Boxster 2.5 Heads on 996 3.4 Block?

[PleGrange]

Gentlemen and Ladies,

Story:

My 2.5 Boxster engine is comming out and I am fitting a 996 3.4 engine. The 2.5 engine has done 210k km's and is using a lot of oil, therefore I have this 2.5 engine that I cannot really sell as a very good engine. I have to either overhaul the engine or throw it away. To overhaul the 2.5 is going to cost me a lot of money anyway.

Possible answer:

It seems to be a good idea to get a new 3.4 block from the factory (includes pistons) at about US$ 5k, and fit all the 2.5 engines equipment on the 3.4 block.

There I have a "new" 3.4 996 engine.

The Question is:

Is it possible to fit the 2.5 heads on a 3.4 block? Is there any machining involved? I know the 996 3.4 has bigger valves and has approx. a 150cc bigger bore cylinder, or do I have to get 996 heads aswell?

The only other issue is the crank. How much does the 996's crank differ from the 2.5's crank. Bigger big-ends? different bearing pattern?

Can you get a good 996 crank easily or do I also have to get the crank from the factory?

Am I trying to do the impossible?

Regards

Pieter

[savowood]

Spend the extra $3500 and get the whole motor.

Either way, you're going to need headers by my recollection. I think the problem is space. The 996 motor is wider or something like that, so you need different headers. If you want the authoritative answer, tholyoak is the man. He's done several swaps and can tell you for sure whether the headers will work or not. I'd recommend doing the intake, headers, cats, and muffler. It's a bigger motor that wants to eat more. If it eats more, it's going to poop more. The restrictiveness of the stock Boxster system could cause issues.

-Michael

[PleGrange]

Spend the extra $3500 and get the whole motor.

Either way, you're going to need headers by my recollection. I think the problem is space. The 996 motor is wider or something like that, so you need different headers. If you want the authoritative answer, tholyoak is the man. He's done several swaps and can tell you for sure whether the headers will work or not. I'd recommend doing the intake, headers, cats, and muffler. It's a bigger motor that wants to eat more. If it eats more, it's going to poop more. The restrictiveness of the stock Boxster system could cause issues.

-Michael

Hi Micheal,

Thans for your reply.

It just seems to be a waist to throw the 2.5 in the trash bin.

Pieter

[PleGrange]

Spend the extra $3500 and get the whole motor.

Either way, you're going to need headers by my recollection. I think the problem is space. The 996 motor is wider or something like that, so you need different headers. If you want the authoritative answer, tholyoak is the man. He's done several swaps and can tell you for sure whether the headers will work or not. I'd recommend doing the intake, headers, cats, and muffler. It's a bigger motor that wants to eat more. If it eats more, it's going to poop more. The restrictiveness of the stock Boxster system could cause issues.

-Michael

Hi Micheal,

Thans for your reply.

It just seems to be a waist to throw the 2.5 in the trash bin.

Pieter

Or shall I say a waste! (this project did let me loose a kilogram or two around the waist ..lol.)

[1schoir]

Spend the extra $3500 and get the whole motor.

Either way, you're going to need headers by my recollection. I think the problem is space. The 996 motor is wider or something like that, so you need different headers. If you want the authoritative answer, tholyoak is the man. He's done several swaps and can tell you for sure whether the headers will work or not. I'd recommend doing the intake, headers, cats, and muffler. It's a bigger motor that wants to eat more. If it eats more, it's going to poop more. The restrictiveness of the stock Boxster system could cause issues.

-Michael

Hi Micheal,

Thans for your reply.

It just seems to be a waist to throw the 2.5 in the trash bin.

Pieter

I don't know if the cost of shipping your engine would eat up any possible cost savings, but perhaps you might put your 2.5 motor up for sale either as a whole or in parts (heads by themselves, for example). Someone might be interested if they can use your 2.5 as their "core" if they are getting a new 2.5.

You might contact Jake Raby at Flat6innovations.com. He's always looking for motors.

Regards, Maurice.

Or shall I say a waste! (this project did let me loose a kilogram or two around the waist ..lol.)

[PleGrange]

Spend the extra $3500 and get the whole motor.

Either way, you're going to need headers by my recollection. I think the problem is space. The 996 motor is wider or something like that, so you need different headers. If you want the authoritative answer, tholyoak is the man. He's done several swaps and can tell you for sure whether the headers will work or not. I'd recommend doing the intake, headers, cats, and muffler. It's a bigger motor that wants to eat more. If it eats more, it's going to poop more. The restrictiveness of the stock Boxster system could cause issues.

-Michael

Hi Micheal,

Thans for your reply.

It just seems to be a waist to throw the 2.5 in the trash bin.

Pieter

I don't know if the cost of shipping your engine would eat up any possible cost savings, but perhaps you might put your 2.5 motor up for sale either as a whole or in parts (heads by themselves, for example). Someone might be interested if they can use your 2.5 as their "core" if they are getting a new 2.5.

You might contact Jake Raby at Flat6innovations.com. He's always looking for motors.

Regards, Maurice.

Or shall I say a waste! (this project did let me loose a kilogram or two around the waist ..lol.)

Thanks Maurice I will contact Jake Raby.