Forged engine carbon build up on pistons?

dac69er

dac69er

Super Moderator
Noticed I have a lot of carbon build up on the tops of my pistons. A worrying amount based on the mileage! It wasn't even that bad on my stock pistons when I took the engine apart!!!!

It's a forged build that has only done about 1000km.

Engine doesn't seem to use any oil. I've done a compression test and got 170,170,165,165

Any ideas?
 
dac69er

dac69er

Super Moderator
Jay said:
Can't keep them gleaming forever :D

Does it look equal across all four?
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I'm not expecting shiny, but they are worse than 80k mile pistons and they have done less than a thousand miles!!!

Build up is Pretty equal from what I can see. Number 2 plug is a bit darker than the rest, so I suspect the injector is leaking a bit or something. I did have them cleaned and tested so should be fine.
 
G

gorganl2000

Lifer
just dropping some thoughts/questions as i'm not too clued on this situation
but is it possible it could be due to the bore/ring tolerances and the engine still being quite young---still bedding/running in?
how about the type of gas being used--any ethanol content?

as jay mentioned,, the type of driving being done---since its a new engine, that could be a lot of slow/calm driving in that 1000km

the relatively similar compression and carbon across the cylinders does seem like everything is good with the engine though

i've seen clean intake and engine cylinders/pistons only when water injection is used---acts like a steam clean when driving
 
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dac69er

dac69er

Super Moderator
gorganl2000 said:
as jay mentioned,, the type of driving being done---since its a new engine, that could be a lot of slow/calm driving in that 1000km
Click to expand...

I've been beating on it pretty hard considering it's low mileage tbh. Definitely haven't been driving it slowly apart from when I get stuck behind old dears

I've noticed the exhaust seems to spit more black carbon spots out all over the back of the car compared to my reasonably stock GT. I assume it's just running on the rich side. I probably need to tweak the map a bit tbh, but I was just concerned with the amount of carbon build up after such a short period of time!?
 
Jay

Jay

Admin
Worth a quick chat with the tuner I'd say.

The compressions sound within tolerance so you might just being seeing the results of a rich mixture.

Could run a bit of injector cleaner through it as well in case it helps too. Obviously stick to the super unleaded best you can.
 
dac69er

dac69er

Super Moderator
Jay said:
Worth a quick chat with the tuner I'd say.

The compressions sound within tolerance so you might just being seeing the results of a rich mixture.

Could run a bit of injector cleaner through it as well in case it helps too. Obviously stick to the super unleaded best you can.
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I have stuck some injector cleaner in it just incase.

I could give the tuner a call, but tbh, I don't think I will get much from them tbh. They were ok, but aren't that clued up on starlets or power FC.

I will see what they say though
 
dac69er

dac69er

Super Moderator
I checked my daily GT and that does actually have black specs over the back, so scrap what I said about that. I guess I just don't notice it as much on the daily as it is either a bit dirty anyway or gets washed off with all the rain we have!

It is overfuelling, but isn't by loads.

I have bought a little cleaner thing and will try and get some of the bigger bits off. It may have got some build up from before when I was only running it for short periods after the rebuild. I would have thought it would have blown out by now though!!!
 
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