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Discussion Starter #1
Hi,

I own a 1991 NA SW20, and I'm considering swapping the engine.

The obvious choice is a 3S-GTE, but I'm wondering how much modification would be required if I try to fit a newer 3S-GE instead. I'm considering a BEAMS red top from an ST202 Celica GT for example.

Appart from the engine, ECU and wiring loom, would I need to replace a lot of things? Can I adapt my stock gearbox for example? Will the fuel pump be good enough?

Thanks for you help,

Dirk
 

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The MR2 was available with the red top BEAMS engine but as cool as the engine is it's weak, you might gain 20hp swapping your 3SGE non BEAMS to the red top.
 

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If you want to stay with I-4, I’d get the nicest gen-2 motor you can find (they go cheap)... get a stand alone ecu,
Turbo, injectors, DP and manifold... it’ll be a bulletproof machine... that’s my .02
 

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I disagree, I wouldn’t swap a gen2 at this point. Think about how much you’d have wrapped up in that gen2 compared to a gen3/4/5. Unless you’re planning on making huge hp 400+ I wouldn’t touch a gen2. Even if you were going to 400 I wouldn’t use a gen2 as the base engine to build off of unless you got a crazy deal on it.
 

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Discussion Starter #5
I'm not planning on going for huge power. It would be nice to be able to break 300hp but I'd be happy with anything around 200 honestly. I plan to drive this car mostly on public roads so it needs to be driveable.
 

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200 crank is all you get with the red top, that's equivalent to a gen2 3sgte in stock form which barely breaks a 15 second quarter mile. As cool as the BEAMS engine is it's not meant for the SW20, it's simply too heavy. Now if you were building the engine for a turbo that might be a different story it'd be cool to see a turbo VVTi 3S but I don't see that happening.

Gen3 3SGTE onward will make 300 crank but getting 300 wheel pretty much requires a different turbo.
 

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The BEAMS go quite well and it was a factory motor for Japan. They are responsive and rev out unlike the GEN2 3SGTE that is slow to respond and doesn't like to rev.

Wiring one in wouldn't be too much different to a GEN4 3SGTE as they use the same wiring diagram. Except you'd have to do it yourself as I don't think anyone provides this service for an MR2.

You would gain 70hp which is more than 50% of the current 130hp of the 5SFE. But then that's it. Gaining any more power other than maybe buying an aftermarket ECU will cost you a lot of money. The GEN4 3SGTE is another 65hp on top of that plus room to add more power a lot easier.

As for changing parts, I think the right side engine mount is different for the BEAMS redtop into an MR2 but it will bolt up to the factory gearbox no issues.

Fuel pump, not sure if the stock 5S pump would be ok for the BEAMS but if you can find the flow rates for the 5S vs 3S pumps you can make the decision from there.
 

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I disagree, I wouldn’t swap a gen2 at this point. Think about how much you’d have wrapped up in that gen2 compared to a gen3/4/5. Unless you’re planning on making huge hp 400+ I wouldn’t touch a gen2. Even if you were going to 400 I wouldn’t use a gen2 as the base engine to build off of unless you got a crazy deal on it.
but if you change the items listed above it will be a great motor... I’ve done it... 500hp with HKS Kai-T51
 

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but if you change the items listed above it will be a great motor... I’ve done it... 500hp with HKS Kai-T51
I agree with you man, the gen2 can be a great engine it just requires more base work and add ons, a lot of this applies to gen3 as well.

COP gen4/5 have this stock, you can adapt gen2/3 for COP but it's added expense (I know the distributor is perfectly fine but read my next point)
External cam and crank sensor (stock distributor it notoriously difficult to setup with a standalone plus Toyota don't make new ones, most leak oil at this point)
gen2 TVIS plate which can be blocked off but it's just added complication and another connection for vacuum/boost leaks
Side feed injectors, you can convert to top feed but that's added expense
gen2 inverted oil filter, gen3 onward fixed this problem (You can fix this with a filter relocation but that's more expense and complication) I like the 2 piece oil pan as well on gen3/4/5
gen2 shim over bucket head, I know gen3 is shim under bucket which is better but not shimless like gen4/5 (I guess you could throw this out because you're going to be replacing the cam on any gen engine at 500whp so you would probably have to replace some shimless buckets to get clearance right and they are a drop in upgrade for any generation head.)
 

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Hi D.J., I actually translated the Japanese ST202 3S-GE ECU wiring diagram into English, to make it easy for others to do the same swap. It's 90% completed (I haven't gotten around to translating the COP Ignition System diagram yet).

 

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Discussion Starter #11
Thanks that could be super useful! Not sure I'll go through with this swap (lots of other parts to fix/replace first anyway), but if not for me it could definitely help others!
 
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