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BOOST 101

5K views 34 replies 11 participants last post by  Bryan071973 
#1 ·
BOOST 101
The topic at hand is that we have to know what we are talking about here. First of all it seems that Mr."Xedos" is the only one that raised his hand and knows that the Miller cycle engine has about 14 PSI from the factory. But we seem to have certain individuals that think that with a increase to 9 PSI the motor will dyno 234 hp to the wheels. Now class add 30% loss on the dyno would be about 275-280hp to the crank with ONLY 9 PSI? That would be more like 120 hp! Are we being truthful class? Lets keep it real. NOS is the only way to get numbers like that without boost and you will probably fry the blower. That motor is very sensitive so be careful who you listen to mod-wise.Dont throw out anything because you dont know who might read it and just say "not another one" Class is in sesson_____

Depending on the blower or turbo size 1 PSI = 7-10 hp. SO FOR THOSE THAT DONT KNOW 3 PSI/30HP WILL MAKE A BIG DIFFERENCE.On a small blower or turbo 15 PSI will feel like 8 PSI on a larger application and vise-versa. Smaller blowers like ours spin faster to make small amounts of power. When a big Vortex blower will make big power with only 6 PSI. Our blower spins at over 10,000 rpms which a pulley 1cm smaller may create 5 psi but the shafts may be spinning faster than they are designed to withstand which will result to 0 psi/ $$$.It takes money / research / trial & error to make a reliable upgrade. Any questions? :shifty:
 
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#2 ·
what the hell are you talking about. sea level pressure is 14, which means 9 would be making 23, which just isn't happening, the miller-cycle engine pushes about 21 at peak. not to mention you will not see those kinds of power increases.

I'v said it before and I'll say it again, if your not happy with a car unless you need to completly change it then you brought the wrong car. My millenia's certainly not the fastest thing on the road, but it has its strong points, it has teh style, its not a cookie cutter type car, and its damn fun to drive.
 
#3 ·
Originally posted by Platinum Miller cycle@Jun 2 2004, 08:33 PM
BOOST 101
The topic at hand is that we have to know what we are talking about here. First of all it seems that Mr."Xedos" is the only one that raised his hand and knows that the Miller cycle engine has about 14 PSI from the factory. But we seem to have certain individuals that think that with a increase to 9 PSI the motor will dyno 234 hp to the wheels. Now class add 30% loss on the dyno would be about 275-280hp to the crank with ONLY 9 PSI? That would be more like 120 hp! Are we being truthful class? Lets keep it real. NOS is the only way to get numbers like that without boost and you will probably fry the blower. That motor is very sensitive so be careful who you listen to mod-wise.Dont throw out anything because you dont know who might read it and just say "not another one" Class is in sesson_____

Depending on the blower or turbo size 1 PSI = 7-10 PSI. SO FOR THOSE THAT DONT KNOW 3 PSI/30HP WILL MAKE A BIG DIFFERENCE.On a small blower or turbo 15 PSI will feel like 8 PSI on a larger application and vise-versa. Smaller blowers like ours spin faster to make small amounts of power. When a big Vortex blower will make big power with only 6 PSI. Our blower spins at over 10,000 rpms which a pulley 1cm smaller may create 5 psi but the shafts may be spinning faster than they are designed to withstand which will result to 0 psi/ $$$.It takes money / research / trial & error to make a reliable upgrade. Any questions? :shifty:
you're going to want to pull up a chair and take a seat in the back...

its too late for night school, but i'll make sure to step in and lecture tomorrow...
 
#4 ·
I made a correction (Depending on the blower or turbo size 1 PSI = 7-10 hp not psi) Also I am not relating boost to sea level variation. No matter where I have driven my car in the country high or low my boost is always between 14.5-15 PSI. Now maybe you guys can educate me on the sea levels and how they effect boost. I do know that denser or thinner air vs the temperture will effect power but no matter what sea level I will still get 14.5-15 PSI unless my blower is going.When you have compressor rotors spinning at rpms of 21,000 and up to 35,000 you have to be sure of how much more it can handle without upgrades.Then what fuel / spark and air mixture adjustments or upgrades need to be made.

BHRpowered I agree with you that, if your not happy with a car unless you need to completly change it then you brought the wrong car. The Millenia is a beautiful
car and satifies me. But I have to step up for all of us when someone is not being truthful or just trying to falsely impress with numbers like 9psi from a miller cycle= 234hp. I am not Einstein but I know a lot so if I am missing something tell me I am never too old to learn.
 
#35 ·
Where would you find a pulley at for the 2.3. I ported the heads and intercooler pipes plus i put on a cold air intake and made a ABS box around the air filter so it doesn't get hot air. I know that motor inside and out. I replaced all the vacuum lines and T's with brass ones so they won't crack again. It runs like a top. I put a Boost gauge on it and yes it only makes 14 psi but recently it's only making 10 psi but i cant find anything wrong with the motor. Any suggestions? Im car carguy on the mazda forum. I was thinking of putting a fogger in the back charge tube after the intercooler and a fogger in the front after the intercooler. Wet kit with y-blocks. Starting with a 50 shot. What do you think teach?
 
#5 ·
I don't know much about FI so I will take up a seat and listen to whoever has something to teach. I will be cross referencing of course so please no one talk out your ass. Oh by the way a 30 percent loss on the dyno sounds like to much, but if it were correct or evev close that would mean I already had 194 hp at the crank and 202 tq. Like I said, it sounds a little high.

Marcus
 
#6 ·
Originally posted by ///BHRpowered@Jun 2 2004, 11:37 PM
happening, the miller-cycle engine pushes about 21 at peak.
why does press kit say 28 psi?
 
#7 ·
today's reading lesson:
http://www.stealth316.com/2-3s-compflowmaps.htm
it's about compressor flow maps, but there's info there pertainant to what we're discussing. Read sections "Air Flow" and "Pressure Ratio"

Please note that horsepower is calculated using mass flow in lb/hr. For example, 30 lb/min is 1800 lb/hr of air flow. At a 12:1 mixing ratio, 150 lb/hr of fuel would be needed. Using a brake specific fuel consumption (BSFC) of 0.5, that 150 lb/hr of fuel might produce 300 crank horsepower. For an engine able to use this much flow from two turbos, 600 bhp could be developed.
Boost pressure means jack unless there's the volume to back it up. I mentioned in another thread, you can take a turbo off a greyhound bus and put it on a civic, and get 75 extra horsepower from 1psi BECAUSE you're getting so much more air.

I've never found definate numbers for flow with the milly's supercharger. I've seen extremes on both ends, many people saying it delivers 14psi. You gotta ask yourself though, how many car companies run that amount of boost from the factory? current GM vehicles that are FI only run about 6psi, and from my recollection mazda had the 3rd gen rx-7's turbos running at 7psi and 10psi respectively. True, the milly's SC is on the small side so to make up for that it probably has to run higher boost, but i wouldn't say it goes higher than 12psi at WOT, and probably runs anywhere between 4-9psi during regular driving. It sure would be nice to know how many CFMs it flows at!
 
#8 ·
This may be terribly ignorant but hey I am interested to know due to possible future projects. Isn't the reason the milly psi is so high due to the phase at whhich the air is pushed into the cylinder due to it being a miller cycle. I always thought it was compressing air in during the exhaust or filling phase of the engine. Can't remember exactly what I read. Anyway continue on.

Marcus
 
#9 ·
I think the A4 1.8 runs at 14psi stock.
 
#10 ·
The Audi/VW 1.8T runs about 12psi (11.6) stock older models run 8psi. Thats my other car.That little turbo makes 12psi feel like 8psi on a big turbo. That is the whole reason the Miller cycle has to run 14psi to make up for how small the blower is. Have you looked at how small the compressor is lately? The GM 3800 blower is much larger with more power/less boost but no where as efficient as ours.

FOR REFERENCE:
Intake valve duration is from two degrees before TDC until 70 degrees after BDC, while the exhaust valve duration is from 47 degrees before BDC to five degrees after TDC. The intake valves remain open for around an additional 30 degrees of crankshaft rotation beyond "normal". This kind of valve timing reduces the effective compression ratio from 10:1 to a little under 8:1.
Unusual is the fact that the compression stroke is reduced but the power or expansion stroke remains the same. This is one of the critical points of difference from the Otto-cycle engine where the relationship between the expansion and compression is the same.

In the Miller-cycle engine, however, this is where the compressor comes to the rescue. Any loss of intake charge through "back flow" is more than compensated for by the density of the charge provided by the compressor. Under these circumstances, the Lysholm compressor is more efficient (lower pumping loss) at carrying out the job of filling the cylinders than a reciprocating piston.

The Miller-cycle engine leaves the intake valve open during the part of the compression stroke, so that the engine is compressing against the pressure of the compressor rather than the pressure of the cylinder walls. The result is a increased efficiency of about 15%.

The highly efficient Lysholm compressor consists of a male and female rotor, with three and five lobes respectively. Rotor speeds are up to 35,000rpm for the male and 21,000rpm for the female. Maximum discharge pressure is up to 150kPA / 1.0 Bar. Advantages of the belt driven compressor include no lag, non-contacting rotors and none of the temperature extremes associated with turbocharger operation.

1.0 Bar =14.22 psi PRESSURE CONVERSTION ?kg/cm2 x 14.22=? psi
example 0.5kg/cm2 x 14.22= 7.11 psi
So guys if we want to fabricate a pulley the motor/compressor should be able to handle about 3-5psi more.Here are some pulley specs: from 3.12" to 2.93" = 3psi
The miller cycle pulley is 4" so a 3.7-85" pulley should give about 4psi.Then we would need bigger injectors, chip or AFC and possibly a new intercooler set-up.



You might find this interesting http://www.fastlane.com.au/Reviews/mazdaeunos.htm
 
#11 ·
Not a bad explanation. :thumbsup: Cleared up some things pretty well.

Marcus
 
#13 ·
I am not trying to impress anyone with knowledge or numbers. Im just here to help and in order to successfully inform each other we have to do our homework. ;)

The main problem with our cars that I see is the intercooler system.We cant increase boost with core temps at 80+ at times which is very bad. The system, no doubt, is a engineering marvel and amazing to look at with its ram air hood.But Mazda made it that way for convience so that the motor/intercoolers dropped in as one unit. I noticed the a hugh difference when the intercooler core temp. is lower. But if you have ever removed the units you will see that a they can not be replaced with a FMIC. The system has a perfect balance of the intake charge from each core to be compressed by the blower. If it was 1 intercooler we would be in business. But with 2 the piping to the FMIC would have to balance from the center point at top of the blower where the OEM piping bolts up.And dont even try to mount a FMIC in place of just the front intercooler.

So instead of repalcing the units we can use several solutions depending on your wallet: (cheapest to high dollar) 1) water sprayers (for intercooler) 2) Nos sprayers(for intercooler) 3) Alcohol injection (also possible #3 and 1 or 2)

Then we can up the boost (via pulley)because the cores have metal end-tanks and can handle more boost.
 
#17 ·
Fuck this is a long post, but I'm bored so...

It's possible for a more efficient (larger) compressor @ 10psi to make more power on the same engine versus a less efficient (smaller) compressor @ 15psi. You can only go so far though or you begin to violate the laws of thermodynamics. You also have to take into account the parasitic losses of the supercharger. A turbocharger is basically the same principle without the disadvantage of the parasitic loss since its powered by the free energy of the exhaust to spin a turbine. You can increase the boost all you want on a turbo car until you either blow a head gasket or burn out the turbo (well, not really, but to keep things simple...).

A supercharger, however, will sap power from the engine during its operation just like the A/C compressor does (car's slower with the A/C on, right?). Install an overdrive pully to increase the boost and the load it places on the engine also increases. At some point, the additional load cancels out the hp gained by increasing the boost. Superchargers and turbochargers are designed to be most efficient at a certain flow range. Increase it too much and all it begins to do is heat the air going into the engine instead of compress it. That's why you typically have to upgrade the supercharger/turbocharger to increase the boost much. It really depends on how much "reserve" is in the factory design.

The S isn't the most mod friendly. If you want a project car, go pick up an early '90s Eclipse GSX all-wheel drive with 200k miles and bad paint for $700. Get a $30 boost controller, ditch the factory exhaust, fill up with race gas and run low 13 second passes at the local quarter mile track. Upgrade the clutch and drive it like you stole it and 12 second passes on street tires is repeatable.

Since you have a Millenia and presumably drive it on a daily basis, install a respectably quiet high flow exhaust (headers too if you can), do what you can with a cold air intake. If there's a proven ECU chip mod out there, that might be a good next step. If you can manage it, maybe an extra 2psi of boost with a pully, but only after you've done everything else. I don't think I'd take it any further than that. All those mods should work with the factory fuel system without having to go to larger injectors, an AFC, or any of that stuff. At most, I would rewire the fuel pump with some heavy gauge stereo amplifier wire to increase the voltage. The flow capacity of a fuel pump varies dramatically with voltage. One or two extra volts at the pump can be almost as good as a fuel pump upgrade and costs practically nothing.

The above mods would definitely give a noticeable increase in performance. If it's still not enough, what can I say except you've outgrown your vehicle and it's time to go car shopping.

BTW...

The second generation Eclipse turbos peak at nearly 15psi with the factory boost control solonoid. The first generation Eclipses came with larger turbos but only peaked around 12psi from the factory. At sea level, a factory second generation Eclipse will pull away from a factory first gen every time because of the higher boost. However, place the same two cars at an altitude of 20,000 feet and perform the same drag race and the first generation Eclipse is now beating the second gen even though they're still running their factory boost. Why? Because the first generation Eclipse has a larger turbo hence it's more "efficient". Design attributes of supercharges/turbochargers also affect their efficiency. For example, a turbo with a ball bearing turbine shaft has less friction and is more efficient. Okay, I think I'm done for now.
 
#19 ·
Clue the 1st gen has 195hp / 2nd gen has 210hp /auto 205hp.

Millyowner thats some good shit on DSM's / you are exactly correct except for a few things. The first gens boost is more like 10psi stock and it has more than a larger turbo when compared to the 2nd gen. The 1st gen has larger ports in the head/ larger intake manifold/larger TB in addition to the larger DSM 14B turbo.The 2nd gen has a smaller Garrett T25 ( similar to a 11B). Also the 2nd gen would pull the 1st gen off the line but from a roll the 1st gen would win / pull on top end.The info on thermodynamics is on point but a simple solution to solve that problem is like you said not to over exceed boost levels and a bigger/more efficient intercooler.
 
#22 ·
Originally posted by Platinum Miller cycle@Jun 6 2004, 10:21 PM
:clap: OK I get it you just want some attention. Did we leave you out? Sorry grown men talking. Bed time Shadow. :zzz:
no, that sounds more like you...

you obviously don't know me and that i know a helluva lot more than you do...

mabye its you that should go to bed, you're wasting everybody's bandwitdh having to read all your nonsence

you post all these grand posts about how you know so much... well, i'm not impressed because none of your theories back themselves up...

take for instance the intercooler theory...

there are many other cars than the millenia that use 2 intercoolers that are converted into one FMIC... you know all that is required here???

just plain and simple math.... (which may still be over your head)

your TB theory is also incorrect...

yes, there is a gain... but there would probably be more of a gain from you taking out your spare tire than from doing this mod. you throw around unbacked numbers and claim there is a difference which YOU WOULD NOT BE ABLE TO TELL WITHOUT A DYNO... just not goin to work pal.

i've researched, learned, studied, and worked on these engines a helluva lot longer than you have, and if you think i'm wrong, you're sadly mistaken.
 
#23 ·
SOOOOO.............If you know so much then why dont you help us that arent so intelligent as yourself instead of bashing others ideas MR BRAINS. Unlike yourself I have given ideas that I know work on MILLENIAS to help these guys since the aftermarket world has forgotten the MILLENIA. Do you even own a MILLENIA? Hell why dont you go and invent a new motor that runs on NOTHING. Since I am full of shit, a asshat and dont know anything. OH I forgot bad in math, Lets here your ideas (that will work) on making more power from the 2.3 or 2.5 MILLENIA MOTOR that wont cost a arm/leg. Dont forget we need PROOF / DYNO slips / Quarter mile MR.BRAINS. ;)

By the way I had a 02 RSX (piece of shit) thats why I flipped it.
 
#24 ·
I think it's time someone intervened. Platinum Shadow is our self proclaimed No It All and Periodic Asshole..........Just some FYI for you.
 
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