Engine Build Progress and Questions

[XT6Wagon]

Its interesting how many people are blowing these motors with heavy oils.

I know one person suffered engine failure with thier built STi engine shortly after switching to some heavywieght racing synthetic.

Seems to me that the good 5-30 synthetics are getting the job done tempature wise, so is there any reason to go with the heavier stuff at all?

[longassname]

Yep, your story sounds all too familiar now. I'm going to set my oil clearances to the top of the factory specified standard range. The factory specified oil clearance range is .0008-.0018. I think it's safe to say that the bearing failures we are seeing are on the journals with oil clearances towards the .0008 side. The rule of thumb for a racing engine is 1 thousandth per inch of journal size. So the rule of thumb would say to shoot for .002 on an SVX. .002 is what the factory service manual specifies as the limit. So I figure go for the top of the standard range, .0018" and we can eliminate a lot of these bearing failures even if you stick with a tri-metal bearing (which I'm not going to).


Getting the piston pins out is the pain. You need the circlip pliers to install the circlips. You could probably get the circlips out fumbling around with a long screwdriver--though i'm only speculating.

I have the factory circlip pliers for the 3 liter h6 and they work very well. You could make your own knock offs of them. Get some regulary needle nose pliers and lop off the handles then replace them with about 3/16" rod to make some long handles and you'll be able to get by. If you file a groove inside of them to really hold the clip well it will help a lot--it makes the rather expensive factory tool work very well.

I turned my own piston pin installer which I am quite confident is better than the factory tool version. If you take a piston pin to a machine shop with a lathe they can easily cut you a tool out of 1 inch round (though i bet it won't be as nice as mine).

I just ordered the factory tool for pulling out the piston pins. I found the one I made myself very unsatisfactory. I managed to get by though by taking out both the front and rear pistons before trying the middle and used my pin installer to knock the pin through instead of trying to pull it out. (while the pins are floating pins and go in by hand they don't come out that easily. Varnish and what not outside of where the circlips are make it tight and you'll want some good tools or at least some good drinks after hours of frustrated fumbling).

Originally Posted by dynomatt

Subscribing to keep up with developments.

LAN, my big end went in the last rally...started and failed very quickly. I was running Castrol GTX3 (a 15W-40 mineral oil).

I haven't pulled it down yet to see whether the heads survived (gee I hope they did).

What special tools are required to get the pistons out? (is that the only unusual bit with the middle piston??).

Also, FWIW, we were running about 2 degrees cam retard...when I wonder if it should be up around 7 degrees? (probably the wrong thread for this).

LCA's were 110 and 105.

M

[longassname]

I think at this point anyone who has 40 weight or higher in their suby should immediately drain it and go back to 10w30.

Those of us who are very familiar with racing mechanics often go up in viscosity when switching to synthetic because synthetic is a little thinner and because we are racing we know we are putting higher pressure on the oil and want it to be able to resist it. But the evidence sure looks to me like a lot of these Subaru engines don't have the oil clearance to tolerate it.

I'd say for a stock car just don't ever run thicker than 30 weight. For racing applications we need larger oil clearances to maintain oil films under high load and high rpm. If you have a stock car that needs crank work there's no reason not to set your oil clearances to the safer side of the factory spec'd range assuming your crank shop is good enough to maintain the tollerances.

Originally Posted by XT6Wagon

Its interesting how many people are blowing these motors with heavy oils.

I know one person suffered engine failure with thier built STi engine shortly after switching to some heavywieght racing synthetic.

Seems to me that the good 5-30 synthetics are getting the job done tempature wise, so is there any reason to go with the heavier stuff at all?

[cdigerlando]

Originally Posted by longassname

I think at this point anyone who has 40 weight or higher in their suby should immediately drain it and go back to 10w30.

Those of us who are very familiar with racing mechanics often go up in viscosity when switching to synthetic because synthetic is a little thinner and because we are racing we know we are putting higher pressure on the oil and want it to be able to resist it. But the evidence sure looks to me like a lot of these Subaru engines don't have the oil clearance to tolerate it.

I'd say for a stock car just don't ever run thicker than 30 weight. For racing applications we need larger oil clearances to maintain oil films under high load and high rpm. If you have a stock car that needs crank work there's no reason not to set your oil clearances to the safer side of the factory spec'd range assuming your crank shop is good enough to maintain the tollerances.

I'm glad I've been running Amsoil 10W30 synthetic. I did not have any bearing problems. We will see what was causing the blowby. I'm guessing ring lands. I'm hoping to pull the heads this weekend. Good advice on the bearing tolerances Mike.

[cdigerlando]

Mike:

How much was the circlip removal tool from subaru? Did it work well?

[longassname]

The circlip pliars are about $180 and they work very well.

The piston pin remover was $200 or $300, I don't remember which. I'm also not sure if it's the right one yet. The factory service manual listed part # for the tool doesn't come up in their info to even give a supercession #. They just kind of had to guess that another piston pin removal tool with a part # that ends in 600 instead of 500 is the superceeding tool and I had to buy it to try it to see. When it gets here we will see.

Originally Posted by cdigerlando

Mike:

How much was the circlip removal tool from subaru? Did it work well?

[longassname]

It sounds like your mental image of what tri-metal bearings are needs a little revision. It sounds like I need to hash out the explanation of what I meant by "aluminum" rod bearings too.

Tri-metal bearings have a steel backing, copper plating, then babbit material for the friction surface. That babbit material friction surface is only about 0.0007" thick and has a melting point of 400 degrees. Because the friction surface is so thin it has very limited "embedability." That's industry jargon that means flecks of stuff in your oil can tear the babbit material instead of just embeding into it.

"Aluminum" rod bearings have a steel backing onto which a very thick friction surface (18 times thicker than the babbit material on a tri-metal bearing) of a high silicon aluminum alloy is bonded. They have very high embedability, meaning that grit in your oil which would quickly cause a rod bearing failure with tri-metal bearings will just embed into the aluminum bearing and sit more or less harmlessly for the life of the engine. The aluminum doesn't just "dissipate heat" faster as you said; It has an 1100 degree melting point as opposed to the 400 degrees of the babbit material on a tri-metal bearing. When the oil film on a crank pin starts to break down it starts making heat. With an 1100 degree melting point the bearing is better able to survive those brief moments of extreme operating conditions where an oil film might start to break down. These are the bearings used on 5,000hp top fuel drag cars. They are also being used by oem's in the engines that they specify a service life of over 150,000 miles for.

Originally Posted by cdigerlando

Maybe this is a good time and place to talk about bearings. I know squat. Like you said aluminum dissipates heat much better than steel. But I wonder if steel would last longer as a wear item or if aluminum would be strong enough. I know that Tom had some pretty strong opinions regarding this issue. I'd like to hear from him on this.

[cdigerlando]

Originally Posted by longassname

It sounds like your mental image of what tri-metal bearings are needs a little revision. It sounds like I need to hash out the explanation of what I meant by "aluminum" rod bearings too.

Tri-metal bearings have a steel backing, copper plating, then babbit material for the friction surface. That babbit material friction surface is only about 0.0007" thick and has a melting point of 400 degrees. Because the friction surface is so thin it has very limited "embedability." That's industry jargon that means flecks of stuff in your oil can tear the babbit material instead of just embeding into it.

"Aluminum" rod bearings have a steel backing onto which a very thick friction surface (18 times thicker than the babbit material on a tri-metal bearing) of a high silicon aluminum alloy is bonded. They have very high embedability, meaning that grit in your oil which would quickly cause a rod bearing failure with tri-metal bearings will just embed into the aluminum bearing and sit more or less harmlessly for the life of the engine. The aluminum doesn't just "dissipate heat" faster as you said; It has an 1100 degree melting point as opposed to the 400 degrees of the babbit material on a tri-metal bearing. When the oil film on a crank pin starts to break down it starts making heat. With an 1100 degree melting point the bearing is better able to survive those brief moments of extreme operating conditions where an oil film might start to break down. These are the bearings used on 5,000hp top fuel drag cars. They are also being used by oem's in the engines that they specify a service life of over 150,000 miles for.

Thanks for the info. Please read this and tell me what you think.

http://www.aa1car.com/library/2005/eb030526.htm

This article discusses a lot of advatages that you brought up about aluminum, however it mentions that loading should be no more than 100 HP/Liter for even a high quuality aluminum bearing. There is a huge argument in this article going both ways. You may already be familiar with the article, but I thought you would be interested. There is also a strong argument for running coated bearings at the very end.

On another subject....I received the cams on Friday. I was so busy this weekend, I have been unable to check them out. Thanks for the fast turn around time. I would like to send my heads to be done to your machine shop in Miami. I'll wait until the springs and valves are delivered. Also, I wanted to see if they also do bottom end assembly. I would really like to send the whole longblock to them if you recommend them.

[longassname]

Ok, I read it (despite not really having the time for internet article crap). They said normal aluminum bearings made from 500 or 600 series aluminum can't take as much loading per square inch (by the way....that's what SVX main bearings are, the ones that DON'T go bad). Then they said every bearing manufacturer out there said their bearings are the best...including the ones who make the bi-metal, high silicon alloy aluminium bearings I'm talking about using--which often are used in nitro-methane drag cars running many many many times more than 100 hp per liter.

Originally Posted by cdigerlando

Thanks for the info. Please read this and tell me what you think.

http://www.aa1car.com/library/2005/eb030526.htm

This article discusses a lot of advatages that you brought up about aluminum, however it mentions that loading should be no more than 100 HP/Liter for even a high quuality aluminum bearing. There is a huge argument in this article going both ways. You may already be familiar with the article, but I thought you would be interested. There is also a strong argument for running coated bearings at the very end.

On another subject....I received the cams on Friday. I was so busy this weekend, I have been unable to check them out. Thanks for the fast turn around time. I would like to send my heads to be done to your machine shop in Miami. I'll wait until the springs and valves are delivered. Also, I wanted to see if they also do bottom end assembly. I would really like to send the whole longblock to them if you recommend them.

[XT6Wagon]

If it lives even a 1/4 mile under nitromethane, its going to be fairly tough

[TomsSVX]

Dropping off my block at the machine shop tomorrow.... We will see how everything makes out... I am also going to check to see how much it will be to have the crank balanced

Tom

[cdigerlando]

Originally Posted by longassname

Ok, I read it (despite not really having the time for internet article crap). They said normal aluminum bearings made from 500 or 600 series aluminum can't take as much loading per square inch (by the way....that's what SVX main bearings are, the ones that DON'T go bad). Then they said every bearing manufacturer out there said their bearings are the best...including the ones who make the bi-metal, high silicon alloy aluminium bearings I'm talking about using--which often are used in nitro-methane drag cars running many many many times more than 100 hp per liter.

Yes it is frustrating to read. Everyone puts in their plug. My conclusion was that if a high quality bearing is used and installed properly it will suite our needs, aluminum or otherwise. The plug for coated tri metal bearings was interesting.

[cdigerlando]

Originally Posted by TomsSVX

Dropping off my block at the machine shop tomorrow.... We will see how everything makes out... I am also going to check to see how much it will be to have the crank balanced

Tom

Awesome news. Keep us posted on your progress.

[longassname]

Bolt your block together, torqued to the factory specs before dropping it off. The block should be honed bolted together.

Originally Posted by TomsSVX

Dropping off my block at the machine shop tomorrow.... We will see how everything makes out... I am also going to check to see how much it will be to have the crank balanced

Tom

[TomsSVX]

I know you had mentioned that before... My only question... keep the crank in the block or no??

Tom