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+--- Thread: positive displacement blower displacement (/showthread.php?tid=5846)
positive displacement blower displacement - bricktron - 09-15-2014
hi folks! is this true or false? at sea level, an ideal 1.5L PD blower on a 3.0L engine, geared to run at 2x engine speed, would contribute nothing, since the ambient air is already at one atmosphere of pressure. at 4x engine speed, it would blow air at 2 atmospheres or 14.5 PSI boost.
apart from all the issues of heat and bypass - is that correct?
RE: positive displacement blower displacement - Hario' - 09-16-2014
No, a 3.0L 4-stroke engine displaces 1.5L per revolution (as 4 cylinder cycles requires 2 revolutions), so your 2:1 geared 1.5L PD blower will be displacing 3.0L per engine revolution while the engine is only consuming 1.5L.
Ergo: There will be 14.7psi at the manifold with a theoretical 100%VE.
With PB blower at 4x engine speed you would find a theoretical 45psi at the manifold but the charge air might be a bit hot hot hot..
RE: positive displacement blower displacement - bricktron - 09-16-2014
thank you Hario for your response! i forgot all about the four-stroke, 720 degree aspect. very helpful stuff, just what i wanted!
RE: positive displacement blower displacement - Eric78 - 09-17-2014
(09-16-2014, 06:50 AM)Hario Ergo: There will be 14.7psi at the manifold with a theoretical 100%VE.
With PB blower at 4x engine speed you would find a theoretical 45psi at the manifold but the charge air might be a bit hot hot hot..
If it's a Roots type or similar (like any Eaton/Magnuson model) they can't really do much more than 10psi reliably, they also don't do any compression inside the supercharger, they just move air, they use the manifold as a compression space so the manifold needs to be strong & intercooling is difficult. A Lysholm(screw) type can reliably do fairly high pressures, they actually do compress inside the unit, they run a little hotter in the unit itself but the charge temp is cooler & they are easy to intercool.
RE: positive displacement blower displacement - Hario' - 09-17-2014
Absolutely, but here in the UK at least, an Eaton M112 (1.2L) can be had for around £150, whereas any Lysholm is more like £4-5k, no matter how sexy they are they're reserved for serious investment projects here..
RE: positive displacement blower displacement - Eric78 - 09-18-2014
(09-17-2014, 07:15 AM)Hario Absolutely, but here in the UK at least, an Eaton M112 (1.2L) can be had for around £150, whereas any Lysholm is more like £4-5k, no matter how sexy they are they're reserved for serious investment projects here..
In Aus it's different, even an M45 is close to a grand & any larger Eaton is multi grands unless it's thrashed, but the Hitachi Lysholm from the Mazda Millenia/Eunos 800 can be had for a couple of hundred dollars.
RE: positive displacement blower displacement - bricktron - 09-18-2014
i think the eaton numbers are cubic inches. looked around last night and the M45 is way more expensive than the M62 or M90 here in the US.
RE: positive displacement blower displacement - Eric78 - 09-19-2014
(09-18-2014, 10:30 AM)bricktron i think the eaton numbers are cubic inches. looked around last night and the M45 is way more expensive than the M62 or M90 here in the US.
I thought they were CFM with a the zero taken off the end.
M62s & M90s might be cheap there because they were used on Buick v6s & arious Ford v8s, M45 was used on the 4 cyl Merc Kompressors, might be why they are less available secondhand.
RE: positive displacement blower displacement - Hario' - 09-19-2014
Wholy shit I stand corrected!
M then in3/rev!!
Taken from the Eaton FAQ:
Q: Supercharger model names… I am confused!
A: Eaton has produced many OEM superchargers throughout the years. The “M” series units are denoted only by their displacement in cubic inches. For example, an M90 is 90 in3/revolution. The newer TVS series superchargers are denoted by their displacement in cubic centimeters. For example, a TVS R2300 is 2.3 liters/revolution or 2300 cm3/revolution. There are different configurations of each displacement and they are not generally interchangeable. The aftermarket supercharger partner companies create their own prefixes but generally retain the displacement number. For example, “MP” series units are produced by Magnuson Products, “HTV” series units are produced by Harrop Engineering, and “E-force” series units are produced by Edelbrock.
Shit we are going to have to recalculate our SC gearing for our project having based it all on the figure after M being metric!!! LOL
RE: positive displacement blower displacement - bricktron - 09-19-2014
haha better to find that out before installation!
i think i figured how i would gear and bypass an M62 to support the low end on a twincharged OM617 but i haven't found the space for it yet. FWIW, at a 1:2.8 gearing i calculated that it would provide 1.9 bar. the efficiency peak is somewhere around 2300 RPM, about when the turbo kicks in. a smaller supercharger would be better but i won't even consider spending $1000 on one.
RE: positive displacement blower displacement - Hario' - 09-22-2014
Why are you planning to bypass? WOuld that be with drive disengagement also?
I ask because by compounding a turbo into a supercharger, the positive pressure from the turbo onto the supercharger inlet actually reduces the pressure ratio of the SC, allowing it to spin faster as revs rise and stay in a more efficient map zone.
I understand that practical application of this will be much more tempremental that the theory, but it overcomes the fundimental shortcoming of positive displacement cahrgers which is their inefficiency at drawing atmospgeric air through the inlet..
To be fair I am very biased towards my own schemes.. heheh
RE: positive displacement blower displacement - bricktron - 09-22-2014
Hario, good question. i was under the impression that once the turbocharger gets spinning, there is no use to expend any more power on the belt drive. i read one report online that an eaton bypass only parasitically used 1/3 HP, but of course no citation on that and i'm sure it gets worse at higher revs. the best possible bypass might be an EM clutch + electrical bypass operating in tandem as a kind of backup system.
i can't dispute anything you posted....
the last few days i've been figuring that if a similar controller device is necessary either way, it should be simpler to install an electrically actuated variable vane turbocharger rather than to twincharge. i think i can make a simple electrical controller more easily than i can (a) room and (b) a strong enough bracket.
RE: positive displacement blower displacement - Hario' - 09-23-2014
Ah I meant compound (series) the turbo into the supercharger for higher boost by multiplying the pressure ratio of each, not staged sequential as you suggest with a bypass.
Your supercharger would supply manifold pressure from idle, then as revs build and supercharger begins to become inefficient, your turbo(s) spool start to pump into the supercharger, bringing back its efficiency, and ofcourse compounding the boost (by multiplying the PR's together. But I agree packaging is an absolute nightmare!
if your SC and turbo are both capable of PR's of 2.0:
1 Bar (atmospheric) x PR2 x PR2 = 4Bar (-atmospheric) = 3 Bar boost (45psi)
Wooo..
RE: positive displacement blower displacement - bricktron - 09-23-2014
i admit i'm confused about the words "sequential", "series", and "compound" in this context. this arrangement pictured is like what i had in mind; the bypass gets triggered when the turbo gets boosting, since intake manifold pressure never need exceed 2 bar (i don't have a fancy injection pump yet). for goals of several bar, i'm sure other configurations may be better.
RE: positive displacement blower displacement - Hario' - 09-24-2014
Ah the above would be sequential (literally one at a time, one after the other) - PR of one compressor at a time.
Compounding would be series (literally both, one after the other in a chain) - PR's of both compresssors.
Parallel means both side by side feeding a common plenum - (turbos on each bank of a V8, both feeing the IM - PR of one comperssor.
MM you won't need to compound with out a serious pump, although the point of compounding is to have the advantages of a large and a small turbo but without the disadvantages of either, a 'side-effect' is very efficient high pressure ratios
RE: positive displacement blower displacement - Hario' - 09-26-2014
superturbocompound like so..
![[Image: SC-turbocompounddiagram.jpeg]](http://s1250.photobucket.com/user/Mercedes_Power/media/SC-turbocompounddiagram.jpeg.html)
RE: positive displacement blower displacement - F.R.A.S - 09-28-2014
We @ F-tune Performance have this in the pipe actually.
Our idea is to machine a billet chargecooler that fits directly on the cylinder head of the om605/606 in one end and bolt on to the Eaton m90 in the other (with the correct distance to the belt and so on...). Only thing to hook up is the water for the chargecooler and belt.
The turbo should boost through the intercooler and in to the chargecooler.
Most easy setup ever and I personally thinks that we have a winner with this.
Ergo: NO more custom intake or similar, just a big bad Eaton directly on the engine.
Thoughts on this?
RE: positive displacement blower displacement - CRD4x4 - 09-28-2014
Your idea is to replace the intake manifold with a water:air IC?
I like it!
(09-28-2014, 03:20 AM)F.R.A.S We @ F-tune Performance have this in the pipe actually.
Our idea is to machine a billet chargecooler that fits directly on the cylinder head of the om605/606 in one end and bolt on to the Eaton m90 in the other (with the correct distance to the belt and so on...). Only thing to hook up is the water for the chargecooler and belt.
The turbo should boost through the intercooler and in to the chargecooler.
Most easy setup ever and I personally thinks that we have a winner with this.
Ergo: NO more custom intake or similar, just a big bad Eaton directly on the engine.
Thoughts on this?
RE: positive displacement blower displacement - hooblah - 09-29-2014
I've seen it done before where people have welded the a/w cooler onto their inlet manifold. This sounds similar, but with a flange on the inlet side for the Eaton. Do you have a pic of what sort of design you're aiming for?
RE: positive displacement blower displacement - Hario' - 09-30-2014
How do you plan to make the SC pulley clear the PAS pulley?