Turbo'ing my 3SGE, rebuilding engine for it.

Have you considered a 2gr?
 

Your direct questions - boost will vary on your build / injectors / other factors and will be decided on a dyno tune. You can run 3sgte or 3sge or aftermarket camshafts, this will vary where and how much hp you make.

Speak with wtf auto as to local advice/specialist.

Depends on your driving / performance requirements. Mr2 is a personal choice. Options options

3sgte build. Requires so many components and costs not listed, clutch, dyno time - too many to list before even the nice to have like e153 gearbox etc. I have reservations at your cost vs outcome. You would be best finding a smashed mr2 turbo to put everything across, or caldina (gen4 swap, injectors, ecu, plug and play almost).

Realistically if you want 3sgte sell your mr2 and buy a turbo car for your turbo fun, there are many differences in brake components, options. Turbo cars are for sale, freight to wa from east coast around $1500.

2gr - 2grfe - $12-$15k for amazing drivability and low rpm power (will out perform 3s build spec). Use your car for the transplant. If you destroy the engine they are cheap off the shelf.

K20 swap. K20a engine / donour car with ecu etc, conversion kit from Hux Racing. Little more voodoo to K20a swap. If you destroy the engine they are cheap off the shelf.

5sgte. 5sfe block, 3s head. Stroker pistons, head gasket, aftermarket ecu etc is similar costs to your proposed 3sgte build path / costs. 5s blocks can be found for a couple hundred and is about the only additional to your 3s build path. More drivability, more potential. This will likely be more expensive than options above, depending on build spec, however potential depending on turbo selection.

Budget $10-$15k for whichever way you go in engine swap where that you can drive it with confidence (service items done). You can do it cheaper and often you will need to spend more.

2gr/2grfe = v6 meaning great torque (feels fast and can tow a boat) and 300rwhp.
Kswap will produce (hp) for what you spend from n/a 200hp to turbo at 800rwhp. Great option that will be cheaper than a 2gr, but you can build on it over the years to have more performance/hp than 2gr. There is no “cheap” big hp reliable solution, it costs to play.
Caldina provides modern technology, simple bolt ons and will see 300rwhp with the fun of turbo.
My personal choice is 5sgte, staying with a Toyota engine, ease of build, ability for gentle performance in low rpm and then boosted performance in mid - high rpm, flexibility in hp (how fast it works) by changing a couple of components that will yield 250-600rwhp.

Or sell yours and buy something where it has the engine you prefer.

Get to some club meets to see other cars with what you are thinking, get to wtf to talk through what you are thinking and what their advice is (and local costs).

Dont like k-swaps, thinking of substituting my 5sgte with a k24 😁

I know this is an old post but after reading so many like this I thought I would finally register and though my 2 cents in for what it is worth.

I personally think it is a fine idea to rebuild a 3gse to run a turbo.  Let's have a quick look at the advantage to doing this over buying a half cut or dropping something else in like a 2gr or K20.  You will have a fully rebuilt motor v's something that you don't know if it's had the guts flogged out of it or if it has been serviced or really anything at all about the motor you would be buying.  Sure it might pass a compression test but really that doesn't mean much..
 
So if you get a 3gste and you want to get a bit of power out of it you will want to do a few things to it to ensure it gets good power and is reliable.  Guess what that list looks like? 
 
3SGTE Forged Pistons (or forged lower comp pistons)
3SGTE Forged Con Rods
3SGTE Injectors (larger size)
Walbro 255 Pump
Standalone ECU (optional)
Turbo timer (optional)
Boost controller
Cold Spark Plugs
Intercooler (stock MR2 leaves a bit to be desired)
Lots of other little things as well
 
Notice there is not that much difference between the original poster's list and this one?  Sure you won't have a couple things like the oil squirters and you have to tap the oil for the turbo line and drill a return - though gives you a good opportunity to run an oil cooler as well. 
 
Clutch was mentioned as well but if you are doing any sort of work on your car you will be most likely doing the clutch regardless of what engine you are using.  Yes it would be nice to run a e153 over the s gearbox but the s will last a good while if you treat it with some respect.  And start saving or a E swap while you are there you may want to get an LSD installed.
 
TonyMR2 did make a good point about the brakes though.  I have seen them going for around the 400 mark but they are getting harder to get hold off.  There are a few aftermarket options out there though if you look around.
 
A lot depends on how much work you are going to do yourself and if you want a fresh engine or not.  I am almost finished my Red top BEAMS high compression with an Eaton SC running 8psi to drop into my MR2 so I am a bit biased but damn I am so tired of people saying it wont work or it is not worth it etc..  so far it has set me back around 5500 though I still need to pick up an aftermarket ECU so I am thinking 7k with tuning by time I am finished.  That is not much more that a low millage half cut with shipping.  
 
In a nutshell, if you want a good fresh engine a little different rebuild what you have to suit.  If you want to run a engine where you don't want to do a refresh get a half cut and cross your fingers.  If you have the money to burn get a half cut and refresh it.
 
I am sure this is going to upset a few people but high compression low boost is the way to go for a good streetable engine.
-- 
Cheers
Clint.

Yeah, 2gr swap has gotten a lot cheaper over the past few years.

If youre happy with 250-260whp (which is enough thanks to the torque) you can just go the 2gr and be done.

I can't recall how much the 3s engines weighs, but my 2gr complete minus E153 turbo gearbox weighs 156kg.

Sent from my SM-J320ZN using Tapatalk