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Bumping compression?????

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Old Nov 17, 2009 | 12:12 AM
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Default Bumping compression?????

I just recently did a new heads/cam package on my forged 347 and put down 450 rear wheel and 407 tq on a dyno dynamics dyno out here in sac... My compression ratio is right around 10.6 to 1 but my tuner says that if i go with a thinner head gasket and bump it up to 11.2 to 1 ill see closer to the 470 rear wheel i was expecting from this package... Does this sound right???? My mods are as follows....

Forged 347 M6
Moser 12 bolt 4.11's
Textralia clutch
Spohn top gun ds
EWP
215cc TEA/TFS heads milled to 62cc
Vengeance vindicator cam
1 3/4 kooks long tubes ory with cutout
Ported FAST 90
Racetronix FP and 36 lb injectors

The car feels WAY faster than before but i want to know if it would be worth it to pull the heads back off and swap gaskets?
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Old Nov 17, 2009 | 12:39 AM
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How thick are the gaskets you have now and what would you go down to?
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Old Nov 17, 2009 | 12:58 AM
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That is pretty damn good power through a twelve bolt and 4.11's. Sure you would make a little more power with higher compression, but you have to decide if it is worth pulling the heads again. If you are up for the labor go ahead and do it. Sweet combo btw. What are the stats on the vindicator?
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Old Nov 17, 2009 | 12:58 AM
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It has .055's in it now and my tuner wants to go with .030's or .035 depending on PTV clearance...
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Old Nov 17, 2009 | 01:05 AM
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Originally Posted by mwatson185
That is pretty damn good power through a twelve bolt and 4.11's. Sure you would make a little more power with higher compression, but you have to decide if it is worth pulling the heads again. If you are up for the labor go ahead and do it. Sweet combo btw. What are the stats on the vindicator?
Thanks bro... Yeah it ***** and gets now. I raced my buddy's 99ss with a 383 dynoing 501 rear wheel on a different dyno and walked all over him 4 times in a row. I just want to maximize everything on the motor before i spray it but i just want to know if what my tuner says has some substance...
The vindicator specs 240/244 596/608 on a 112...
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Old Nov 17, 2009 | 07:10 AM
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Bump the compression... Not only will your peak #s jump, but power under the curve will improve as well.

59cc heads/.040 Cometics will do the trick!!
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Old Nov 17, 2009 | 11:08 AM
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Yea, I'd change the gaskets if you have the time or $$$
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Old Nov 17, 2009 | 11:15 AM
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Do you have valve reliefs cut into your pistons?
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Old Nov 17, 2009 | 11:56 AM
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If you pull the the heads to change the gaskets you might as well mill the heads to 59cc to get even more. How far are this pistons out of the hole? That will dictate how thin of a gasket you can go with.
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Old Nov 17, 2009 | 12:58 PM
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Are you running the -2cc Diamonds? I'm 59cc/.040 cometic/-2cc Diamonds /TSP 347 and yes I think its worth it to raise your compression
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Old Nov 17, 2009 | 01:16 PM
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I wouldn't go with a .030 gasket, probably too thin to seal effectively with out flatmilling the block. I had a dickens of a time getting the cometics to seal and went with a Mr. Gasket .042 from autozone... less than $30 ea, it was a steal and sealed everything right.

That cam has quite a bit of duration on a 112, you could advance the cam a bit and install on a 110 or 108 intake centerline to give a little more low end and power under the curve.

You have a really nice set up, I would enjoy it for a while and eventually you'll find a half dozen more things you wish you had done and get back in there anyway.
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Old Nov 17, 2009 | 01:27 PM
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Yep i have -2cc valve reliefs in these pistons... Now my question is the valves reliefs are for a standard 15 degree head. Now that my TFS's have 13.5 degree angle i wonder if ill have any PTV clearance issues if i mill em to 59cc's and throw a thinner gasket on there...I know the only way to know is to check, just try to get a general idea... I'm almost positive the pistons actually sit IN the hole slightly so that should help out some...
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Old Nov 17, 2009 | 01:39 PM
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If the piston sits in the hole more than stock (stock comes out of the hole), you could not only have more clearance, but your compression might be lower than what you think. Have you verified actual compression?

I would think that pistons with valve reliefs would have larger reliefs to fit mutiple applications. Like you said, only way to know for sure is to check.
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Old Nov 17, 2009 | 02:09 PM
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Nice numbers, sounds fun LOL. If its that close and if you drive it a fair bit I would just have some fun and leave it alone. You more than likely can't hook at all right now with what you have on the street without some DR or other tires and then its not that great of a hook (speaking from my experience) but you would make a little more power but is it really worth the work to do it if you do it yourself or paying someone to do it and the extra parts (head bolts, gaskets ect.). Good Luck on your decision.
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Old Nov 18, 2009 | 05:50 PM
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Originally Posted by Greenthumb LS1
Yep i have -2cc valve reliefs in these pistons... Now my question is the valves reliefs are for a standard 15 degree head. Now that my TFS's have 13.5 degree angle i wonder if ill have any PTV clearance issues if i mill em to 59cc's and throw a thinner gasket on there...I know the only way to know is to check, just try to get a general idea... I'm almost positive the pistons actually sit IN the hole slightly so that should help out some...
The 13.5 degree valve angle actually provides more PtV clearance than the stock valve angle. In addition the valves on the TFS will still line up with your valve reliefs (I remember that being a question that was asked a while back when the heads were first released).
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