Sonic Test Results

[Indycars]

I had a Sonic Test done on my block and this is how the machinist described the process.

He checks every cylinder from top to bottom in one continuous motion. He does this at each of 4 positions; 12, 3, 9 and 9 o'clock. When he finds a location that is marginal, then he checks again on either side the thin location. For example on cylinder 1, he found at 6 o'clock 0.094" so he checked also at 5 & 7 o'clock and it was 0.220" and 0.229"

Below are the results. It certainly went below the 0.200" number, but it was always between adjacent cylinders and not on a thrust face. Cylinder number 4 has the single lowest number at 0.064", but on either side its 0.221" and 0.124". The lowest thrust face thickness was 0.220" on cylinder 8.

It never seems to be a black & white decision. I didn't think to ask at what height in the cylinder the thin locations were. And does the thrust even have much to do with the stress on the cylinder walls, is it more about the combustion pressures that are being exerted equally in every direction. The closer the thin section of the cylinder wall is to the top of the cylinder, the worse it would be for the engine......right??? Makes me wonder if I should have purchased a Dart SHP block for about $1500, I will have close to $900 in mine by the time it's done. I may have to go that route anyway, what do you all think, can I use my block for an engine that putting out 450-500 hp with 10:1 CPR, Max RPM=6400, street only with occasional blasts at full throttle ???

Any opinions are appreciated!


Rick Miller

 

[Indycars]

[attachment=4448:SonicTest01_800x600.jpg] I had a Sonic Test done on my block and this is how the machinist described the process.

He checks every cylinder from top to bottom in one continuous motion. He does this at each of 4 positions; 12, 3, 9 and 9 o'clock. When he finds a location that is marginal, then he checks again on either side the thin location. For example on cylinder 1, he found at 6 o'clock 0.094" so he checked also at 5 & 7 o'clock and it was 0.220" and 0.229"

Below are the results. It certainly went below the 0.200" number, but it was always between adjacent cylinders and not on a thrust face. Cylinder number 4 has the single lowest number at 0.064", but on either side its 0.221" and 0.124". The lowest thrust face thickness was 0.220" on cylinder 8.

It never seems to be a black & white decision. I didn't think to ask at what height in the cylinder the thin locations were. And does the thrust even have much to do with the stress on the cylinder walls, is it more about the combustion pressures that are being exerted equally in every direction. The closer the thin section of the cylinder wall is to the top of the cylinder, the worse it would be for the engine......right??? Makes me wonder if I should have purchased a Dart SHP block for about $1500, I will have close to $900 in mine by the time it's done. I may have to go that route anyway, what do you all think, can I use my block for an engine that putting out 450-500 hp with 10:1 CPR, Max RPM=6400, street only with occasional blasts at full throttle ???

Update: I just talked with the machinist and he said the thin spot was about 2.5 inches down from the top of the cylinder and was about the size of 1/2 dollar to quarter dollar size.

Any opinions are appreciated!


Rick Miller

 

[one finger john]

Was the block already .060 over when you got it? Were you thinking of a quick hone job and rering? Are the bores straight?

 

[Mike]

There are two ways of looking at this -

1. If you had no access to a sonic tester, what would you be doing?

2. Since you do know how thin that block is, you need to find a new owner for it. Paper weight, boat anchor, swap meet material, etc. Just get as far away from it as you can, afore you are tempted to actually use it.

Anything under .100" is thin ice, as well as thin wall.

I suspect your estimate of power output is more than a bit generous, as making 500 HP with no more compression than that is going to be a real challenge for you. But even applying a more realistic number, we're still talking about five cylinders that are going to be too thin for reliability.

As for your question about an aftermarket block, my answer is yes. Unless you've already invested in pistons, that is. The Dart block will let you start fresh with standard bore, allowing you rebuilds down the line. I think the deck thickness on that block is .625", so it will stay straight through a lot more heat cycles. You'll get priority main oiling, which will help keep the bottom end alive (check, re-check and check the bearing clearances again, to get them right). The splayed center main caps will keep things in place a lot better than a straight 4-bolt cap.

It seems like a lot of money, but if you can find a good block, 9 times out of 10 the owner knows what he has and wants to charge you for it. You're going to pay to have it tanked or cooked/blasted to clean it and then to have it sonic-checked, to be safe. Then you have to do all the machine work to get things straight, square and true. And you end up with nearly the same amount of dollars invested in a block that has been bored. The first time you over-heat it, the decks and cylinder walls will wave at you when you see them. It just doesn't pay to try to build serious horse-pressure with a stock block any more.

 

[Indycars]

Was the block already .060 over when you got it? Were you thinking of a quick hone job and rering? Are the bores straight?

No I had it bored, then got scared and had it sonic tested for cylinder wall thickness. Yes the bores should be straight now, all the bores should need is finish honing to size after I decide on pistons.

With the Dart SHP block, can I run OEM style lifters on a aftermarket cam, then that should save me roughly $400......right??? Compared to a Gen I block and retro-fit lifters.


Rick

 

[Indycars]

There are two ways of looking at this -

1. If you had no access to a sonic tester, what would you be doing?

2. Since you do know how thin that block is, you need to find a new owner for it. Paper weight, boat anchor, swap meet material, etc. Just get as far away from it as you can, afore you are tempted to actually use it.

Anything under .100" is thin ice, as well as thin wall.

I suspect your estimate of power output is more than a bit generous, as making 500 HP with no more compression than that is going to be a real challenge for you. But even applying a more realistic number, we're still talking about five cylinders that are going to be too thin for reliability.

As for your question about an aftermarket block, my answer is yes. Unless you've already invested in pistons, that is. The Dart block will let you start fresh with standard bore, allowing you rebuilds down the line. I think the deck thickness on that block is .625", so it will stay straight through a lot more heat cycles. You'll get priority main oiling, which will help keep the bottom end alive (check, re-check and check the bearing clearances again, to get them right). The splayed center main caps will keep things in place a lot better than a straight 4-bolt cap.

It seems like a lot of money, but if you can find a good block, 9 times out of 10 the owner knows what he has and wants to charge you for it. You're going to pay to have it tanked or cooked/blasted to clean it and then to have it sonic-checked, to be safe. Then you have to do all the machine work to get things straight, square and true. And you end up with nearly the same amount of dollars invested in a block that has been bored. The first time you over-heat it, the decks and cylinder walls will wave at you when you see them. It just doesn't pay to try to build serious horse-pressure with a stock block any more.

Mike,

Your right I don't think I will be getting 500HP (Rear Wheel HP), but I wanted to make sure any opinions that I received would be on the conservative side when viewed from the factory block being a viable option.

It's not just the price of the Dart block I must consider. It still needs to be decked to the right height and finished honed. So no matter which block I use, I will still have these costs. Anything else that I have not considered in my price comparison???

It's easy to see which side you fall on hear, thanks for the feedback!!!


Rick

 

[one finger john]

Mike,

Your right I don't think I will be getting 500HP (Rear Wheel HP), but I wanted to make sure any opinions that I received would be on the conservative side when viewed from the factory block being a viable option.

It's not just the price of the Dart block I must consider. It still needs to be decked to the right height and finished honed. So no matter which block I use, I will still have these costs. Anything else that I have not considered in my price comparison???

It's easy to see which side you fall on hear, thanks for the feedback!!!


Rick

Rick, unfortunately, even though you have an 010 block, which I believe is a truck block and preferred for hipo applications, it is never recommended to bore over .030 over without a sonic check. Now we see why. All of Mike's descriptive expressions apply. It may be good for a stock rebuild, MAYBE, but for any hi performance work that block is toast. Dart, again I believe, has short and long blocks of differing sizes, but their inexpensive bare blocks are cast in India. Same place you get your computer tech support. I'd be leery of that deal.

John

 

[Mike]

Rick, the block would have to be finish honed. As for cutting the deck, it's anybody's guess until you've assembled to check it.

John, an 010 block is a large journal, 4.000" bore block. Period. Fini. Full stop. The 010 designation is one of the most misunderstood in the industry. It merely indicates the block was a 4.000" block and that it had the large main bores for the large journal cranks. You cannot tell anything else by that number.

 

[Indycars]

What about installing a cylinder sleeve??? What's the pros and cons of taking this path???

Rick Miller

 

[Mike]

The problem with trying to sleeve the block is there are five cylinders that would need it. We've certainly installed multiple sleeves in a block, but I'm not a fan of putting them in adjacent cylinders. And you would have that situation in #'s 2, 4 and 6. You have already removed a lot of metal from the block and removing even more to install a sleeve results in the sleeve not having adequate support. Then you cut the hole next door and install another sleeve? :nod: That metal just moves around too much to make it any thinner than it already is.

 

[RPM]

Way way back a long time ago when I worked in a machine shop. We sleeved all 8 cylinders in a 350 block. We actually moved the cylinders closer to each other to help unshroud the intake valves. We didn't have a sonic tester way back then, so no reports there. The motor didn't run any better than the stock block engine it replaced. This was for an econo dragster.

 

[Indycars]

The problem with trying to sleeve the block is there are five cylinders that would need it. We've certainly installed multiple sleeves in a block, but I'm not a fan of putting them in adjacent cylinders. And you would have that situation in #'s 2, 4 and 6. You have already removed a lot of metal from the block and removing even more to install a sleeve results in the sleeve not having adequate support. Then you cut the hole next door and install another sleeve? :nod: That metal just moves around too much to make it any thinner than it already is.

I was kinda hoping you would say something like that, it helps when I really want to go with the Dart SHP block.:win: Besides then I can blame you when the wife asks, why so much money for this engine. I'm thinking that's the way to go, it just might take longer!

Is Dart the only game in town, other than GMPP, for a similar quality/cost block???

Thanks again Mike for your input!


Rick Miller

 

[Indycars]

Way way back a long time ago when I worked in a machine shop. We sleeved all 8 cylinders in a 350 block. We actually moved the cylinders closer to each other to help unshroud the intake valves. We didn't have a sonic tester way back then, so no reports there. The motor didn't run any better than the stock block engine it replaced. This was for an econo dragster.

How would you compensate for the pistons being offset???

Rick

 

[RPM]

How would you compensate for the pistons being offset???

Rick

They were only off set something like .050" so the pistons just floated over there on the rods no problem.

 

[one finger john]

[attachment=4448:SonicTest01_800x600.jpg] I had a Sonic Test done on my block and this is how the machinist described the process.

He checks every cylinder from top to bottom in one continuous motion. He does this at each of 4 positions; 12, 3, 9 and 9 o'clock. When he finds a location that is marginal, then he checks again on either side the thin location. For example on cylinder 1, he found at 6 o'clock 0.094" so he checked also at 5 & 7 o'clock and it was 0.220" and 0.229"

Below are the results. It certainly went below the 0.200" number, but it was always between adjacent cylinders and not on a thrust face. Cylinder number 4 has the single lowest number at 0.064", but on either side its 0.221" and 0.124". The lowest thrust face thickness was 0.220" on cylinder 8.

It never seems to be a black & white decision. I didn't think to ask at what height in the cylinder the thin locations were. And does the thrust even have much to do with the stress on the cylinder walls, is it more about the combustion pressures that are being exerted equally in every direction. The closer the thin section of the cylinder wall is to the top of the cylinder, the worse it would be for the engine......right??? Makes me wonder if I should have purchased a Dart SHP block for about $1500, I will have close to $900 in mine by the time it's done. I may have to go that route anyway, what do you all think, can I use my block for an engine that putting out 450-500 hp with 10:1 CPR, Max RPM=6400, street only with occasional blasts at full throttle ???

Any opinions are appreciated!


Rick Miller

I was looking at the diagram of the sonic testing performed on your block and I am curious what type of boring bar was used? Was it one of those that is indexed off each cylinder or was it some sort of fixture indexing affair? As you can probably tell I'm not up to date as far as modern machine shop set ups.

Thanks, John

 

[Indycars]

I was looking at the diagram of the sonic testing performed on your block and I am curious what type of boring bar was used? Was it one of those that is indexed off each cylinder or was it some sort of fixture indexing affair? As you can probably tell I'm not up to date as far as modern machine shop set ups.

Thanks, John

I think it indexes off the mains, but I can't be absolutely sure about that.

Rick

 

[Telman2]

I was kinda hoping you would say something like that, it helps when I really want to go with the Dart SHP block.:nod: Besides then I can blame you when the wife asks, why so much money for this engine. I'm thinking that's the way to go, it just might take longer!

Is Dart the only game in town, other than GMPP, for a similar quality/cost block???

Thanks again Mike for your input!


Rick Miller

When my 350 died last fall I built a 383 using a Dart SHP block. I think it's a great bang for the buck, my machinist said the same thing. It makes 452 hp (at the crank) on the dyno. I've put about 1300 miles on my bucket so far this summer and have not had any problems with it.

 

[Indycars]

When my 350 died last fall I built a 383 using a Dart SHP block. I think it's a great bang for the buck, my machinist said the same thing. It makes 452 hp (at the crank) on the dyno. I've put about 1300 miles on my bucket so far this summer and have not had any problems with it.

Did you use a local machinists or did you buy it online? What machine work did you do to get it ready for assembly? I'm thinking about using "CNC Blocks Northeast", does anyone have experience with them???

BTW, I had to chuckle when I ready your tag line.:nod:

Rick

 

[Telman2]

Did you use a local machinists or did you buy it online? What machine work did you do to get it ready for assembly? I'm thinking about using "CNC Blocks Northeast", does anyone have experience with them???

BTW, I had to chuckle when I ready your tag line.:nod:

Rick

I used a semi retired local machinist, I picked out the parts I wanted to use for the short block, he ordered them, did the machine work and assembled the short block. He said he's built a number of engines using Dart blocks in the past and never had a problem with them.

 

[Screaming Metal]

Normal street engines can run at about .100 on the wall thickness....like Mike said....thats thin. If your gonna build a motor, you can get a good block thru Dart Or World. The Merlins are good, but a bit overpriced in my book.

The sleeving thing can be done, but only trust someone thats done it before and has folks saying he does good work. If not done right, you get into block flex and all sorts of wierd stuff. I use only seasoned liners, and I freeze them with nitrogen gas and warm the block, and I leave just enough meat in the bores so when the press fit comes into play....there won't be any splitting of whats there. When I do it though, I do it like the diesel wet liners, leave plenty for a liner t sit intoat the bottom of the bore, and I have a large supporting lipat the top. That way, if water fron the internal wall where the liner is slide into seeps some, the locktitereally holds it into place and helps seal, and the steps where the liner goes in also helps.

Sleeving a block is a science, and isn't just boring a hole out and putting a sleeve into it, and reboring it. Theres alot more to it than that.

Just don't go too thin on your block. Like Mike said......100 is thin, thats less than 1/8 wall thickness. For 500 Horses and for Blown motors up to 500+ @ 6000 rpm or TunnelRammed & cammed at over 6000rpms, do not go any less than the .120 Making sure the bores are centered. This is even more critical on long stroke or 'stroker' motors.

There is nothing more sickening than to have a bore split while the motors running and seeing that smoke and you hear that noise just a split second before loosing that motor....Don't chance your motors life on a thin bore....theres alot of stress in there, 1 good backfire, or if you really throw a load to it DragRacing, or a overrev....it could be the end....Better to be safe than sorry....