Bolt-on HP estimates?

[PulsarBeeerz]

Originally Posted by Pete

My mistake

Still, that is even more interesting then. The 2.0 liter responded well to mods and forced induction. With more displacement + stronger rods I can't wait to see what the tuning shops can do with the 2.4.

Did they say the rods where stronger? I mean they could have added just enough material to compensate for the heavier pistons..


I'd be more interested in if they improved the oiling system.

[Kona61]

Originally Posted by PulsarBeeerz

Did they say the rods where stronger? I mean they could have added just enough material to compensate for the heavier pistons..


I'd be more interested in if they improved the oiling system.

Go read my post about the in depth changes to the FA24.

[Mitch]

Originally Posted by Kiske

Keep in mind that Japan also runs a higher octane fuel (98-100) for their premium unleaded gas than most of the west readily offers.

Just a note, Japan uses the RON method of measuring octane. The US uses AKI ((RON+MON)/2).

93 AKI = 98 RON
91 AKI = 96 RON
E85 is 94-96 AKI = 102-105 RON

So if you live in a place that has 93 octane gas, the difference between what you have at the pumps and the best pump gas in Japan is minimal. And if you have access to E85, you have even higher octane available at the pumps.

[TommyW]

Originally Posted by PulsarBeeerz

Did they say the rods where stronger? I mean they could have added just enough material to compensate for the heavier pistons..


I'd be more interested in if they improved the oiling system.

All it would take would be rod bearings similar to King's with oil slots rather than holes

[stilesg57]

So why is this engine less efficient than the FA20 anyway? Any thoughts? Less aggressive cams emphasizing more low-end?

I mean, with the same redline and a similar torque curve I’d expect a horsepower increase to be roughly equivalent to the displacement increase, which would put it at 246hp. But this engine is a full point higher in compression, yet still gets an 11% hp bump out of a 20% displacement bump? Doesn’t feel right; I thought specific output would go up, not down.

[timurrrr]

Originally Posted by stilesg57

But this engine is a full point higher in compression

It's not, please re-read the official specs. They say 12.5:1.

Originally Posted by stilesg57

I mean, with the same redline and a similar torque curve I’d expect a horsepower increase to be roughly equivalent to the displacement increase, which would put it at 246hp.

The clearly prioritized the mid-range "fat" torque curve over peak horsepower.
And that was a pretty good decision, in my opinion.

[stilesg57]

Originally Posted by timurrrr

It's not, please re-read the official specs. They say 12.5:1

Nice, I'd read somewhere awhile ago that it was 13.5:1 which might bode even worse for FI so I'm glad to hear that's not the case.


Regarding the tq curve: how is that emphasized when there's still a dip (albeit a smaller one) and even it's not a full 20% gain either? Just seems like this engine is all-around less efficient than the outgoing FA20.

Maybe I'm just grumpy because the other cars I've looked at on this search are just so much damn faster and I need to get over that, ha

[timurrrr]

Originally Posted by stilesg57

Nice, I'd read somewhere awhile ago that it was 13.5:1 which might bode even worse for FI so I'm glad to hear that's not the case.

Trust me, you're not the first one...

Originally Posted by stilesg57

Regarding the tq curve: how is that emphasized when there's still a dip (albeit a smaller one) and even it's not a full 20% gain either? Just seems like this engine is all-around less efficient than the outgoing FA20.

It's not just more displacement, but also more air they suck in through the intake (possibly more losses?), the pistons have to be bigger (and heavier), connecting rods stronger (and heavier), the exhaust header still needs to go a weird way around the steering rack, etc.

They've put more stuff into basically the same dimensions and overall weight, so it's reasonable that they couldn't just simply achieve the same 20% gain associated with the 20% extra displacement.

It would be a different story if they created a boxer-8 FA40 by combining two FA20's together on a dyno stand

[humdizzle]

215-220whp on pump without the car being too much louder than stock would be ideal

thats the power to weight of a E46 M3. 275whp/3400 lbs = 220whp/2800 lbs

[stilesg57]

Originally Posted by timurrrr

Trust me, you're not the first one...

In my defense, that 13.5:1 figure comes up A LOT in both Google and thread searches…I just didn’t read far enough through those threads to catch where it was debunked


Re: that 220whp idea, I’d bet that will be pretty obtainable with a header and an E85 tune. If that’s your goal you should be in good shape staying NA. I don’t want to touch the exhaust and am looking for more like 260whp to match the 981 Cayman S’ power & weight, so I’m still pretty sure I’ll go FI if I get a new Twin.

[timurrrr]

Originally Posted by stilesg57

In my defense, that 13.5:1 figure comes up A LOT in both Google and thread searches…I just didn’t read far enough through those threads to catch where it was debunked

Yeah, that was a Subaru PR fiasco

[ZDan]

Originally Posted by stilesg57

Regarding the tq curve: how is that emphasized when there's still a dip (albeit a smaller one) and even it's not a full 20% gain either? Just seems like this engine is all-around less efficient than the outgoing FA20.

You shouldn't just go with PEAK power and PEAK torque alone.

The earlier engine sacrifices power and torque throughout the range for a couple of peaks over limited rpm ranges. Likely the new engine's cams have a bit less duration and overlap, hence broader less peaky power curve.

At hp *peak* of 7000rpm, the new 2.4 indeed only makes 11% more power vs. the 2.0 and not 20% more as displacement would suggest, all else equal. And the new 2.4's *peak* torque is only 18% more vs. the old 2.0's *peak* torque (close to but not quite 20%).

However, if you look at power and torque at the old engine's torque dip around 4000rpm, the new engine is making about 38% more power and torque there.

On average you're going to see ~20% more power and torque throughout the powerband. The peaks have been rounded off a bit, but the midrange trough has been massively filled-in. For sure they could have kept the same amount of peakiness and same power/liter, but at the expense of midrange. I would bet that actual overall performance is the same, but without the lull in the midrange.

Here's my plot of rwhp/torque of 2022 (scaled based on the dashboard readout) vs. 2017:

[stilesg57]

This makes me feel a little better, thank you. AUC does look like a ~20% bump, esp when you see how that TQ bump from 6300-6900rpm on the FA20 is responsible for a good bit of its peak HP number.

[Lantanafrs2]

Power increase and displacement increase aren't always or even usually, commensurate.