Spawne's supercharged B20, sponsored by DDTECH
So




Yes thats right, I have the only YCP pistons on the planet that are PRESS FIT FOR OEM RODS ONLY. Which means now I am completely F'ed in the A right now as to how to proceed from here. I loosened up the P2W clearance with the hone to accommodate the new cast pistons without ever even realizing there was a problem with the piston/rod fitment.




Yes thats right, I have the only YCP pistons on the planet that are PRESS FIT FOR OEM RODS ONLY. Which means now I am completely F'ed in the A right now as to how to proceed from here. I loosened up the P2W clearance with the hone to accommodate the new cast pistons without ever even realizing there was a problem with the piston/rod fitment.
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No I dont. Dave at Rsmachine just gave us the option. We ended up going a different route though. I thought it was something like $80 for a set. I'm not sure on that price though, it was a while ago that we had talked about it.
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So updates updates updates....
- RSmachines 84.5 pistons on the way, selling the YCP set (cheaper and easier)
- head is going out for machine work this week, then onto the flow bench.
- block is 25% back together again
- Precision 3431E is on its way in the mail :D
- SPA bottom mount manifold is on order
turbo pics courtesy the marketplace add from which it was purchased



- RSmachines 84.5 pistons on the way, selling the YCP set (cheaper and easier)
- head is going out for machine work this week, then onto the flow bench.
- block is 25% back together again
- Precision 3431E is on its way in the mail :D
- SPA bottom mount manifold is on order
turbo pics courtesy the marketplace add from which it was purchased



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http://www.ebay.com/itm/3-1-2-Engine...bef63c&vxp=mtr
sorry i dont have any pics of it in my garage, but thats the exact one i bought, off ebay as well, and then the cylinder wash brush. You have to use fast strokes with it and dont exceed 1200rpm on your drill. Typically i was doing about 2 strokes (up and down) per 1 second, maybe slightly faster, for between 5-10 seconds. It WILL open up your bore despite what some have said that 400 grit is too fine for it to make a difference. I took about .002 off with about 15 seconds of use using tap magic (cutting oil).
sorry i dont have any pics of it in my garage, but thats the exact one i bought, off ebay as well, and then the cylinder wash brush. You have to use fast strokes with it and dont exceed 1200rpm on your drill. Typically i was doing about 2 strokes (up and down) per 1 second, maybe slightly faster, for between 5-10 seconds. It WILL open up your bore despite what some have said that 400 grit is too fine for it to make a difference. I took about .002 off with about 15 seconds of use using tap magic (cutting oil).
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http://cgi.ebay.com/ws/eBayISAPI.dll...m=230912822119
the size of the hone will vary depending on your bore size, these were both for a 84-89mm bore.
the size of the hone will vary depending on your bore size, these were both for a 84-89mm bore.
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do you own a dial bore gauge? im looking at the fowler digital gauge. its 188.00 shipped and goes up to 6" and reads down to the 0.0005
Thats the other option im debating.
Its between those two. I like the digital one a little better because you can measure the bore, set the gauge at the size you want. then it tells you when you're over or under.
The only downside im seeing is its a bitch to set up and you need the tutorial that comes with it almost everytime you use it.
Its between those two. I like the digital one a little better because you can measure the bore, set the gauge at the size you want. then it tells you when you're over or under.
The only downside im seeing is its a bitch to set up and you need the tutorial that comes with it almost everytime you use it.
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according to precision, 545hp lol
• 57mm inducer compressor wheel
• "E" compressor cover 3.0" inlet/2.0" outlet
• 57mm exducer T31, 76 trim turbine wheel
• Turbine housing options:
- T3 .63 A/R with 4 bolt discharge
• 360° journal bearing system
• 57mm inducer compressor wheel
• "E" compressor cover 3.0" inlet/2.0" outlet
• 57mm exducer T31, 76 trim turbine wheel
• Turbine housing options:
- T3 .63 A/R with 4 bolt discharge
• 360° journal bearing system
Those are 56mm/75mm exducer ("57" trim) equivalent.
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So if i didnt mention it before, I had to order a set of RS machines pistons designed for floating pin rods, maching costs on the YCP's were too high to warrant using them vs the price for just buying another set. Since no one has been as dumb as me and bought two sets of CAST pistons back to back like this, I decided to take a look at the rs vs ycp and see just what was different.
As far as I can tell the RS machine has a slightly higher dome then the YCP pistons. Actually, looking at it now, i would describe this as a decent amount more compared to the YCP. Looks to be a +2 or +3 cc dome. Piston height appears to be exactly the same, and the second ring land is only a HAIR larger then the YCP, negligible difference.
I think the biggest difference here comes with the skirt. Aside from being fully coated rather then just teflon coated on the sides, the skirt is actually thinner on the RS pistons. Another noticable difference is the under side of the dome. As far as I can tell the dome is slightly thicker then the YCP, but I cant measure this directly. I can see a significant amount more material around the valve relief areas compared to the YCP pistons, and the RS pistons have a spark plug quench pad as well in the center of the dome.

As far as I can tell the RS machine has a slightly higher dome then the YCP pistons. Actually, looking at it now, i would describe this as a decent amount more compared to the YCP. Looks to be a +2 or +3 cc dome. Piston height appears to be exactly the same, and the second ring land is only a HAIR larger then the YCP, negligible difference.
I think the biggest difference here comes with the skirt. Aside from being fully coated rather then just teflon coated on the sides, the skirt is actually thinner on the RS pistons. Another noticable difference is the under side of the dome. As far as I can tell the dome is slightly thicker then the YCP, but I cant measure this directly. I can see a significant amount more material around the valve relief areas compared to the YCP pistons, and the RS pistons have a spark plug quench pad as well in the center of the dome.

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I wanna say that the YCP's are based on the P73-A0 dome and the RS machines are based on the P73-00 from what i can tell.
Nice ! I bet you'll never make that mistake again lol (it was an easy me to make). At least you got to do a hands on experience though.
Did those RS pistons come with a spec sheet ? If so what did they recommend ?
Did those RS pistons come with a spec sheet ? If so what did they recommend ?
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no spec sheet, im going with just outside the service spec limit on these. As far as i know they are designed to be OE replacements, so you follow OE specs.
this thread is an amazing source of first hand information with lots of info for the diy engine builder.
now ive used ycp and rs machines pistons in the past on various engines but never had them together at the same time. the side by side pics are fantastic. really goes to show how short the skirt is on the supertech's. i also wish there was a way to know pretty precisely how much of a difference in thickness there is in the center of the piston under the dome.
spawne, im really thinking about buying that dial bore gauge since i started honing my own blocks. how easy is it to make estimations between the .0005 graduation? easy to tell the difference between say .0016 and .0018? being able to make a solid estimation is a great reason to pick up this gauge over say a digital one that runs out of decimal places.
now ive used ycp and rs machines pistons in the past on various engines but never had them together at the same time. the side by side pics are fantastic. really goes to show how short the skirt is on the supertech's. i also wish there was a way to know pretty precisely how much of a difference in thickness there is in the center of the piston under the dome.
spawne, im really thinking about buying that dial bore gauge since i started honing my own blocks. how easy is it to make estimations between the .0005 graduation? easy to tell the difference between say .0016 and .0018? being able to make a solid estimation is a great reason to pick up this gauge over say a digital one that runs out of decimal places.



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