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comp cam xr274r vs 288ar BB

8K views 14 replies 9 participants last post by  holgerth 
#1 ·
Hi!
Iam building a 454 Hi-per street, large ported cast iron heads, 11.0 cc comp, Holley 800 dp, dual plane intake, 2.73 gear in 12 bolt end..now to the problem..i thougt i find the best cam for this comp cam Xtreme Energy 11-770-8 but a friend told me that its problem whith Xtreme Energy cams and i should go for a more proven concept a magnum 11-692-8..then i put this cams in comp cams "CamQust" i ll get better curves with the "Xtreme Energy 11-770-8 " = very low end peak torque.. Do someone have experiance about this 2 cams??

Regard Mattias
 
#2 ·
I know a 396 with the first cam(11-770-8) it dynoed 511 hp. 2.73 may be a little low, personally I would like 3.73. What trans and if auto stallspeed? Also get the cam on a billet core with cast gear option.

Marcus
 
#5 ·
Bit of a mismatch with such high compression and no rear gear. Your going to need a larger cam to bleed cyl pressure off, but the larger cam wont like the 2.73's.
 
#9 · (Edited)
I've run the 288AR-10 Astra-Tempered (8 Suffix) Solid Roller with CC-933 Springs in a 9.8:1 454 & 3.08 Gears with Good Results but it really doesn't start hauling until 3000rpm and liked to cruise above 2400rpm.

With Gears between 3.31 to say 3.08's I suggest you look at the Lunati LUN-502A1 and A3 112 LSA SR Billet Cams with CC-933-16 Springs (200/500 ftlb - 490 Rate Springs) and Dial In an 8.2:1 DCR with an .036" to .044" Quench.

All the above SR Cams with the 933 Springs with a Forged Rotating 454 will will hit 7000rpm.

If you're NOT running a Forged Rotating Assembly, and considering the 10.5 or 11:1 Static Compression and Hwy Gears, I suggest the HFT XM278H-12 or XM288H-12 with CC-925 Springs for a Strong 6200 rpm 454.
 
#11 ·
Little? I think alot better give it at least 3000 in stall and go for the 11-770-8. If you hav´nt bought pistons yet buy a set that will give 10-10.5 instead.

Marcus
 
#14 ·
I am currently running the XR274R 11-770-9. The specs are the same except the -9 is a solid core cam (I special ordered it, $300). The cam has a nice but subtle lope, I still have about 12lbs of vacuum which I need for power brakes. It idles good around 850 rpm and I have been twisting it up to 7000 rpm with no problems.

My motor is a 410 cubic inch Big Block with 10.4 compression, Muncie M22W, 3.73 gears with 28" tall tires. The car has run high 12's at 108mph so far.

Feel free to ask me any other specific questions. :thumbsup:

Kurt
 
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