Zach L

This ^^^ ...also the 2.9L heads are set up for port injection. All the higher displacement builds are going to be utilizing DFI. The 2.9L was the only 9A1-era engine that wasn't direct injected. In fact, it utilized the older Bosch ECU rather than the Seimens ECU used on all DFI cars. Part of doing a 3.8L swap on an original 2.9L car is to use a harness adapter such as the one from BGB, or to completely replace the engine harness/ECU to one from a 3.8L car. Only then would a displacement increase be practical, on the 3.8L engine.

Zach L

I don't think I'd trust that resource ...it incorrectly lists the 2.9L engine as DFI.

Andres R.

Rick,

Do the 2.9 heads have any untapped potential? Generally speaking oem heads on anything other than a halo car aren’t developed for maximum efficiency/power. I’d like to find out if there’s worthwhile torque gains available from removing cast flash/ridges, improvements in bowl area, valve job, throat diameter, combustion chamber, etc with a focus on air velocity. Is 110-120hp/L achievable with an 8K revlimit? I’ve even contemplated having runners 3D printed. I don’t necessarily have a HP target, rather a response/feel/sound that’s Motorsport if that makes sense.

​​​​​​​ Thank you.

Rick DeMan

Only one way to find out! Good luck...

XuTVJet

To achieve 110hp+/L, it would also likely require larger cams plus some level of tuning to make it run correctly. Unfortunately, our 9A1 port fuel injected motors, while robust and overbuilt (closed deck, forged crank, rods, pistons, tons of cooling and oiling), don't have much of any aftermarket support. Given the 265hp, 7200rpm power peak and 7500rpm limiter, and 2.9 liter size, this motor is already impressive with its naturally aspirated 91hp/liter. I also think this motor is slightly underrated and making more like 275hp-280hp on 93 octane based on the performance figures (102-103mph trap speed in the 1/4 mile).

I don't think there's any power to be found in the runners or headers either as the 2.9 uses the same intake manifold and headers from the 320-330hp S and R models. There is some power (about 10whp/wtq) in going to 200 cell cat converters vs the OEM ones, but that's not going to change where peak power hits, it only elevates the overall power curve.

Andres R.

If I go through with the head work I’ll have custom cams made as well. A custom tune is a must.

I really think 110-120hp/L is in reach, but at what cost.

Ric In RVA

Should be fascinating to watch. And if it works I am sure there is a market, albeit small, for this. Honestly I like the fact you have to work the car harder to go anywhere....something about a slow car driven fast vs a fast car driven slow. (Since I have no good place to drive a fast car fast, except on track)

As far as I can tell there is no easy HP available for these engines beyond a simple uncorking of exhaust and cats and a basic tune. Am I missing something?

Also can anyone point me to a good 3.8 swap thread? Not in my near future but maybe one day.

Andres R.

The thought of possibly making ~320 HP from the sweet little port injected 2.9L (no carbon buildup or hpfp to worry about) has me seriously considering this. Anyone have a cylinder head to contribute to the project? There’s a local performance machine shop I can take it to do some testing. I see some cylinder heads on eBay calling my name.

I might start a new thread…

Zach L

The Dundon intake runners make power on every size engine they've been bolted onto, significant extra power. Designed for 3.8L 911 engines, but just as effective on the 3.4L engine. They're right there with catless headers in being the best power adder for these engines, around +25whp peak and no torque loss down low. I'd be surprised if they didn't add power on a 2.9L as well.

Check out MotoiQ's 987.2 Cayman S build series. Great 8-part track-prep build and absolutely no internal engine modifications. Just bolt-ons brought power up to 354whp (yes, wheel) @ 7,200rpm. And that was on a Mustang dyno too. Assuming a conservative 12% driveline loss, that's over 118hp/L (104whp/L).

https://motoiq.com/category/projects...he/cayman-987/

JCP911S

I have a 987.1 with a stock 3.6 conversion, and a troubling engine condition... I have explored several options. Good replacement engines for these cars are hard to find, and will cost minimum... $15K..add shipping and install, and you are looking at $20K+++ for a pig in a poke...

I have a rebuildable 3.6 core, this can be done... I'm still looking well north of $25K from a reliable builder... but putting that kind of money into a car that... on a good day, is worth $35K looks like a bad investment, frankly... it's P**sing in the ocean...

Bottom line, one can do anything with enough money, but come sale time, you won't see 20 Cents on a Dollar... so pay your money and take your choice... (but it's a losing prop, IMHO).

Personally, I'd cut bait... a C7 Corvette will kick anything you can build dead on the curb for about $40K, or if you want a Porsche, a used 718 Cayman S PDK with a bit of setup is a really fast car for maybe $65K and will hold its value...

Jus' sayin'

Andres R.

The problem is the 2.9 is port injected not dfi and dundon does not make runners for this engine. I’ve thought about scanning the stock runners, having them redesigned and 3D printed in GT3 fashion, we’ll see.

Andres R.

Believe me, I know none of my brainstorming makes any financial sense…

I specifically chose the 987.2 with 6spd manual & the 2.9L for its relative simplicity (long term reliability?), NA high revving nature, & hydraulic steering. It’s that analog formula that I’d like to enhance. I want linear power right up to my 8K redline; a baby midengined GT3. The 718 doesn’t tick those boxes for me.

Zach L

Ah, I wasn't thinking about the mounting connection being different on the non-DFI 2.9L head.

sectachrome

@Andres R. I like your enthusiasm. It's crazy but I'd love to see where it goes lol. To me, it seems like trying to get more power out of the 2.9 is a pretty fruitless endeavor with a very unfavorable cost to benefit ratio. I haven't even done headers because I suspect I'd be disappointed. If they were half the cost I wouldn't hesitate. I've opted to invest in handling, weight savings, and experiential improvements instead. I've toyed with the idea of a lightweight flywheel as well to not add actually more power, but to make it feel faster. Not sure the risk is worth the reward there either so never pulled the trigger. One day if I become a lot wealthier and still have the car I'll send it to BGB for a 3.8.

XuTVJet

I would have to agree that the time, effort, and cost to do one-off cams, intake manifold, and tuning would be extremely pricey, especially given that it's a Porsche thus everything tends to 2X-3X more expensive than most other makes. My guess is this is something like $10K-15k. Not sure how the ECU would handle the cams either as the stockers already seems pretty aggressive. I'm excited to see where this goes though. Those Dundon Motorsport intake runners look awesome, but damn $3800? Really? Unfortunately, the Dundon runners won't bolt up as the 2.9 runners have recesses for the fuel injectors.

In my mind, the most readily accessible performance would be Carnewal 200 cell headers and finding someone to do a deeper gear set. The stock headers flow fine and most of the power in the exhaust are the pre-cats. These cars really would wake up with 15% deeper gearing.

I'd love to add around 20whp/wtq to my 987.2 Cayman base 6mt, but even in stock form, I'm pretty happy with it. It jumps off the line like an AWD car and is plenty quick for sub 100mph B road driving so as long as you keep the rpms above 4500rpms. Even though my car has "Sport" mode, the Sprint Booster makes a world of difference in the way the car responds and feels. I actually prefer to run with Sport mode off, the Sprint Booster at 5 in "Race", and PSM off (which really isn't fully off). I plan to do Carnewal 200 cell headers and a tune (if I can find one). I've managed to rip off 5.2 0-60s with my ob-board timer which is quite a bit quicker than Porsche says. 5.2 0-60s equate to lower 13 second 1/4 miles. That ain't bad for a 265hp/221tq 2,920lb car. I look at my Cayman as having more of the older Porsche performance recipe.