CrossT

I have had an issue with misfiring on cyl 3 accompanied by coolant consumption. Diagnosis is a cracked cyl. So, that's bad news. But, since the motor needs replacing, I am in process of replacing the 3.4 l with a 3.6 l motor.

This car had the original motor replaced at about 30k by Porsche under warranty. The second motor lasted 70k. From my experience, these 3.4's probably weren't Porsche's best achievement.

Wasn't planning for an expense of this magnitude, but at least the new motor being built will be warranted and will be more powerful, if there's a good side to this.

Todd
99 coupe soon to be 3.6

5CHN3LL

Bummer about the old motor, but congrats on the build. What's the power goal for the 3.6?

halik

What year was second 3.4L put in? I would've thought they fixed the casting issues at some point...

alpine003

Were you the original owner? I ask because I find often times that some owners cheap it out with maintenance and/or also beat up on their cars and use the motor as a scapegoat. I'm not implying anything to you directly but if you bought it used, there's really no way to know how it was treated previously.

Loren

Of course you know that is not just a direct swap?
Your 3.4 liter has Variocam and a 3.6 has Variocam-Plus - this will require a different DME (program and wiring).
The fuel return system on a 3.4 liter is different than the "returnless" system used with the 3.6 liter cars.
This might be more effort and trouble than you want for 20 more HP.

jrgordonsenior

If your mechanic hasn't educated you on all the additional work required then he's either incompetent or not acting in your best interest. You're talking about at least $3k in additional work, probably more. This also make me wonder how he knows you have a cracked cylinder. Did he tear down your 3.4?

Alternately you can "sleeve" your 3.4 out to 3.6 or 3.8 even. If you cases are salvageable that would be the most economical way to go. We're seeing 310 RWHP (Dynojet) out of those motors. There's 2 builders doing them here in So Cal...

Flat6 Innovations

If you don't have a need for the old core, we'll buy it. We are needing so many core parts, because the same thing is the case with most every engine we see.

That said, you have several complications to overcome to carry out this "conversion".

jrgordonsenior

Jake you should have bought up all the "Sandy 6's & 7' just for the drive trains...

alpine003

Don't worry, with all these climatic changes, I'm sure there will be a lot more catastrophes. For example, with all the icing and snowing conditions in the south that rarely see's snow, I'm sure there are gonna be P-car guys running their summer tires and driving like normal. BOOM...

Imo000

From previous posts, looks like they are buying up every non running 996 that's out there.

porsche-t

I left the day before the sleet and snow, and took my car to California to enjoy the weather. Brought it back four days later after the bad weather, drove like a bat out of hell AND I have a new set of summer tires!

CrossT

It is being built from a 3.4 to a 3.6, not an 02-04 motor. Better sleeves, pistons, etc. i.e., what should have been built originally. The guy doing it is well known and reputable. It was stranded in Scottsdale (which is not where I live).

I unfortunately haven't the time right now to jump in and get involved with the shop on this. That said, I am looking forward to a few more ponies. At least that will make the expense sting a little less.

I didn't detect anything at all odd with the car's running until the misfiring and coolant usage started.

Thanks

Todd
99 coupe

jrgordonsenior

Good to hear. You'll need larger exhaust manifolds, I suggest 997S 3.8 manifolds. For even more fun send your throttle body to Maxbore.com for a little more juice, the best $100. you'll spend. Keep your stock airbox but use a BMC filter....

CrossT

Got the car back. The added power is noticeable! We did all the "while you're in there" items. Probable cause of the issue? AOS

Fortunately, I like the car enough to keep it for a long time.

Todd
99 coupe 3.4 --> 3.6

alpine003

That was pretty darn fast. Was this a local shop that did the work? Did they put in a OEM 3.6 block and mate it to your existing top end?