383, 11.6 compression, pump gas advice

[rewguy]

11.6-1 383 chevy. Solid roller 249/255 @ .050, .670/.640 on 106. Aluminum brodix IK200 heads, single plane,
850 carb. 3400lb camaro with th350 and 5200 converter. Is this something I can even possibly run on 93 octane shell fuel? Like 32 degrees of timing, or?? Is there even a pump gas tuneup that would go 7300 rpm safely? Or is this strictly a mix or race gas only setup? Who has done this and is confident in it? I've never dabbled in the pump gas/ high compression thing. Thankyou

Ps... would rather not run e85.

[1980RS]

11.6-1 383 chevy. Solid roller 249/255 @ .050, .670/.640 on 106. Aluminum brodix IK200 heads, single plane,
850 carb. 3400lb camaro with th350 and 5200 converter. Is this something I can even possibly run on 93 octane shell fuel? Like 32 degrees of timing, or?? Is there even a pump gas tuneup that would go 7300 rpm safely? Or is this strictly a mix or race gas only setup? Who has done this and is confident in it? I've never dabbled in the pump gas/ high compression thing. Thankyou

Ps... would rather not run e85.

I wouldn't with a 106° LCA, maybe a 112 LCA would work better.

[ProPower engines]

11.6-1 383 chevy. Solid roller 249/255 @ .050, .670/.640 on 106. Aluminum brodix IK200 heads, single plane,
850 carb. 3400lb camaro with th350 and 5200 converter. Is this something I can even possibly run on 93 octane shell fuel? Like 32 degrees of timing, or?? Is there even a pump gas tuneup that would go 7300 rpm safely? Or is this strictly a mix or race gas only setup? Who has done this and is confident in it? I've never dabbled in the pump gas/ high compression thing. Thankyou

Ps... would rather not run e85.

I would not do it. Too much comp. and too tight on the cam center. the cyl. pressure will be stupid high. Good if you run the right fuel in it but pump fuel is very risky. Even the best pump fuel at 93 just is not up to it.

Yes there will be guys that say they run it with 12-1 comp. but do they really have that or is it just a guess.

If you have the fuel system for gas then go gas its easier then E85 to start out with as there is a learning curve and the fuel at the pump is not as consistent as you are lead to believe. Buying it by the barrel would be a better option and no moisture issues like at the gas station to dilute the fuel.

[HQM383]

FWIW
I think your 93 octane is the same as our down under 98 RON. If your cam installed straight up will have intake valve close 51* ABDC @.050”. My 383 engine is 11.4:1 static and cam that intake closes 48* ABDC @.050”, timing 34*. Never heard a ping with our 98 RON fuel. If your heads aren’t ported they would flow less than mine but I don’t have .670” intake lift so maybe ingesting a similar amount of fuel air. Other factors involved but that’s my experience for you to observe.

[rjpower]

Water injection. Even a simple homemade system with a washer pump works great. No supercharged cars
leave my shop without it. It's dam little trouble for the parts it saves.

[KnightEngines]

Pump fuel for street, with a 5200 converter you won't get enough load on the motor to ping.
Race fuel for the strip.

[F-BIRD'88]

If I was going to try it I would tighten up the valve lash a good bit to increase seat to seat duration.
More seat to seat valve duration tends to ward off detonation at low mid rpm. (you don't need to move or change your cam)
I would fatten the jetting a bit.
I would run the diz locked out so that it tends to self retard as rpm climbs.. A HEI diz module will loose 4 to 6 degrees at high rpm, when run locked out.
iId start at 27 deg btdc and work up. 30 ish.. +/-

The water meth injection is a great thingie.
As said even a DIY windshield washer system is better than nothing. Any engine will tolerate more than optimum amount to ward off detonation.

( Water meth injection always works better on a Roots supercharged engine as there is ALWAYS an aboundance of EXCESS heat to be absorbed by vapourization in the hot blower.
But the DIY W/M inj on a N/A does work.. Multiple smaller spray orrifices are better.)

If blending in (110 unleaded) race gas to good pump gas you only need what you need. 98 ish octane? Won't cost that much. Install a under hood fuel cell to allow mixing and running smaller amounts of blended fuel. the only way to know is to test.
I'd try a 33% blend. (2 Parts 93 pump to 1 part 110 octane unleaded)

11.6 is not going to run very long on pump gas without one of these detonation prevention strategies.

(Running tighter running valve lash also tends to increase the service life of roller lifters.)

[F-BIRD'88]

When your engine experiences high speed WOT detonation (this is the stuff that destroys engines very FAST).
YOU WILL NOT HEAR IT.

[F-BIRD'88]

Why not just remove the cylinder heads and increase the net total chamber volume by 9cc to 10 cc on each cylinder , to lower the CR so it reliabily will run on your 93 octane pump gas?
On this 383 sbc is there a dome on the pistons?

[stealth]

Why not just remove the cylinder heads and increase the net total chamber volume by 9cc to 10 cc on each cylinder , to lower the CR so it reliabily will run on your 93 octane pump gas?
On this 383 sbc is there a dome on the pistons?

I agree, 11.6 CP is in no-man's land - Too high for pump gas - Too low for race. Just doesn't make any sense.

I'd strongly suggest knocking the cp down to 10.5 max. Maybe less with that cam.

[Fusion Works]

What is the piston to deck clearance?

Why no switch to fuel injection where you can properly control the timing curve and get better fuel distribution. That should help cylinder variability that could contribute to detonation.

[skinny z]

Solid roller 249/255 @ .050, .670/.640 on 106.

How do you calculate the duration at .006" off the seat?
That's obviously after lash and the valve has started to move.

[ClassAct]

11.6-1 383 chevy. Solid roller 249/255 @ .050, .670/.640 on 106. Aluminum brodix IK200 heads, single plane,
850 carb. 3400lb camaro with th350 and 5200 converter. Is this something I can even possibly run on 93 octane shell fuel? Like 32 degrees of timing, or?? Is there even a pump gas tuneup that would go 7300 rpm safely? Or is this strictly a mix or race gas only setup? Who has done this and is confident in it? I've never dabbled in the pump gas/ high compression thing. Thankyou

Ps... would rather not run e85.

Get the tune up right and it will run on pump premium.

[F-BIRD'88]

Can you put 2 pounds of baloney in a 1 pound bag?

[Super_Stock]

Hehehehe... Aussies know how to run high comps on pump gas.