Questions on bolt-on turbo set up

bwhit88 · 08-19-2010, 01:14 AM

I have an 09 impreza 2.5i, no turbo

. I want to know what it would take if i would try to put on a turbo kit and if the transmission and rest of the driveline could take the power, or different pistons would need to be installed. What all would have to be done to the car if i would decide to turbo my subie

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JJ21 · 08-19-2010, 01:22 AM

From what I've heard, your money is better spent on other upgrades. You can always do a cold air intake under the hood, but that 6k or so that you would be putting into the turbo would be MUCH better spent towards suspension, wheels, and exhaust.

Ogden · 08-19-2010, 09:31 AM

You'll get more information in the "Naturally Aspirated with bolt on Forced Induction" forum, or wahtever it's called. That's for the bolt-on turbos and superchargers.

That said, get used to this response to this question:

Q: "What's the best way to turbo an N/A Subaru?"

A: "Trade it in and buy a WRX."

It's not so much the tranmission and driveline that you should worry about. While the WRX 5-speed, I believe, gets different gearing, most of it is the same between the cars. What you need to worry about is the engine. The N/A 2.5 liter engine is not just the turbo'ed 2.5L without the turbo. They are significanly different animals. The open-deck design of the NA engine limits it's ability to be turbo'ed vs. the closed-deck design of the turbo'ed engine. You can run some low boost (6-7psi) on the NA 2.5L, but people have even had problems at that level, and blown their engines.

To run higher boost, you will need significant modifications to the engine internals and once you get to that level and the amount of money you will have spent, you are better off just buying a WRX to begin with.

For the money you would spend on turboing the NA car, if you traded up to the WRX you would get the turboed engine, AND you would also get the sportier seats, bodykit, spoiler, upgraded suspension, hoodscoop, etc. that come with a WRX above and beyond the turbo.

I know that this is probably not what you want to hear (and you won't be the first, or last, to be disappointed to find out what it really takes to turbo the NA engine), but to truly turn an NA Subaru into a WRX is a very, very expensive proposition. If you want a hobby and have some cash to burn, it could be fun. If you just want a turbo, WRX is the better way to go.

This is why most NA Suabru owner focus on suspension mods and things beyond the engine. There just isn't a lot of bang for you buck there.

formula91 · 08-19-2010, 12:25 PM

Quote:

Originally Posted by Ogden

You'll get more information in the "Naturally Aspirated with bolt on Forced Induction" forum, or wahtever it's called. That's for the bolt-on turbos and superchargers.

That said, get used to this response to this question:

Q: "What's the best way to turbo an N/A Subaru?"

A: "Trade it in and buy a WRX."

It's not so much the tranmission and driveline that you should worry about. While the WRX 5-speed, I believe, gets different gearing, most of it is the same between the cars. What you need to worry about is the engine. The N/A 2.5 liter engine is not just the turbo'ed 2.5L without the turbo. They are significanly different animals. The open-deck design of the NA engine limits it's ability to be turbo'ed vs. the closed-deck design of the turbo'ed engine. You can run some low boost (6-7psi) on the NA 2.5L, but people have even had problems at that level, and blown their engines.

To run higher boost, you will need significant modifications to the engine internals and once you get to that level and the amount of money you will have spent, you are better off just buying a WRX to begin with.

For the money you would spend on turboing the NA car, if you traded up to the WRX you would get the turboed engine, AND you would also get the sportier seats, bodykit, spoiler, upgraded suspension, hoodscoop, etc. that come with a WRX above and beyond the turbo.

I know that this is probably not what you want to hear (and you won't be the first, or last, to be disappointed to find out what it really takes to turbo the NA engine), but to truly turn an NA Subaru into a WRX is a very, very expensive proposition. If you want a hobby and have some cash to burn, it could be fun. If you just want a turbo, WRX is the better way to go.

This is why most NA Suabru owner focus on suspension mods and things beyond the engine. There just isn't a lot of bang for you buck there.

Good post, although I've heard that it's not so much the open deck, so much as the other things like the compression ratio, piston face design. Other than open deck, the WRX and 2.5 are more similar in internal parts that most people would make you believe. Compression ratio is already way too high to be boosted well. Most people won't dare use 10:1. 9:1 is pushing it even. However, this wouldn't be as bad were it not for the fact that the piston face is horrifying for boost, because the with boost the dynamic compression ratio must be through the roof with this piston face.

Also

----------------------------->
Bolt on Turbo Forum, that way.

PA-Outback2000 · 08-20-2010, 10:37 AM

WRX engines are semi-closed, not fully closed and r good to 18psi. closed decks are good to or over 30psi with the proper mods.

for my turbo project, i am getting a 2.5L STI block and internals to run 18psi. i plan to do heads and cams and maybe go over 20psi at some point.

driveline can handle power, but u should think about upgrading when u near 400HP or more.

08-19-2010, 01:14 AM	#1
bwhit88 Scooby Newbie Member#: 252335 Join Date: Jul 2010 Chapter/Region: Tri-State Location: New Holland, PA Vehicle: 2009 Impreza Black	Questions on bolt-on turbo set up I have an 09 impreza 2.5i, no turbo . I want to know what it would take if i would try to put on a turbo kit and if the transmission and rest of the driveline could take the power, or different pistons would need to be installed. What all would have to be done to the car if i would decide to turbo my subie * Registered users of the site do not see these ads.

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08-19-2010, 01:22 AM	#2
JJ21 Scooby Newbie Member#: 254987 Join Date: Aug 2010 Vehicle: 2007 Impreza 2.5i Obsidian Pearl Black	From what I've heard, your money is better spent on other upgrades. You can always do a cold air intake under the hood, but that 6k or so that you would be putting into the turbo would be MUCH better spent towards suspension, wheels, and exhaust.

08-19-2010, 09:31 AM	#3
Ogden Scooby Specialist Member#: 1748 Join Date: Jun 2000 Chapter/Region: NESIC Location: Boston, MA, USA Vehicle: '09 Outback Sport OBP over DGM	You'll get more information in the "Naturally Aspirated with bolt on Forced Induction" forum, or wahtever it's called. That's for the bolt-on turbos and superchargers. That said, get used to this response to this question: Q: "What's the best way to turbo an N/A Subaru?" A: "Trade it in and buy a WRX." It's not so much the tranmission and driveline that you should worry about. While the WRX 5-speed, I believe, gets different gearing, most of it is the same between the cars. What you need to worry about is the engine. The N/A 2.5 liter engine is not just the turbo'ed 2.5L without the turbo. They are significanly different animals. The open-deck design of the NA engine limits it's ability to be turbo'ed vs. the closed-deck design of the turbo'ed engine. You can run some low boost (6-7psi) on the NA 2.5L, but people have even had problems at that level, and blown their engines. To run higher boost, you will need significant modifications to the engine internals and once you get to that level and the amount of money you will have spent, you are better off just buying a WRX to begin with. For the money you would spend on turboing the NA car, if you traded up to the WRX you would get the turboed engine, AND you would also get the sportier seats, bodykit, spoiler, upgraded suspension, hoodscoop, etc. that come with a WRX above and beyond the turbo. I know that this is probably not what you want to hear (and you won't be the first, or last, to be disappointed to find out what it really takes to turbo the NA engine), but to truly turn an NA Subaru into a WRX is a very, very expensive proposition. If you want a hobby and have some cash to burn, it could be fun. If you just want a turbo, WRX is the better way to go. This is why most NA Suabru owner focus on suspension mods and things beyond the engine. There just isn't a lot of bang for you buck there.

08-20-2010, 10:37 AM	#5
PA-Outback2000 Scooby Specialist Member#: 161832 Join Date: Oct 2007 Chapter/Region: Tri-State Location: PA Vehicle: 2000 Outback Limited Black	WRX engines are semi-closed, not fully closed and r good to 18psi. closed decks are good to or over 30psi with the proper mods. for my turbo project, i am getting a 2.5L STI block and internals to run 18psi. i plan to do heads and cams and maybe go over 20psi at some point. driveline can handle power, but u should think about upgrading when u near 400HP or more.