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

[steved0x]

This is a very interesting discussion and I just found the other big thread by TRK on using the bigger TB and Plenum. Very interesting stuff.

Steve

[Bigsmoothlee]

Originally Posted by BYprodriver

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.




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

Yes, I am aware of that. That's exactly what I did, but you make it seem ALOT simpler than it actually is. Being that both of my engines were out, I made a template for the 2.7 manifold and outlined the holes on the 3.4 head. I then removed the heads, and drilled the mounting bosses on a drill press since I wanted them 100% accurate and straight. I set up levels, used a lot of shims under the head, and then clamped it down to the machine to make sure the drill bit was exactly 90 deg to the hole I was tapping. Since it was a used engine, I didnt mind changing the valve seals and lapping the valves anyway.

I dont know if I'd have the nads to just take a home depot drill into my engine bay and try to drill the holes for the 996 manifold, but im sure it can be done.

[Bigsmoothlee]

Originally Posted by JAAY

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

Jaay, did you have trouble with the shifter cables being too short when you installed the 3.4 manifold without lowering the engine?

Which 987 engine cover did you use? Was it from a Cayman/Boxster S?

[BYprodriver]

If you put 3.4 heads on a 2.7 you lost compression ratio & undoubtedly low rpm torque due to the bigger valves.

[Jake Raby]

Originally Posted by BYprodriver

If you put 3.4 heads on a 2.7 you lost compression ratio & undoubtedly low rpm torque due to the bigger valves.

Hmmn, what head gasket was used? With the difference in bore size at a whopping 10.5mm of bore size difference I'd expect issues. What cams were used with this?

I think he is stating that he had a 2.7 and did a 3.4 engine conversion...

[BYprodriver]

Originally Posted by Jake Raby

Hmmn, what head gasket was used? With the difference in bore size at a whopping 10.5mm of bore size difference I'd expect issues. What cams were used with this?

I think he is stating that he had a 2.7 and did a 3.4 engine conversion...

I bet you are right Jake, he did say he had 2 engines side by side in his post. Happy Veterans Day Jake & thank you for your service, both abroad & on Raby hill !

[Bigsmoothlee]

Originally Posted by Jake Raby

Hmmn, what head gasket was used? With the difference in bore size at a whopping 10.5mm of bore size difference I'd expect issues. What cams were used with this?

I think he is stating that he had a 2.7 and did a 3.4 engine conversion...

Yes, that is correct. I did a full 3.4l conversion, but drilled the mounting bosses in the 3.4 head to attach a 2.7 intake manifold to it. This allowed me to avoid lowering the drivetrain. I drive my car to work every day and the roads here in the Northern NJ/NYC area are atrocious, so lowering the engine 1.5" to accommodate the 3.4 manifold was a risky proposition. One raised manhole cover and bye bye engine!

I want to install the 3.4 manifold with a 987 raised engine cover, do all of them work or is it only the "S"model that has the raised portion for the intake manifold?

[golonaus]

Originally Posted by JAAY

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

same here
987 cover got nice bump in the middle. you just need to trim off some of the carpet padding

[golonaus]

Originally Posted by Bigsmoothlee

Jaay, did you have trouble with the shifter cables being too short when you installed the 3.4 manifold without lowering the engine?

Which 987 engine cover did you use? Was it from a Cayman/Boxster S?

dont know about Jaay,but In my install yes cables are too short
just a bit tho
Simple solution is to move shifter console about 1/2"
I drilled new mounting holes and shifter boot covered it
looks and works as it should
I'm curious how Jaay solved it too, tho
btw
I'm using cover from a cayman s

[JAAY]

I ran my cables under the intake manifolds.

[Bigsmoothlee]

Originally Posted by golonaus

same here
987 cover got nice bump in the middle. you just need to trim off some of the carpet padding

Excellent, thanks.

Originally Posted by JAAY

I ran my cables under the intake manifolds.

Did you use a 987 S cover or a standard 987 cover? I see both have raised bumps, I wonder if they're different?

I didn't think it was possible to run the cables under the manifold until now... Thanks

[JAAY]

I don't know what cover I used. I think there the same though.

[The Radium King]

make sure jaay hasn't deleted his AC ...

[JAAY]

My a/c is still in. I have my top up mostly. It gets hot here.

[Nine8Six]

Originally Posted by steved0x

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?

Steve

You can! Get 6 (six) custom ultra-light pistons machined out of titanium (e.g. the flat piston style, F1 tech, same as in the GT3), and get a tuner to design/machine you a set of cams with tad rounder/longuer intake lobes. If you have the cash, you could also get your crank re-machined and ballanced for the flat 6. Custom mapping and all, big big roars

A small and modest $20,000~$30,000 mod (350~400bhp)!

Horses are not cheap these days mate. Hence the higher price on those upper Pcars models.

[Bigsmoothlee]

Originally Posted by Nine8Six

Y

Horses are not cheap these days mate. Hence the higher price on those upper Pcars models.

I beg to differ. The power was intentionally left out of the 3.2 for marketing reasons... My 3.4 986 humiliates non-gt3 996s at autoxs

[woodsman]

Originally Posted by Bigsmoothlee

I beg to differ. The power was intentionally left out of the 3.2 for marketing reasons... My 3.4 986 humiliates non-gt3 996s at autoxs

what's that got to do with horsepower?????

[Bigsmoothlee]

Originally Posted by woodsman

what's that got to do with horsepower?????

The lack of power wasnt from a lack of funding, it was done intentionally to keep a gap between the 911 and the Boxster. Equal power ususally results in the 911 having its ass handed to it by a boxster

[Jake Raby]

Originally Posted by Bigsmoothlee

Yes, that is correct. I did a full 3.4l conversion, but drilled the mounting bosses in the 3.4 head to attach a 2.7 intake manifold to it. This allowed me to avoid lowering the drivetrain. I drive my car to work every day and the roads here in the Northern NJ/NYC area are atrocious, so lowering the engine 1.5" to accommodate the 3.4 manifold was a risky proposition. One raised manhole cover and bye bye engine!

I want to install the 3.4 manifold with a 987 raised engine cover, do all of them work or is it only the "S"model that has the raised portion for the intake manifold?

That 2.7 intake is killing the potential of that engine. The 2.7 intake is inadequate even for a 2.7 engine.

[jaykay]

Originally Posted by JAAY

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

Jaay does the cayman cover mess with the soft top? Were you able to adapt ithe insulation cover to fit over it ?