ajw45

Kinda. There's a lot of assumptions in there but all things being equal, if you give an engine more displacement you'll get more torque across the rev range though realistically with diminishing returns at the top end assuming no changes to intake and exhaust where the limit is less the capacity of the engine and more the capability of it being able to flow that much air at that much rpm. The X51 is kinda the opposite, all intake modifications to breath better higher up in the rev range and no real change in the engine's max torque. Intake is bigger, runners are bigger, intake cams are tweaked (no idea if longer duration or higher lift or both), and the heads are flowed all to allow for more air and extra resonance flaps are really there to try not to LOSE torque down low. Without more displacement and again all things being equal, the intake and exhaust work can't make a bunch more peak torque/L but it can try to change the shape of the curve, a lot, either higher, lower. If you look at the official Porsche dyno below comparing 991.1 S base (dashed) and x51 (solid) you can see that black torque curves both hit the same peak torque number and in some places the x51 has less torque than the base engine but after 6500 RPM the two lines diverge dramatically. That provides a big HP bump but no peak torque increase and really, under 6500rpm zero performance increase. On the other hand, a bump in displacement alone would be like having a second dashed line of similar shape but 5% higher. so you would get a performance increase across the rev range, not just at the top.

Still, we don't really know what Porsche is doing. They could do a 3.8 with a multi-flap intake ala 991.2 GT3 that provides a flatter torque curve down low and up high, who knows. I don't think the 718 GT4/Spyder will get the x51 exactly since even the GT3 didn't get a fancy aluminum intake manifold. I think they'll have a new (plastic) intake manifold specific to the GT4 with a full 911 size tb (finally) and other intake/exhaust revisions to extend and push torque higher in the rev range to get their 420hp w/o actually increasing peak torque much since the 981 is already on the edge of the torque limit of the gearbox which was carried over to the 718. That said, if you already have a 981, might as well call Deman or BGB and go 4L x51 now instead of waiting another year or two. My 4L X51 has been running like a champ since before the 718 Spyder/GT4 speculation threads existed

Suicide Jockey

^^^^^^ Thanks for your detailed explanation. The issue is clearly more complex than my simplistic understanding, but I have a much better sense of some of the variables at play that Porsche will be working with. Appreciate it.

guab

Good explanation. Unless the 718 Spyder offers a dramatic improvement over my 981 with Dundon race headers, I will pass. The ability to spec one for MSRP might sway me, but that would probably be about it. Otherwise, will hold for a few more years and perhaps go the 4.5L route that Dundon keeps talking about should I desire more power. Seeing as I didn't even bother with the tune, I doubt I will -- but 4.5L so who knows.

JAM2

Suicide Jockey

TB = throttle body, correct?

ajw45

420hp is huge in Porsche land. That's +35hp! 991.2 GT3 got +25hp, GT3rs got +20hp. 991.2 GTS got +20hp, 991.2S got +30hp. I know 420hp seems like nothing burger these days but it's still a solid gain between generations.

JAM2

Suicide Jockey

If the 982 Spyder does have 420 hp, it would actually be +45 hp over the 981 Spyder's 375 hp. This hp increase would be less than the +55 hp jump between the 987 Spyder (320 hp) and the 981 Spyder (375 hp).

CAlexio

same. my spyder was a pleasure to drive after TB, sport headers and Cobb ECU tune. dramatic difference from the stock engine. i can't imagine that this significant difference wouldn't have happened if the engine hadn't been so neutered from stock. i wonder if the new engine will have such responsiveness for tuning.

spyderphile

I never considered a detuned GT3 a viable option. Too expensive. 3.8 + X51 setup has proved to be effective in the past. Budget-friendly to stay within the price curve. All they had to do is to make it compliant to new regs. They may have tested various engine setups, including turbo. But, that could have been for a # of reasons. That's what product development/testing is all about. Those who advocated against it argued that there is no production 3.8. Well, with just-in-time manufacturing and supply chain management, you can pretty much spin up a line in a short period of time. The tooling is already there. The volume is more than enough to make a tidy profit for all the parties involved.

If X51 peaks power near the redline, would be a great news for guys like me. Even among enthusiasts, guys like me are a tiny minority. I don't want low and mid-range torque. Just make it linear and peak near the redline. If I want to pass or enjoy the imminent straight, plan ahead; drop a gear or two and be in the sweet-spot of rev range. And, get ready for the rush and soundtrack! To me, that's an essential aspect of driving! Of course, lower gearing makes all these even more enjoyable. Sadly, Porsche thinks the gearing is fine! So, we got no prayer there.

Those who are expecting a dramatic improvement in performance from 981, are in for a disappointment! That's not how Porsche rolls! Think evolution; not, revolution! Each model cycle sees incremental and evolutionary progress. To me, that's perfectly fine! These days, we may be seeing slightly more than HP jump, if any, between cycles due to HP wars brought on by turbos/hybrids/electrics. Porsche doesn't usually participate in HP wars. They know perfectly well that it's all about the overall package and driving dynamics. For the street, I actually don't want more power than the 981! I value the driving dynamics and styling more than power/torque.

WAY

Selo

Given the current torque and 0 to 60 specs on the 718 Boxster GTS, Porsche won't have difficulty gerrymandering the 0 to 60 time to where they need it to be. First of all, even if they slap in a power kit 9A1 motor and don't mess with it at all, the torque is higher than the current Boxster GTS. Also, plenty of other tricks they could do, with the pdk transmission, with the width and compound of tires, Etc. But they're doing it all for show, really. I don't think they really care about that number too much.

WAY

digitalrurouni

I guess I am in the minority wanting more power. If I get the chance I will definitely upgrade. Especially if I can customize my car to how I want. That opportunity alone is very enticing. Also I like the rear LED lights and the overall silhouette of the car. I don't like the interior vents and the Sport Chrono clock altogether. But I guess it's not enough for me to not want the newer one. And if a car comes from factory without me needing to tweak or feel there was more left on the table - all the better! Another good argument for me to swap is especially if the rumor is true that mechanically both the GT4 and Spyder get the same exact hardware - suspension/wheels/tires. Then it's a no-brainer! But how much of that is true I do not know. Time will tell. Bummed they got rid of the Sapphire Blue color though. That color turned everyone's heads whenever I drive my Spyder!

SpyderSenseOC

I'm thinking Brewster Green with black wheels and cocoa brown full leather interior or Zanzibar Red on black. Mmmm