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Concerned With New Engine On Dyno

jarrod83

By jarrod83,
in Engines & Forced Induction

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jarrod83 Community Regular

jarrod83

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Hey, i got to watch my car on the dyno the other day and noticed it had heaps of air/white smoke coming out the cam covers breather hole as i had the catch can setup disconnected, it started at 3000 as it started to make boost and by 7000 it was a pretty substantial plume of smoke/air, alot more smoke than i would of expected for blow by..

The engine has done roughly 1300kms, used 9:1 cp pistons and rings, i compression tested it the other day when it was cold, since the car is missing a radiator atm and got roughly 158-160 for pistons 3-6 and 155 for 1 and 2, wont be able to compression test it warm until i get my new radiator.. should i get a leak down test done as well or is this usual for a forged engine and im just being a bit paranoid?

Cheers

Jarrod

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jarrod83 Community Regular

jarrod83

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i built it myself, first time i have attempted anything like this, made harder by the choice to ceramic coat everything

Elite Racing:

Cheers for the advice, i just wasnt expecting it to breathe so much.. almost looked like more air was coming out the breather than the exhaust

Jarrod

The Dan Grand Master

The Dan

Posted
Posted
i built it myself, first time i have attempted anything like this, made harder by the choice to ceramic coat everything

Elite Racing:

Cheers for the advice, i just wasnt expecting it to breathe so much.. almost looked like more air was coming out the breather than the exhaust

Jarrod

Yeah a lot of people freak out when they see it. It's gas fumes created by the approx 10%-15% of leakdown that every engine has. Imagine the cylinder pressure once you throw in 15 to 20 psi of boost. On a 100psi regulated leakdown test you would see a value of approx 15 psi escaping. When you are cramming boost in and combustion pressure also, that increases to around 300psi cylinder pressure or there abouts possibly more. So you can have around 40-60 psi of pressure bypass the rings but not constantly. It's just little amounts as the combustion and stroke is so fast.

Add 6 cylinders all doing the same thing and it's almost like a mini steam train if you leave the breathers off.

With compression of 160psi on all 6, it sounds like you did a decent job of the build.

It's when it starts blowing raw oil out that you need to be concerned.

116.hks Community Regular

116.hks

Posted
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My did the same thing, even blew a bit of oil out of the catch can, that was even after running the engine in after 5000k's. Found that after the motor ran had done approx 7k, the breathing stopped. On the other hand, a mates 32 GTR does the same thing and has done more k's then I have and he's using CP pistons and rings like you. I had read somewhere that the CP rings had dramas with sealing properly and scoring the bore, but I think they fixed that problem. See how it goes with a few more k's on the engine, it might settle down.

jarrod83 Community Regular

jarrod83

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Elite Racing:

thanks alot for that elite, thats a real load of my mind, my main concern was that i had done something wrong or it was something out of the ordinary, a mini steam engine is definitely the right description for it.

116.hks:

Yeh i had heard that as well and that they had fixed it as i was considering sticking in ACL rings, hopefully it seals up a bit better as it clocks up more kms.

Cran:

haha jason, ill make it there oneday, just got to figure out why the torque was dropping off earlier now.. which i think is due to the cams maybe being advanced, hopefully the radiator arrives next week sometime and the car will have the new exhaust made up.. and ill be able to take you for a spin

Jarrod

jarrod83 Community Regular

jarrod83

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Status: id say it was steam.. more so than smoke.. i just remember thinking it looks alot like a kettle.. my piston to bore clearance was 3.5 thou from the pistons size before they were ceramic coated, the ceramic shop said because the pistons were getting ceramic coated they wouldn't expand as much. So the dry film lubrication layers thickness wouldn't effect the piston to bore clearance.. hard to say exactly what the clearances were without buying a micrometer and checking them myself, which i was considering, the bore was bored out 1 thou extra than the specs since the machine shop measured them and claimed the pistons were all 1 thou bigger, which i had double checked by a engineering shop.. i did roughly check the clearances with a feeler gage, but considering the bore and pistons are both round n they feeler gages dont like to bend it isnt very accurate, off memory (which isnt very good) i managed to get the 1.5 thou size in, but the 2 thou clearance was extremely tight..

Jarrod

SiR_RB Grand Master

SiR_RB

Posted
Posted

when i was looking at r32 gtrs begining of the year, i had this white one idling, i opened the oil filler cap on the engine, it was "choofing" masses of white misty air, it was pretty high pressured too the smoke was almost going up to the bonnet !

what does this exactly mean? i always thought it was blow by/ alot of blow by, so im assuming worn rings? low compression ?

116.hks Community Regular

116.hks

Posted
Posted

What does it smell like? If the rings aren't sealing correctly it will have that combustion/oily smell. Makes ya feel a bit sick in the gut after a while. From what I've seen and heard, it only has happen to motors running CP piston and ring combo. Just keep an eye on it mate, if it does stop with more k's, get it checked.

jarrod83 Community Regular

jarrod83

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i didn't end up sticking in a oil restrictor as i did the internal vct oil feed where it gets its oil feed from the oil gallery, i assumed once the vct turns off after 4k that the oil would also be draining from the vct oil return line, i did install the rear oil drain kit and drilled the oil returns out larger in the head, which seems to be adequate enough

Cheers for all the input guys, ill monitor if it changes over the next few 1000kms and see if its losing any oil

Jarrod

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