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

[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 Jake Raby

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

The 3.2 plenums look to be the same size as the 2.7s. They look to be an even smaller volume than the 2.5s....squashed down. The 3.4 plenums look voluminous by comparison...going by pictures. The entrance into the 3.4 plenums are larger too

One has to wonder what the 3.4s would do atop a 3.2