Engine technology thread.

[Ryephile]

We'll have to wait and see of course. If they were smart, they left service clearance. If they were sloppy, hopefully some U-joints and innovative tools will work. If they were dumb [i.e. NA Miata oil filter] there will be lots of expletives and bloody knuckles.

[Homemade WRX]

what valve adjusting is everyone talking about?!! the only subaru EJ heads that have needed them are the SOHC NA heads. These FA and FB heads are a hydraulic and rocker arm setup.

Plugs aren't nearly as bad as most guys say. On a stock engine bay, GD chassis, it takes me about 45 minutes in no rush...in my coupe (race car), about 10 minutes

As for this chassis and engine, I'm wondering what provisions they've made for plug changing. I'm also wondering if the manifold will drop out AS easily. I'm thinking we may to knock the motor mount nuts off and pick it up a bit to clear the x-member. I'll know soon enough.

[Dimman]

Originally Posted by Homemade WRX

what valve adjusting is everyone talking about?!! the only subaru EJ heads that have needed them are the SOHC NA heads. These FA and FB heads are a hydraulic and rocker arm setup.

Plugs aren't nearly as bad as most guys say. On a stock engine bay, GD chassis, it takes me about 45 minutes in no rush...in my coupe (race car), about 10 minutes

As for this chassis and engine, I'm wondering what provisions they've made for plug changing. I'm also wondering if the manifold will drop out AS easily. I'm thinking we may to knock the motor mount nuts off and pick it up a bit to clear the x-member. I'll know soon enough.

Have you had a chance to directly compare the FB with a Toyota GR motor?

I'm curious but since Toyota's involvement the FB did some of the same things that the GR did when they went from the MZ, roller rocker, separate cam carrier are what stand out to me. But what about piston pins, rod sizing, etc..?

Reason I'm asking is I'm a bit curious about whether the 94mm D4-S pistons from the 11.8:1 2GRFSE could be used in a frankenstein FB25 with FA20 head, or be suitable for a 94mm bored FA24, while keeping the startup normal (or whatever the hell the funny piston crown is for on the D4-S).

[Homemade WRX]

someone is catching on

I'll be bring internals to the market, like I already do. I'll be making piston and rod combo for the pretty much exactly what you're talking about.

Now that you know part of the plan...

[Tradewind]

I am only familiar with the SOHC versions of Subaru engines hence talking about manual valve adjustment

[Maxim]

Having had a look at the exhaust piping under the car, and having read the reviews that mention that the vehicle runs out of gas a little bit before the redline, I'm pretty convinced that switching to a minimally restrictive single pipe exhaust (with a little black plastic cutout to cover the hole in the rear diffuser), along with a good cold air intake, will result in 20-25hp or so with a good tune.

The engine is just a glorified air pump. Falling off in power before reaching any kind of mechanically limited RPM point (floating valves, etc) means there's room for improvement in the air pump.

Changes with the mechanical inner-workings of the engine to increase the redline will of course improve power as well, but I think there's likely quite a bit of room for optimization even without internal changes.

[madfast]

Originally Posted by Maxim

Having had a look at the exhaust piping under the car, and having read the reviews that mention that the vehicle runs out of gas a little bit before the redline, I'm pretty convinced that switching to a minimally restrictive single pipe exhaust (with a little black plastic cutout to cover the hole in the rear diffuser), along with a good cold air intake, will result in 20-25hp or so with a good tune.

The engine is just a glorified air pump. Falling off in power before reaching any kind of mechanically limited RPM point (floating valves, etc) means there's room for improvement in the air pump.

Changes with the mechanical inner-workings of the engine to increase the redline will of course improve power as well, but I think there's likely quite a bit of room for optimization even without internal changes.

exhaust manifold is probably the main restriction in the whole exhaust system. who knows how creative the aftermarket can get with header design given the limited space.

[Maxim]

Hmm. I'm more inclined to think that the cat and that terribly designed muffler which looks to redirect the exhaust flow at least twice are more restrictive than the header.

[Tradewind]

I doubt there is more than 10hp in exhaust fiddling, if I am wrong then so be it. In the past SOHC Subaru's have had significant losses in the air filter/intake system in the order of near 10hp, but nothing as significant was available for gain on the exhaust side.

But this is a new beast so - maybe the tables have been turned

[old greg]

Originally Posted by old greg

Yeah, but on the AS1 the engine seems to be sitting right on top of the front subframe, so it may not be all that easy.

I take it back.

[OrbitalEllipses]

That's an EJ.

[old greg]

Yes, but with an AS1 crossmember and from all appearances, an AS1 header/cat.

[Maxim]

Originally Posted by Tradewind

I doubt there is more than 10hp in exhaust fiddling, if I am wrong then so be it. In the past SOHC Subaru's have had significant losses in the air filter/intake system in the order of near 10hp, but nothing as significant was available for gain on the exhaust side.

But this is a new beast so - maybe the tables have been turned

Oh I agree that there's probably no more than 10-12hp to be had from road-legal cat-back modifications. A cold air intake and a tune to take maximum advantage of the new intake/exhaust though....yeah I dont think 20hp will be a stretch at all.

Full headers/exhaust/intake/tune I think we could see RX-8 levels of power out of the car without any problem. Maybe not quite the peak numbers, but given the wide torque range of this engine compared to the peaky Renesis....area under the curve should probably exceed the RX-8.

And it weighs 250+ pounds less.

[bambbrose]

Didn't see the official brz dyno chart in this thread yet.