What plugs should I run with 9psi peak boost?

[GsxrMike]

My head is spinning from all of the stuff I have read. I need to know what (if anything) I should change about my spark plugs. Do I need a cooler plug and smaller gap? Should I upgrade my ignition? I think I have them set at .040" and they seem to be doing ok but I am getting a lot of pinging at higher rpms. I'm getting it dynoed next week so I can send off for another tune. This is on a 1996 vortec 350.

 

[Jessie James]

My head is spinning from all of the stuff I have read. I need to know what (if anything) I should change about my spark plugs. Do I need a cooler plug and smaller gap? Should I upgrade my ignition? I think I have them set at .040" and they seem to be doing ok but I am getting a lot of pinging at higher rpms. I'm getting it dynoed next week so I can send off for another tune. This is on a 1996 vortec 350.

Pinging = detonation. If you are running a turbo/supercharger, and you're pinging, you're about to completely destroy your engine. Force induction engines have almost ZERO tolerance for pre-ignition.

I don't think anyone can diagnosis this over the web without a ton more information. Engine? How it's fed? What mods you've done? Who did them? When did this start? What does the manual recommend for your exact setup? Are you stock? Etc.

First, stop driving it and get it to a shop. Personally, I would tow it. You are VERY likely to destroy a number of internal parts on a FI engine and very, very quickly.

Obviously, with a FI engine you should be running super unleaded, 93+ octane. Are you?

A cold plug can help, but ... nothing personal ... it sounds like you're guessing. And guessing with a FI engine means failure. Major, major failure. I'm not going to recommend you just guess.

Do yourself a favor and pick up the book "Maximum Boost" by Corky Bell. You'll be glad you did.

 

[Philly87]

EDIT: So I read up on your supercharger and it looks like it comes with a booster pump and custom programmer... If you're still getting detonation I'd say the tune is still off and I'd be easy on it until the detonation is gone. Get the tune right and the detonation will be gone. Since this is meant to work on a stock truck I'd say factory plugs are fine but checking with the supercharger manufacturer is your best bet.

I couldn't agree more. A forced induction motor is a whole new animal even at conservative boost levels. If you continue to drive the truck with it detonating you'll find yourself with holes in pistons and needing a new bottom end. Detonation is like slamming the top of your piston with a hammer; it can be detrimental to the piston and rod bearings.

Don't get me wrong I love the idea of the supercharger just be careful and don't get in too big of a hurry to push the motor until you are sure the tune is right.

How does the system increase fuel to the motor? Is it strictly relying on the tuner to do this? Did the kit come with anything to boost the fuel pump as boost pressure increases? If this kit came with a tuner it should help compensate for timing to prevent detonation.

If not I can help you with MSD part numbers that will automatically retard timing in relation to boost...

-Phil

 

[Stomis]

Back off your total timing to like 22-25* until you get it tuned properly. This will help with detonation alot. Especially if your still running like 32-36* total. Thats no good.

 

[bronc3buster842001]

He has a vortec 350. Can't adjust the timing on them. Have to change it in the ECM.

 

[GsxrMike]

The kit cam with an FMU and I ran it tonight and I am getting about 64lbs of fuel pressure under boost.

I am taking the truck to house of boost next week to get it dyno'ed and then send the data off to Black Bear Performance so he can tune my computer. The truck drives fine under 3500 rpm so I will just take it easy until I get the computer right. After I get the new tune I will take it back in to HOB and see if everything is good.

The guy I got the Powerdyne kit from said he never ran the pump that came with the kit and his truck ran fine. I told him I wanted the pump and he said he didn't have it but he would order me one. I think that will help with volume but not pressure. I think when I get it dyno'ed we are going to install an adjustable FMU so we can get the AF ratio close and let Black Bear handle it from there.

Does running lean cause more engine knock or less. I always thought running lean was a cause of engine knock but I just read a whole article about the computer leaning out the motor to stop engine knock?

 

[GsxrMike]

Oh yeah sorry, 1996 vortec 350, longtubes, dual 3" exhaust through a 50 series flowmaster, MSD coil, black bear tune, egr delete. I think thats it? Don't know if it matters but my truck weighs 7500lbs and I tow about 9000lbs with it on occasion.

 

[GsxrMike]

Oh yeah, the kit says to run 92 octane and around here they only sell 91. Right now I am running 91. I think BP might sell 92 or 93 but I will have to check into that.

I also hooked up a boost gauge tonight and I think I am going to make 6psi of boost instead of 9psi. PO said it would run 9psi as is but I think you have to change the pulley.