408 on 91 octane, will this combo work ???
06-02-2006, 10:57 PM
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408 on 91 octane, will this combo work ??? Hey guys,
I am in the process of biulding a 408 motor for my Silverado SS. I am running a Vigalante 3000 stall, need to run on 91 octane, and am looking to make peak power at 6300, shift around 6500 rpm. I need some advice on if this cam and compression are ok for a daily driven truck .
XE-R lobe, rated 285(236 @ .050) / 287(238 @.050) .619/.623 lift w/1.75 ratio. 112 + 2 (patriot gold springs)
RHS heads w/ 62 cc chamber, diamond -14cc reverse dome, cometic 4.050 bore x .040 thick gasket, piston .005 above deck.
I came up with a SCR of 11.05, and a DCR of 8.30.
Is this DCR to high for 91 octane ??
Would I be better off running less compression and more timing ??
Is my cam sized for the rpm I am looking for ??
Does anything in the combo not look properly matched ??
I will be running a 90mm SSR truck intake at first, and then maybe switch to a FAST 90 when I save up.
Thanks for the input
I am in the process of biulding a 408 motor for my Silverado SS. I am running a Vigalante 3000 stall, need to run on 91 octane, and am looking to make peak power at 6300, shift around 6500 rpm. I need some advice on if this cam and compression are ok for a daily driven truck .
XE-R lobe, rated 285(236 @ .050) / 287(238 @.050) .619/.623 lift w/1.75 ratio. 112 + 2 (patriot gold springs)
RHS heads w/ 62 cc chamber, diamond -14cc reverse dome, cometic 4.050 bore x .040 thick gasket, piston .005 above deck.
I came up with a SCR of 11.05, and a DCR of 8.30.
Is this DCR to high for 91 octane ??
Would I be better off running less compression and more timing ??
Is my cam sized for the rpm I am looking for ??
Does anything in the combo not look properly matched ??
I will be running a 90mm SSR truck intake at first, and then maybe switch to a FAST 90 when I save up.
Thanks for the input
Last edited by SuperSporttruck; 06-03-2006 at 11:44 AM.
06-02-2006, 11:19 PM
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I think you might be close to the edge, but your DCR is a little lower than some I have seen, so maybe ok, I am no expert on that. I have heard shifting that high is hard on the tranny, but yours is not the 4L60E, something stronger I believe. Nice ride though, have you seen any numbers with those heads? I havent heard much about them, they have the 12* angles?
06-04-2006, 09:20 AM
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I have run a very similar combo on my 408 for awhile now.
My cam is a xer 238/242 113+2. My SCR is 11.49 DCR is 8.46, no problems at all on Ca. gas. Granted, I will splash a touch of Torco if I know I'm gong to beat the hell out of it just in case. All in all, it's mega streetable and reliable.
I peak at 6,300 RPM with a 50' IVO. My cals. put your SCR @ 11.03 DCR @ 8.29 and IVO @48'. It should peak a bit before 6,300, but your low end TQ should rock!!
My cam is a xer 238/242 113+2. My SCR is 11.49 DCR is 8.46, no problems at all on Ca. gas. Granted, I will splash a touch of Torco if I know I'm gong to beat the hell out of it just in case. All in all, it's mega streetable and reliable.
I peak at 6,300 RPM with a 50' IVO. My cals. put your SCR @ 11.03 DCR @ 8.29 and IVO @48'. It should peak a bit before 6,300, but your low end TQ should rock!!
