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rb20dett into a subaru forester (1999)

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That's a lot of money hacking away at a functional car for an engine that's basically a sidegrade. 

For the money spent, you're better off doing a full rebuild and addressing any weaknesses in your current engine with aftermarket parts and upgrading the turbo. The car would be just as fast if not faster, more usable, and cheaper.

I don't know laws in Finland, but Europe in general is quite strict about engine swaps meeting engineering standards. Unless you have a Forester shell with no engine you're intending on using for racing only, it's likely far more expensive than you realize, especially if you intend to keep the AWD. 

Fully expect any swap to cost $5k USD at an absolute minimum, probably more like $10k.

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So you have an engine. Now you have no means of mounting it, so you need custom mounts. Now you have no means of mounting the transmission, so that's custom. Now you need a new custom driveshaft to put that power to the rear wheels. Now you need to upgrade the diff because the R160 diff it comes with is tiny and is not meant for that kinda power ALL to the rear wheels. Now you need new axles.


So you've got the engine physically mounted now, great. Now you gota turn it on. Now you need a new wiring harness that'll adapt to the chassis components and the engines ECU which hopefully comes with the engine. Oh it doesn't have the ECU? Now you gota learn megasquirt and deal with all that shit because an actual standalone ECU that'll do what you need it to do is well over 5 grand.


Now you need new gauges because the ECU you have doesn't want to talk to the ones in the Subaru unless you can pull off some slick electric engineering. Since you just dropped THOUSANDS on this damn car, you're gonna want some suspension components to go along with this because you'll be damned if this heavy beast can't really corner for shit. 


Now it's 10 years later and you're staring at this damn thing which doesn't run either at all, or poorly, and you're wondering, "Why the hell didn't I just change the head gaskets and buy a bigger turbo for the stock engine? I'd be done years ago!!!"


More time goes by, you finally kick your alcoholism that you needed to cope with the neverending torment of this unfinished project and you get serious and put in some serious money to just get the damn thing working. It finally turns on, everything is working just fine. You go down your street...and you realize it's not any faster at all then a freggin stock Forester turbo. Darkness sets in.

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@Neverdone That is a HILARIOUSLY bleak outlook haha. But it's accurate.

@Subaruuuuuuuboii - take it from me, no build is a budget build. I paid $300 for the first Z I got. It became mostly a donor for engine and interior parts. I got the shell I'm currently in for $1200+shipping from another state. That's VERY Close to where you're starting with an engine and the car. I'm in my car $15-$17k after paint/suspension/STOCK brake replacement/Megasquirt ECU/upgraded differential/coilovers/body replacement stuff/wheels/tires. That doesn't count all the small hardware I keep having to buy and the engine block is still STOCK

If I had ignored paint and body interior stuff completely and just did a high powered engine I'd still be at about $8-10k JUST for shell/engine/brake refresh/suspension/upgraded differential/Megasquirt/wiring, and I've done literally every bit of that myself. That doesn't even include what you'd have to do chopping away at the original car, custom engine and trans mounts, and a custom drive shaft, never mind either all new sensors on the engine, or new gauges that easily add up to $1k on their own.


Unless you have big money to do an RB26 and somehow keep AWD, what you're planning is a sidegrade at best and will only make the car worse. Sell the engine or save it for another project, and spend the money cleaning up the car. I'm amazed this thread isn't already in the tool shed since it's not even related to Z cars, but it looks Neverdone and I are the only ones nice enough to explain the complications and real costs.

Edited by Zetsaz
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I see no benefit to this swap. The engine is in the very front of those cars, since the front axles come out of the transmission like a transaxle. The stock motor is low in the chassis and short in length, and likely lighter than the RB. The RB is long, heavy, and has more weight higher up. It's going to make the car worse, and you're going to put a lot of effort and expense into ruining your car. I also doubt it'd even fit within the confines of the stock body work. 

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General rule is thumb: if you can’t find it on engineswapdepot.com than it’s either really creative or stupid hard. Also @Neverdone that’s depressing ;) why would anyone get into cars ever :) 


only thing similar I could find: https://engineswapdepot.com/?p=53173


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On 12/10/2020 at 4:24 PM, Subaruuuuuuuboii said:

Hello. I was wondering if a rb20det swap could be possible on a 1999 subaru forester turbo s


Ummmm, I have a silly question:  would you have better luck searching for this information on a Subaru forum? 


Personally, I like these two; but I'm sure there are several other good ones out there.



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