legacycentral bbs

could anyone give me an idea or pointer to a place to look/person to talk to figure out a comparison between boost and compression ratio.

is higher boost = to raising compression? or am i just way off base?

for examples sake, is adding 8 psi of boost to a n/a motor w/9.5:1 compression the equivelant of raising an identical but N/A motor C:R to, say, 13:1?

i just used those values to illustrate my scenario i have no idea what they actually would be.

greg

BAM!

http://www.smokemup.com/auto_math/eff_cr.php
http://www-unix.oit.umass.edu/~tcroy/ar ... tivecr.htm
http://home.dmv.com/~carlb/sc/ecr-chart.html
http://www.rapidline.com/calc/turbo/pctcomp.htm
http://www.autocomponenti.com/boosted_t ... ession.htm

searched google.com for "effective compression ratio"

thanks jason

i cant belive i didnt think of that. great links. i need to do some homework.

so a high C/R n/a motor's ratio would be the static ratio while the c/r of a boosted engine that i would compare to the n/a is the effetive c/r?

greg

one of our engineers correct me if i'm wrong, but ALL engines have the static compression ratio, this is what your engine will always have at least. Since you are forcing induction on a boosted engine, this has the effect of more compression, hense "effective" compression ratio.

so a high C/R n/a motor's ratio would be the static ratio while the c/r of a boosted engine that i would compare to the n/a is the effetive c/r?

Yes.

so what is the highest C/R i can get away with in a ej22 N/A while still running the 92 octane swill i'm stuck w/here in ND? if i fugure out what the effective C/R is on a stock/mildly modified ej22t that still runs on pump gas i should be able to get away w/a similar C/R on my N/A motor.
i am getting closer to trying my phaseII ej25 block w/ej22 heads and want to do it as right as possible. of course i should just get a second set of heads and just try it rather than use my good 2.2 heads in case it blows up real good.

I don't think the effective CR on an EJ22T will give you a good idea of how far you can push a non-turbo EJ22; there's a lot of other stuff going on that affects knock tendency (high temperatures, increased fueling, retarded ignition, etc).

so i would need more fuel in a high CR motor?

any tips on how to do this?

i cant change cam timing, is that a problem?

how would i change ignition timing? retarding the ignition timing will help to prevent what exactly?

i could put a water injection system on it but what would i do in the winter?

greg donovan wrote:so i would need more fuel in a high CR motor?
any tips on how to do this?

Bigger pump, bigger injectors, and adjust the pressure.

how would i change ignition timing? retarding the ignition timing will help to prevent what exactly?

Ingnition timing can be changed with piggyback computers or a standalone.

how much more flow can i get out of the stock injectors? what do they flow at now?

how much more pressure can i squeeze out of the stock system w/a rising rate fuel pressure regulator? what is the fuel pressure now?

would turbo injectors and fuel pump be enough?

any tips on a piggyback computer to change ignition timing? and how necessary would that be?

greg donovan wrote:how much more pressure can i squeeze out of the stock system w/a rising rate fuel pressure regulator? what is the fuel pressure now?

rising rate bad. Adjustable good. Look for aeromotive fuel pressure regulators.

would turbo injectors and fuel pump be enough?

Depends on high you've planned.

any tips on a piggyback computer to change ignition timing? and how necessary would that be?

Emanage for piggyback. Necessity is base off your end goals. That's something you'll need to decide.

just found your link to the aeromotive stuff. looks spendy and cool. as for my goals i just want a little more power. and this project is basically free. unless i start adding on stuff to make it more reliable. what is more important fuel or timing?

if fuel is more important what is more important AFPR, higher flow pump or injectors?

if i had to spend alot of money i would not do this motor stuff i would buy a KAAZ front lsd for my car.

greg donovan wrote:what is more important fuel or timing?

They are both quite important and must be considered together when building up a car.

if i had to spend alot of money i would not do this motor stuff i would buy a KAAZ front lsd for my car.

I hate to say this, but i find myself repeating it more and more the longer i'm in the car community: If you don't have excess to spend, then do not undertake the project. I haven't known one project to NOT have creeping costs with it, a little piece here and a little piece there and some fittings here and some new hoses here... It all adds up. No money = no modification.

the appeal of this project is that it could be free. it is for my rallyx car as i will soon be buying another street car. or i will pull the good ej22 and get some used heads and slap them on the ej25 and see what happens in the name of science an the pursuit of more power. and if it blows up then we will all know what will happen and how far we can go wrt to CR.

From all the stuff I have seen......too much timing seems to be the more common cause of problems because people don't want to deal with it.....ie piggy backs, tuning, etc. Fuel seems to be something that is typically taken care of....people add larger pumps, larger injectors, rrfpr......but even then.....you really need some form of additional control for those injectors other then the stock ecu.

when you say timining. do you mean cam or ignition timing? since the emange controls fuel what would be a good piggyback for retarding ignition timing? or am i missing some of the features of the emanage. i really have limited knowledge in this are and really appreciate everyones help. this is a project that i will have a master tech. helping me with. more likely it will be me helping him.

emanage can control timing and do a lot of other things too, if you either get the emanage laptop connection thing or a profec eo1 boost controller/emanage programmer/datalogger

If you have to pull too much ignition to run a higher CR it may negate any power gain unless you put in higher octane and can bring back the timing. These engines are already relatively high CR, so I don't think there's very far to go before you'll be getting retardation unless you spend good money on tuning, but there goes your free deal... If you had higher octane available it would be a lot more effective.

Steve

sounds like water injection would be the way to go and find a way to keep it from freezing in the winter. unless i can find some 94 or 93 in the area.

I was mainly referring to ignition timing. The n/a cars have a lot more ignition timing then the turbo cars.....so if you slap a turbo on a n/a car....you need keep some of that in check.