Author |
Message |
Senna6094
| Posted on Monday, October 05, 2009 - 01:21 pm: |
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Hi all, Can someone tell me what mods, from stock, have been done to the thunderstorm heads? Thanks, Dana-C |
Sportyeric
| Posted on Monday, October 05, 2009 - 01:42 pm: |
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The stock heads on the S2 were 9:1 compression ratio. It had flat-top pistons in a hemispherical head. The Thunderstorm heads have a piston with a 15 degree dome. The heads have a corresponding 15 degree shelf. This design produces a better burn and allows a higher compression ratio. The valves are also larger. The Thunderstorm engine became the stock set-up in 98 or 99. |
F_skinner
| Posted on Monday, October 05, 2009 - 02:02 pm: |
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allows a higher compression ratio. 10:1 I think. |
Phelan
| Posted on Monday, October 05, 2009 - 02:55 pm: |
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They were also highlight-less on the fins . |
Senna6094
| Posted on Wednesday, October 07, 2009 - 12:42 pm: |
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Good stuff thanks guys. One other question. Im going to have the top end done and while it's apart I'm going to have new rings installed(gaskets are also leaking at the base of the jugs). It has been recommended that I go .010" over and put in new pistons to get the piston/cylinder clearance back to the pre-worn condition. Where is the bast place to get new 15degree pistons? Thanks again. Dana-C |
Phelan
| Posted on Wednesday, October 07, 2009 - 02:06 pm: |
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I'd contact one of the dealer sponsors here. Stock pistons can be had in .010 over configuration, and last I checked they run about $50/ea. |
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