M96 Frankenstein? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

ike84 · 08-26-2021, 06:36 PM

Everyone's asleep so I decided to stare at the pet pdfs for a minute. And something struck me ... There is a ton of overlap between the 2.5, 2.7, 3.2, and 3.4L motors of the early cars

This makes sense to me - Porsche is on the verge of bankruptcy so reuse as many parts while still offering variety.

The crank rods are the same across all models. The crank cases have different part numbers though. Is this because the different cases and heads have different bolt patterns?

Obviously the cases halves are different, but only by bore. Again, maybe bolt pattern?

Heads have different part numbers but at least the valve guides and cams of the 3.2 and 3.4 are the identical. Again, is this just a difference in bolt patterns?

My brain naturally went wild with this thought - Scavenge together a 3.4 from different parts ( crank and bearing set from any motor other than a 2.5, any rod set, 3.4 Pistons, 3.4 case halves and heads, and then valve train from a 3.2 or 3.4). Or better yet, instead or trashing old 3.2s for a 3.4 swap, just rebuild the 3.2 with 3.4 case halves and Pistons for a few grand.

Has anyone done something like this before?

Has anyone ever held all these pieces of in their hands to know something that I'm missing?

I must be missing something here...

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ike84 · 08-26-2021, 06:52 PM

On a side note, if the 2.7, 3.2, and 3.4 all share the same rods and crank shaft, why is the redline different?

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Quadcammer · 08-27-2021, 11:50 AM

Are the redlines different? I believed only the 2.5 revved lower.

That said, you aren't missing much. That said, most if not all case halves that have 80-100k miles will be worn beyond the point which you can just slap some new rings in. That brings you back to having to do new sleeves, at which point you can just start with a smaller motor and enlarge.

If by some miracle you could find some pristine 3.4 case halves and pistons, then do rings and bearings and have at it.

ike84 · 08-27-2021, 05:32 PM

Quote:

Originally Posted by Quadcammer

Are the redlines different? I believed only the 2.5 revved lower.

That said, you aren't missing much. That said, most if not all case halves that have 80-100k miles will be worn beyond the point which you can just slap some new rings in. That brings you back to having to do new sleeves, at which point you can just start with a smaller motor and enlarge.

If by some miracle you could find some pristine 3.4 case halves and pistons, then do rings and bearings and have at it.

Do you know if the blocks for a 3.4 will bolt to a 2.7 or 3.2 crank case?

I think that I'm mistaken about the redline question. For some reason I thought than the 3.2 and 3.4 redlined at 7800 but I think that is incorrect.

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Quadcammer · 08-28-2021, 05:44 PM

Should bolt to the carrier yes. The 3.2 and 3.4 rev to 7200 i believe, while the 2.5 was 6800 or 7000

itsnotanova · 08-29-2021, 04:42 AM

Jake Raby has stated that he dislikes the 3.4 more than the other M96 because of the thin bore walls. I don't like the 3.4 cost over a 3.2. You can find 3.2's for half the cost of a 3.4 and the only real difference between the two is the intake. I put a 3.4 in my boxster but the variocam adjusters and lifters went out shortly after installing it. I then installed a 3.2 with the 3.4 intake to temporarily take its place while I fixed the 3.4. I couldn't feel any difference in power between a 3.2 with a 3.4 intake than the 3.4/3.4 intake. I only went back to the 3.4 because I had stuck so much money into it and it only had 37k on it. If i could do it all over again I would have sold the 3.4 and stuck with the 3.2. Biggest problem with the 3.2 is the intake and exhaust system

ike84 · 08-29-2021, 05:28 AM

Quote:

Originally Posted by itsnotanova

Jake Raby has stated that he dislikes the 3.4 more than the other M96 because of the thin bore walls. I don't like the 3.4 cost over a 3.2. You can find 3.2's for half the cost of a 3.4 and the only real difference between the two is the intake. I put a 3.4 in my boxster but the variocam adjusters and lifters went out shortly after installing it. I then installed a 3.2 with the 3.4 intake to temporality take its place while I fixed the 3.4. I couldn't feel any difference in power between a 3.2 with a 3.4 intake than the 3.4/3.4 intake. I only went back to the 3.4 because I had stuck so much money into it and it only had 37k on it. If i could do it all over again I would have sold the 3.4 and stuck with the 3.2. Biggest problem with the 3.2 is the intake and exhaust system

Woody! Long time! How's the toy shed going?

The reason for the interest in the 3.4 is mainly in the availability of aftermarket parts. Pistons and custom head gaskets can be found somewhat easily, whereas these parts are not easily available for the 2.7 and 3.2.

I figured If I can find a set of 3.4 blocks that don't have ovality or bore scoring, I can rebuild my 2.7 with those blocks along with JE Pistons, carillo rods, thick head gaskets, and wind up with a motor that could take 10-12 psi boost turbo setup for under $10k.

Maybe I should source a 3.2 and send it to lne to have them do that though. More rabbit holes to explore...

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itsnotanova · 08-29-2021, 02:05 PM

It's great! It's nice having so much more room. Anyone thinking about building a shop, build it as big as you can afford. Of course now I'm broker than broke. lol

I've never seen a forced air injected M96 live a long life. That's why I'm going with an Audi 2.7. They can handle tons of boost and you can almost get them for free

ike84 · 08-29-2021, 08:06 PM

Quote:

Originally Posted by itsnotanova

It's great! It's nice having so much more room. Anyone thinking about building a shop, build it as big as you can afford. Of course now I'm broker than broke. lol

I've never seen a forced air injected M96 live a long life. That's why I'm going with an Audi 2.7. They can handle tons of boost and you can almost get them for free

I've not going many documented cases of FI conversions, ever the guy from Ohio that did one with success and then sold the car a few years later. Do you know someone who has blown one up? I would love to talk to them!

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itsnotanova · 08-29-2021, 09:08 PM

Quote:

Originally Posted by ike84

Do you know someone who has blown one up? I would love to talk to them!

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I don't know anyone personally. I sold a motor to a shop twice that had installed a turbo on a 2.7. First time they had to replace it they wrote it off as a bad motor. Second time they realized the turbo was a bad idea and were just throwing a motor in it to sell the car. Each time the motor only lasted a couple of months with a turbo. I want to say I sold another motor to someone(another shop) that was replacing a blown up motor that had a turbo on it. I also think there has been someone on here with problems after they threw a turbo on.

ike84 · 08-30-2021, 04:40 AM

I guess that's not surprising...these motors definitely aren't optimized for FI. Of you just threw a t3/t4 amazon special on there and turned the boost to 15 psi them I'd be amazed if they made it home from the shop.

The TPC turbo kits and older SC kits ran around 5psi of boost and I don't think I've heard of anyone grenading their motor on one of those systems. (Although I am certainly not vouching for those systems, when I spoke to those guys on the phone I wasn't sure they even knew what a 986 was).

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flmont · 09-20-2021, 04:30 PM

can you install a 3.2 intake system and heads on a 3.4 Ltr short block / case.??
I have a 2000 S intake system with heads,.the 3.2 case has a large hole in the top,.picked up a 2000, 3.4 Ltr with bore scoring,and NO heads just the short block/ case..can I marry the two systems somehow,.?? Thanks frank

ike84 · 09-20-2021, 05:48 PM

Quote:

Originally Posted by flmont

can you install a 3.2 intake system and heads on a 3.4 Ltr short block / case.??
I have a 2000 S intake system with heads,.the 3.2 case has a large hole in the top,.picked up a 2000, 3.4 Ltr with bore scoring,and NO heads just the short block/ case..can I marry the two systems somehow,.?? Thanks frank

No, I don't think so. The bore on the 3.4 is 3mm larger that the 3.2, so the heads wont match up (unless you an had the head bored out).

Out of curiosity, why rebuild a motor that has bore scoring? I feel like that's just asking for heartache.

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flmont · 09-20-2021, 06:36 PM

Well I paid 100.00 for it , and I thought maybe sleeve it then machine the bore's to match the 3.2 heads just spit balling to see if its even possible, with all these parts being so close to each M.Y...sounds like I will need a 3.2 case for sure , if I cant have it machined ...Thanks !