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Discussion Starter #1 (Edited by Moderator)
Suppose I have unlimited time and money. The XV matches my perfect car except for one criterion:

  • I like how it looks;
  • I like how it handles;
  • It has a good AWD system (I live in snowy shitty weather area);
  • It has good MPG;
  • It DOESN'T have decent power.

To remedy the power problem, I could get a WRX, but I don't like that as a daily; the ride is too rough/stiff to my liking. I could also get an older Forester XT, but the MPG is not great on that.

Now, again assuming time and money aren't a concern, what modification could I do to increase the power by a bit: I don't want as much power as an XT or an WRX. To me my sweet spot is 190-230 HP. So what mod is best? Add a small turbo? Swap with a 190-230 HP engine that would still offer good MPG, like the GTI?


Thanks in advance; this is my first forum post so if there's anything I'm not doing correctly please LMK!
 

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Welcome to the forum!

The question of performance increase modifications to the current engine has been asked, debated, answered in various threads. Basically, you aren't going to get Earth shattering performance with the stock engine. Heck, you probably won't be able to get to your sweet spot of 190-230 HP even if you throw a lot of money at it as it would be at least a 30% increase in power. Especially if you consider that the Forester's 2.5L FB25 engine outputs 175 HP (which is still under your sweet spot by a whole lot), the possibility of getting to your sweet spot without wholesale changes would be tough.

But if you are going to try, I would try to shoehorn that Forester engine (FB25) into the engine compartment first. It can be done as one older member was able to do it but had a few technical issues and then stopped posting so I'll assume that he ran into issues that he wasn't willing or able to solve. But let's assume you got that 2.5L in place and it's running smooth, then you can try some of the many things like tuning to get a few more HP out of it (maybe to 180 to 185 HP) and then some of the other things like making a Billet Power Block for it which if you believe the promises, you might get that remaining few HP to get you into your sweet spot range.
 

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Discussion Starter #3
Welcome to the forum!

The question of performance increase modifications to the current engine has been asked, debated, answered in various threads. Basically, you aren't going to get Earth shattering performance with the stock engine. Heck, you probably won't be able to get to your sweet spot of 190-230 HP even if you throw a lot of money at it as it would be at least a 30% increase in power. Especially if you consider that the Forester's 2.5L FB25 engine outputs 175 HP (which is still under your sweet spot by a whole lot), the possibility of getting to your sweet spot without wholesale changes would be tough.

But if you are going to try, I would try to shoehorn that Forester engine (FB25) into the engine compartment first. It can be done as one older member was able to do it but had a few technical issues and then stopped posting so I'll assume that he ran into issues that he wasn't willing or able to solve. But let's assume you got that 2.5L in place and it's running smooth, then you can try some of the many things like tuning to get a few more HP out of it (maybe to 180 to 185 HP) and then some of the other things like making a Billet Power Block for it which if you believe the promises, you might get that remaining few HP to get you into your sweet spot range.

Hi, thanks answering!

Might not be in that pretty random range of HP but 175HP isn't bad at all for my usage and I think it's very satisfactory. The swap sounds great! Also, could the swap be done on the newer FB25 engine (suppose in the future, if I find one)? I think they have a little more power and some other improvements over the previous 2018 and earlier models.
 

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With enough money anything is possible. A WRX drivetrain swap is probably not outrageously difficult. Rebuilding your stock engine with forged internals and putting on a small turbo is also probably not terribly difficult. You could even possibly wedge a 6 cylinder from another Subaru in the engine compartment. The modifications would probably be expensive but... unlimited money. And then there's always the option to swap in a powertrain from a completely different brand. Custom work to do that is expensive but, again, unlimited money.

A 2.5 from a Forrester is probably the easiest and cheapest swap as it's pretty close on all of the outside dimensions to the 2.0 that comes in the XV. It's not the power level you are looking for but you could probably have a performance shop do some tweaking. I don't know how big you can go with a bore and stroke to get more cc but more displacement gives you more power. But even if you just went with pistons that bumped up your compression ratio and a tune for premium gas, you could get the 2.5 up to the power level you want.
 

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Hi, thanks answering!

Might not be in that pretty random range of HP but 175HP isn't bad at all for my usage and I think it's very satisfactory. The swap sounds great! Also, could the swap be done on the newer FB25 engine (suppose in the future, if I find one)? I think they have a little more power and some other improvements over the previous 2018 and earlier models.
Realistically, while a swap was done, we don't know if it ended up to be 100% successful or not. I'm assuming, like the DI FB20, the newer FB25 will be very similar in configuration to the previous model and if anything shares a lot of similarities with the DI FB20.

You should read through the thread - https://www.subaruxvforum.com/forum/engine-drivetrain/58946-fb25-6spd-swap-progress.html. Near the end of the 15 pages after the engine has been swapped, you will see some driving impressions with the FB25 in comparison to the FB20. I suspect that you will find that comparison useful to evaluate how 175 HP compares to what you have now.
 

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What's that old saying? Speed is just a question of money. How fast do you want to go? ;) You can make any car out there quicker, faster, or perform better if you're willing to throw enough money at the problem. There's plenty of YouTube videos out there of people that have done crazy things with their cars. The stock engine just doesn't have much to give without going to something like a turbo. Or, as previously mentioned, an engine swap. Good Luck and keep us posted on what you decide to do.
 

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Didn't feel like reading responses, but your mention of unlimited time and money has brought me to share my dream. Forester 2.5 liter and 6 speed swap. My '03 OBS (spiritual start of the Crosstrek) had the 2.5 and 5 speed. It was fantastic for its time and what it was.
 

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Turbo, billet blocks and tune would get you close at the cost of mpg's. A switchable tune would be the ideal; one for performance, one for cruise.

artosa
 

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Well, Crawford built a high HP Crosstrek motor. There are conflicting reports, and as it was built for a race team, they’ll never share their secrets. But, I do know the HP achieved was well above your sweet spot, so it is VERY possible.

My understanding is they had to keep the FB20 block for rule purposes, in order to still call the vehicle a Crosstrek, it had to retain the original power plant. But it was bored/stroked to 2.5L. It is still N/A, meaning no turbo and no supercharger.

We are still in the early days of the FB series motors. Back in the early days of the EJ, people complained about not being able to do anything to those as well. It just takes time for these companies to build stuff. Subaru is basically going all in to the the F Series motors, the EJ is going away. Do you really think shops that have been building Subaru’s for two decades are just going to up and walk away because of a new engine platform? Nope. As the EJ’s lose relevancy, the FA’s and FB’s will slowly start to take over.

Need proof? When I bought my Crosstrek, there were only a select few, small mom and pop guys making lifts. Now? We are getting the big boys coming to play. Eibach makes springs now, Fabtech is looking for a vehicle to do development work on, as well as a few others. It just takes time for companies to see the potential.

I guess to directly answer your question, you really have a few options:
1). Turbo kit. AVO makes one, or you could DIY.
2). Supercharger. Raptor makes a kit, or you could DIY (like PhilXV did).
3). Motor swap, since “unlimited money,” you’d have a few good options. FB25, FA20F (WRX/XT), FA20D (BRZ), or even EE20 (diesel) which would give you loads of torque and an obscene MPG figure. A dude here in the states has swapped his Forester with the diesel. I don’t think we have the space in the engine bay for a flat 6, although that’d be cool as hell.
4). Have Crawford build you a motor. They have blueprints from mild to wild.


Sent from my iPhone using Tapatalk Pro
 

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Well, Crawford built a high HP Crosstrek motor. There are conflicting reports, and as it was built for a race team, they’ll never share their secrets. But, I do know the HP achieved was well above your sweet spot, so it is VERY possible.

My understanding is they had to keep the FB20 block for rule purposes, in order to still call the vehicle a Crosstrek, it had to retain the original power plant. But it was bored/stroked to 2.5L. It is still N/A, meaning no turbo and no supercharger.

We are still in the early days of the FB series motors. Back in the early days of the EJ, people complained about not being able to do anything to those as well. It just takes time for these companies to build stuff. Subaru is basically going all in to the the F Series motors, the EJ is going away. Do you really think shops that have been building Subaru’s for two decades are just going to up and walk away because of a new engine platform? Nope. As the EJ’s lose relevancy, the FA’s and FB’s will slowly start to take over.

Need proof? When I bought my Crosstrek, there were only a select few, small mom and pop guys making lifts. Now? We are getting the big boys coming to play. Eibach makes springs now, Fabtech is looking for a vehicle to do development work on, as well as a few others. It just takes time for companies to see the potential.

I guess to directly answer your question, you really have a few options:
1). Turbo kit. AVO makes one, or you could DIY.
2). Supercharger. Raptor makes a kit, or you could DIY (like PhilXV did).
3). Motor swap, since “unlimited money,” you’d have a few good options. FB25, FA20F (WRX/XT), FA20D (BRZ), or even EE20 (diesel) which would give you loads of torque and an obscene MPG figure. A dude here in the states has swapped his Forester with the diesel. I don’t think we have the space in the engine bay for a flat 6, although that’d be cool as hell.
4). Have Crawford build you a motor. They have blueprints from mild to wild.


Sent from my iPhone using Tapatalk Pro
The only problem I would have with a Crawford motor would be long term reliability and the ability to get someone to repair it. Going with an engine swap with a few tweaks may be the best bet to get someone into a higher power range with longer term reliability - ie how many FB25 engines are out there and have been running for years now?
 

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Suppose I have unlimited time and money. The XV matches my perfect car except for one criterion:
[*]It DOESN'T have decent power.
I guess power is relative. I've been driving nothing but 4-cylinder vehicles since 1981 and I think the Crosstrek has decent power. For example, I just drove I-25 from north of Denver to southern New Mexico during the past 24 hours. Speed limit mostly 75mph, relatively high elevation with lots of up hills and running Colorado's 85 octane fuel. Not once did I feel that my Crosstrek was under-powered.
 

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I just don't understand that with unlimited money and wanting lots of power, why anyone would buy a Crosstrek. It's a great little car, but there are better choices if high power is a priority. Some of the other choices may not be as reliable, but again, nothing that money can't handle.
 
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