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Old 10-17-2020, 02:15 PM   #1
Abdmohieddin
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Default Supercharger on STI?

Looking to install a supercharger on a 2004-2007 STI (year is trivial). I want to take out the intercooler and replace it with a supercharger (will disconnect the turbo). But i only need 50-100 HP from it. Are there any turbo kits under $3k? Like anything will work but I am only able to find those 1200HP for mustangs that are like $4k or so. If anything I said was wrong please let me know. I dont plan on swapping engine internals. And I will replace the downpipe.
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Old 10-17-2020, 03:13 PM   #2
Vancouver98STi
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I have a '98 JDM Subaru Impreza WRX STi, which of course is turbocharged from the factory. Just out of curiosity, I was seeing what was available in regards to a supercharger for the boxer engine. I watched a few videos, and what struck me the most ...was the whine!



I like what a supercharger can do, but I don't think I could tolerate listening to that racket for too long.

Quote:
Originally Posted by Abdmohieddin View Post

I want to take out the intercooler and replace it with a supercharger (will disconnect the turbo).
What makes you think the supercharger wouldn't require an intercooler?

Last edited by Vancouver98STi; 10-17-2020 at 03:20 PM.
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Old 10-17-2020, 10:18 PM   #3
Abdmohieddin
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I meant the stock intercooler, as the supercharger could go on top of the engine and have a smaller intercooler (since the engine is not that high and the stock intercooler seemed to be a bit high).
Either way, would you know if im way too off with the cost of the supercharger?
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Old 10-18-2020, 02:21 AM   #4
Vancouver98STi
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Quote:
Originally Posted by Abdmohieddin View Post

would you know...?
Sorry, I know next to nothing about superchargers... other than they whine.
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Old 10-18-2020, 10:31 AM   #5
Abdmohieddin
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Yes the fact that the whine is so addicting is why I'm considering them.thry should offer quicker response but my budget seems to be too low 😭
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Old 10-18-2020, 06:40 PM   #6
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On a list of good ideas, this is up there with invading Russia in winter. If you only need a small bump in HP, you should do it using KNOWN methods that work. A Supercharger is custom and custom is time and money and you can bolt on and tune a bigger turbo for pennies compared to a SC setup.
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Old 10-18-2020, 11:06 PM   #7
Abdmohieddin
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Really wanted that whine.
I think i saw a garret turbo somewhere for like $1000 or so im not sure. Now does it have to be super high quality or no? And do I have to do anything else then change the turbo back exhaust and upgrade the headers?

I'm just trying to see how much it will roughly cost in the end so that I can adjust my budget. Thanks
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Old Yesterday, 02:56 AM   #8
tabrad
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Quote:
Originally Posted by Abdmohieddin View Post
Really wanted that whine.
I think i saw a garret turbo somewhere for like $1000 or so im not sure. Now does it have to be super high quality or no? And do I have to do anything else then change the turbo back exhaust and upgrade the headers?

I'm just trying to see how much it will roughly cost in the end so that I can adjust my budget. Thanks
Fortunately there is a pretty nice write up about the turbo's on our Subarus and how you would go about upgrading to a different turbo https://forums.nasioc.com/forums/sho....php?t=1218459

Lots of turbos are made to be "bolt on", and typically those will be the best bang for your buck because you don't have to upgrade quite as much to use them.
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Old Yesterday, 09:39 AM   #9
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I'm curious why you're looking into a supercharger. There are combo charger cars out there (use both a turbo and supercharger in series), but not as a kit. In general, a supercharger gives you boost from any RPM while a turbo is a drag on power at low RPM, with all it's gain at high RPM. Superchargers are also much easier to "tune" for. With lots of those Mustang superchargers, a rising rate fuel pressure regulator is all you need. With these, fuel pressure follows RPM, thus boost. No screwing with the ecu at all. But at the high end, superchargers are less efficient.

Back in the day, Rimmer (OG guys can puke and spit now) made kits for our N/A 2.2 and 2.5 engines. The theory was that with the high compression ratio, a supercharger at low boost (like 5 pounds) made sense. I do know guys who had cars with these on them back in the day and they worked pretty well. But we're talking 200 hp kind of numbers.

If you want to do high boost (if you're doing a combo, I'd assume that), you'd need to work closely with a tuner. Here's a combo charged Exige that for a time was the fastest accelerating car in the world (pre-crash).
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Old Yesterday, 10:33 AM   #10
Abdmohieddin
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I want it because I want an increase in power, but superchargers sound better, respond better, and easier to work with. Its not that I dont want to replace the turbo its just that if there was a cheap kit I would prefer it. If not then whatever I guess
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Old Yesterday, 10:56 AM   #11
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Quote:
Originally Posted by Abdmohieddin View Post
I meant the stock intercooler, as the supercharger could go on top of the engine and have a smaller intercooler (since the engine is not that high and the stock intercooler seemed to be a bit high).
Either way, would you know if im way too off with the cost of the supercharger?
I don't understand where you plan on putting an intercooler?
well designed supercharged cars have very complex coolers because they basically have to be in between the supercharger and engine, unlike a turbo where you just pipe it up front and back again.

How do you think you are going to achieve that?
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Old Yesterday, 11:02 AM   #12
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Quote:
Originally Posted by Abdmohieddin View Post
I want it because I want an increase in power, but superchargers sound better, respond better, and easier to work with. Its not that I dont want to replace the turbo its just that if there was a cheap kit I would prefer it. If not then whatever I guess
there will not be a cheap kit since there really isnt one in production. you will have to piece it all together and get it all to work. I wold put the cost somewhere near the 5000 dollar range all said and done
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Old Yesterday, 12:04 PM   #13
Wayne Suhrbier
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You could make a recording of the whine and play it back from a mp3 player through a speaker in the engine bay.
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Old Yesterday, 12:05 PM   #14
Abdmohieddin
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Okay thanks. I thought I was just bad at finding superchargers. Now I have to decide weather to port and polish or use a vf-30.
I dont even have the car yet so yeah
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Old Yesterday, 12:13 PM   #15
tabrad
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Is it just me, or would you actually lose horsepower if you put a supercharger (unless its giant) on an STi?
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Old Yesterday, 12:56 PM   #16
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Quote:
Originally Posted by tabrad View Post
Is it just me, or would you actually lose horsepower if you put a supercharger (unless its giant) on an STi?
ummm, yes it's just you.

How on earth would you lose power by adding forced induction?
A 2.5 liter would not require anything close to giant. It needs to be sized properly.
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Old Yesterday, 01:00 PM   #17
tabrad
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Quote:
Originally Posted by rtv900 View Post
ummm, yes it's just you.

How on earth would you lose power by adding forced induction?
A 2.5 liter would not require anything close to giant. It needs to be sized properly.

STi's already have forced induction. So its not adding forced induction. Its replacing one type of forced induction for another.
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Old Yesterday, 01:47 PM   #18
rtv900
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Quote:
Originally Posted by tabrad View Post
STi's already have forced induction. So its not adding forced induction. Its replacing one type of forced induction for another.
oh well ok, that's totally different but the sky is the limit
You could easily put on a supercharger to outperform the stock turbo or put on some insane turbo to outperform "x" supercharger.
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Old Yesterday, 02:12 PM   #19
tabrad
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Quote:
Originally Posted by rtv900 View Post
oh well ok, that's totally different

Read the first post. The thread is about "disconnecting" the stock STi turbo and adding a supercharger. The superchargers that have been mentioned here, as well as the generic $5k estimate a few posts above, seem to me like they would actually cause a loss of power.

And yes you could also put a rocket booster on the trunk and create a quicker car that way too. Is it cost effective or realistic? No. Is a large supercharger going to be cost effective or realistic? Probably not. I think Unabomber's analysis is pretty accurate on this one
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Old Yesterday, 03:56 PM   #20
Abdmohieddin
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Quote:
Originally Posted by Wayne Suhrbier View Post
You could make a recording of the whine and play it back from a mp3 player through a speaker in the engine bay.
🤣 okay but if I wanted instant power with a whine I'd just play the sound over a tesla 🤣
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Old Yesterday, 04:10 PM   #21
Vancouver98STi
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Quote:
Originally Posted by Abdmohieddin View Post

Yes the fact that the whine is so addicting is why I'm considering them.
Maybe just get a car with a bad transmission.
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Old Yesterday, 07:01 PM   #22
Abdmohieddin
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I dont like honda oddeseys that much 🤣
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Old Yesterday, 08:14 PM   #23
Ernest
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Sell car, get BRZ and supercharge it.
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Old Today, 12:08 AM   #24
Abdmohieddin
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Quote:
Originally Posted by Ernest View Post
Sell car, get BRZ and supercharge it.
Now that's a good idea but again I'm only finding supercharginr kits over 5k. I only need 50 to 100hp and have under 3k for the supercharger in my budget
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