Should I be worried about my rings? Rebuild*

[ziggo0]

At 250 miles...tossed a compression tester on for fun.

Cyl 1 - 95
Cyl 2 - 105
Cyl 3 - 95
Cyl 4 - 105

Kinda disapointed...ring gaps were in spec, top ring was a bit loose. Fresh hone. Been doing a lot of rpm decellerations since the car got on the road. Idles great around -19 or -18 vac. Am I worrying for no reason?

 

[MichaelSuch]

Seems normal for a fresh rebuild, mine was about the same when I built it with only a few hundred miles on it. I would check again in 1000 miles. Did you do it with the engine HOT and throttle wide open?

 

[ziggo0]

I wouldn't say hot, probably sat for a hour - hour and half. Yes it was wide open throttle.

I'm reading on various sites that sometimes cast rings can take 1000 miles or more to set. As long as I get some compression back I'll be happy

 

[crash89]

How did you do your "break in?" I dont really have any experience with fresh motors and how long it takes for rings to fully seat but, it would seem to me that the numbers should be a little higher!

 

[SrKegler]

I would recheck those readings with a different compression guage. With numbers that low I don't see how the engine would start.

 

[LiquidX]

You have been boosting to around at least 15psi right and going throuh a full range of RPMs?

 

[ziggo0]

You have been boosting to around at least 15psi right and going throuh a full range of RPMs?

No boost, about 4k, sometimes 5k at most, no wot either. Been babying it quite a bit.

 

[LiquidX]

You HAVE to boost it. The best way to break in a motor is to run it hard out of the box. Top fuel cars, how do you they break their motor in. I'm sure they aren't driving around for x amount of miles before running 9000hp. No, they break it in on their first run of 9000hp.

Without doing that, your rings aren't seating properly to where boost will show. You will have blow by and lower power babying it.

 

[ziggo0]

Very well. I shall dial the safc in and give it the nuts today.

 

[e85_4g63]

It might be to late already, just saying. I'm working on a guys TSI that is in the same situation as your describing. He installed a new clutch with a fresh rebuilt motor, didn't get into the car hard because of breaking in the clutch, now the motor is back out for a rebuild again...

 

[jb2zero0six5]

Just set boost at around 10 psi, it will push the rings for a better seal. Do a nice 2nd gear pull and let the motor decelerate. Make sure to reply back with results!

 

[ziggo0]

It might be to late already, just saying. I'm working on a guys TSI that is in the same situation as your describing. He installed a new clutch with a fresh rebuilt motor, didn't get into the car hard because of breaking in the clutch, now the motor is back out for a rebuild again...

That's the biggest reason I've been babying it, new clutch

 

[e85_4g63]

Hopefully your case isn't as bad as his.. but I'm thinking you might be in the same boat.

 

[donniekak]

A new clutch shouldn't stop you from doing 10psi pulls/engine braking.

 

[jb2zero0six5]

A new clutch shouldn't stop you from doing 10psi pulls/engine braking.

Thats what I was thinking..

 

[ziggo0]

Managed to do 3 good pulls. First one scared me to death, oil pressure dropped to 0...car off...vibrations loosened the senders nut *whew*. It felt progressively better but I think its going to take a lot more of beat and a bit of luck I hope.

 

[Fejery4491]

You HAVE to boost it. The best way to break in a motor is to run it hard out of the box. Top fuel cars, how do you they break their motor in. I'm sure they aren't driving around for x amount of miles before running 9000hp. No, they break it in on their first run of 9000hp.

Without doing that, your rings aren't seating properly to where boost will show. You will have blow by and lower power babying it.

They also use different types of rings such as moly rings which seal INSTANTLY.

The best way to break in a motor isn't just beating the crap out of it. Rather controlled varie throttle. Varying cylinder pressures helps seat the rings. I know you weren't implying to just do nonstop WOT runs to break in your motor, I'm just adding to what you said

 

[ziggo0]

Still smoking/oily smell - I hope more miles do the trick...a hone would make the bores to big, i'd have to go .040 over and new pistons

 

[Burnett03]

You HAVE to boost it. .

NO you don't. I have broken in many motors on low to no boost, not to mention cars that don't have a turbo at all break in just fine. Vary the rpm's and use a non detergent oil for break in and the motor will be fine.

 

[LiquidX]

NO you don't. I have broken in many motors on low to no boost, not to mention cars that don't have a turbo at all break in just fine. Vary the rpm's and use a non detergent oil for break in and the motor will be fine.

Let me rephrase. While you don't have to boost a turbo motor, the rings won't be worn properly for the boost you will be running in the future. you should never baby a motor to break it in.

The bearings will be broken in upon the first 5 second of the engine running due to little or no lubrication film. The rings want to be pressed out into the cylinder walls and that needs higher cylinder compression. So, boosting it more the better.

Of course NA motors won't get boost, they are seeing their highest cylinder compression at WOT.

Do some research bud, you see the reasons why you would want to break the motor in on a track run or dyno.

Being your car, you can do it however you want. If you want a proven way that makes more power and little to no blow by then run it hard. Otherwise baby it and enjoy leaky rings and less power from not sealing the higher cylinder pressures that you now run it at.

 

[ChiTownHussla]

there was a topic on this a while back guys. I remember there being a link to some guys website explaining why and how to break in turbo motors...He stated to boost it and do WOT pulls through 2-4 gear while engine breaking to slow down and rinse and repeat.....

 

[LiquidX]

there was a topic on this a while back guys. I remember there being a link to some guys website explaining why and how to break in turbo motors...He stated to boost it and do WOT pulls through 2-4 gear while engine breaking to slow down and rinse and repeat.....

This is the link you were referring to.
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

 

[crash89]

This is the link you were referring to.
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

If someone didnt link that to this I was going to!

 

[talonDSMerr]

10-20psi of boost will not "push" the rings for a better seal. Boost isn't what helps seat the rings. 10-20psi is nothing compared to combustion pressures.

The idea behind boosting a motor during break in isn't so much getting positive pressure in the intake - it's putting load on the motor. Loading the motor is what is important during break-in and what helps the rings seal. Combustion pressures with load on the motor reach much higher levels and this is the pressure that pushes rings outwards so they can seat.

If boost was so important to breaking in motors, you would see N/A motor builds breaking in their motors by slapping on turbos...

 

[LiquidX]

Boost increases pressure and load is needed to build up pressure. So for us to "dumb it down" you want to boost around I.e. Loading the motor.