Milky oil and alcohol

Old 08-24-2011, 08:15 AM
  #111  
hammertime
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Originally Posted by shawnp
That's what I meant. You are not buring off the amount of fuel that was going thru that motor. It has to go someplace and into the pan is the only place to go. It will increase the crank pressure and explain why it is pushing to get out thru the catch can. On the plus side, your oil pan and intake must be sealed very well if it is not trying to push oil out in those 2 places.

On the cam selection, an alky motor will always want to have more exhaust duration to run as efficient as a gas motor.
x2 on what Shawn said, the fuel has to go somewhere, but its still not explaining why it slows down when you take fuel away, it should pickup.
I actually think it'll be faster on gas right now
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Old 08-24-2011, 08:49 AM
  #112  
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Originally Posted by shawnp
That's what I meant. You are not buring off the amount of fuel that was going thru that motor. It has to go someplace and into the pan is the only place to go. It will increase the crank pressure and explain why it is pushing to get out thru the catch can. On the plus side, your oil pan and intake must be sealed very well if it is not trying to push oil out in those 2 places.

On the cam selection, an alky motor will always want to have more exhaust duration to run as efficient as a gas motor.
With a normal engine there should be only one way unburned fuel can get into the crankcase. It has to go past the rings / pistons / cylinder walls.
Unless there is a crack in the block which allows cylinder pressure to get into the crankcase.
Do you guys agree?
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Old 08-24-2011, 10:41 AM
  #113  
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Looking at the build sheet, the 1 thing that's missing is the piston to wall clearance, i'm a little curious as to why that was left off. If there's excessive clearance and as short as the piston skirts are you will have piston rock and even gapless rings will not seal properly. the other question that hasn't been ask, do you have any sleeves in this block? Either way if you have to pull it back down i would definatly pressuse test the blk.

JMO

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Old 08-24-2011, 10:58 AM
  #114  
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Originally Posted by kod99
With a normal engine there should be only one way unburned fuel can get into the crankcase. It has to go past the rings / pistons / cylinder walls.
Unless there is a crack in the block which allows cylinder pressure to get into the crankcase.
Do you guys agree?
You keep dumping this much fuel in the motor and you will end up washing a cylinder out. The fuel ends up in the pan traveling with the oil. This is why your oil is milked so bad.
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Old 08-24-2011, 11:18 AM
  #115  
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Originally Posted by shawnp
Originally Posted by kod99
With a normal engine there should be only one way unburned fuel can get into the crankcase. It has to go past the rings / pistons / cylinder walls.
Unless there is a crack in the block which allows cylinder pressure to get into the crankcase.
Do you guys agree?
You keep dumping this much fuel in the motor and you will end up washing a cylinder out. The fuel ends up in the pan traveling with the oil. This is why your oil is milked so bad.
That's what I am afraid of, washing out a cylinder or diluting the oil so badly I wind up with bearing damage.
I have to locate and solve the problem before anymore runs on alcohol.
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Old 08-24-2011, 11:21 AM
  #116  
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Originally Posted by zipper06
Looking at the build sheet, the 1 thing that's missing is the piston to wall clearance, i'm a little curious as to why that was left off. If there's excessive clearance and as short as the piston skirts are you will have piston rock and even gapless rings will not seal properly. the other question that hasn't been ask, do you have any sleeves in this block? Either way if you have to pull it back down i would definatly pressuse test the blk.

JMO

Zip.
I never noticed that zipper. I will check with the builder and see what the piston to wall clearance was.
I don't have any sleeves in the block. It was a new Dart Big M block about 20 passes, and two rebuilds ago.
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Old 08-24-2011, 07:57 PM
  #117  
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I don't know what other builders, run but i limit the clearance to .0065/.007 on alcohol or nitrous, on gas i come down to .0055/.006, with forged pistons. The other question comes to mind is the piston. The build sheet says SRT 14.5 to 1. Did he mean SHP pistons? if so the expansion rate on the SHP and a true forged piston. If so the SRP piston is a high silicon piston and the expansion is less than a 2618 forged piston. I personally will not run a SHP pistion, although that's what a lot of builders use because they are about $150.00 cheaper and they are not a good alcohol piston (in my opinion). I've seen more of them burn down on alcohol than any other high compression piston. JE sells more SHP pistons than any other piston they sell. The other thing is that he says on the end gap on the top ring is .035 and the second ring he says .032, but then he writes gapless, i have never file fit a gapless ring, but maybe i'm missing something. I'm not critising the engine builder, just looking for the problem same as you are

Zip.
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Old 08-25-2011, 04:53 AM
  #118  
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Originally Posted by zipper06
I don't know what other builders, run but i limit the clearance to .0065/.007 on alcohol or nitrous, on gas i come down to .0055/.006, with forged pistons. The other question comes to mind is the piston. The build sheet says SRT 14.5 to 1. Did he mean SHP pistons? if so the expansion rate on the SHP and a true forged piston. If so the SRP piston is a high silicon piston and the expansion is less than a 2618 forged piston. I personally will not run a SHP pistion, although that's what a lot of builders use because they are about $150.00 cheaper and they are not a good alcohol piston (in my opinion). I've seen more of them burn down on alcohol than any other high compression piston. JE sells more SHP pistons than any other piston they sell. The other thing is that he says on the end gap on the top ring is .035 and the second ring he says .032, but then he writes gapless, i have never file fit a gapless ring, but maybe i'm missing something. I'm not critising the engine builder, just looking for the problem same as you are

Zip.
I noticed the samething on the gapless rings
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Old 08-25-2011, 07:08 AM
  #119  
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Thanks guys for all the input. I have a lot of good questions to ask the engine builder when I take the car to him tomorrow to do a leak down test. I will update you on Saturday after the test. Thanks again guys!

My goal is to get the problem worked out this year, as our racing season is over in a few more weeks and I don't want to start next season fighting problems again.
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Old 08-25-2011, 05:38 PM
  #120  
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One of the reasons i questioned the SRP pistons is about 2 or 3 yrs. ago we had a person who was posting here that worked for JE pistons and i told him i wouldn't put a SRP in my lawn mower. At the time i was a little upset about melting down the top of a piston for about 1/4" to the first ring on my 1471 blown 358 sm/blk chevy, causing masive damage blowing oil out filling up the catch can and even oiling the right side slick and spinning 4 rod bearing and 2 main bearing and scrapping the crank. He responded with we won't sell SRP pistonn for lawn mowers, and that the SRP piston is only good for 100 HP per hole, anything over that you're flirting with danger.
I'm sure the thread is gone by now, but maybe some remember.

Zip.
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