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A sneak peak of TSP's 18:1 pistons

tanman_2006 said:
I'm you have answered this before but why valve reliefs? Are you making a cam that will need them?
Click to expand...

Well if someone want's to go 1.6 or higher ratio rockers, like me for instance, this is one area that would need the clearance, and how many times have we seen someone remove heads and wonder why their is a imprint of valves on the top, carbon build up, slack timing chain, valve float, etc their is very little valve to piston clearance in stock form as it is..

So while I am machining 3 p400 sets that require the clearance, I have 10 new sets to machine to sell, 5 sets will be 18.0:1 with valve clearances, 5 sets 18.5:1 without valve clearances.

Just giving a couple options for those that may be considering different options.

The pockets won't affect anything being their for a basically stock motor, but would be a factor if moving towards other mods...
 
IfI were not such a chiggin, I`d pull the engine from My truck, drop the bottom end for a rebuild and a set of Your coated pistons, just too much risk of the block being cracked in the mains area.
if I would ever do a different engine, it would be from Teds trucks, then, have them install the gapless rings and Your coated 18:1 pistons.
 
ak diesel driver said:
Just curious are the machining marks being smoothed out or is the coating supposed to take care of that?
Click to expand...

You can't feel the marks at all, this one has just been rubbed with scotch bright a little and those disappear. It just the nature of a flat end mill I guess, in person they are glass smooth, once coated you won't see anything..

Got them all done today, here are the 18.5 version without pockets.

007.JPG
 
MrMarty51 said:
IfI were not such a chiggin, I`d pull the engine from My truck, drop the bottom end for a rebuild and a set of Your coated pistons, just too much risk of the block being cracked in the mains area.
if I would ever do a different engine, it would be from Teds trucks, then, have them install the gapless rings and Your coated 18:1 pistons.
Click to expand...

You might be surprised @MrMarty51. Yours is a 2000 like mine if it’s the original engine. Mine has 298,000 miles on it and when I pulled my engine last year to check it out after it ran real hot and she wasn’t cracked. If I was a betting man I’d bet yours is probably not cracked.
 
Jaryd said:
You might be surprised @MrMarty51. Yours is a 2000 like mine if it’s the original engine. Mine has 298,000 miles on it and when I pulled my engine last year to check it out after it ran real hot and she wasn’t cracked. If I was a betting man I’d bet yours is probably not cracked.
Click to expand...

My new (to me) block is a 2000 GM 506 block so I'm hoping you're right.
GM continued to improve the block up till the last of the production run so it's looking like the later GM 506 blocks are mostly crack free.
But then, I destroyed an Optimizer, so who knows?
 
I like the idea of the valve relief area. The 18 to 1 engine I have always showed marks in the carbon on top of the piston.

So I'm curious as to the differences in what you're doing to lower compression vs what others have done. The low comp set that I have was built by the Diesel Depot way back in 2003. I'm not sure where they source the pistons but I only had one cracking and it was due to contact with an intake valve. Just a hair line crack, but cracked none the less.

The main reason I ask is because I'm thinking of building another low comp engine for my stepside. The set I have is both use able and balanced. But if there's a better version I'm willing to replace them.
 
I don't know what DD did, you have a pic?

The old Kennedy pistons cc out @ 17.2:1, I have used them and have a set here.. Mine are a true number per 3 different ratio calculators...

I had a supplier that had these NOS GM OEM pistons, these aren't off shore cheap pistons they are real GM branded pistons.

Most just shave the tops off, this design keeps the quench area of the piston and moves the combustion pressure around the piston during the injection event, I noticed less rattle due to the piston being better loaded during injection..
 
I've never tore one of these down that didn't have valve strikes on the pistons...

The main reason I did it at all is my P400 is getting 1.7 rockers and needed clearance , so after thinking I decided to run 5 sets that others could consider and have a choice.. If they don't sell I'll use them in customers motors..
 
This is the .020 over piston that DD used. I know I bought a replacement for the cracked one from pennisular and it matched when I measured it.

Thinking back my low comp engine was fairly quite even with the timing way advanced. The marks were a solid 1/8th inch apart. It was a very cold hearted though, had to sit and build some decent heat before driving.
 

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KrisML said:
Thinking back my low comp engine was fairly quite even with the timing way advanced. The marks were a solid 1/8th inch apart. It was a very cold hearted though, had to sit and build some decent heat before driving.
Click to expand...

Yes, with lower compression more advance works great, their is not as much cly pressure for one thing, that is why more fuel & air are able to be burnt cleaner.. making the container a little bigger holds more volume in turn making more power..
 
Jaryd said:
You might be surprised @MrMarty51. Yours is a 2000 like mine if it’s the original engine. Mine has 298,000 miles on it and when I pulled my engine last year to check it out after it ran real hot and she wasn’t cracked. If I was a betting man I’d bet yours is probably not cracked.
Click to expand...
Hink said:
My new (to me) block is a 2000 GM 506 block so I'm hoping you're right.
GM continued to improve the block up till the last of the production run so it's looking like the later GM 506 blocks are mostly crack free.
But then, I destroyed an Optimizer, so who knows?
Click to expand...
I too am hoping so. I did not know that about the blocks. I`m not a throw away sort of a person, I enjoy rebuilding, but, with only 255,000 on this engine, and a new timing chain set, I`m hoping to get it to over 300,000 before opening it up, then We shall see.
My cousin, racing number 07 at the Roseville speedway in Sacramento, cali; He was taking the 350 diesel engines and converting them back to gas. he told Me that He now has an engine that will run a lot of races woithout having to do a tear down and rebuild on the bottom end. He said that the only problem is the tops of the pistons were eroding off. I told him He did not have enough room between the top ring land and the top of the piston to dissipate the heat. I told Him if He did not have enough room between the wrist pin hole and the top of the piston to move the rings down, to have Wisco {one of his sponsors} build Him pistons with the oil ring below the wrist pin then He would have enough room and the lowered oil rings would help stabilize the pistons in the bore. He said, You cant do that, I told Him You surely can, I have seen a number of pistons built like that back in the day. I made it to Cali about a year later, Al was at My brothers, He walks straight down the driveway, gets right in front of Me and proclaimed, it works. I asked, what works, he said the pistons. LOLOLOL He was really kicking tails on that track. LOL
 
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