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Old 07-25-2005, 09:02 PM   #1
down_for_the_scooby
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Default supercharge my 2.5

Has anyone put a supercharger on their RS? I was looking at upgrading instead of a turbo. So if anyone has done it can you tell me what kind you have, the gains, the drawbacks and most importantly the cost. Thanks
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Old 07-25-2005, 09:13 PM   #2
Subie Gal
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good luck

never. ever. have i seen one 'work'

block blows

usually doesnt take that long either.

do yourself a favor and just do an EJ20 swap
you will be much happier in the long run
and $ ahead

Jamie
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Old 07-25-2005, 10:15 PM   #3
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PM happyparrot, he used to have a supercharger on his RS, but has taken it off and is normally aspirated now. From what he told me, it ran great and was CRAZY fast. meh.
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Old 07-25-2005, 11:15 PM   #4
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supposingly on rs25 there are a couple in production

as subie gal said ive never seen one reliable one they only work for some time then really mess things up

id just go swap
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Old 07-25-2005, 11:39 PM   #5
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It does work. Period.

But you have to do it yourself.

There are no "kits" available now but one is "almost" done available from Australia

http://www.hotkey.net.au/~shatteredf...scsystems.html

and then there is a member here called Hamfist who is working on one but it seems to have disappeared.

I have built one setup myself. And it works close to perfect. It took my wagon from 100 whp to 152-160 whp at 7 psi and took almost 1.8 seconds off my 1/4 mile (for now).

But just like turboing a 2.5, you can't go cheap if you want to boost over 5-6 psi EVER! If you do, you need to upgrade injectors, intercool and get some sort of engine management to retard timing. Just like turboing. Boost is boost baby.

I am currently boosting at 7 psi, and all I have really done is upgraded my injectors and have a good AWIC setup. I have no knock/detonation currently. I will be upgrading to a Perfect Power but only when I have another custom crank pulley to get my boost up towards 10-12 psi (that will be about 200-220 whp).

I HAVE BLOWN TWO MOTORS. Both because of too much boost combined with nitrous and NO engine management. I am also running the old 90-94 engine block which is stronger than the 2.5 rs motor usually.

It can be done, it can be done easily, and it can be done cheaply (less than $750) if you are mechanically inclined and do not want more than 4 psi.

Here is my story.

http://forums.nasioc.com/forums/show...d+supercharger

I also won Best Legacy at WCSS7 for what I have done!
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Old 07-25-2005, 11:47 PM   #6
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+1 to what Subie Gal said. She is dead on.

Not to mention, she knows her ****

Good luck if you decide to go this route. It's a BIG caution.
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Old 07-26-2005, 12:05 AM   #7
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Hey don't turbo your car either.

and don't swap a motor it either, it might blow up...

Its all about how much boost you put in and how you control the engine management. The engine cares not one whit how its boosted.

If your looking for a kit and don't know one end of the wrench from the other, your out of luck. If you are creative and can see outside the turbo blinders, then you can do it.

If you read my thread, you can avoid all the hassle I went through and do an install fairly easily. Good luck.
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Old 07-26-2005, 09:27 AM   #8
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superchargers fail.

this is ancient 2.5RS history

turbo swaps are PROVEN and work well

wanna supercharge? go for it. but your $ is IMHO better spent elsewhere.

engine management choices are endless for turbo swaps at this point.
prime example is my better 1/2's car....



4 years he's been racing this EJ20 conversion
and it's still going, still winning





Jamie
www.subiegal.com
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Old 07-26-2005, 09:32 AM   #9
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Nice set of cars Jamie.
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Old 07-26-2005, 11:16 AM   #10
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So Jamie, why'd they fail? Any facts? Any support to this? Or just hearsay?

Any I am not doubting the ones that failed, actually failed. But why did they fail?

You are aware it is a thing called "boost" that blows motors? And not the item that causes boost?

Hell, mine failed. Twice. Had nothing to do with the supercharger. Had to do with that little thing called TOO MUCH BOOST.

And this guy ------> His name is Sarcasm. My point being you can blow a motor with a turbo. Wow, what a suprise. In fact, I have seen more than five blown motors at Rallitek. In person. All turboed. Does this mean you shouldn't turbo it? Of course not. Same goes for the supercharger.
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Old 07-26-2005, 11:24 AM   #11
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I will definately admit if you want huge power, then you have to swap. The 2.5 platform is not strong enough to safely handle big psi in the hands of noobs with no money. Static compression is not forgiving on a high compression motor, especially when combined with weak pistons.



And remember his question. Turbo vs Supercharger. Not "do I do an engine swap?"
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Old 07-26-2005, 12:28 PM   #12
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I am going to have to side with Reddevil on this one. The failures with SC's are ancient history. We have come a long way with these cars since Rimmer's "Kit" and all of it's problems.

For starters, all the early attempts to SC these cars used an Eaton blower, and that required a special manifold. The newer centrifugal blowers offer more options to mount it, and make it much easier to intercool a well.

And with new easy to use EM units like the E-manage and PP, you can tune it much easier as well. Ultimately, I think the supercharger ceased to be explored once the WRX hit the states, because a turbo engine swap is just so damned easy to do.

As for Hamfist's kit, it isn't actually his. He is party to it, but I have it from a local source, that it is actually Rimmer doing the R&D. Who knows if this will ever come to market or not. But as Reddevil said, if you are mechanically inclined, you can make you own. But you need to know your way around an engine and an ECU, and be willing to trouble shoot it. There is no "kit" that is fail safe for you to buy like an AVO turbo kit...
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Old 07-26-2005, 08:28 PM   #13
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Audi used to have a turbo -> S/c kit for the 1.8T that used to seriously lower underhood temps and benefit the powqer delivery better...

made me think... if you SC a WRX motor and put some nice headers on it...

awww F it.. nice idea though...
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Old 07-26-2005, 10:41 PM   #14
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Quote:
Originally Posted by shipjumper
made me think... if you SC a WRX motor and put some nice headers on it...

awww F it.. nice idea though...
I think it would be something cool to tryout, back a awhile ago i think it was Sports Compact Car had a eclipse that was supercharged and had a water cooled manifold on it, thing was bad ass.
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Old 07-26-2005, 10:57 PM   #15
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And what I suspect was the Rimmer failure might have been lack of IC, not the use of the HUGELY SUCCESSFUL Eaton supercharger. Thats what I use.

If you boost, you must cool. Fact. To a point. Sometimes. Maybe. Everyone wander around confused. But in the end, thats about the truth.



As it is, I can effectively boost about 12 psi on premium with proper engine management with my 9.5-1 compression.

A 2.5 RS can do this but probably a little less reliably cause they have slightly higher compression ratios.

All based on static compression ratios.
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Old 07-27-2005, 07:58 AM   #16
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isn't the new RS and n/a EJ25 around 10.2:1?

If you want to supercharge an EJ25, in my opinion, you need new internals. then supercharge it and give it some boost. engine management + injectors + other mods for benefit (headers, exhaust, ect.)
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Old 07-27-2005, 11:26 AM   #17
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You don't need to put in new internals. Just like Cometic made a nice thin head gasket to bump my RS to 11.5:1, they could make a big fat thick gasket to get you down to around 9:1. And stock RS injectors can easily support 250chp(which Shiv, as have others, exceeded with his turbo project), which is probably around where a 7psi SC would put you. And I would think it obvious that a guy who hasn't done the bolts ons, like headers wouldn't be seriously considering SC'ing their RS...
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Old 07-27-2005, 12:24 PM   #18
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Retard the timing, up the fuel, and keep boost below 10psi.

^^^How to make a supercharged RS live in 500 words or less...

Yeah, ole Rick is doing the R&D on the blower and mechanicals. I helped out with some tuning, but it's really just the same hacks you guys use. A timing retard device (J&S), an rrfpr, and colder plugs. A new fuel pump is optional and still recommended. That's IT for tuning. It's far simpler than you've been lead to believe here, because it's useless arguing about. I don't have much to prove because it ALL has been done before. For some reason, S/C'ing a Scoob is a "taboo" subject almost. There's a dude putting about 240 to the wheels on abuilt n/a car with nitrous. That ride sounds like a blast. Does he get all the attention? No. Despite the fact his car is reliable, fast, and tuned correctly. Personally, I'd rather swap over to alcohol and run a higher compression ratio. These cars take well to modification, N/A or boost. I've never found one I didn't like. I don't own the fastest car on the planet, but it's been great for never having opened up the block. The thing has been very low maintenance, but it's a 6 year old car with 50,000 miles.

One big point that's missed is that you really CAN build up your car any way you want. N/A, boost, nitrous. It doesn't matter much anymore. They can all be fast. None are fast for very long. Something always explodes. If the motor lives, the tranny doesn't, or vice versa. "Winning" depends on the racing you're doing and the competition that day. Personally, I've kind of given up on racing except for a fun day's activity. I just want a fast car. You can build one of those almost any way you want as long as it's tuned right.

Ninja Edit: We'll have Jr's car up here soon, permanently. The hacked Civic-truck is still pieces, too. If we can swap my car over to alcohol and make an n/a screamer with it, we'll have a small army of cars that all have a different flavor. All are fast. All are fun. All built any way we wanted to do it...

Last edited by HamFist; 07-27-2005 at 12:35 PM.
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Old 07-28-2005, 10:22 AM   #19
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Quote:
Originally Posted by Subie Gal
superchargers fail.

this is ancient 2.5RS history

turbo swaps are PROVEN and work well

wanna supercharge? go for it. but your $ is IMHO better spent elsewhere.

engine management choices are endless for turbo swaps at this point.


Please explain the difference between "SC boost" and "turbo boost".

Oh that's right - there isn't one.

SCs work just fine when properly implemented.



Personally, I'd love to have a SC on my car. 5lbs of boost would do just fine. I have yet to see a good kit, though (no hood bubble, thanks), and I honstly don't trust my tranny to survive either...
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Old 07-28-2005, 02:01 PM   #20
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S/c boost is very turbulent. Turbo boost has a very laminar flow. This is speaking in regards to a roots style blower, not a centrifigal style. the airflow is VERY different.

5psi of boost with a S/C is quite different than a turbo with 5PSi
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Old 07-28-2005, 02:01 PM   #21
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Part of properly implementing it is using a recirc valve/relief valve. A few kits that got some fanfare here didn't use one. That was in addition to not providing enough fuel or retarding the timing. Intercooling? Well, some have used one, but didn't provide more fuel like that cooler air needs. It wasn't a matter of upping a bit of fuel pressure. It needs a LOT more fuel when you do that. Air out of a blower is colder than air out of a turbo. That colder air wants more fuel. Sometimes, fuel has to be added in HUGE amounts, kinda like trying to run alcohol. I have to double my fuel capacity to be able to run it. Tuning involves the right combination of parts and the right balance among those parts. Fuel, air, and spark don't change. Despite that simplification, there's still a balance that has to be maintained among them. Mess up that balance and you'll be replacing parts in short order.

Take the alcohol I ran for a short bit, I half expected the thing to blow because it ran lean. I got lucky and it didn't. I went back to gasoline quick enough. I gathered the data I needed to go back and make further adjustments. You don't HAVE to experiment as FAST as you possibly can. Some people are in too big of a hurry to just pile on a compressor, up the boost, and completely ignore tuning. then, they cry when it blows because they took no preventative measures. In the meantime, I'm reading reading reading. I do 10 times as much reading as I do spending money. The money I spent on books has saved me THOUSANDS that I would have spent on parts constantly experimenting with the thing. IMO, Books help PREVENT bankruptcy.
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Old 07-28-2005, 02:59 PM   #22
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Quote:
Originally Posted by shipjumper
S/c boost is very turbulent. Turbo boost has a very laminar flow. This is speaking in regards to a roots style blower, not a centrifigal style. the airflow is VERY different.

5psi of boost with a S/C is quite different than a turbo with 5PSi
Open mouth, insert foot.

I've never heard of this before. Any more information on this? What does the airflow have to do the the engine's likelyhood to explode?
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Old 07-28-2005, 03:35 PM   #23
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If I remember my what my books taught me is that the turbo air flow is more laminar and can more more CFM with the same PSI than a S/C.

its all in how the air is moved and compacted. the air in a turbo charger is compacted PRE throttlebody and then moved towards th eintake ports, the S/C air is compacted past the TB and bounces off the valves to compact. In other words, the S/C has a larger volume to compress than the Turbo does.

I could be wrong but it all sounds right in my head.... Its what I remember...
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Old 07-28-2005, 03:48 PM   #24
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Not quite...read more. I'm not gonna debate, I'll just suggest more reading. I think you're mixing up the fact that roots style blowers pump air scoop by scoop and it makes a lot of turbulence in the process. It's "stuffing" the air in like a bike pump and a tire. The air doesn't get blown in as much as just "moved there". A turbo or centry blower "fans" the air into the intake manifold with ridiculous velocity. (Kinda like a boat prop in the water.) Positioning of the TB doesn't make the difference you are referring to. You could put the throttle body in front of a turbo but it's not common practice. I'd actually like to see someone do this just to see what happens.

My .02
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Old 07-28-2005, 04:01 PM   #25
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I have the Eaton M62 and its prethrottle body. And works just fine thank you.

While it may be "choppy" compared to a turbo, I have serious serious doubts that by the time the air is hitting the valves, that the choppiness is going to be felt, much less may a difference.
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