cfm at the motor. But it isn't each compressor is considered to be running 600cfm on the sheet. They are still right in the middle.
My point is that at a given engine RPM, the motor can only ingest so much CFM.. it's a direct function of VE, temp, RPM, and displacement... Using 2x 351's trying to push 4:1 pressure ratios isn't going to work, you're bordering on surge at 2000 RPM using only one of them.
So 5.9L/2 x 2000RPM x .8VE = 4.4 M^3/min.. if you're running at 4:1 PR (44PSI boost) that's 17 M^3/min, or considering 1 m^3 is 35 cu ft, it's right at 600 cu ft/min.. that's the max amount of air the engine can ingest, regardless of what the turbo(s) are capable of producing.
If you have 2 HE351's in parallel *TRYING* to push 4:1 PR into a 5.9L at 2000 RPM, each one will be moving half of the 600 cfm, or 300 CFM, but each has to still do the 4:1 ratio.. thus if you plot that on the graph, you'll see you're WAY off into surge land, while if you only have one of them, it gets to move all the airflow, and it's sitting about as close to the surge line as you'd ever want to design it for.. 120,000 RPM, 600 CFM, and 4:1 PR.
Now if you were revving to 4000 RPM and kept a reasonable VE, both turbos would be happy at 4:1, while a single would be way out on the right side choking itself
this is about as good as we can get. holset m2
https://www.youtube.com/watch?v=7jXTAIBLWDQ (https://www.youtube.com/watch?v=7jXTAIBLWDQ)
I could only watch the first few seconds of that vid, looks interesting, but it looks VERY similiar to what the 3rd gen FD Rx7's had from the factory.. they were twin parallel turbo, and had TONS of problems because the controls to get them to work together were so finnicky and intricate..
There was the primary turbo, which always had no controls on it, but the secondary was a nightmare.. It had a valve in the cold side outlet to prevent backflow, as well as a bypass valve.. On the hot side, it also had 2 valves, one was a "prespool" valve that opened when the primary turbo built up about 9 PSI, it would open, allowing some exhaust to spool up the secondary, when it got going the bypass valve would close and the check valve would open, with very specific timing events.. and of course since everything was vacuum controlled with solenoids, one cracked hose anywhere would throw the whole thing for a loop.. it had so many sensors and solenoids it would make your head spin.. I got the car cheaper than asking because it wouldn't start.. it wouldn't start because the coolant temp sensor was broken and the ECU defaults to thinking it's at 210F, so it wouldn't go into cold start mode (simple fix!)
I ended up tearing the twins out and putting a T66-1 in with a Microtech ECU... 10% of the wiring, 200% of the power.. Yeah, you had to wait a little for the turbo, but it was worth the wait, 3500 RPM came along and YEEEEHAW... It's making over 500 RWHP now on that same turbo.
I'm going to try to convince him to put a lil'bb and VGT on it with a 68mm wheel.. I think even if peak power doesn't increase much, it'll be quicker
Wait doesn't VE go over 100% when you super charge *rolls eyes* kind of the idea behind 'forced induction'.
Volumetric Efficiency (and the REAL factor: MASS AIRFLOW), by EPI Inc. (http://www.epi-eng.com/piston_engine_technology/volumetric_efficiency.htm)
QuotetHere is an example of how useful that relationship can be. Suppose you decide that a certain 2.2 liter engine would make a great aircraft powerplant. You decide that 300 HP is a nice number, and 5200 RPM produces an acceptable mean piston speed (explained HERE). How reasonable is your goal?
The required VE for that engine will be:
Required VE = (9411 x 300 x .45 ) / (134 x 5200 ) = 1.82 (182 %)
Clearly that's not going to happen with a normally aspirated engine. Supercharging will be required, and you can use the 1.82 figure to calculate the approximate minimum Manifold Absolute Pressure (MAP) needed (1.82 x 29.92" = 54.5" MAP, or 24.6 inches of "boost") for that power level.
There's no theoretical maximum VE a motor can use boosting, until metal fatigues from pressure. That's how we make small motors pretend to be big motors. Going over the 85% VE
With VGT, I don't see why no one has actually twin'd a pair of 351's
my little 2.3 would have to spin 9000 rpm to reach full boost with twin he351.
Anything below 9k would be on the surge line.
I thought about twins on a 5.0 ford but found a nice he561 instead saved a little weight lol
A series parallel system would be neat for a lower boost setup.
Ya exactly, 2 800lbs turbos or 1 hanging off the motor.
I look at it where I can spool around 9-11cm, so I have room to go down. The downside of course is loosing the brake. Which is pretty dang handy.
It depends if you're talking about VE as compressed gas or VE as ambient air volume
I consider it as compressed gas, as that changes little with boost, and then factor in the pressure/density ratio when looking at the turbo.
Using the Compressed VE, it stays about the same as an NA engine, the point of max VE is probably close to your max torque, and you have numbers you can estimate.. if you use don't do it that way, your VE changes with boost and it's hard to figure anything out.
Your right, MASS air flow is the only thing that *really* matters when looking at power outputs, but VE will tell you how good a head design you have, factor in boost/MAF and you can get a good estimate of what power outputs are possible.. it's a little harder on diesels I think since they have a wider range of "happy" A/F ratios, depending on how much smoke and EGT's you're willing to push
Missed page 2
I think on cummins 5.9, a 561 over a 351 could be an interesting compound setup :).. If your have figured out a way to hold the head down, you could run about 20:1 pressure ratios, or 300 PSI boost.. that would be scarey!
reminds me of a tractor pull where the engine split just below the cylinder bores. only the crank and pistons were left in the engine compartment. now that's some boost.
There was one called "European maid", it wasn't running diesel, no smoke, but it had twin (or more) turbos, and it blew the top of the engine off, and he drove over the whole top end.. I figure it was running methanol or something exotic... I don't know how it happened, but you could see there was a flash in the turbo a split second before it all went to hell.. perhaps a valve stuck igniting the intake charge? Could be all sorts of stuff.
yep that's the one I was thinking about.
https://www.youtube.com/watch?v=qBF6iZfguF0 (https://www.youtube.com/watch?v=qBF6iZfguF0)
There was another one that threw a rod... and they shut it down, and it was just slowly spinning down, throwing rod after rod out the side of the block.
On that one, what I'm noticing is a lot of the wrist pins seems to have walked loose... Perhaps the keepers failed?
still catching up reading with everyone here from thier different other boards... been studying and
researching all of this. And this thread finally answered one question, can drive two vgt :)
On another note i finally did find he561vgt spec
70 or 71 in by 114
86 by 72 ex
16-36 A/R
11mm big through shaft
Is the address of the 561 different than the 351?
don't know most 561 are 24v my 5?? has a 73.6mm 105.8 mm comp 85mm 80mm turbine only one ive seen. and custom he351 actuator.
the measurements are of the wheels.
QuoteWith VGT, I don't see why no one has actually twin'd a pair of 351's
I am currently building a twin he351 setup.
454 chevy 8.5:1 with 320cc aluminum rectangle port heads and a Lunati roller cam. Custom EFI setup and water to air intercoolers. Should push my 3200 lb '74 Firebird nicely :)
Its a slow build thats been ongoing for quite a while, with a long way to go still. But I'll post here when I have good stuff to show.
It does make sense to do in a V8 application, also the airflow through a V8 gasser is WAAAY higher than on a cummins diesel, not only because of better port flows, but because of higher RPM capability.
I would try to find a way to have the left turbo feed the right side cylinders.. If there's any deviation between turbo characteristics, this will help even it out, though it would require 2 intercoolers :(
As long as everything is well matched, having both turbos commanded to identical positions should work alright.. I'd want to take shaft speed readings off both of them to make sure their workload is balanced.. There is a chance you might need to run a second CAN bus for the one of them if they aren't acting in unison properly, unless it's possible to re-address them
Right now I'm planning to use separate controllers, but programmed identically.
Both turbo's are going into a very big single plane manifold through a single 101mm throttlebody. To do the right feeds the left strategy would require a modified cross ram or Individual Runner type manifold, which would tend to provide a more peaky top end hp, but usually a lot less power "under the curve". Ok for drag race only setups where you stay near peak hp all the time but sucks for street/strip cars. Also that manifold type is way expensive, and my rectangle port manifold with a 4500 Dominator carb flange cost me under 200 bucks. I think manifold runner tuning and such is probably much much more critical on a performance gas engine than a diesel, where max hp, max torque and most efficient cruising rpm's are all fairly close together. Thats why I believe the VGT may actually show a larger advantage over traditional turbos on gas engines.
As for the intercooler, I am planning to use 2 water-air coolers. 1 would work, but I can shorten the plumbing even more with 2, and also keep the weight a little farther back, and in a 3200LB big block car I need to try to move as much weight as far aft as I can. Also water hoses are less bulky and easier to route than longer intake piping.
A custom VGT setup on a diesel is really like early pioneering right now, and on a gas engine its more or less exploring mysterious new lands. These are exciting times.
The conditions these turbos will be so very very different than what is needed on a Cummins, it will be very interesting to say the least.
But right now I have 2 other car projects and a CNC mill upgrade to take care of before I can do much more on the bird. I strongly doubt I'll get it on the road in 2017, probably more like summer 2018. and I plan to hold off on the controller hardware until near the end just so I will be running the latest greatest version when the time comes.
I watch this board a couple times a week and am very glad to have found it. My own attempt at controlling the VGT about 5 years ago was with a 32Mhz avrX-Mega, and got as far as building the driver to directly controll the Brushless motor as a servo. I just de-soldered the original circuit board from the motor and replaced it with a board design of my own that just interfaced the motor pins, hall sensors and the position sensor on the gears. I decided to relocate the electronics away from the turbo into the control box. Anyhow, My project got as far as motor control and GUI on a small graphics LCD. I never got as far as any actual real control logic. Even if I had the time, it would have taken me at least a year or more to even get half as far as the lilbb is now. I'm so happy to have found this site.
twin he351ve should spool good on a big block. my 2.3 starts getting boost around 1500 rpm .5 psi at 3000' elevation.
but around 3500- 4000 rpm she really comes alive at 4500rpm 30psi boost is no problem.
I look forward to updates on this as things go on... I love doing new and eccentric stuff myself.. I was thinking of putting a small turbo on my XR500, but the plumbing would have been too much of a nightmare with twin carbs and twin exhausts.. and I have enough trouble keeping a head gasket in it as it is :P
I think the turbos will be good for your application, though you may need wastegates in addition... Also, in an ideal world you may look for a compressor wheel that is designed to flow higher air volumes more efficiently at lower pressures... I don't think you will be able to make use of all the pressure these are capable of delivering, and if you can trade a little of that for volume it may be worth it.
Good luck with it all and keep us posted!
yep waste gates and higher flow compressor would be good.
Ya, I already figured I'll need wastegates, since the DSM guys need them with this turbo on a 2.2 4cyl. IIRC once they started making boost they said that even if they opened up the turbine all the way it still kept climbing.
I've got almost 3.5x the motor and only twice as much turbo as those guys.
I'll be starting with the standard HE351VE compressor and we'll see how that does for starters.
Right now I'm just using a cast crank/pistons 2-bolt stock 454 bottom end. I have a couple other 454's at my disposal and one of them is going to be used for a new 496 shortblock. Using a forged stroker crank, bad ass rods, forged blower pistons and of course splayed main caps. If it looks like the 454 needs bigger compressors then I'll probably do it when I swap out the shortblock later on.
But this car is a little on the backburner right now. I have 3 EFI conversions and a Northstar-Corvair swap lined up that have to get done first.
I also may be installing an HE351VE in my fathers 96 1 ton chevy with a 454 vortec. He says he just wants about 5-6 PSI and he already has the turbo and a dodge intercooler that he wants to use.
Anyhow I better stop before I run this thread too far off the rails.
I'm not sure on needing a wastegate, you won't be able to keep boost under 30psi, but surely shaft speed under 110k @ wide open no doubt.
My 5.9 can and will spool @ max open as well, but it can't get over 115 until 9k rpm
wastegates for sure, I dont intend to run over 15 PSI. I'm trying to keep the HP under 1100. Above that and everything starts getting way more expensive than I want to deal with on this car.
HAHAHA.. "trying to keep the HP under 1100"
I know, sounds ridiculous.
Here's what I've been looking at for a primary.. pipe dream.. cattle prices are down so I'm just window shopping
Garrett GT4202R Turbo (http://vancouver.craigslist.ca/rds/pts/5836395537.html)
I have data logs of shaft speed kissing 130k on a 2.3 32psi manifold pressure around 37psi at compressor outlet
If I ever build a exhaust manifold that does not leak i'll put the waste gate back on.