2.5 to 3.2 swap
 

Dear All,

I`m still exploring the options of what I could do to my 1999 base Boxster with the blown engine. Now I could pick up a cheap basket case of a 3.2 engine from a local guy, so I gave it a thought.

I remember reading an old thread from someone who did this swap (I can`t find it any more), and if I remember correctly he:
- used the original 2.5 ECU that he reprogrammed
- he used the 3.2 intake plenum but combined with a manual 3.4 throttle body to overcome the egas issue

This is all I remember he did and allegedly it worked fine. Question is, whether reflashing the ECU would cause a fail at the smog test in California?

Also, 78F350 posted a picture of the 2.5 coolant tubes vs the 3.2, and they are very different in size. So I assume I would have to upgrade that together with adding a third radiator to match the cooling capacity of the 3.2. Anything else? Would the transmission fit the 3.2 engine? How about the clutch? Exhaust?

Now that I`ve got to the end of this post I`m already leaning toward not doing it, lol.. Anyways, has anyone done this? Thoughts?

I understand it's much easier to use the m96 3.4 into a 2.5.

Yes. However, I think the only factor that makes it easier than the 3.2 is the mechanical (cable operated) throttle. Otherwise everything else should be the same...?

Every time this is brought up I read it getting strongly discouraged by those who do this sort of thing for a living.

Pelican has an article on suggested engine swaps. https://www.pelicanparts.com/techarticles/Boxster_Tech/11-ENGINE-911_Engine_Swap/11-ENGINE-911_Engine_Swap.htm

Here's a thread I remember discussing replacing a 2.5L engine with a 2.7L:
http://986forum.com/forums/performance-technical-chat/70417-1998-boxster-2-5-2001-2-7-engine-swap-upgrade.html

I think that what 'Erlinrys' did covers a lot of what you would do to swap a 3.2L in. I didn't think that the intake from a 2.5L would fit and seal to the 2.7L block, but he said that it worked.

Here's a pic I posted a while back comparing the 2.5L with the 2.7L. To put a 2.7L intake on a 1997 engine, I just had to drill a couple holes for the bolts to line up. In the parts catalog looks like the 2.7L and 3.2L use the same intake parts.
http://986forum.com/forums/uploads02...1562091215.jpg

Also note that 2003 - 2004 engines will bring more complications. If you do it, stick with a 2000 - 2002 3.2L or do some serious rewiring to change to a DME 7.8.

I just remembered that 'truegearhead' swapped a 2.7L engine into his 1997 before he got into the twin-turbo 4.2L V8. In his, he simply swapped the cable throttle body onto the 2.7L intake (with some adaptation). That is probably the best and simplest way to go with the 3.2L except I'd want to look at a cable throttle body from a '99 3.4L 996.

PM truegearhead.... I'm bet he'd be happy to give some input.

Thanks, I`ve come across that one.

Thanks, lots of great info in a very entertaining thread :D

I remember that picture of yours. I was going to use the 3.2 intake though with the 3.4 cable operated throttle body with an added wire for the flap and a reflash of the DME. This was at least described in a post that I read on Renntech, but the site is no longer available.

Btw, I vaguely remember you said somewhere you like the old 2.5 engines the most, now that I`m thinking swapping that out I wonder what you meant by that.

I did it.

In short, the 3.2 bolts right in (00-02 model years). Use the 3.4 throttle body from a cable 996, I used the original ecu with softronic tune for a 3.4. I used the 987 airbox with the stock maf.

I also later switched to a set of 3.6 intake manifolds.

stock clutch and exhaust bolt up fine. no issues running a 5 speed.

Perfect. Why did you not use the 3.2 intake combined with the 3.4 throttle body?

That sounds like the best way to do it.

I enjoy both base and S, but for driving twisty back roads I don't need the added power of the 3.2. Just going out for the fun of driving - running through the gears and hearing the engine sounds from 4,000 rpm up - my 1997 2.5L was the best. For a long drive to get somewhere, I choose the '04 S.

2.7 engine with low miles for sale
 

Not mine, just sharing..
https://rennlist.com/forums/market/1321639

I did for a while, but when you look at it, you realize that the 2.7 intake and 3.2 intake are the same. My car is track only, so I was ok giving up a bit of low end to potentially gain some top end power. Not a huge difference in power and the 3.6 intake swap is a bit of a fuss to do, so I'd just run the 3.2 intake

Makes sense. I see you are in NJ, but do you happen to know if the softronic tune is compatible with the smog test required here in California?

Thanks, not bad, indeed...

That makes sense. The 2.5 has the great Porsche sound while staying quite docile. I assume the 3.2 is harder to make it stay on the road on the twisties when it starts screaming.

not really. My personal opinion is that the 2.5 is just a bit gutless. The extra grunt of the 3.2 makes the 986 really enjoyable. Its still not a "fast" car, but it really just feels much better with the additional power. I don't think I could go back to a base model. When you combine the 3.2 with several hundred lbs of weight reduction, you get a car that will surprise quite a few people.

I guess I should try one and see what difference that makes. I also found the 2.5 sluggish when I tried for the first time but I got used to it.