Re: 1.5 versus 1.6 Rockers
[Re: GTXMEX]
#3099250
12/03/22 04:33 PM
12/03/22 04:33 PM
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Joined: Jan 2003
Posts: 5,484
SoCal
Brian Hafliger
master
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master
Joined: Jan 2003
Posts: 5,484
SoCal
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I bought 1.5 rockers and am reconsidering seeing if I can return them for 1.6 . Using DynoSim6 to see the possible difference, with a 508", 10.5 to 1, 850 carb (I may go bigger later), these are the differences. Probably not worth the hassle and added cost of the return for a primarily street, occasional strip car?
I always use higher ratio if starting with new setup...
Brian Hafliger
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Re: 1.5 versus 1.6 Rockers
[Re: GTXMEX]
#3099259
12/03/22 05:01 PM
12/03/22 05:01 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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If the cam is smaller than optimum, they (almost) always help.
If the cam is too big it gets worse.
Generally, on higher ratio intake rockers help, the exhaust doesn't need more lift (better: earlier opening).
Boffin Emeritus
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Re: 1.5 versus 1.6 Rockers
[Re: GTXMEX]
#3099721
12/05/22 09:54 AM
12/05/22 09:54 AM
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Joined: Dec 2021
Posts: 1,118
Loudoun County, VA
Brad_Haak
super stock
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super stock
Joined: Dec 2021
Posts: 1,118
Loudoun County, VA
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I don't trust that series of simulation programs to give realistic results any longer... FWIW
Rocker ratio should be selected in conjunction with cam profiles, LSA, etc. That said, my personal experience has been anywhere from no improvements found to maybe 5-8 HP on "best case" scenario.
The other thing is you can't ASSume the published ratios reflect the actual delivered (real valve springs, not checking) ratio. It can also vary a good bit from above to below stated ratio depending upon brand / design. It's one of those areas that the only way to know is to mock up everything with the actual parts and check the net lift.
2021 Challenger 6.4L Scat Pack 1320
100% stock: 1.680, 11.894 at 113.75 (DA 175 ft)
weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008]
pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: 1.5 versus 1.6 Rockers
[Re: Brad_Haak]
#3099751
12/05/22 10:57 AM
12/05/22 10:57 AM
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Joined: Jun 2008
Posts: 3,916
usa
lewtot184
master
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master
Joined: Jun 2008
Posts: 3,916
usa
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I don't trust that series of simulation programs to give realistic results any longer... FWIW
Rocker ratio should be selected in conjunction with cam profiles, LSA, etc. That said, my personal experience has been anywhere from no improvements found to maybe 5-8 HP on "best case" scenario.
The other thing is you can't ASSume the published ratios reflect the actual delivered (real valve springs, not checking) ratio. It can also vary a good bit from above to below stated ratio depending upon brand / design. It's one of those areas that the only way to know is to mock up everything with the actual parts and check the net lift. this.
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