99 Block
09-26-2004, 06:58 PM
#12
RE: 99 Block
Ok.... Here goes:
Adding PI heads to a block, whether PI or not will not raise the compression any when using different pistons. The compression ratio is only raised when adding PI heads to a non-pi car b/c the pistons are non-dished. If you have custom pistons, adding the PI vs. Non-Pi heads won't make a difference.... Or so it seems.
Adding PI heads to a block, whether PI or not will not raise the compression any when using different pistons. The compression ratio is only raised when adding PI heads to a non-pi car b/c the pistons are non-dished. If you have custom pistons, adding the PI vs. Non-Pi heads won't make a difference.... Or so it seems.
09-26-2004, 10:56 PM
#15
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RE: 99 Block
i was thinkn somthn around 11.5 or 12 to 1 maybe, aslo i plan on doing it to a non pi motor. thats why i asked if the 99 block was the same as the 98, but i guess if ur saying if i change the set up for more compression the heads wont have a thing to do with it? well im not exactly an expert on it yet, but if someone can help, basically im lookn for wat to do to make a beastly NA motor?
09-27-2004, 12:14 AM
#16
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RE: 99 Block
Here you go.
To know the TRUE compression ratio..........the engine needs to be in pieces so you can determine things you HAVE TO KNOW.
1) The CCs in the head.
2) The thickness of the head gasket or the amount of CCs in it (listed by FelPro and others)
3) The deck height......the amount that the piston lacks coming ALL the way to the top of the block when at TDC.
4) the bore and stroke of the engine.
5) type of piston.........it either displaces CCs ( a pop up ) or it is dished for valve reliefs.
You figure all the parts...........add the head CC, the head gasket CC, the deck height CC.........factor the piston CC ( add or subtract CCs ) and arrive at a total. Then you divide the area of the bore X stroke by the added CCs of the head, head gasket, deck and piston factor. The ratio !!
Example ..real simple.......
If all the head, head gasket and stuff I listed added up to 5 inches and the bore X stroke is 40 inches.
40 divided by 5 is 8 so the ratio would be 8 to 1.
To know the TRUE compression ratio..........the engine needs to be in pieces so you can determine things you HAVE TO KNOW.
1) The CCs in the head.
2) The thickness of the head gasket or the amount of CCs in it (listed by FelPro and others)
3) The deck height......the amount that the piston lacks coming ALL the way to the top of the block when at TDC.
4) the bore and stroke of the engine.
5) type of piston.........it either displaces CCs ( a pop up ) or it is dished for valve reliefs.
You figure all the parts...........add the head CC, the head gasket CC, the deck height CC.........factor the piston CC ( add or subtract CCs ) and arrive at a total. Then you divide the area of the bore X stroke by the added CCs of the head, head gasket, deck and piston factor. The ratio !!
Example ..real simple.......
If all the head, head gasket and stuff I listed added up to 5 inches and the bore X stroke is 40 inches.
40 divided by 5 is 8 so the ratio would be 8 to 1.
09-27-2004, 08:50 PM
#18
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RE: 99 Block
what do you plan to do for fuel for this high compression engine??? I'm running a stock '88 5.0 on 100 octane racing gas since I have the timing bumped up too much for 93 octane street gas and it costs $4.00 a gallon, so what do you plan to do for your fuel????? I guess you could always go up to the 112 or 116 octane pro stock gas at $6.00 a gallon though.
09-28-2004, 03:18 AM
#19
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RE: 99 Block
that was the other question actually, im not exactly sure. how high of compression can u go wiht jus premium fuel? im pretty sure i have about 10.5 right now and that seems to work fine, but the goal here is prob 11.5-12. maybe im goin about this the wrong way, wat wuld be the best way to make a beastly NA motor??
09-28-2004, 10:42 AM
#20
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RE: 99 Block
Roundman knows what he is talking about. Truth is you cant go much higher than 10-10.5:1 without running racing fuel i.e. 100+ octane. You dont have 10.5:1 now. I think stock was 9.0:1 and with the PI heads maybe 9.5, Im not sure someone correct me if Im wrong. Im damn sure that you aint goin higher than 10-10.5:1 without 100+ octane though.