NOTE: This post picks up where my "C.R. / Quench / Cranking Pressure dilema" threads leaves off.

Let's talk real-world exprience and whether the following combination will be able to run on 93-octane fuel. I'm basing a purchase decision on it and have some concerns.

RB Short block:
4.360" x 3.75" --> 448 c.i.
Flat-top pistons at zero deck height

Heads:
Edelbrock Victor (heart-shaped chamber)
.040" quench
Calculated CR = 11.1:1

Cam:
Comp Xtreme solid street roller
298/304 at .015", 260/266 at .050", .627"(1.6)/.597" (1.5)
LSA 108, installed straight up
Lash spec = .016"

My Engine Analyzer Pro simulation program says this combination should crank 199 psi and will definitely be in the "detonation danger zone" running 93 octane.

My real world experience is that my 452 w/ 10.8:1 CR and a 298/298 at .020", 266/266 @ .050", 108 LSA solid flat-tappet cam installed on 106 ICL has been running OK on straight 93 octane. But the extra .3 in static compression AND the shorter cam duration could definitely change the dynamics of the situation. There's probably 15 psi difference in cranking pressure between the two.

Is my simulation program spouting bogus data in this situation? I don't place 100% faith in it, although it's given me valid data for trend analysis, etc., before. And if the cranking pressure estimate is accurate, does the rest of the combination still look "93 friendly" due to the chamber design, quench height, etc.?

I have the same motor setup,If I stay off the cam(keep the rpms below 2500)it runs fine on 93 other wise I run 110 30% plus the 93.It's no fun driving around and you can't step on it without the detonation. Might be ok with a thicker hear gasket.

Maybe post up seat duration on both cams.

I have a 471 with higher compression (11.8) and nearly the same dimention flat tappet cam. I get no detonation. HOWEVER, I'm at altitude. That changes everything. So I would say you would be into the detonation area. Mix of gas will probably be needed. By design, it's very important to keep the quench in the .040 range. So a thicker head gasket will,imo, make it worse.
I'd build it and work with the timing to help to lessen the detonation effect. Mix the fuel and hold on.

I am surprised you are considering less duration than you have now. In fact, I think the current one is conservative on duration. And 272ish would be more pump gas friendly.

I have a true 12.11 comp and crank in the 170`s w/275-280 @ .050 and drive everywhere on 91 calif junk however, I wouldn`t race this way and mix 110 when racing. Go bigger on the cam.......

Brad, please provide the cam timing events @ .050

Brad maybe this will help you some maybe not! But when i talked to Ray Barton Racing and my current junk is setup 11 to 1 and told them its mostly a pump gas street car they called bullet and here is the grind I got!

Bullet
269/269 @ 50
110*
in at 106
.430 lobe / .645 1.5's / .688 with 1.6 / .731 1.7's
IO 28.5
IC 60.5
EO 68.5
EC 20.5

.050 quench

4.500*4.250stroke 540

I think you'll be close. My CR is at 10.8. Cranking, it blows 185 psi on the gauge. IC (@ 0.050") is 60 ABDC.