What should my spark plug gap be on a 200 shot using a B8EFS and also on a 300 shot B9EFS. I am currently 30 on the 8's.

What is the downside to closing the gap? Why not run a say 28 on everything.

 

I run .028 on my 8's and 200 shot

 

How about on 300?

I did the unthinkable and sprayed 300 on the B8's without pulling timing but with VP. Someone challenged me to a grudge match that I know runs 10.5s and on 200 I ran 11.1 so I uppted the shot to 300. It hurt me cause I ended up running 11.4 to his 11.1 but his front driveshaft broke on that run.

The B8EFS re gapped to 30, should I close it?

 

more gap is associated with better efficiency, increased economy and more complete burning/use of fuel and air. The larger the plug gap the better the spark performance- until it "blows out" of course. I would seek to increase the power of my ignition before gapping down, unless it was too expensive or I was simply willing to give up the advantages a larger gap and more powerful ignition system might have for my application. In other words, gapping down is free, and it works. But I wouldn't do it unnecessarily or unless I had no other realistic option.

 

On LS engines how does that play out. Better coils and/or wires?

MSD coils Granatelli Wires?

 

Well ya gota be careful now. The OEM ignition system is a great thing, reliable and consistent. Keep that in mind before you go touching and modifying anything, because IMO the last thing you want is a problem associated with coil dwell time or some other electronic issue that suddenly crops up, seems to happen too often these days. And remember what I said about plug gapping being free- if it works, you don't have to spend any money and I am not suggesting you do.

If you are dead-set on improving ignition performance mostly for the sake of economy, I would still try to keep as much of the OEM system as possible to avoid electronics problems. That said, something simple like an MSD box (what we all used in the old days) might be what you are looking for, it will allow you keep most of the OEM hardware if not all of it, improves spark output, and lets you run a larger gap. I don't know if there is an MSD box for the LS-X (you might have to run two DIS-4's or something stupid I never tried it, although you said wires which implies a standard box would work) Anything more than that- I would copy somebody's setup exactly (find someone using the nitrous you are using), find out exactly what they are using and for how long, and make sure they are having the large plug gap you are looking for, AND have been using the setup reliably for 2-5 years at least. And even then, don't cut or move any wires that are OEM, simply move them out of the way and shrink them off if necessary, that way if you DO have problems you can always go back to the OEM ignition to diagnose them.

If I had a street car with 500~bhp I would keep the OEM system, with possibly brand new components for maintenance measure (if they have 150k+ it might be beneficial to renew them), use a high quality compatible plug (iridium if possible), and make sure you do everything in your power to ground the engine and chassis properly, protect any electronics with heat shields and blankets (minimizing heat absorption/retention in electrical systems traditionally improves their performance). Then start with the gap they come with and boost it. If it blows out, gap it down bit by bit until you hit the safe spot for your setup for consistent performance. Turn the power up just a bit extra to make sure you have headroom, and use all "special devices" such as meth/water injection while you do so. Nitrous is another story; I am not sure I would want to blow out my spark during a run with nitrous. Extra safety precautions are required for nitrous. My recommendation mostly revolve around you having access to the power full time (forced induction) and being a daily driver/ street car.

 

For now I am going to close the gap on the B8's to 28. What should I gap the B9's too for a 300 shot?

 

Do you really think .030 to .028 is going to make a difference?

It won't. The OEM coils can fire across an .060 gap, so they have plenty of juice. Closing the gap is more about getting away from a huge long ground strap like on a projected tip and keeping the ground strap from becoming a glowing ember for detonation.

While my ignition is a single MSD it also fires 7 times more than the OEM individual coils. I had asked my engine builder (Tony Bischoff) about gap and his reply was "have a gap"... So I simply check each plug with a 0.025 feeler.

 

this is good thinking. The only thing I want to point out is that in traditional MSD ignition setups, the multiple spark only occurs below a certain RPM threshold. So it would not be in effect at say, 5,000+rpm iirc. Unless they have changed things since I was kid.

 

I have 1 coil firing all 8 cylinders versus 8 coils firing 8 cylinders .

Not referring to the multiple spark discharge.

 

I just wanted to get in line with everyone else running 28 gap so next time I swap plugs I will use that. For now I am still on 30.

On B9's I will go to 26 or 28?

 

On the 300, close the 9's down to 26 to help with heat-

 

I'd go with a 26 gap on them.

-Chris

 

I gap mine at 26 also. better safe then sorry. from 150 to 300, just keep mine consistent that way

 

stock coils, MSD wires, you would be surprised what the stock coils can fire. I have driven home on a 6:07 pass in the 8th and had two burnt plugs and the 3rd, strap was almost all gone and the car ran like it didnt have a problem till I checked the next day when i thought the idle was a little odd lol

 

Next plug change we will gap the B8s to 26 just in case we get lazy when we use the 300 shot.

 

Post up how it does if you do go to the 300!