jkoravos

I watched a YT video the other day and the guy was showing how he cleaned up the carbon build up in his intake. There was quite a bit there so, out of curiosity, I put my borescope down into the intake manifold while I had the plenum off for other work. I wasn't able to see any build up down there (picture below). Now I'm wondering why this guy in the video had so much buildup on a 33,000 mile car while my 82,000 miles car has virtually nothing. There was definitely oil getting past the AOS in my car, as well. I'm not sure if it had ever been replaced. Aside from a major AOS failure, is there something else that might cause the level of buildup he had?



987.2 2.9L w/ 82,000mi

plafondles

Wow, yours look almost brand new. Whatever you are doing, keep doing it. I wonder if Porsche designed the intake a certain way to alleviate buildup? Your valves are almost unbelievable to me with how clean they are at 82k. I am a convinced that any DI engine will have buildup and will eventually need cleaning. Even if your whole intake and vacuum system is working perfect, just the nature of blowback from the combustion process will cause build up over time on DI engines.

My first DI engine was on a completely stock brand new 2012 Mazdaspeed3. I used nothing but non-oxy gas and premium oil. I pulled the intake manifold around 65k on that car and the valves were GUNKED. I used walnut media to blast them clean. It was a PITA on that car, which had excellent access to the valves from the front of the car. I cannot imagine the hassle and mess it would be on the 987 to clean these valves. Same thing with an '08 RS4 I looked at. Horrible carbon buildup on those early DI V8 engines.

jkoravos

I've only had it for a few months. I suppose the previous owner may have had it cleaned but the car appears untouched outside of required maintenance so it seems unlikely. He gave me his last few years of service records and it didn't say anything about intake/valve cleaning.

The Duke

Carbon buildup is potentially an issue with all FI engines. With the 987.2 9A1 3.4L DFI engines, the potential is greater still as atomized fuel is sprayed directly into the combustion chamber, and not on the back of the intake valve.

Your 2.9L does not have DFI, so it doesn't have the same risk profile.

Still, that one clean set of ports and valves!

plafondles

Ah, yep, I missed that his engine is the 2.9. Thanks Duke. I never knew the 2.9 continues with port injection. Learned something new.

I understand the reason for DI, but cant argue that port injection helps keeps things clean. Probably why companies like Toyota have dual injection (i.e. port and direct injection) on some of their engines. Best of both worlds.

JKoravos, I would not stress about valve cleaning if your 2.9 is port injected. The fuel should keep those valves looking pretty for a long time.

KrisA

Your post is probably the best advertisement for the 2.9L engine I've ever seen! That thing is freeking spotless!

jkoravos

That makes sense, I had forgotten about that. That area is continuously being sprayed with solvent!

Snakebit

Cheers to the sweeeeet so called "Base" flat 6!
They also are said to be closer to square and considerably understressed, relatively speaking.
Regardless, they really are a great motor and they sing a beautiful note in the Flat6 choir.

KrisA

I'm biased (2012 2.9L 6MT owner) but I completely agree. I have zero desire for more displacement and I like that the 2.9 has slightly shorter gearing as well. My only quibble is I wish the throttle was a bit more aggressive, but I'll probably fix that with a tune.

The "base" car is the deal of the Porsche century, so engaging, so solid and yet sells at a substantial discount to the S. Let's not even talk about R's and Spyders! In my mind if a mint 987.2 S with low miles is a 50K USD car these days the 2.9 should be a 47K car, not a 37K car.

I bought my 2.9 as my forever car, the fact that carbon cleanings won't ever be required was one of the selling points. My Golf R should I keep it long term I expect to carbon clean it every 50,000KM.

Schwinn

Not to throw the thread off topic, but If I'm reading you correctly, you may want to consider a Sprint Booster instead. Easier and probably lower cost than a "tune"...

KrisA

something about an additional piece of hardware in the car upsets my OCD!

Also, the extra 10hp and sound would be appreciated.

jkoravos

A Sprint Booster is definitely one of the top items on my upgrade list. The lazy throttle mapping is one of the few things that I didn't like about switching from a 997.2S to a 987.2.