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Old 08-18-2007, 06:59 PM   #1
japslapr
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Default Redline. Who says when?

I was informed that the EJ205 should not exceed 7800-8k with stock heads. Reason being shims tend to slide out from the bucket and cause major problems as well as stock oil pump cavitaing causing oiling issues with bearings. Makes sense. Now... I have built my motor with shimless buckets and have a 12mm pump. NO shims to come loose and have a larger wheel pump to stop the oil from being "beat up" and oxygenated. So... good to go now, right? 8k-8.5k shouldn't be an issue. Well... why not 9k-9.5k. What else will cause problems up there? My rotating assembly has been balanced to .25g's. I know the weight of it is also an issue. This I have done nothing with. I'm running an OTS Stage 4 crower cam, +1mm valves.. none of which is lightened (not to mention running a completely sotck crank). What is "safe." When is "when?" I'm trying to get the 205 into the 10.'s and have no choice but to run a monster snail so the extra rpm will only help.

So... spin it to 9 or be happy with the 8.5 line?

(for those that have followed my build... the Green is gone. Nothing smaller than 55lb/min will be in its place.

-Derf
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Old 08-18-2007, 07:48 PM   #2
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Did you do anything to your valve springs? replace ,upgrade to a higher tension, or to titaniums ? that would help get you where you want to go
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Old 08-18-2007, 09:37 PM   #3
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Yeah... have the springs to run the cam. BC pieces.
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Old 08-19-2007, 11:55 AM   #4
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stress increases exponentially the higher the rpm you go. 7-8k, big difference. 8-9k...even HUGER difference.

IMO, keep it at 8k, unless its a pure track car......then try 10k and see where it gets you

BTW, Im interested in seeing if you pump all the oil out of the pan, into the heads, with that 12mm pump.....I hope you don't starve your bearings by cavitating if this does happen.
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Old 08-19-2007, 07:00 PM   #5
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well, your crank will be a limitation due to oil pump most likely...what oil pump do you have and is it worked over? bearing clearances?
also wonder how much side loading the block is going to see at 9k...being no sleeves or supports for the side of the cylinder walls.

Just to let you know fred, initially I'm spinning mine to 9200...then inching upwards to 10k to find the limit of the 12mm on my build.
Then I'm going drysump
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Old 08-19-2007, 11:48 PM   #6
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Reading up on piston speed helped me decide how far I was willing to go for a road, road race, car. I run to 8000RPM soft, and 8300 hard and have cams to help the top out.
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Old 08-20-2007, 04:36 AM   #7
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I thought about going external pump but thought Dry sump was a bit much for a car that will see 7k a year of road time. The block is pinned so there is some support behind piston walls. Pins were pressed in to help support the walls.

I was under the impression that the 12mm pump would help considerably with maintaining sufficient oil pressure without airating (sp?) the oil itself.
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Old 08-20-2007, 11:03 PM   #8
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well the 12mm pump has some areas that need massaging too...it isn't flawless but with flow higher volume...yes, dry sump would be overkill for what you are doing...glad to hear of the bigger, better turbo though...two stepping first gear and getting out of the hole will be nuts...
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Old 08-21-2007, 12:18 AM   #9
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How about an accusump to pick up any additional oiling stress at those RPM's?

In comparison to my dry sump setup an accusump setup is cheap!
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Old 08-21-2007, 01:10 AM   #10
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How about an accusump to pick up any additional oiling stress at those RPM's?

In comparison to my dry sump setup an accusump setup is cheap!
very true for a budget track car or a serious street/race car...for me though, I'm an engineering nerd so toy like dry sumps make me happy
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Old 08-21-2007, 07:06 AM   #11
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I guess I just figured that it was stock on JDM STi's... and they rev to 8k....Never heard of Accusump... I'll look it up.
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well the 12mm pump has some areas that need massaging too...it isn't flawless but with flow higher volume...yes, dry sump would be overkill for what you are doing...glad to hear of the bigger, better turbo though...two stepping first gear and getting out of the hole will be nuts...
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Old 08-21-2007, 12:00 PM   #12
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I guess I just figured that it was stock on JDM STi's... and they rev to 8k....Never heard of Accusump... I'll look it up.
IIRC, Not stock on "ALL" jdm sti's. Only ones with dual AVCS.....(which aren't very many)
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Old 08-21-2007, 12:42 PM   #13
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Old 08-21-2007, 05:19 PM   #14
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One question to ask yourself is do you need to go higher. Take away the reliability issue of the build for a second.

You need to look at the engine as a dynamic system. There are many variables that dictate where you make power. Your camshaft, your valve size and your turbo size are some of them. You mentioned those, but that still doesn't touch on intake manifold (runner length and plenum volume), head porting (shape and volume of the runner), compression ratio, exhaust backpressure, or anything of that nature.

Someone touched on piston speed which is an important element when trying to figure out how 'high' to take your engine. Sending it to an arbitrary 9500 is just that...arbitrary. You have to consider intake charge velocity and if it can keep up with the piston as it travels down the bore. Through that you have to decide what is the proper (not saying yours are necessarily incorrect) camshaft and cam timing for what you're looking to do (this has to do with dynamic compression ratio).

What turbo do you have? You have to consider where your turbo will run out of air...you have to consider what turbine and housing you have on the car to determine if it can support that airflow while maintaining a good ratio of boost to backpressure.

There are a ton of elements that dictate where an engine is efficient...if you make peak power early and torque falls off hard, shifting higher is just hurting you, not to mention all of the reliability issues we didn't touch on.

As a general guideline, you want to go higher in revs when your engine displacement is the limiting factor. When that is what's 'holding you back' per se, the focus of the engine build (if you're building it for peak power mind you) is to sustain high rpm torque which obviously translates into horsepower since they are a function of eachother. 300lbs of torque at 10,500 is 600hp. Perfect examples of this would be Formula One cars, they rely on rpm and high rpm volumetric efficiency to yeild high horsepower numbers.
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Old 08-21-2007, 06:06 PM   #15
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This is exactly why I was asking. I figured that displacement was going to be my limiting factor. All I've ever heard about as far as getting the motor to rev higher is shims and oil... never anything else so I was wondering why I just can't spin it a bit higher. I obviously didn't think about nor consider most of these other factors. I'm actually running a stock exhaust header right now... stock intake manifold (rotated)... So how do I play this out? Get the car on the dyno and see if it's continuing to make power as it approaches 8k? I had a 7cm Green and new that it would be well choked up before 8k. The SZ55 should have more room... but how much more? Will it be restrictive as well? I am NOT trying to destroy this motor so there is certainly a "for safety's sake" here.
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Originally Posted by Mark@RealStreet View Post
One question to ask yourself is do you need to go higher. Take away the reliability issue of the build for a second.

You need to look at the engine as a dynamic system. There are many variables that dictate where you make power. Your camshaft, your valve size and your turbo size are some of them. You mentioned those, but that still doesn't touch on intake manifold (runner length and plenum volume), head porting (shape and volume of the runner), compression ratio, exhaust backpressure, or anything of that nature.

Someone touched on piston speed which is an important element when trying to figure out how 'high' to take your engine. Sending it to an arbitrary 9500 is just that...arbitrary. You have to consider intake charge velocity and if it can keep up with the piston as it travels down the bore. Through that you have to decide what is the proper (not saying yours are necessarily incorrect) camshaft and cam timing for what you're looking to do (this has to do with dynamic compression ratio).

What turbo do you have? You have to consider where your turbo will run out of air...you have to consider what turbine and housing you have on the car to determine if it can support that airflow while maintaining a good ratio of boost to backpressure.

There are a ton of elements that dictate where an engine is efficient...if you make peak power early and torque falls off hard, shifting higher is just hurting you, not to mention all of the reliability issues we didn't touch on.

As a general guideline, you want to go higher in revs when your engine displacement is the limiting factor. When that is what's 'holding you back' per se, the focus of the engine build (if you're building it for peak power mind you) is to sustain high rpm torque which obviously translates into horsepower since they are a function of eachother. 300lbs of torque at 10,500 is 600hp. Perfect examples of this would be Formula One cars, they rely on rpm and high rpm volumetric efficiency to yeild high horsepower numbers.
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Old 08-21-2007, 06:32 PM   #16
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One thing i noticed that hasn't been mentioned is cross drilling the stock crank. Japslapr says his crank is stock and i thought that the staple for high rev ej's was cross drilling the crank? Or has this been disproved since i last saw that thread?


I'm really liking where this thread is going. Alot of intelligent conversation here.
except for mine
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Old 08-21-2007, 07:01 PM   #17
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Originally Posted by japslapr View Post
This is exactly why I was asking. I figured that displacement was going to be my limiting factor. All I've ever heard about as far as getting the motor to rev higher is shims and oil... never anything else so I was wondering why I just can't spin it a bit higher. I obviously didn't think about nor consider most of these other factors. I'm actually running a stock exhaust header right now... stock intake manifold (rotated)... So how do I play this out? Get the car on the dyno and see if it's continuing to make power as it approaches 8k? I had a 7cm Green and new that it would be well choked up before 8k. The SZ55 should have more room... but how much more? Will it be restrictive as well? I am NOT trying to destroy this motor so there is certainly a "for safety's sake" here.
Well I tell you what, EJ engines have a big bore and a decent head. They make alright power although from what I've seen they run relatively low timing numbers which hurts them. (I'm assuming it's for safety sake though so it's necessary).

The comments about shims and oil are absolutely worthy of mentioning, and honestly they are more important than everything I listed above because they have to do with the engine actually living...most of what I was discussing is just suiting the powerband.

There are many things to consider in terms of reliability and even oiling just past using a 12mm pump and keeping pressure high. There are things like bearing velocity at high rpm (the larger the journal, the more you're at risk in that regard), the oiling of the crank itself - dependant on the angles and radii of the crank's oiling holes, at a point it would actually be possible for the oil flow to slow, and potentially even start moving backwards due to centrifugal force.

As for the stock exhaust header, I haven't done any true testing on it in terms of backpressure at given power levels with given turbos, but it's most likely not going to be very efficient flow wise. If I were you I'd try to improve efficiency of the system before putting unnecessary stresses on the engine. You have to look at it this way, if you have a restrictive exhaust/turbine system, the burnt mixture has a harder time clearing the cylinder. What this does is effectively lower your dynamic compression ratio - which means there is less fresh air getting into the cylinder - aka less power.

I don't know if you're doing this yourself, if you are - Godspeed...otherwise if your shop REALLY understands how an engine works, they will be able to explain this to you. Sadly those shops are few and far between.

One word of advice though...don't make things too complicated if this is a street car, sometimes simple is faster, and it's more reliable almost always. I'm basically having an engineering discussion with you and these aspects usually would only need to be looked at if you were getting into a very competitive race class.
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Old 08-21-2007, 07:39 PM   #18
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relatively low timing numbers is actually beneficial so long as you have the heat (i.e. pressure) to make a complete burn (100***37; never happens though)...constant volume combustion is a wonderful thing and actually makes for higher bmep as less imep is lost with advanced timing (lots with rod ratio and bore sizing here too).
Yes, both intake and exhaust manifolds as well as port design and cam design all need to be addressed in a high revving build. Bore size also should be addressed too. Instaneous piston speeds and accelerations should be known to design your cam so those are already considered in this case.

with those rpms don't forget you get into the nitty gritty of individual cam lob timing if you really want to make peak power...that crankshaft does twist and an events "real" timing

then of course you have the quench height/rod stretch issue to work out too.
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Old 08-21-2007, 07:58 PM   #19
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Originally Posted by Homemade WRX View Post
relatively low timing numbers is actually beneficial so long as you have the heat (i.e. pressure) to make a complete burn (100***37; never happens though)...constant volume combustion is a wonderful thing and actually makes for higher bmep as less imep is lost with advanced timing (lots with rod ratio and bore sizing here too).
Yes, both intake and exhaust manifolds as well as port design and cam design all need to be addressed in a high revving build. Bore size also should be addressed too. Instaneous piston speeds and accelerations should be known to design your cam so those are already considered in this case.

with those rpms don't forget you get into the nitty gritty of individual cam lob timing if you really want to make peak power...that crankshaft does twist and an events "real" timing

then of course you have the quench height/rod stretch issue to work out too.
I absolutely agree that low timing is beneficial if you were getting that '100 percent' burn we are always looking for...my comment was more directed towards the fact that from what I have seen, these engines use comparatively low timing numbers compared to what you would normally see on a nearly 4" bore. As you obviously know, it takes a certain amount of time for the flame front to make it to the edge of the bore. This amount of time increases with cylinder pressure, higher octane, etc.

Maybe I haven't seen enough examples of high powered EJ engines, this is very possible.

I must admit though, I'm not sure that I completely understand what you saying with BMEP and IMEP. I think you are referencing the optimal 100 percent combustion which (obviously) has a higher BMEP. In reference to you saying less IMEP is lost with advanced timing, of course that's true since IMEP is simply an average of the cylinder pressure through a cycle of the piston. The sooner you light off the plug, the quicker the pressure is ramping up. If I misunderstood you, I apologize.

BMEP is really what anyone is after since it's simply a rating of how efficiently an engine is producing torque. The question is how long does the engine live if you give it that high BMEP.
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Old 08-21-2007, 09:38 PM   #20
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The question is how long does the engine live if you give it that high BMEP.
Who cares? As long as you beat the "other" guy
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Old 08-21-2007, 11:08 PM   #21
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BMEP is really what anyone is after since it's simply a rating of how efficiently an engine is producing torque. The question is how long does the engine live if you give it that high BMEP.
so true, so true...and you pretty much got the gist of the mean effective pressure bits...really don't like getting too technical in the threads as I like having most understand what is being discussed...so no more effective pressure talk from me

I must say I'm really anxious to see how my motor turns out, especially as my big custom pistons showed up today!!
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Old 08-22-2007, 12:50 AM   #22
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Jeesuz.

Please.. both of you remove your pocket protectors and tell me to.. or NOT to rev to 9k. LOL.... there was some talk going on that I wasn't even sure remained in the english language. Sounded more like modern day shorthand to me...lol, roflmao,ttyl,, bmep, imep, type stuff.

With the brains that have entered the room... you have to be able to give me a reasonable answer or calculated response. With a mods list I can provide.... I'm sure you could punch in some sort of algorithum (sp?)... TQ vs load, minus atmospheric pressure, divided by manifold pressure, sin, cos, bmep type ****.



This is WAY beyond me... I just want to make 450+awhp and run a 10.999999
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Old 08-22-2007, 12:57 AM   #23
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J
This is WAY beyond me... I just want to make 450+awhp and run a 10.999999
You can do that on a stock rev limit...stock block.

IMO, run the stocker to 7.5k.....you'll have lots of 450whp and 10.99's on a det free tune.
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Old 08-22-2007, 01:18 AM   #24
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you can make 450 with 8500 redline on your almost 30r...your cams will play a big role in how well you hold you top end torque...from there you will need intake and exhaust manifold work...
so yes, you can do that fred...
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Old 08-22-2007, 01:19 AM   #25
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You can do that on a stock rev limit...stock block.

IMO, run the stocker to 7.5k.....you'll have lots of 450whp and 10.99's on a det free tune.
keep in mind he's a 2.0...so 8k with a 30r will probably be more likely to be his shift point. if he has good cams it may carry a bit better
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