Timing with a Procharger

[1969Swinger]

I've been running a P-1SC ATI Procharger for about 2 years now. 410CI smallblock,8.3:1 cr quench dome pistons, 4150 carb, water injected, 11psi boost
So far I've been running about 28 degree's timing, just to be on the safe side. but I've been told with intercooling or water injection at these boost levels I can run pretty much full timing. This engine makes the best N/A power with about 36 degrees. I was thinking about bumping up the timing to 32 or 34 for an upcoming dyno run/drag run.
So my question for those of you have have experience with this, how much is too much timing for that combination Running on 92 octane? Race Gas?
Thanks.

 

[moper]

I think the problem lies in the pump gas deal. What heads are you running? Pump gas is not real conistant, so getting closer to the edge of detonation with it may be a bad thing. I'd suggest a few things. Grad a timing master, where you can dial up or down to adjust the timing, then get some dyno time with race fuel, and std pump fuel. I'm assuming the engine has good pistons,(built for boost) already. Then, experiment a little. The second the engine goes into detonation, the EGTs go up significantly, or it beahves strange, stop dialing more. With good chambers and alumiunm heads, I'd think somewhere between 30-32 on pump fuel would be the limit, and closer to 35+ with race fuel. Also keep in mind, you are adding a lot of stress with that extra timing, so if you have trouble hooking the car now, the whole exercise is just a waste of effort, and tempting breakage.

 

[1969Swinger]

The Heads are Eldelbrock RPM's ported, Commetic MLS head gaskets, and arp studs. Pistons are Diamond Forged. Mainly I'm looking to see the full capabilities of this engine, even if I tune it back down for the track. I'll probably use a race gas blend and start the timing out at 30 then maybe 32.
I don't have a egt probe, where is the optimal place in the exhaust to install one? and do they make one that'll fit in an o2 bung? I'll have the wideband o2 on the dyno so I won't need mine.
Thanks for the suggestions.

 

[moper]

Make sure the dyno O2 is the one that threads into the header. Not the one stuck in the tail pipe. EGTs are best stuck int he header pipes about 1" away from the header to head flange. As long as all of them are the same distance back from the flange, you're ok. If one is further away than another, it will read a difference when comparing two identical cylinders. I would say if you dont have them, dont bother with them. Just watch the A/F mix very carefully, and listen for any signs of audible detonation. Then, read the plugs for any signs of speckles from the pistons. Detonation is not always audible, but it is always destructive if it occurs for long enough. That's a brutal looking set of power curves tho. Nice job...