997Troy

I’m looking at a possible engine rebuild in the next few weeks( great way to start the new year..). Long story short, engine appeared to be running healthy until a faulty o2 sensor caused a cat to fail, melt and cause a blockage resulting in possible bore scoring and slightly seized block. If I can reuse the block I’m wanting to stroke the motor to a 4.0L.

Im looking for some guys on here that have done this conversion whether it was a 997.1 or .2. I’m looking for nice big bump in torque along with reliability haha.

My main questions are:

1. How much mileage have you put on your new motor?
2. Who built your motor?
3. Any change in regular maintenance required?
4. How does your car hold up against some faster cars out there? Any good comparison?
5. Did you go with the ductile sleeves, Nickie’s or the Coated cylinders?
6. Was there any noticeable change in sound throughout the rpm band?
7. Are there any expected/required rebuilds suggested after a certain mileage?
8. Can you post up a dyno chart or some numbers for reference?
9. Any regrets on not doing another swap?(LS, Mezger etc)

If you can answer as many of those as possible it would help with my ultimate decision.

Thanks!

CAVU

As you explore the displacement increase options, are you going to have a borescope, top and bottom of the cylinders performed?

cwheeler

Asking these questions, it seems as if you may not want to rebuild your engine. It appears that you're lacking in knowledge and ability to research. Which will not serve you well during the engine building process.

997Troy

Taking it a bit further and probably doing a tear down and inspection. Motor wouldn’t crank over and there’s a ton of metallic dust in the oil.

Lol of course I don’t want to rebuild the engine..but I def have to at this point. I’ve researched everyday since Nov 7th when I got the news. Doesn’t seem like any actual owners post up info about their experience so I’m just asking some specific questions to help with my decision.

SilCab

Sorry to hear about your motor.

There are threads on here about guys having their motors rebuilt and/or upgraded.
There are even a couple on here by guys rebuilding their own motor.

YouTube has several helpful videos about the rebuilds/upgrades of these motors.

Check Flat 6 Innovations, LN Engineering, are two companies you might want to search for posts from on this site.

Good luck.

JRBucks

As a natural born hotrodder I've searched for some of the answers you're seeking. From what I gather, no one dyno's their cars before or after. No one compliments their builds beyond bigger pistons, (Cams, head work, intakes, tuning, etc.). Everyone says to "Just buy a turbo if you want more power" or "You'll never get your money back". But some us need to tinker and like to actually pull out the wrenches and do the work ourselves. There is a tremendous bond you create with your car when you are the one that has built it or done most of the work. You just can't that by writing a check.
Ok enough of that, I'm starting to sound like a cheesy springsteen song.

As for sleeves, the two experts in the industry highly recommend aluminum sleeves. I'll preface the next part by saying their reputation and experience with these motors would have me using them too. But I don't understand why iron sleeves wouldn't work unless they are installed incorrectly or there is and inherent design flaw with the M9x engine. Iron sleeves work great and are very reliable in high hp applications with both the LS and Coyote platforms, and those motors easily push 1,xxx rwhp for 10's of thousands of miles and countless pulls.

I would love to have a screaming 4.0 making about 400+hp and be able to build it myself.

997ajk

I would start reading and get in contact with Baz and get some for info....he posts a bit on 911uk site.

http://911uk.com/viewtopic.php?t=145483&highlight=
https://jzmporsche.com/news/gen-2-bo...g-smoking-gun/
http://911uk.com/viewtopic.php?t=128...7dadbb64e05d68
https://rennlist.com/forums/997-foru...-please-2.html

9.1.1

Did the engine gave you any codes before all that happened? Melting a cat sounds crazy

Atgani

A poor remap that either overfuels or runs lean, can rapidly lead to cat failure, and a faulty o2 sensor will cause either of those two scenarios.

End result :








Good luck on your journey OP.

997Troy

I’ve found a great bit of info which ultimately lead me to those questions. I really want to keep a flat 6 in there!

Haha yes a lot of what you said is very common. I’m used to working on all my cars so it’s def strange to hear some suggestions, but it’s all in good faith. Also the ductile sleeves have always been the “cost effective” way of making power. I’m considering that because whether I do a stock rebuild or buy a used/new motor, the same 30k problem can be just waiting to happen again…

Thanks for the links!

You know now that I think of it, I may have started from a leaking exhaust gasket after the cat. Maybe that somehow cause the o2?sensor to fail(secondary) and melt the cat. That happened in the summer and I was told it wasn’t a big deal. I guess it was after all…

Thanks! Did you end up fixing that motor?

Atgani

No, complete new motor required. It was a 996 GT3, and Mezger's don't come cheap ... :

bgoetz

I am going the FSI route. If you setup a ticket on their website he will get you a link to a sales webinar. It is like 2-3hrs but well worth the time, he covers power gains in those webinars. I have a thread that discusses how I came to my decision to go with FSI. The more I researched the more FSI became the obvious choice for me.

I would 100% avoid any builder or DIY that uses anything but Nickies or you will be doing this all over again in a few years.

Durling21

FSI is gonna be the cream of the crop for builds. I for sure would still check out some LN engineering builds. You can go up to 4.2 on the 9a1. Keep us posted. I’ll probably do a build on my 10 c2 In a couple of years. With prices of S and GTS models a big build is kind of worth it.

997Troy

It unfortunate there’s no warranty for track mileage. Have you seen failures with other builders using those other sleeves?

Petza914

Yep, happens all the time Subscribe to the 997 Engine Builders group on Facebook (or just search there) and you'll see probably 1 a week where the iron sleeves start lifting up or rotating.