pistons n cams

[icingdeath88]

Originally Posted by Crazy_pilot

The problem is I'm fairly sure the ECUTune pistons call for a slight boring out of the cylinders. Fairly minimal, but not something you'd be able to do with the block intact.

I've got a set of Mike's cams waiting for me at home. I was hoping to have them in this summer but there was a back-log at the manufacturer and I had to put my engine back together before Mike could get them to me. My plan is to just drop those in and see what happens. It's very likely that between the cams, my exhaust (a bit more free flowing than stock) and hopefully my new intake I'll be able to max out the stock MAF. Should be fun...

Hmm. I might look into the pistons a bit more after I do my 6-speed swap. How much do you think the cams by themselves would add?

[ZephTheChef]

Am I the only one lol-ing at the fact that this was posted in "Interior Mods"?

[icingdeath88]

Originally Posted by ZephTheChef

Am I the only one lol-ing at the fact that this was posted in "Interior Mods"?

Weird, I thought it was under "today's posts"

But yea interior =! internals.

Any thoughts on the actual question? Is it even remotely ok to swap in new pistons without having machine work done on the engine?

[Cam]

I have been told that our cylinders wear into ovals. Mine were slightly out of round before my machine work. Suppose you would have issues with rings seating properly perhaps...

[Huskymaniac]

Why not just avoid the hassle and just replace the MAF, injectors and maybe the cams? Unless you are going to do forced injection, what is the reason to change the pistons?

[ZephTheChef]

I agree, internal engine mods are about the worst bang for your buck there is. But yes, if you're replacing pistons, you really should do machine work. I've done so on my other cars with just a good cylinder hone, but they weren't out of round or damaged in any way. To "do it right" you really need to have the block machined to the right tolerances.

[Cam]

You can raise the compression ratio, put thermal coated bearings in, blueprint the engine, etc. All these things are essential for a true performance build. Subarus have tight oil clearances from the factory, which makes them incredibly prone to losing bearings or other parts of the bottom end. thermal coating components of the bottom end negates thermal expansion and allows for tighter tolerances to be run. It is a must if your engine is to be "perfect".

[ZephTheChef]

Originally Posted by Cam

You can raise the compression ratio, put thermal coated bearings in, blueprint the engine, etc. All these things are essential for a true performance build. Subarus have tight oil clearances from the factory, which makes them incredibly prone to losing bearings or other parts of the bottom end. thermal coating components of the bottom end negates thermal expansion and allows for tighter tolerances to be run. It is a must if your engine is to be "perfect".

I personally can't see spending $5,000 on an engine build when they can be had used for $250-500 all day long. I promise you that built engine isn't going to last 10x-20x as long as a junkyard replacement...odds are it probably won't even last 3x as long. I consider EG33s disposable engines due to their low cost. The only reason I could see for building one like that would be if you're on an unlimited budget, or you just plain don't like turning wrenches.

[Cam]

Originally Posted by ZephTheChef

I personally can't see spending $5,000 on an engine build when they can be had used for $250-500 all day long. I promise you that built engine isn't going to last 10x-20x as long as a junkyard replacement...odds are it probably won't even last 3x as long. I consider EG33s disposable engines due to their low cost. The only reason I could see for building one like that would be if you're on an unlimited budget, or you just plain don't like turning wrenches.

I spent the money because I like turning wrenches. I also like doing things right. I have learned an incredible amount from doing my engine the way I have done it. And treating EG33's as disposable is the same attitude that has depleted a lot of the resources we have for parts and service. That being said, I find your project very interesting and am excited to see how it works out.

[ZephTheChef]

Originally Posted by Cam

I spent the money because I like turning wrenches. I also like doing things right. I have learned an incredible amount from doing my engine the way I have done it. And treating EG33's as disposable is the same attitude that has depleted a lot of the resources we have for parts and service. That being said, I find your project very interesting and am excited to see how it works out.

I understand the desire to do things "right", and the joys of doing so. And if I had the time and money, I would absolutely do things that way. I'm much more about getting the performance I can out of what I have than sparing no expense to get what I feel are overall, very slight improvements.

I'm not saying I'd just blow an engine up and throw it away, but I won't be doing performance rebuilds either, if I do get into rebuilding them...I'll be doing it as cheaply as is reasonable...or, more likely, selling the core to a rebuilder who will "do it right". I understand where you're coming from, and it sounds like you understand where I'm coming from, so I guess all is well.

The only thing I'd argue against, is that people have treated EG33s as disposable, lol, and that there's a lack of parts availability (salvage anyway). The transmission problems with these cars have left salvage yards rich with SVXs, and parts gloriously cheap, in my experience.

[oab_au]

Originally Posted by Cam

You can raise the compression ratio, put thermal coated bearings in, blueprint the engine, etc. All these things are essential for a true performance build. Subarus have tight oil clearances from the factory, which makes them incredibly prone to losing bearings or other parts of the bottom end.. thermal coating components of the bottom end negates thermal expansion and allows for tighter tolerances to be run. It is a must if your engine is to be "perfect".

I can't really agree with this Cam. Modern engines have close bearing fit, and run low viscosity oil. I think, "incredibly prone to losing bearings" is way off the mark. The engines that have had big end problems have had more to do with high rpms, and increased bearing clearance.

Also, "thermal coating components of the bottom end negates thermal expansion". I guess you are talking about coating the bearing surface. This won't stop the rod and shells from expanding due to heat from combustion.

Harvey.

[ZephTheChef]

Plus, the bearing coatings are usually a dry-film lube, as opposed to ceramic for thermal purposes. Coating the pistons and head can certainly lower temps overall, though.

[Cam]

It should go without saying that the only parts not affect by thermal expansion are the coated parts. Suppose I could have been more clear about that. And I say that they are prone to losing bearings because they do so at RPM's that many modern cars are comfortable at. 9k rpm is not much, especially when Porsche has engines that near 20k rpm redlines.

[ZephTheChef]

Originally Posted by Cam

It should go without saying that the only parts not affect by thermal expansion are the coated parts. Suppose I could have been more clear about that. And I say that they are prone to losing bearings because they do so at RPM's that many modern cars are comfortable at. 9k rpm is not much, especially when Porsche has engines that near 20k rpm redlines.

Fair enough!

[icingdeath88]

Originally Posted by Huskymaniac

Why not just avoid the hassle and just replace the MAF, injectors and maybe the cams? Unless you are going to do forced injection, what is the reason to change the pistons?

11:1 comp ratio.

Originally Posted by Cam

You can raise the compression ratio, put thermal coated bearings in, blueprint the engine, etc. All these things are essential for a true performance build. Subarus have tight oil clearances from the factory, which makes them incredibly prone to losing bearings or other parts of the bottom end. thermal coating components of the bottom end negates thermal expansion and allows for tighter tolerances to be run. It is a must if your engine is to be "perfect".

What if it doesn't have to be perfect, though? Is it a corner worth cutting? The expense makes me think that it could be. I mean, I have 2 spare engines, one complete in a parts car and one just the longblock. So from a reliability standpoint, I could handle losing an engine. I realize it wouldn't be anywhere near as reliable as what you'll be running, but for half the cost, I think I could live with that.

I'm gonna talk with LAN and see what he thinks considering he's the one who designed the pistons in the first place, but if it's worth a try, I'll go for it next semester.

Originally Posted by ZephTheChef

I personally can't see spending $5,000 on an engine build when they can be had used for $250-500 all day long. I promise you that built engine isn't going to last 10x-20x as long as a junkyard replacement...odds are it probably won't even last 3x as long. I consider EG33s disposable engines due to their low cost. The only reason I could see for building one like that would be if you're on an unlimited budget, or you just plain don't like turning wrenches.

I'm feeling you about the cost issue. My current SVX (the one in my sig was in a wreck ) only cost $800. I can't see spending more than a few thousand on the engine.