Xmas in October
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Seasoned HDF Member
Joined: Oct 2019
Posts: 10,804
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From: OH
Understood that actual C/R would always be lower than theoretical, did NOT realize how much influence cam specs could have on these numbers.
Took djl`s advice ( thank you) and experimented with the BB calculator. I arrived at the following recipe(s) which hopefully minimize fuel sensitivity ( my concern) and tuning woes. ( again djl )
.045 head gasket / 3cc pistons/ assumed 83cc heads/ assumed .005 below cyl deck
current 510`s yield 9.35:1 194 CCP
570`s 9.27:1 192
I assume these are close enough to be interchangeable regarding fuel & tuning
I assume the 570`s will generate slightly more hp.
That being said, I`m not chasing a hp number and rarely encounter the stock rev limiter
Per S&S: 510`s are 3-5.5K rpm c/r under 9.7 and stock heads 570`s 3.2-5.7K rpm also "bolt on" ( been running the 510`s for 17 years and seem to be quite linear , no complaints )
Took djl`s advice ( thank you) and experimented with the BB calculator. I arrived at the following recipe(s) which hopefully minimize fuel sensitivity ( my concern) and tuning woes. ( again djl )
.045 head gasket / 3cc pistons/ assumed 83cc heads/ assumed .005 below cyl deck
current 510`s yield 9.35:1 194 CCP
570`s 9.27:1 192
I assume these are close enough to be interchangeable regarding fuel & tuning
I assume the 570`s will generate slightly more hp.
That being said, I`m not chasing a hp number and rarely encounter the stock rev limiter
Per S&S: 510`s are 3-5.5K rpm c/r under 9.7 and stock heads 570`s 3.2-5.7K rpm also "bolt on" ( been running the 510`s for 17 years and seem to be quite linear , no complaints )
Last edited by eighteight; Oct 28, 2019 at 09:37 AM. Reason: typo
Thread Starter
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Seasoned HDF Member
Joined: Oct 2019
Posts: 10,804
Likes: 7,444
From: OH
I`m sure I`m over analyzing and I appreciate everyone's patience and input
The S&S recommended C/R of under 9.7 is the static number, if I fiddle the calculator to give 9.7 static it creates 8.8 corrected
My desired recipe of 9.35 is a half point higher, is that a concern for detonation ? S&S chat line say`s yes
I could buy the 570`s w/ inner gears (p/n 33-5166)
I can spin a wrench and did several iron XL & shovel top ends back in the day, There were fewer variables and a lot less readily available knowledge back then !
Evo & T.C. work has been limited to cam changes up to now
I would really like to do this work only once !
Thank you
The S&S recommended C/R of under 9.7 is the static number, if I fiddle the calculator to give 9.7 static it creates 8.8 corrected
My desired recipe of 9.35 is a half point higher, is that a concern for detonation ? S&S chat line say`s yes
I could buy the 570`s w/ inner gears (p/n 33-5166)
I can spin a wrench and did several iron XL & shovel top ends back in the day, There were fewer variables and a lot less readily available knowledge back then !
Evo & T.C. work has been limited to cam changes up to now
I would really like to do this work only once !
Thank you
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,116
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From: Poolville
If you run a .030 head gasket and increase your static to 10.17:1 with the 40* ivc your corrected would be 9.33 with a 194 ccp. Keep in mind the .030 head gasket will help to reduce the squish winch will actually help to decrease detonation and make it easier to tune..
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Seasoned HDF Member
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From: OH
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HDF Community Team
Joined: Jun 2006
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From: san antonio
Having said that, at 10.2 the 570 will be happy but the OEM ignition should be replaced with a programmable ignition as previously suggested. The ignition curve will be important at the level of compression and it will be important to get the ignition curve close ASAP and premium fuel would be a good idea.
a
Thread Starter
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Seasoned HDF Member
Joined: Oct 2019
Posts: 10,804
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From: OH
Thank you.
I assume the O.E. ignition will advance too quickly ?
Hope the Daytona Twin Tec comes with directions !
( Shooting for corrected of 9.36:1)
I assume the O.E. ignition will advance too quickly ?
Hope the Daytona Twin Tec comes with directions !
( Shooting for corrected of 9.36:1)
Last edited by eighteight; Oct 29, 2019 at 01:43 PM. Reason: add