For a forced induction (turbo) engine is it better to have a small sparkplug gap(035-045) or a wider one(050-060)? Does it depend on the temp of the plug or what? I want to use Bosch Platinums.

 

smaller because it reduces blow out of the spark.....

 

WHat does the car fell like when the spark gets blown out? I'm assuming you get high speed mifires, but is there any other signs?

Oh yes, I second the what you said about the tight gap. I run my TT IROC down to .030", even with an MSD. Have never tried larger gaps though (I may be able to open them up a bit for my mild boost).

 

it feels like a mild version of fuel cut, or if you put a few of the plug wires on in the wrong place and tryed to run high rpm

 

I got a little of that drag racing my Turbo Z24 the other night. It also popped a ittle out the exhuast. The problem only seems to be present at above 8psi of boost and high RPM. I was thinking it may be 'blown out' spark. I'm def going to wide-band it again- if the AFR is cherry, I'm going straight to the plugs. I was running .040" for over 5k miles now on the 3400, so I'm thinking some ignition misfires may be occuring.

 

exactly, it feels like a high rpm misfire with all the symptoms, popping out the exhaust, power loss…

I know a few serious (fast) forced induction guys that swear by .022-.026” gaps, even with aftermarket ignitions…. Gaps that small will tend to misfire slightly at idle, but will run fine when pushed. The other side effect of small gaps is that the plug runs hotter, so you really don’t want to run a smaller gap then optimal either.

 

speaking of your turbo z24, my friends and i put a t4 on a 3400 grand am.... we should exchange info and what not, i would like to see what your set up involves.

 

So for say around the 6psi mark on a stock-ish motor, we are agreed on about 0.030"?

 

Sounds reasonable I think.

I run .028 in my Talon with up to 24 psi, but it's stock ignition system is fairly healthy from the factory.
I was blowing out the spark occasionally at 7000+ rpm on 21 psi when I had worn plugs that had opened up to ~.032.

I know it's not a small block Chevy but good for reference anyway. I'd think an MSD setup on a small block should be at least as strong as my Talon's stock ignition.

 

6 psi... with an ignition box, probably somethign in the 32-36* range.

 

and what on a about stock ignition setup?

 

that really depends on the rpm that you intend to turn. Sub 5500, I'd say that you'll be OK with somethign in the .028-.034" range.