Modified 911 - Oil Consumption

[trentwat]

Hello Pelicans! Let’s talk oil consumption…at around 120K miles on my new to me 911 3.2L (circa 2015), I got concerned about oil consumption…nursed it for years and then pulled the trigger on a 3.4L rebuild (specs similar to dyno image below from Steve Wong’s website with more). The performance is great, but it consumes oil. My buddy said he could see black smoke out the exhaust. It is a highly tuned motor…essentially a de-tuned race motor (parts, etc.). What would be considered typical oil consumption on a modified motor like mine?

[silverlock]

What is the consumption you’re measuring? A quart per 1k? Less? More?

I have a very similar build (3.2SS, 10.2:1 Mahles, 993SS, chip, ported heads & TB, etc) and use very little oil, even with some very hard driving. Maybe 1qt every 3k miles or so, if even that.

[trentwat]

Originally Posted by silverlock

What is the consumption you’re measuring? A quart per 1k? Less? More?

I had been seeing the needle on the oil gauge stop floating around 1,100 miles….give or take. It is more like 700-800 most recently.

[brighton911]

It can take a while for everything to settle in, how many miles since the rebuild ? I too wouldn't be happy with 800 per quart. I installed the same P&C on my nephew's car and his consumption is negligible. Your buddy's comment about black smoke, is that on acceleration or cruise ? Black smoke is indicating a rich situation, oil consumption is blue smoke.

[silverlock]

Originally Posted by trentwat

I had been seeing the needle on the oil gauge stop floating around 1,100 miles….give or take. It is more like 700-800 most recently.

Don’t rely on the gauge. Use the dip stick. On a 3.2 the difference between low and high on the dipstick is about 1.75 qts.

Fill it to the mid point (don’t overfill) once warmed up + level, reset the trip meter and drive it like you normally would. Check again (level ground, warmed up) after 500mi or so.

[trentwat]

Originally Posted by silverlock

Don’t rely on the gauge. Use the dip stick. On a 3.2 the difference between low and high on the dipstick is about 1.75 qts.

Fill it to the mid point (don’t overfill) once warmed up + level, reset the trip meter and drive it like you normally would. Check again (level ground, warmed up) after 500mi or so.

Fair statements…assuming the gauges work within an acceptable range and the mechanic properly fills the oil level after a change, if I fill the tank to the same gauge level, then I have the oil consumption over the mileage.

[trentwat]

Originally Posted by brighton911

It can take a while for everything to settle in, how many miles since the rebuild ? I too wouldn't be happy with 800 per quart. I installed the same P&C on my nephew's car and his consumption is negligible. Your buddy's comment about black smoke, is that on acceleration or cruise ? Black smoke is indicating a rich situation, oil consumption is blue smoke.

It has ~6K on the rebuild…a mechanic that works on another German car of mine suggested the rings might not fully seat until 10K miles. No clue.

Good point about the smoke…my friend who observed the smoke reminded me of the same thing. I remember the mechanic stating that when they revised the tune after the break-in, they modified the tune for mid-band performance. I was doing full throttle shifts…guess that might be the black smoke.

T

[Kevin Stewart]

Can I ask if you used synthetic for break in or a dino oil? If you didn't break in the motor with dino (regular oil no synthetic) You will need to dump all of it and you may have to change it a couple times to get everything to seat especially the rings before you put synthetic back in.

I would look at a good break in oil, Brad Penn, Driven, Amsoil, Lucas, Royal Purple, Contains high zddp, (zinc phosphorus) to help break in sealing of Piston rings, camshafts for performance engines. This should not be a long term oil, drained pretty quickly. I use brad penn or something similar, they are not Porsche motors though. When I drain it it is black and like water.

I would at least call brad penn or talk to your engine builder about break in oil as the motor has 6k miles.

Good luck I hope you find it. Kevin

[H-viken]

The way we broke in my engine was that we let it rip right out of the box essentially. Makes sure rings etc seat right away

Basically a race engine as well

[Kevin Stewart]

Have you pulled the plugs to try and isolate the cylinder? Are you running valve seals?

[trentwat]

Originally Posted by Kevin Stewart

Can I ask if you used synthetic for break in or a dino oil? If you didn't break in the motor with dino (regular oil no synthetic) You will need to dump all of it and you may have to change it a couple times to get everything to seat especially the rings before you put synthetic back in.

As far as I know, it was only the Motul Classic currently in the car that was used during the break in period.

[trentwat]

Originally Posted by Kevin Stewart

Have you pulled the plugs to try and isolate the cylinder? Are you running valve seals?

The shop did a leak down test and said the results were reasonable.

[Showdown]

Not to derail, but in my experience anytime a shop does a test and only provides “acceptable” or “reasonable” instead of actual data, that test is highly suspect. Probably a good idea to do the test again and this time get actual numbers. It might not point to a smoking gun but real data>anecdotes.


Sent from my iPhone using Tapatalk

[silverlock]

Originally Posted by Showdown

Not to derail, but in my experience anytime a shop does a test and only provides “acceptable” or “reasonable” instead of actual data, that test is highly suspect. Probably a good idea to do the test again and this time get actual numbers. It might not point to a smoking gun but real data>anecdotes.

Beat me to it!

At the going price for an engine build these days I would fully expect print outs and hard data for things like this. The oil consumption would make me suspect blow by if the rings weren’t seated correctly, although (as others have said) black smoke isn’t typically oil.

I’m also realizing the actual specs haven’t been posted: it’s like the screenshot, a detuned race motor… but what is it? A 3.4L with what P&Cs? Cams? What machine work was done, if any?

[trentwat]

Originally Posted by Showdown

Not to derail, but in my experience anytime a shop does a test and only provides “acceptable” or “reasonable” instead of actual data, that test is highly suspect. Probably a good idea to do the test again and this time get actual numbers. It might not point to a smoking gun but real data>

I reached out to the shop in anticipation of this comment, and they said, “All 6 cylinders showed equally to be at 3.0% cold”. I don’t know how to interpret this.

[trentwat]

Originally Posted by silverlock

I’m also realizing the actual specs haven’t been posted: it’s like the screenshot, a detuned race motor… but what is it? A 3.4L with what P&Cs? Cams? What machine work was done, if any?

Understood…I shared the SW Chips screen clip, b/c it was what I used for my conversation with the engine builder. Here are the essentials for my build:

Piston & Cylinders - Mahle Motorsports 3.4L Conversion (PS98-010) 10:1 compression
Carillo Rods
Custom BBE headers and muffler
ExtrudeHoned intake manifolds
SW Chips rebuilt and bored throttle body
20/21 cams
ARP rod bolts
Competition titanium springs and retainers
Custom chip for a 3.4 conversion programmed for 93 octane fuel

[Kevin Stewart]

Did you check all of the hoses going to the intake, airbox ect for oil residue? Had a diesel rabbit years ago that at 60mph it would blow oil into the air cleaner and blow smoke out of the tail pipe, oh and it was like having your foot on the floor lol.

[dannobee]

If it's blowing black smoke, address that issue first, as excessively rich mixtures can allow fuel to wash the oil from the cylinder walls.

Although 1 qt in 800 miles seems a tad excessive by today's standards, it was actually within spec when the car was delivered. 1.5l per 1000km was the factory spec.

[trentwat]

Originally Posted by dannobee

If it's blowing black smoke, address that issue first, as excessively rich mixtures can allow fuel to wash the oil from the cylinder walls.

Although 1 qt in 800 miles seems a tad excessive by today's standards, it was actually within spec when the car was delivered. 1.5l per 1000km was the factory spec.

Hmmm…maybe it is a combo of the high performance parts and the tune. It is a custom SW Chips chip which is programmed to deliver more mid-band performance.

T

[Magyar Kiwi]

Hi
If you rev it hard, it is going to burn oil.....
Not a problem
See typical Oil Consumption figures from Porsche below.
Cheers
Cheers