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Discussion Starter #1,143
Officially, the donor should be the 2011-2016 Scion tC because that's the transmission and wiring harness you need.

You can use a different harness if you're comfortable with the work that entails, i won't be giving a pinout for any other harness in the near future, but the harness is $550 new from the dealer and the engine is very common in the Camry application (2010+)

The Camry's EB62 can also be used if you change the shift levers to the Scion tC ones. But that really does not matter since it is rare as heck.
 

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Discussion Starter #1,145
That's the "I don't want to mess with it, just order it on e-bay and have it show up to my house" price. The transmissions are starting to show up at pick & pulls and the engines are all over the pick & pulls. If you get it there and pull them yourself you'll be in for about $400-500 total on a regular day and cheaper if you hit up one of their discount days.
 

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Hey Gouky great to see this going well, I haven't been following for the last year. Looks like the price is pretty good on the kit. The 205whp was just by leaning out the top end I assume?

Have you thought about getting the compression ratio up by shaving the head? At a racetrack you're not gonna be running 87 gas anyways haha.

I think your ITB idea is good if you have short and fat runners to put all the torque around 7000rpm. The 2AR has so much displacement for these MR2s I don't think losing a few % in the lower revs is a problem. If the variable intake system can be deleted without any error codes that would make it easy. There's no EGR to worry about on the 2AR either.

One thing I have been kind of wondering is if it's easy to cut the stock plastic manifold at the plenum and at the ports to keep the mounting flanges, then replace the runners with custom ones and put it back together. I think the Toyota ones are kind of rectangular cross section but you could make that work with fiberglass or carbon fiber with some effort. Maybe 3d printed carbon fiber filled nylon or something.
 

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Discussion Starter #1,147
The extra power came from a few different things. The biggest one is just opening up the exhaust, before i could modify the ECU i was getting a bit over 190rwhp just with the exhaust alone. beyond that the velocity stack style MAF tube really helped and then just as you said, leaning out the top end and adding a touch more timing. The mid-range power was also really helped by tweaking the vvt-i maps, those were somewhat neutered for some reason, maybe to reduce exhaust noise?

The stock ECU really looks like it was designed to be as friendly to boost as possible, once you go beyond the stock power the ECU really starts pouring in the fuel and starts targeting AFRs as rich as 9:1 at the top end. This is so rich it kills power but also probably explains why the Scion tC guys are so easily able to add boost. All you need is a bit of extra fuel once the injectors run out but the targets are good enough and so is the timing. Something that is easily in range of a piggy back style system.

I have not considered bumping the compression ratio, this motor is already knock limited above about 5k or so when running premium fuel. more compression would help below 5k though. Alternatively an aftermarket ECU and some E85 and there's more power to be had above 5k by just using more timing.

I agree that the ITB's will probably really wake things up, i need more hours in the day but i do promise i will get to it. Deleting the codes for the variable intake and the tumble valves won't be a problem at all. the bigger concern will be the wall wetting algorithms. With the reaction time between throttle change and air pressure inside the cylinders changing i hope i don't have a short lean spike. i may have to quicken the tip-in fuel and if i have to do that i'm not 100% sure how to do it at this point. My other concern with these is that I would be starting to have a bit of a mismatched set of components, particularly the 4-2-1 header is designed more for mid-range torque than high end power, Unfortunately i don't see how long tube 4-1 headers could be made for this application because of the position of the coolant hose.

As for the intake ports, yes the stock ports are rectangular to account for the tumble valves but again because of those tumble valves i don't think you'll be able to salvage any kind of a flange from the stock manifold. Making an adapter that goes from the stock rectangular ports to about 52mm round runners (equivalent cross section) would not be that difficult though. If you just use round pipe and squish it to a rectangular port you'll have to use 57mm (2.25") tube to get the right perimiter length to deform which isn't that far off from the proper equivalent cross section.

I would love for other people to start experimenting with this motor a bit to see what it can do. My strengths are more into all the parts that i've done so far more than engine power adders.
 

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Interesting. The 2AR is old enough now that I look at the numbers and go "that thing has got to be able to take more compression and make more power", forgetting it's missing all the goodies on new engines. That said, I think all the newer engines using ultra-high compression is an interesting phenomenon to look at. The higher expansion ratio wins back what is lost in VE (or +cooled EGR)/timing. Obviously there's other things going on too though.

I'm guessing the midrange has to do with avoiding knock with the stock exhaust, there's probably some resonance going on.

I forgot about the TGVs, that's true. Eyeballing the cutaway pictures of the manifold, if you gut the longer runner path and valve that opens to the short path, it would take ~2 inches off the total length of the shorter path and massively increase the plenum size. Could be worth a shot, saw it in half, cut away a bunch of stuff, epoxy it back together lol.
 

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Discussion Starter #1,149
The only thing it is missing from the modern super high compression stuff is the direct injection system. It's hard to get knock when there's no fuel in the combustion chamber. For now it's easier to tune a port injected engine with an aftermarket ECU but the aftermarket is quickly catching up to direct injection. But that's ok, in a few years when the 8AR gets cheaper and the aftermarket ECUs have caught up with direct injection i'll make a motor mount for that one and we can have some fun with it :)
 

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Modern engines that are getting away with very high CR are doing so from primarily 3 things:
1) Direct Injection is good for about 1 ratio of extra knock resistance. This has nothing to do with no fuel in the combustion chamber because of course their is. The knock resistance from GDI comes from the heat of vaporization of the fuel, which in DI mostly stays in the mixture (cooler mixture at beginning of compression) as opposed to port-injection where the heat of vaporization mostly gets absorbed by the intake port and intake valve.
2) Improved engine cooling. Computational Fluid Dynamics along with Finite Element Analysis are powerful tools used by engine designers to fine-tune the cooling of the really hot parts near the combustion chamber. Elimination of the hottest hot-spots yields big improvements in knock resistance.
3) Miller (sometimes called Atkinson) valve timing is the technique of closing the intake valve really late (later than for optimal cylinder filling) to reduce the effective compression ratio (below the geometric CR). This works really well at low to mid engine speed. There are engines that do the same thing with really early IVC.

There are other things going on in engine development, but these are the big effects on knock resistance.

Dave
 

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Discussion Starter #1,151
Dave, I have to apologize on that one. I hadn't ever looked deeply into direct injection and i had it in my mind that injection happened immediately ahead of the ignition but i never thought much about it. But your message spurred me to look a bit into it and it of course makes sense that the fuel needs time to mix with the air. I even found this neat chart:



Thank you for the correction.
 

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The fancier direct injectors that are now common allow some fuel to be sprayed at the top of the compression stroke. I think this primarily helps ignition when there's heavy EGR dilution by creating a stratified charge. Usually you'd spray some of the fuel on the intake stroke to create a homogeneous mixture in the cylinder, then create a richer pocket with a second injection.

Miller cycle is as I mentioned standard nowadays. The Skyactiv-G and Dynamic Force engines both have quite a bit of late intake valve closure built in with a longer duration intake cam and wide range VVT. Not as extreme as on the 2ZR-FXE or other Toyota hybrids where a significant amount of power is sacrificed, but much more than current Honda engines. Reducing the torque of the 2AR should easily bump the compression to 11-11.5, like on the 1NR-FE.

With direct injection, the 2AR could probably be at ~12 on regular gas as opposed to ~11. Honda L15B1 is at 11.5 with higher specific torque, and the Skyactiv-G 1.0 is at 13:1 with lower specific torque. The Dynamic Force engines match the Mazda's 13 but have more VE/torque with high tumble intake ports and the other little head cooling improvements.

I think what is pretty impressive is that the peak power in the A25A arrives at a higher rpm than the 2AR despite having restrictive high tumble ports. If you believe Toyota's efficiency map, the airflow rate is pretty similar to the 2AR. I imagine a lot of CFD money went into that design.
 

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Discussion Starter #1,153
Quick update, I just sent what i believe to be the final BEAN code on a body controller module to PhatTires for some testing. If that ends up working properly i will do a small production run in house so i can sell them right away while i align larger scale production.
 

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Discussion Starter #1,158
Sure, so the early version of the body controller i sent to Randy(PhatTires) had an issue completely unrelated to the software and the BEAN stuff.

He plugged it in and got a no start condition which was really odd since the BEAN stuff does not affect any of that. I asked him to probe a few pins to get some voltages including IGSW. Unfortunately it looks like he may have touched the ground pin at the same time and the IGSW trace on the board burned up. This is inconvenient for testing but i'm also quite happy that it happened so i can avoid anyone else having the issue in the future.

The fix there is just to reduce the size of the fuse on the IGSW line. IGSW in a 2AR swap application just gets sensed, there's no more than 10mA load on it at most. So i'll see how much space i have for the trace and make the fuse as big as i can (probably 3A or 5A). i don't need the current but it'll leave the current there if someone has an alarm system or something hanging off that line.

The prototype is now back in my hands, I've fixed the trace and the tentative plan at this point is for Randy to bring his car to me this Saturday to get the last bit of debugging in person.

As for the A/C stuff, I am not starting on that until the BEAN stuff is done.
 

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Discussion Starter #1,160
Sounds good- will I be able to add AC when the engine is in the car, or will I need to drop the engine again?
The A/C is at the very bottom of the motor, it'll be tight to install it after the fact but it should definitely be doable. Since the bolts are long odds are you'll have to put them in the compressor before putting it in the engine bay and then you'll be able to tighten them down from there.
 
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