im interested in pursuing making my ln2 a miller cycle engine, at 10 psi from a m90 charger (yes way oversize), how much of the compression stroke could i leave the intake valves open before the pressure feedback will be too much? im interested in pursuing any means possible to use an m90 to change my engine to the miller cycle & see what kind of mpg/power i get.

if you dont agree with this please dont try to talk me out of it, please just give me good advice rather than "OMG M90 uR TARD"...

Well, I think your missing the main idea of the miller cycle, however your concern is real. Let me explain. The miller cycle's advantage is to reduce power lost early in the compression stroke caused by not having an efficient lever arm. You need to focus more on timing this part right and then go from there...also keep in mind that when you delay the intake valves closing...another one will be opening so your concern is real, but not really as bad as you think. Also, do yourself a favor and get high compression pistons that will end up at a final CR that you had in the first place. If you do this you will actually have a net gain in power output...but not much. You will however get a nice gain in MPG if done right. Unless your doing this for a fun hobby it wont be worth your time. This is already done in the newer cars in the form of adjustable cam timing. The rule of thumb is the bottom 20% of the compression stroke(wikipedia) I can check my books but not for another 6 weeks since I'm not around them right now.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

the M90, or any other Roots style charger will not fit on the 2.2 LN2. only the Centrifugal type will. even then, mounting and location for it would be a problem.

Well honestly if your serious about building a miller cycle engine.....the "it wont fit" stuff doesn't matter. Most major components of the engine will change anyway and a fabricated intake manifold for a positive displacement charger will be about the easiest thing you will have to do.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Brad wrote:the M90, or any other Roots style charger will not fit on the 2.2 LN2. only the Centrifugal type will. even then, mounting and location for it would be a problem.

I bet you could get a T-bird M90 to fit just fine.





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my overall goal in doing this is to boost the power a bit throughout the torque range (not tons, but more than stock would be atleast) & to see just how good of mpg this combination could put out. id need to talk to someone thats good with cam profiles i guess.

SHOoff wrote:

Brad wrote:the M90, or any other Roots style charger will not fit on the 2.2 LN2. only the Centrifugal type will. even then, mounting and location for it would be a problem.

I bet you could get a T-bird M90 to fit just fine.

I would have to see what it looks like, and, where would a possible mounting location for it be?

it would be mounted in a similar fashion to how the supercharged ecotecs are.

you got it...just delay your intake cam profile enough to get a good torque arm on the connecting rod...thats all it is really. Throw a charger on it to make up for the lost airflow...I'd suggest going with a higher compression too...probly like a 10.5:1 or maybe 11:1(spec'd out in a stock fashion motor) Not sure how much lost flow your talking about but really but with a raised comp. you could gain alot of the power lost by keeping your final CR closer to stock.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Jon Mick wrote:it would be mounted in a similar fashion to how the supercharged ecotecs are.

so on the exhaust side?

st ill doesn't solve the problem of where the pulley would go, considering how close the intake already is to the firewall.

Step one is making sure you can even get cams made to achieve the goal, screw the 'position' of the charger. If there is a will there is a way...always. Position of the charger is like step 30, lol, you got a lot of bigger deal breakers to worry about first.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Your problem starts with the fact that as far as I know, with Crane Cams out of business, that no one makes a billet blank for the LN2 cam anymore. And a regrind is not going to be able to reposition the lobes enough to make a miller cycle cam, if I'm not mistaken.




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it would have to be a weld/regrind but im sure it could be done

Joshua Dearman wrote:Step one is making sure you can even get cams made to achieve the goal

x2

unless you're really strong, I doubt you can alter intake and exhaust timing separately on a one-cam engine.

also, do you think the loss of compression and the parasitic drag of a supercharger will be negated by the boost generated?
My initial instinct would say no in big, huge, fat, capital letters

yes it will. Your looking at it wrong. This is why you have to use a positive displacement SC and if you think of the engine as an air pump....figure it up in hp/lb/min of air flow and account for the additional losses and add the gains....then setup the charger so that it will surpass the net overall power loss...it will be possible to make more power. It wont be more power than if you left it alone..persay, but it could be very close if you have the ability to endlessly make cams or make some adjustable cam gears(assuming you got the right duration the first time) and fine tune it. It's going to just be a hobby.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

adjustable cam gears? for a single cam?

how ware you going to adjust intake timing without adjusting exhaust timing when both lobes are on one cam?

the only way to get the timing right is to get the cam profile right. if you had a twin cam you'd have more flexibility but last i checked.. the OHV is a single cam engine.
seems like a pretty narrow margin of error there.. gonna be some $$$ in a few different cam profiles if it isn't right from the start.

^You just proved my post exactly. If you got the duration right...you can use adjustable cam gears if you just need to fine tune when the valves open...duh it's a single cam. The easiest part of this build would be to figure out the duration and go from there(although it would be fixed)....do you understand what is actually trying to happen here? If you get it wrong...yes, you will be grinding another. But on paper you can take the cam profile and work up the optimal miller compression stroke and make up your cam profile...then depending on performance you 'can' adjust the exhaust depending on what the changes cause in your combustion properties.

An adjustable cam gear just might save you from a second grind...see why I mention it now?



Edited 1 time(s). Last edited Thursday, July 30, 2009 10:48 AM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

What compressoin ratio pistons are you going to use? How can u be sure that the supercharger will take less less energy then the piston would use doing the same work?

Quote:

...then depending on performance you 'can' adjust the exhaust depending on what the changes cause in your combustion properties

huh? how can u change just the exhaust....



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You can't but in a miller cycle....the intake is very flexible. If you find that you have some kind of ghost knock or something from an improper duration but you have the miller just perfect....you would normally have to go machine a whole new cam to get it right. Instead you can adjust the cam to 'fix' the exhaust issues and the miller cycle will result in much less impact in performance.


"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Quote:

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Irony at its finest




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i see what you are saying, because with the miller cycle cam grind you can use the adjustable cam gear to change the exhaust timing while lessening or increasing the miller cycle (the period of time that the intake valves are staying open & the SC is doing the compression work-so if you took this into account for your cam grind it most likely will save you from a regrind or if it doesnt it will give you room to play around & see what works best without having to regrind each time.

hes not saying you adjust only the exhaust, thats not an option & hes posted knowing this-hes saying the amount of the cycle that you allow the SC to do the compression work can be played with if you have your cam ground with that in mind & do your homework.

Sorry...double post....I fail. Please see below.





Edited 3 time(s). Last edited Thursday, July 30, 2009 8:37 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

^thank you...I guess that's not coming across in my posts. My point is: Use adj. gears to help dial in the cam...I dont care how many calculators you want to push, it will never be exact until you try it. Giving you a way to dial it in could just save you from another grind. But by all means it's not required.

PJ, I think you read my reply wrong....I wasn't saying the adj. cam gears will change intake and exhaust lobes independently.....I skipped over that sentence in your post....LOL...my bad. I was replying to this part:

DaFlyinSkwir(LS61) /PJ/ OEM+ wrote:

Joshua Dearman wrote:Step one is making sure you can even get cams made to achieve the goal

x2

unless you're really strong, I doubt you can alter intake and exhaust timing separately on a one-cam engine.

also, do you think the loss of compression and the parasitic drag of a supercharger will be negated by the boost generated?
My initial instinct would say no in big, huge, fat, capital letters

JerseyJayLN2 (Scarab) wrote:

Quote:

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

Irony at its finest

JerseyJayLN2 (Scarab) wrote:Your problem starts with the fact that as far as I know, with Crane Cams out of business, that no one makes a billet blank for the LN2 cam anymore. And a regrind is not going to be able to reposition the lobes enough to make a miller cycle cam, if I'm not mistaken.

LOL....like the quote, you sum up my position entirely. Do you really think not having cam blanks would really stop somebody from making a cam much less an engine into a miller modified cycle 4 stroke that wasn't meant to be that way? OMG...what are we going to do....there's no cam blanks batman!?!?!

If you really want to make a mod like this....not having cam blanks will not be your biggest problem much less much of a problem anyway.


Edited 2 time(s). Last edited Thursday, July 30, 2009 5:52 PM

"Never argue with an idiot. They'll drag you down to their level, then beat you with experience!" -Anonymous

yea, i think we were arguing different points here which is where the confusion came from... oh well...


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