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Old 04-16-2004, 03:34 AM   #1
firealhrdcor
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Default revvvs.......................

Hey,

Ive had my 99 rs for a little over a month now. And Ive been reading alot and wondering alot. Our 2.5's have just about the same stroke as a honda b16, which my friend has, and he can rev to 8500 all day long. I know my bore is wayyyy larger than his but arent revs really based on crank speed and stroke?

Ive read of some guys with the ej22's revving over 8. But is there a reason a 2.5 wont? If I added the extra fuel necessary and did everything else. Would it be harmful for me to get more than 6200rpm's out of my motor?

Just curious I guess, not really intent on doing this anytime soon, just trying to figure out why us subaru guys cant rev to the sky like hondas and such.

thanks, later

Chuck
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Old 04-16-2004, 09:20 AM   #2
Pat L.I.
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there are ways to raise the rev limiter but the reason no one does is because we make absolutely no power up there!

If you start getting into full N/A builds then you will start benefitting from a raised rev limiter. Check out posts by Dcoty
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Old 04-16-2004, 12:18 PM   #3
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Your engine is not capable of spinning that fast in stock trim. You could raise the stock redline to 7,000-7,200 and not have any problems (just shorten the longevity). You will need a decent cam grind to make it worth while, and valve springs to control the valve train with upgraded cams and a higher redline.

You have most of the "equation" for RPM, but you forgot an important part, Your firends rod ratio is much better for higher RPM. With shorter rods, the peak accelerations of the piston are higher, and hence maximum piston velocity (what really limits RPM after the parts can physically absorbe the bating) is higher for a given crank RPM.

You can still get 8,500 RPM if you really want it, but it requires a complete engine build, and the cost is substantial. If you really want lots of R's, buy a S2000. It will cost less, and you can still have a factory warrenty in a fun (ie. NOT FWD car) vehicle.

cheeRS,

Greg
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Old 04-16-2004, 10:56 PM   #4
firealhrdcor
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Ok, good stuff guys
thanks for the replies

-chuck
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Old 04-16-2004, 11:01 PM   #5
Kostamojen
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You might want to look into the JDM EJ N/A motors with AVCS heads (variable valve timing), they can and do rev higher than our N/A engines. Also note the new 6-cylinder engine in the Legacies, it has AVCS heads and can rev to like 7500rpms.
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Old 04-16-2004, 11:39 PM   #6
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wow, its cool how i got flamed....but this guy didn't
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Old 04-17-2004, 12:16 AM   #7
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Wonder what it would take to get 7,000 rpm out of it?
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Old 04-17-2004, 08:12 AM   #8
obyone
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Quote:
Originally posted by Alpha_32
wow, its cool how i got flamed....but this guy didn't
You probably came off as an ass.
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Old 04-17-2004, 09:44 AM   #9
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Quote:
Originally posted by obyone
You probably came off as an ass.
hehe not really all i said was

Quote:
any chance of getting to 8k?
and all of a sudden i was a "ricer" as piker so eloquently put it
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Old 04-17-2004, 11:24 AM   #10
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Quote:
Originally posted by jasona
Wonder what it would take to get 7,000 rpm out of it?
Valve springs, and a more agressive cam.

cheeRS,

Greg
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Old 04-17-2004, 11:49 AM   #11
Patrick L
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Well you guys are missing a few things. zzyzx has been running a higher redline on his autocross/road race RS and has had not problem. The reason we autocrossers do it is for the longer gearing. No more toping 2nd out at 55mph.
You can do spring and cams and that's all good but what are you going to do about the oil. The problem Steve ran into with the higher redline is the oil starts to pool up in the heads and even worse in heavy cornering loads. He's looking into run a dry sump system to help prevent this. You can also run breather filters on the valve covers and keep the crank case line hooked to the intake to create a vaccum just in the case to help suck the oil out of the heads and get it back to the pan. BTW, the crank in the block without rods and pistons is good for 10k rpms. This is from Techworks.
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Old 04-17-2004, 11:50 AM   #12
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Quote:
Originally posted by Alpha_32
wow, its cool how i got flamed....but this guy didn't
maybe because he actually provided a reason for asking it. Not saying "I just want to rev to 8k rpms!".

case in point:
http://forums.nasioc.com/forums/show...hreadid=537070

just let the issue die jason.
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Old 04-17-2004, 12:45 PM   #13
piker28
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yo yo man i wantz 2 be like alpha 32 and be pushin dat needle buff 8k with my nawwss flow hittin and the car goin vRROOOM





you ricer





"all comments above pertain to alpha 32 not the maker of the thread"
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Old 04-17-2004, 01:13 PM   #14
dcoty
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I rev to 8k and I my motor failed due to oil starvation because of the design of the block.

Subaru blocks only have 3 oil ports to the 4 con rod bearings on the crank. The two middle bearings are fed by only one port (these two bearing are what failed on my car) and the two outer bearings each have their own port. This explains why my oil was black at 3000KLM. So to fix this the shop who has the motor now is going to restrict the two outer oil ports to increase the flow to the two middle bearings. Also an upgraded oil pump will be added and an oil cooler.

Dry sump would be nice but I think its oretty $$ to get it done.

Good luck on your car, a redline of 7k is fine with the proper supporting mods such as springs and properly ground cams. 8k gets a little more tricky as i discovered!

Dan
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Old 04-17-2004, 03:05 PM   #15
Section 8
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Quote:
Originally posted by Top_Dog
Well you guys are missing a few things. zzyzx has been running a higher redline on his autocross/road race RS and has had not problem. The reason we autocrossers do it is for the longer gearing. No more toping 2nd out at 55mph.
You can do spring and cams and that's all good but what are you going to do about the oil. The problem Steve ran into with the higher redline is the oil starts to pool up in the heads and even worse in heavy cornering loads. He's looking into run a dry sump system to help prevent this. You can also run breather filters on the valve covers and keep the crank case line hooked to the intake to create a vaccum just in the case to help suck the oil out of the heads and get it back to the pan. BTW, the crank in the block without rods and pistons is good for 10k rpms. This is from Techworks.
If you read the entire thread, you will realize that the question is now for 7,000 RPM. No need to even take the heads off of the engine to modify it enough for 7k.

Dan

Use an STi (USDM) oil pump. It has a higher capasity to actuate the variable cam timing while still oiling the rest of the engine.

cheeRS,

Greg
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Old 04-17-2004, 04:21 PM   #16
Patrick L
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The oil pump and heads are fine for no more then 7k. Beyond that you get the oil pooling in the heads. That's what happened to dcoty.
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Old 04-17-2004, 05:57 PM   #17
1 Lucky Texan
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Quote:
Originally posted by Top_Dog
The oil pump and heads are fine for no more then 7k. Beyond that you get the oil pooling in the heads. That's what happened to dcoty.
I would think a higher VOLUME (not neccisarily a different PRESSURE) oil pressure relief valve might help keep some oil in the pan. Doesn't seem like an STi pump would be a good move.
Interesting discussion actually.
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Old 04-17-2004, 11:14 PM   #18
Section 8
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I didn't sugest that the oil pump is the end all solution to the problem.

If there are not enough passages for oil, you make more. More passages at a given pressure means more volume. A larger volume isn't something that can be called for out of a pump. So you change the pump to one that flows a larger volume.

Come on. Oil backing up in the heads is not a problem, unless you think that you can solve it by staring at it.

Demand the oil system to do what you want, by changing how it works. Changing orifice sizes on a system that clearly doesn't work and "seeing what happens" is assinine.

Think about how it should work, not how to "fix" it.


cheeRS,

Greg
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Old 04-18-2004, 11:58 AM   #19
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Quote:
Originally posted by Alpha_32
wow, its cool how i got flamed....but this guy didn't
honestly, you did come across as an ass and ricer who just wanted his car to 'rev' higher....

but, thats ok!
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