Production Toyota FT-86 Details and Design Previewed by Toyota Sports Vehicle Boss

[Want.FR-S]

Originally Posted by Dimman

Bingo! This is why I (and others) have been bitching about the performance potential of the 90mm stroke FB20 (as it is in the Impreza).

The issue is that with an NA motor, all you can do to get more air into it to make power is to spin it faster (with the supporting flow work). So starting with a 94mm bore and 72mm stroke (the de-stroked fantasy FB25 me and Exage discuss occasionally) allows for more safe rev potential, and therefore more NA power without screwing around with replacing rods right away. The side effect of the over-square motors is that to get the displacement back they need bigger bores, which more easily accommodate the larger valves and porting that are needed to move the extra air from the extra rpm. Downside is slow low rpm intake charge speed, which means poorer low-rpm combustion and torque.

Now hopefully Yamaha and FHI have agreed on this and how an 84mm bore and 90mm stroke FB20 is an inappropriate motor for this car. Worst case scenario for me is that it is maxed out (reliability-wise) at 200 hp @ 7kish rpm with the 90mm stroke. Then needing new rods to get into the high 8k range, and porting and increasing valve size is a pain with the smaller bore, etc...

And I believe it was discussed of of one mod to change the rod to decrease the stroke and increase displacement. I think this is what you are referring....

[Dimman]

Originally Posted by Want.FR-S

And I believe it was discussed of of one mod to change the rod to decrease the stroke and increase displacement. I think this is what you are referring....

Yes there are a bunch of ratios that I don't fully understand, but basically to change one thing ends up requiring more things changed too. So to take and FB25 (which has a bigger bore than the FB20) and shorten the stroke to make it 2.0L, then needs the connecting rods to be sized differently, which then changes the compression ratio, which means cutting down the block, which may affect the cooling because of smaller water jackets around the cylinders, etc...

So if they wanted to do this, the easiest thing from a mass production point of view is to have an alternate block cast, one that accounts for the short stroke/deck height and different cooling requirements.

And the Moto post implies that Yamaha required just that. Plus Toyota and Subaru do have a history of using very different blocks (and heads) for the performance versions of 'normal' motors. The 4AGE from the original AE86 is quite different from the 4AFE in the FWD Corollas of the era. Same with my BD Legacy's EJ22 and the EJ22T from a BC Legacy Turbo. Or an EJ25D from a BD Legacy GT and the EJ257 from a late model STI.

So the same base motor designation (EJ, FB, 4A) still allows for huge differences in performance suitability.

Basically what I'm getting at is that I REALLY hope the FT86's FB20X? is modified to be a more rev-friendly shorter stroke design in some way.

[1660]

Longevity aside, the 7000 rpm limit would be the ECU program by Toyota. So, potentially if you take the rev-limiter off you could increase power. Would you be able to take it 9000 rpm without damage? I don't mean redlining the motor all the time, but occasionally.

BTW, thanks Want.FR-S for the wikipedia find.

[SUB-FT86]

How often do you guys rev that high on your daily commute?? I think high revving engines are useless unless

1. They make good power/torque in the mid-range
2. You go to the track very often

[SUB-FT86]

Originally Posted by Traum

Why do you say that? I don't know my Toyota + Yamaha collaboration efforts all that well, except for the 2ZZ-GE. I know retuned / supercharged versions of the engine sit in the Elise / Exige, but on its own merit, the engine was peaky and have had some production issues.

By its own merit, I can't recall any recent-ish mainstream Toyota engine that impresses me from a performance stand point. The Camry V6 certainly has a lot of grunt, but I only find it more or less competitive with similar offerings from Nissan and Honda. And I'd have to say, I like Nissan's VQ better than Toyota or Honda's big V6's.

At any rate, the FB engine started life as a Subaru design. I'd be very much interested in how it performs.

It's my favorite engine period!!!! The 3.5l 306hp/268tq. My co-worker has a 2007 G35 sedan and every time I drive that car I become pissed that I have to drive my RSX. The engine pulls like a V8 from 2800 rpms and never stops pulling till redline and it doesn't even have D/I technology.

[Spaceywilly]

My first car was a 96 maxima. The original VQ . That car had "only" 200hp and it felt plenty fast. If the ft86 engine manages to match the torque of that engine, in a lighter car, it's going to be awesome.

The VQ is a great engine. I don't care what anyone else says, I love that sound.

[LeeT]

The VQ is a great engine, but the VQ37VHR in my old 370Z left a bad taste in my mouth.

[Exage]

Originally Posted by SUB-FT86

How often do you guys rev that high on your daily commute?? I think high revving engines are useless unless

1. They make good power/torque in the mid-range
2. You go to the track very often

Nothing I say or anyone else is going to change your mind. What you call useless, I call fun.

[madfast]

there is no way this engine is going to be a torqueless wonder. no way. cars like that get a bad rep. the best example is the S2000. while a great car in its own right, people endlessly complained about the fact that you had to rev the hell out of it to feel anything. the result was a move from the 2.0L to 2.2L, and a subsequent decrease in redline... i doubt toyota and subaru are unaware of this. and its also not without precedent that the 2012 si is now 2.4L...

"horsepower sells cars, but torque wins races..." -enzo ferrari

[madfast]

Originally Posted by Exage

Nothing I say or anyone else is going to change your mind. What you call useless, I call fun.

its fun to waste gas and rev like a madman in light traffic? not for me at least. the ABILITY to rev high should always be there, but if the trade off is crap torque down low most people would say thats a bad thing. i think there IS a happy medium, and hopefully the FT will be right there. usable tq down low, while still having high rev capability...

imo the best way they can do this is not with displacement, but with compression. the D4-S system allows them to run higher compression. couple that with a square, or imo more likely a slightly undersquare, engine geometry and you should have respectable torque across the rev range.

[SUB-FT86]

Madfast, you honestly believe that this engine wont be a torqueless wonder? I would love to know why you think not. I wish they were using the 2.5l so bad because I think the extra .5 liters would make me happy as hell along with a 6500 rpm peak power. 220hp@6500/185-200tq@4000 rpms with a curb weight of 2750-2800 lbs

[madfast]

Originally Posted by SUB-FT86

Madfast, you honestly believe that this engine wont be a torqueless wonder? I would love to know why you think not. I wish they were using the 2.5l so bad because I think the extra .5 liters would make me happy as hell along with a 6500 rpm peak power. 220hp@6500/185-200tq@4000 rpms with a curb weight of 2750-2800 lbs

well i think not, and i hope not. the market is moving towards better torque and better fuel efficiency. and guess what, a low displacement, DI engine give you just that. its NOT a coincidence that the DI bandwagon is so full right now. its a WONDERFUL bit of kit for regular cars. but the advantages of DI also extend to sporty cars. it allows higher compression and gets better fuel econ. its basically win-win. sooner or later ALL engines will be DI. its inevitable...

now with this all new or heavily reworked engine in the FT. its already confirmed to be 2.0L. so the low displacement is there. its already confirmed to have D4-S so the DI is there. the only thing we dont know for sure is if its oversquare, square, or undersquare. but i ask you this: whats the last all new 4 cyl to come out that was oversquare? its very, very rare nowadays because high rev gets you nowhere in todays market. the people demand tq and fuel econ. for clarification, people dont demand tq per se, but they feel it, and they want it. they may not really understand what they're feeling, but that "push you into your seat" feeling is universally wanted. we know that is tq, but to them its that "oomph" feeling or whatever... and that "oomph" sells...

the problem with a 2.5L imo is simply fuel economy. it need not be that large of an engine for its size/weight. rev capability is also still very important. they wont go so far as to trade off great tq down low with nothing up top. the theme for the whole car is BALANCE. a balance of usable tq and "high enough" rev ability.

so yeah, i think with this many years in development, and with how the market is going, i dont think they're that stupid to put out a high rev, torqueless engine that needs to be above 5k just to feel some acceleration...

[MrVito]

I'd like to see a high compression square motor in this, redline would probably be set at around 7k, would it be safe above that at 86mm X 86mm? Probably, but I'd be surprised to see Toyota/Subaru set the redline higher than 7k. They can set it low, and then when the guys with the 20lb brains making the math nightmare posts find out what it is actually safe to, we'll know what to set our rev limiters at when the car gets a good dyno tune.

[madfast]

Originally Posted by MrVito

I'd like to see a high compression square motor in this, redline would probably be set at around 7k, would it be safe above that at 86mm X 86mm? Probably, but I'd be surprised to see Toyota/Subaru set the redline higher than 7k. They can set it low, and then when the guys with the 20lb brains making the math nightmare posts find out what it is actually safe to, we'll know what to set our rev limiters at when the car gets a good dyno tune.

whether its square or undersquare, i think redline and/or fuel cut will be set between 7-7.5k... realistically speaking, in terms of the stock tune and warranty, etc. 7-7.5k is plenty.