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9/30/09, 10:28 PM   #1
Questions about pistons
Lucky161
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Since Tim brought up pistons in my valve spring thread, I they would be a good topic to go to next. Some of this stuff I've found online somewhere and some of it I haven't. But so everyone knows, I am not looking for arguments with anyone, just information, which may naturally include some differences of opinion.

For instance Tim suggested that stock pistons would be a bad choice and forged pistons would be the best choice, with hypereutectic being a possible compromise. I don't think anyone would argue with that logic all things being equal. But I wonder if Tim was considering the point of Racesaver engine rules is to keep costs down as low as possible? It wouldn't serve much purpose to have an expensive 305 engine in my opinion.

So my questions are
If forged pistons are ruled out due to cost, then which of the other two would be the best compromise? My thinking here is that forged pistons provide a strength factor not needed for this type of engine. Another question I have concerns ceramic coatings for pistons. Is this something that would be desirable and if so what kind of cost are we looking at?
 
10/1/09, 9:53 AM   #2
Re: Questions about pistons
Tim
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Quote:
Originally Posted by Lucky161 View Post
Since Tim brought up pistons in my valve spring thread, I they would be a good topic to go to next. Some of this stuff I've found online somewhere and some of it I haven't. But so everyone knows, I am not looking for arguments with anyone, just information, which may naturally include some differences of opinion.

For instance Tim suggested that stock pistons would be a bad choice and forged pistons would be the best choice, with hypereutectic being a possible compromise. I don't think anyone would argue with that logic all things being equal. But I wonder if Tim was considering the point of Racesaver engine rules is to keep costs down as low as possible? It wouldn't serve much purpose to have an expensive 305 engine in my opinion.

So my questions are
If forged pistons are ruled out due to cost, then which of the other two would be the best compromise? My thinking here is that forged pistons provide a strength factor not needed for this type of engine. Another question I have concerns ceramic coatings for pistons. Is this something that would be desirable and if so what kind of cost are we looking at?
Lucky,

I agree the point of the RaceSaver series is to keep the motor cost down, but I look at it in the long run. Forged pistons should last longer than cast both from a longevity standpoint as well as taking more abuse due to mis-tuning, etc. This should allow pistons to last several seasons before needing replacement, which saves money in the long run. Hypereutectic are the way to go if forged are too expensive but, as I look at the Speedway Motors catalog, the difference in forged vs. hypereutectic is around $200. Cheap insurance to me. I can't comment intelligently on the ceramic coatings except to say it would surprise me if the cost was much less than $200 to coat a set of pistons.

In short, when you build a sprint car engine you can build one as cheaply as you want but, if it doesn't live through the abuse it's going to take, then where's the savings? There are several other outside influences that affect the motor. For instance, hitting the wall with the rear tires while on the gas sends shock waves through the drive train affecting the crankshaft, rods, etc. You can build a motor with a cast crank and stock rods very cheaply but they won't take the shock loading experienced and will soon break, sometimes with dramatic and impressive results.

And, yes, I do understand keeping motor costs down. The car we race with in Indiana, against 410 aluminum block competition, has a stock forged Chevrolet crank, Eagle SIR rods, TRW forged pistons, stock Chevrolet block with original caps, Brodix Track I heads and 2-3/16" injection. Oh, and it's a wet-sump motor as well. I'd gladly take $4000 for the entire motor, which is what I gave for it in 1997. The latest RaceSaver engine I saw on EBAY was going for $5000.

Tim Simmons
 
10/1/09, 2:26 PM   #3
Re: Questions about pistons
Lucky161
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Join Date: Sep 2009
Posts: 243
 

You make good points Tim. And I don't expect that we'll settle on one correct answer. And everything will be a trade off between power, durability and costs. Even in the area of hypereutectic pistons there is a difference of price between $100 Sealed Power and $300 Keith Black.
Now a $4000 engine in 1997 is looking like a real bargain if you've been running that engine regularly for over 10 years. I've not found many Racesaver engines available for even the $5000 you mentioned, but I can see where one could be built for that. Keep in mind that you're looking about about $3600 for a mag, injectors and the Brodix heads. That would mean a $1400 short block. If you use $400 pistons that doesn't leave much for the rest of it. I've talked to a couple of guys and they both said they had about $6500 in their engines.
 
10/1/09, 5:22 PM   #4
Re: Questions about pistons
Tim
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Join Date: Nov 2007
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Quote:
Originally Posted by Lucky161 View Post
You make good points Tim. And I don't expect that we'll settle on one correct answer. And everything will be a trade off between power, durability and costs. Even in the area of hypereutectic pistons there is a difference of price between $100 Sealed Power and $300 Keith Black.
Now a $4000 engine in 1997 is looking like a real bargain if you've been running that engine regularly for over 10 years. I've not found many Racesaver engines available for even the $5000 you mentioned, but I can see where one could be built for that. Keep in mind that you're looking about about $3600 for a mag, injectors and the Brodix heads. That would mean a $1400 short block. If you use $400 pistons that doesn't leave much for the rest of it. I've talked to a couple of guys and they both said they had about $6500 in their engines.
Agreed, if you're going to go with new parts. However, while I'd go with the new heads (around $1200), good used injections can be had for around $800, and good used mags for around $400. You have to know where to get this stuff from folks you trust, but it's out there and readibly available. Now we're at $2400, so we have $2600 for the bottom end. Also remember, the more work you can do yourself, the less you have to give to an engine builder. Most builders charge around $500 just to assemble a motor. If you can do that yourself, you've just bought your forged pistons, along with a few other things.

Tim Simmons
 
10/1/09, 8:59 PM   #5
Re: Questions about pistons
Lucky161
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Quote:
Originally Posted by Tim View Post
Agreed, if you're going to go with new parts. However, while I'd go with the new heads (around $1200), good used injections can be had for around $800, and good used mags for around $400. You have to know where to get this stuff from folks you trust, but it's out there and readibly available. Now we're at $2400, so we have $2600 for the bottom end. Also remember, the more work you can do yourself, the less you have to give to an engine builder. Most builders charge around $500 just to assemble a motor. If you can do that yourself, you've just bought your forged pistons, along with a few other things.

Tim Simmons
That's good info on the used mags and injectors. I haven't been able to find many of those for sale so I only had a feel for the price of new ones. I did find on a site that I had previously looked at but missed the short block price a professional engine builder that sells short blocks for $2700 and change. He gets nearly $10K for complete engine which I thought was pricey, but I am sure he can justify it as well as anyone else. So using his short block and the used parts you suggested someone could get in for around $5100+.
 
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