How can a 911 3.4 have so much more HP than a 3.2 Boxster S?
 

I just went to lunch with a fellow Porsche owner in my town and he has a sweet Red 1999 996 base model, not S. It has a 3.4L and I just looked it up and it has 296 HP. My 2000 Boxster S with 3.2L has ~250 HP

2000 Boxster - 2.7L - 217 HP
2000 Boxster S - 3.2L - 250 HP
1999 996 - 3.4L - 296 HP

How come a .5 liter increase from 2.7L to 3.2L gives only 33 more HP, but going from 3.2L Boxster to 3.4L 911 gives an additional 46 HP? That is 23 more HP per .1liter of displacement?

I have heard that Porsche intentionally limited the Boxster's power to preserve the flagship status of the 911, but I guess I never rode in a 911 until today (it had a lot of pep)

What all else does Porsche do differently in the 911 such that it has so much more power, and why can't we do that same stuff in the Boxster?

I guess this is not a new idea, but I just never really took a good luck at it until today. So I will just say: Dayum!

<iframe width="570" height="321" src="http://www.youtube.com/embed/DcJFdCmN98s" frameborder="0" allowfullscreen></iframe>


Steve

Yep.......

Indeed, the Boxster is castrated with each model year.
Some more examples:
2013 911 3.4 has 350hp
2013 Boxster S 3.4 has 315 hp
2013 Cayman S 3.4 has 325 hp
2013 base Boxster 2.7 has 265 hp
2013 base Cayman 2.7 has 275 hp

From what I understand, the 3.4 engines are all the same internally and intake/exhaust/ECU tuning accounts for the differences. Ouch.
100 hp per litre is no problem (and the GT3 waaay exceeds this number) but we don't even come close.

Then do you want to tell me why a 2001 Boxster base is way more fun to drive than a 2001 911 even though the Box has way less power? That is my perception anyway.:) The steering? Handling? etc etc.

Because you (not "you" specifically) can't drive a 911 the same way as you do a Boxster for go fast fun. Plus, define "fun to drive". Properly driven, nothing lays the power down like a rear engine 911 from early apex to track out.

talking 3.4 996 vs 3.2 986, from what i understand, bottom end, heads and cams are identical, so differences are displacement, intake, exhaust and tuning. porsche limited the last three to depower the boxster. for relatively little money you can undo this. you could potentially put a 996 intake manifold on your car (heads are the same so should bolt right on) but it is taller (which typically means better mid-range torque) and doesn't fit in the engine bay - youd have to lower your engine like the engine swap guys do (or perhaps get a cayman engine cover which has more clearance)(and get 996 fuel rails to match). otherwise, there are diys to add the intake plenum from a 997, throttle body from a 996 and airbox from a cayman to your car. cant fit a 996 exhaust (points the wrong way) but a cayman exhaust will bolt right up (lots around as take-offs from guys upgrading) or topspeed make a good inexpensive solution. with tuning you gotta pay, but i hope to fit a cayman maf housing to my 3.2 this winter and push a row 996 tune to it and see what happens. if it works ill have an inexpensive tuning solution and remove the final restriction in the intake (the narrow 986 maf housing).

The two engines share the same head castings and camshafts as well as the crankcase, with only an altered bore size.

The 3.2S engine has the most potential for additional performance in stock form by far. Thats because it was seriously handicapped at the factory, BUT the factory did this in a way that didn't cost them much money.

330HP from a 3.2 base engine is our starting point these days, 350 is routine with the Gen 5 combinations. :-)

over 100 hp/L is fantastic. A quick tour through tuning company websites (fvd, softronic, etc.) shows 320 hp as a standard number for the pre-variocam+ 3.4L 996 engine with bolt-ons. that's 94 hp/L. that means a 300 hp 3.2 should be possible just with bolt-ons.

A cayman exhaust will bolt right up to a 986 boxster? Does it add any power or just change the exhaust tone? I would consider this if I could find a nice used one somewhere if it added a few hp

here's a thread;

http://986forum.com/forums/general-discussions/34205-cayman-s-exhaust-boxster.html

there's some misinformation in there, but berty and todd holyoak have the facts - it will fit, it is lighter, it requires that the whole system (headers, mid-pipes and manifold) be changed, it may require extending your post-cat o2 sensor wires, and go for a take-off from a 987/987c 's' model. it sounds better and should be good for a few hp (hey, 10 lbs = 1 hp, right?).

Good headers, high flow cats even a stock muffler and you will be doing great. Finish it up with a 987 airbox, I feel that there is a lot to be had by this mod. IPD plenum is a nice little perk too. Get a good tune and you'll be in 3.4 numbers.

Pedros Garage indicates that these changes will give you 31 more horse. Who knows? It will cost you $1400 to find out but may be worth it.

http://pedrosgarage.com/Site_2/TechnoPower2_Kit.html

I would love for Pedro to post Dyno results.

A smaller intake manifold, a smaller exhaust system, and the factory tuning limit the power in the 3.2.

I dont think the 996 intake manifold bolts onto the 3.2 head, I had to drill my 3.4 heads to accept a Boxster intake manifold ( I didnt want to lower my engine 1.5" )

Once my 3.4 swap was complete with a boxster intake manifold and exhaust system, I was very disappointed with the power. Replacing the entire exhaust system with a full NHP exhaust really unlocked some power...I was only expecting a 5-7hp increase, but it felt closer to 20. Im sure the 996 intake manifold will give another solid increase in power...

So I agree, the restrictions of the 3.2 are the complete intake and exhaust systems.

As JR posted the head castings are the same, & all bolt bosses are there. You just have to drill & tap the holes for the intake & exhaust parts you are using.

http://986forum.com/forums/uploads01...1384189194.jpg


986 3.2 head has untapped bolt bosses to mount heat shields in 996s

this has got me thinking about a 996 3.4 intake manifold on the 3.2 with perhaps a cayman engine cover for the additional clearance required (or lower the engine) - I wonder if it has been done?

Yes a 987 engine cover fits. I have one on my 3.4 conversion so I didn't have to lower the engine.

that would be the ultimate intake conversion then ...

987 air box - $250 used
987 engine cover - $100 used
996 3.4 intake manifold - $250 used
997 plenum - $50 new (you could use the 996 plenum, but one assumes the 997 part is an improvement)
996/997/987 throttle body - $100 used
987 maf housing - $100 jobber

$850.

get a softronic tune that let's you use a 987 maf housing - $700 on sale (or $50 labour at your local indy if a 996 3.4 x51 row pre-variocam+ tune will work).

finally, a $500 performance exhaust (topspeed or 987 S take-off) and a $200 underdrive pulley.

so, potentially 300 hp bolt-on (+50) for $1,600 to $2,250 - worth it?

I doubt any of this is worth the loss of low RPM torque especially for 3.2L or less.

My 3.6L does fine with the original intake & 997 plenum T

would there be a loss? the taller stacks on the 3.4 manifold should improve intake tuning at lower rpm? but I guess intake tuning for a 3.4, not a 3.2 ...