Jim Green's 90q 20vt - 636whp 07k
- audifreakjim
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noriceforyou
- audifreakjim
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JShadzi
I noticed that on Jim's Wiseco's that the sharp edge between the valve pocket and the edge of the piston has been removed, whereas on Javad's JE's, it's there. There were some reports on the S2Forum that this thin "edge" can become a hot spot, potentially causing detonation, and in some, it even melted. Those that have gotten JE's since, have ground away this sharp area.
Any thoughts? Javad?
My new JE's are scheduled to arrive Wednesday.
Thanks Javad! :-)
Any thoughts? Javad?
My new JE's are scheduled to arrive Wednesday.
Thanks Javad! :-)
Mark Siggelkow
'90 CQ-R - NASA GTS-4
'12 TT-RS (Wife's DD)
'00 A4 1.8TQ (My DD)
'62 356B (vintage racer)
'07 Toyota Tundra CrewMax (for towing/hauling)
'90 CQ-R - NASA GTS-4
'12 TT-RS (Wife's DD)
'00 A4 1.8TQ (My DD)
'62 356B (vintage racer)
'07 Toyota Tundra CrewMax (for towing/hauling)
- audifreakjim
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The dish on your Wiseco's looks really big, you sure its 13cc's? Also, the valve reliefs are really big, any reason for it?
Yea, that's why I sent you that email. It looks like on your pistons they just shaved it off and didn't really dish it? These maintain the compression hieght all the way around, which would cause the dish to look bigger in the middle.
I noticed that on Jim's Wiseco's that the sharp edge between the valve pocket and the edge of the piston has been removed, whereas on Javad's JE's, it's there. There were some reports on the S2Forum that this thin "edge" can become a hot spot, potentially causing detonation, and in some, it even melted. Those that have gotten JE's since, have ground away this sharp area.
It looks like that's what they've done to me.
I might try and get some clay to see what these actually are. before these go to the machine shop tomorrow.
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olsonjus
- audifreakjim
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- audifreakjim
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Ok, spent all day messing with a bum engine hoist and a centerforce PP that's .4in shallower than the 7A PP that worked perfect. The AAN CF PP causes my slave cyl to bottom out so it looks like I'll be jimmy rigging the clutch with a slave cyl extension since I'm all tapped out of money for the car. Needless to say I didn't CC the pistons, but after did the calcs this morning, it's not necessary.
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JShadzi
RSCoupe wrote:I noticed that on Jim's Wiseco's that the sharp edge between the valve pocket and the edge of the piston has been removed, whereas on Javad's JE's, it's there. There were some reports on the S2Forum that this thin "edge" can become a hot spot, potentially causing detonation, and in some, it even melted. Those that have gotten JE's since, have ground away this sharp area.
Any thoughts? Javad?
My new JE's are scheduled to arrive Wednesday.
Thanks Javad! :-)
I wouldn't call these areas "sharp" on my pistons, they are dimensioned exactly like the stock pistons, the areas are quite rounded over and I don't anticipate any hotspots becuase of the valve relief areas. I haven't seen Jim's pistons up close so I can't comment on those.
Yea, Jim, must be a visual illusion from the pics, and the large ring land rise makes up the difference.
And for referece to others that have mentioned it, the 20vt head's only quench area is right above or adjacent to the intake valves, or basically the "unmachined" area or "raised portion" on my pistons, the rest of the combustion chamber is completely open to the piston and simply makes up the hemispherical combustion chamber.
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pkw
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zepmoreau
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87turboquattro
JShadzi wrote:RSCoupe wrote:I noticed that on Jim's Wiseco's that the sharp edge between the valve pocket and the edge of the piston has been removed, whereas on Javad's JE's, it's there. There were some reports on the S2Forum that this thin "edge" can become a hot spot, potentially causing detonation, and in some, it even melted. Those that have gotten JE's since, have ground away this sharp area.
Any thoughts? Javad?
My new JE's are scheduled to arrive Wednesday.
Thanks Javad! :-)
I wouldn't call these areas "sharp" on my pistons, they are dimensioned exactly like the stock pistons, the areas are quite rounded over and I don't anticipate any hotspots becuase of the valve relief areas. I haven't seen Jim's pistons up close so I can't comment on those.
i don't know if you guys have looked at the pistons after running.but i had the same thing on my bbc weisco pistons,i like javad,rounded them over because from the factory they were sharp.when sharp,they melted away and disappeared down to a certain level.the rounded ones stayed put.neither engine had a detonation problem.engines are still running strong and haven't been pulled apart for 2 yrs of beating on the water.
- audifreakjim
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- audifreakjim
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olsonjus
- audifreakjim
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- audifreakjim
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A little update, the bottom end and head are assembled, I was supposed to get the stupid thing in the car tonight, but I forgot my Bentley and needed a bunch of torque values, so now I get to update my thread and clean the bathroom. :frustrated:
ARP Fasteners, 034 rods.

Mmm,,,

Ported Head with water manifold machined in.



Electric PS pump. :woowoo:

ARP Fasteners, 034 rods.
Mmm,,,
Ported Head with water manifold machined in.
Electric PS pump. :woowoo:


