Mods vs possible BRZ STI

[Thunderchicken]

Originally Posted by ThatGuy

I was hoping for an increased displacement engine. It make some sense if they want to continue with emulating the Cayman and leaning on the LFA engineering/marketing.

If they pushed the bore out a few mm and the stroke up to 90mm they'd be around 2.4L capacity. A few slightly more exotic materials, give it a decent voice through a revised intake and exhaust (just a few extra db) and they could push out 235-240hp. This would put it into the mid-low 14 second 1.4mile bracket. I'd also like to see new flared FRP front guards (offset the weight increase) and slightly pumped rear guards to allow another 20mm track, RAYS forged 17 x 8.5" wheels with 10mm more offset (keeping 17" to reduce weight and allows them to talk about pure sports ethos over fashion, bla bla). Put some grippier 235/40/17, some larger ~324mm brakes up front with 2-piece rotors. A few bits of the underbody bracing from TRD, drop the height ~15mm, a few harder rubber bushings and ~15% firmer springs and add 1mm to the anti-roll bars. Plus an STi badge to let everyone know you have the disease.

Just detail changes everywhere, the type of stuff owners do to their cars over the years.

This would sell well !

Sorry to burst your bubble but in order to get that long of a stroke 90mm Subaru has to do crazy stuff to the rods in order for the engine to fit. What is sounds like is you want the Subaru FB25 motor with Bore x Stroke = 94 x 90, 170hp @ 5800 rpm and 174tq @ 4100 rpm it's not going to rev as much because of piston speed.

[Dimman]

Originally Posted by Thunderchicken

Sorry to burst your bubble but in order to get that long of a stroke 90mm Subaru has to do crazy stuff to the rods in order for the engine to fit. What is sounds like is you want the Subaru FB25 motor with Bore x Stroke = 94 x 90, 170hp @ 5800 rpm and 174tq @ 4100 rpm it's not going to rev as much because of piston speed.

Where do you think this motor came from? Also have a look at the pics of the stock FA20 rods...

[Thunderchicken]

Originally Posted by Dimman

Where do you think this motor came from? Also have a look at the pics of the stock FA20 rods...

FA shares very little in dedicated parts with the FB engine, with a different block, head, connecting rods, and pistons.

If you were to put the FA20 rods side by side with the FB20/FB25 and the EJ25 they will all be different with the EJ25 being straight, FA20 with a ever so slight bend and the FB20/FB25 having a major bend in the connecting rod.

The longest stroke you can get from the EJ25 is a 79mm rod, to go to a longer stroke you run in to package constraints aka the motor would be too wide to fit in the frame rails. So to stroke the EJ25 you have to go with a 84mm stroker crank.

Just keep in mind Toyota / Subaru are going to kept it simple and spend very little engineering dollars on future power upgrades, what that means is allowing the heads to spin a little higher in the rpm by using better value springs and cams, redesign of the exhaust to allow it to breath better, and larger throttle body.

Since this is a new motor Subaru isn't going to make drastic changes. They will do small changes so they can continue to meet EPA regulations and possible power upgrades for the FRS/BRZ or other future cars.

[arghx7]

A higher flowing head means further loss of tumble flow, which could make emissions and combustion stability targets difficult to meet. More displacement will hurt fuel economy.

The industry is moving towards smaller displacement and lower revs. It would be surprising to see either higher displacement or increased engine revolutions in the future. Maybe they planned for it already though.