I've used the autolites before, they worked fine for me. Ran 10psi.

My engine builder (Rotary Dynamics) has used these for a long time and he's running around 400whp and heavily tracks the car on a regular basis.

He's experimented with colder plugs at different points in time, but has used the autolite 9's successfully for a few years.

 

Good info, Thanks

Barry

 

Time to resurrect a dead thread... Has anyone actually need a definitive difference between the 11s in Autolite vs. NGK? About dyno tune for 29psi and I have NGK 11s at $30/ea but I can pickup autolites at $3/ea. Trying to see if it will actually make a different and the $120 will be well spent.

Thanks.

-Marc

 

Sorry. Apparently I can't think or type tonight... this is what the message was supposed to say.

Time to resurrect a dead thread... Has anyone actually seen a definitive difference between the 11s in Autolite vs. NGK? I'm about to dyno tune for 28-29psi and I have NGK 11s at $30/ea but I can pickup autolites at $3/ea. Trying to see if it will actually make a different and the $120 will be wasted when I could use them for a track day or something.

Thanks.

-Marc

 

I've used the autolites for years and they've worked great for me (boost into the low 20's) and will last for several thousand miles. The expensive NGK's will last a lot longer--if they're not fouled.

 

Yeah thats the problem I'm running into right now with the hotter NGKs is that they are fouling out very fast so we are looking to move to colder plugs. I bought the race plugs from NGK but I'm hesitent to use them until I can be sure of what is causing the engine to foul out. So I figured the Autolites would be perfect.

 

Uleepera, Did u mean to say.... moving from colder to hotter plugs? I would expect colder plugs to be more prone to fouling.

I think that folks often make a mistake of running plugs that are too cold. A lot of power Can be made on 9's or 10's, at least until you turn the boost way up or have a long high load duty cycle and risk overheating them. Inspecting and reading the plugs is probably the best guide to determining what you need.

 

No I meant it the way I said. However the planned boost range for the car will be about 17psi low end and 29psi high end. The tuner and shop I've been working with suggested a colder plug for the higher boost level.

That said the fouling issue is unrelated in that we think either the plugs aren't holding up to 18psi where I'm tuned to right now or I need a smaller meth nozzle. I'm trying to test the cheaper fix first before buying a new nozzle for the meth system. My power-band at present is excellent through about 6000-6500 and then it just breaks up and I lose acceleration. Originally when this issue happened we pulled the plugs to find that they were fouled out and needed to be replaced. Now we've got the issue again a few months later albeit on reasonably newer plugs but I thought as long as I'd have to go to colder plugs to tune for higher boost I might as well test it out now for about $12 in plugs.

I'm probably looking at the Autolite 10Xs instead of 11s right now.

 

Ok gotcha, that makes more sense.... In my experience either brand plug should hold up fine at the boost levels you're considering; as long as the rest of the ignition is good.

I think I would try to clear up the overrich condition before going any colder as the colder plug is likely to exasperate the fouling situation. It's an interative process. Running smaller gaps will also help with the fouling. The selection of the correct heat range is really heavily influenced by how long you maintain a certain power level and is always compromise to some extent. A few seconds of higher boost on a 10 won't kill you. So I would start with 9's or 10's, clean up any map issues and go colder, if needed, after that.

 

I'm going to try to kill 2 birds and drop in 10xs and reduce my meth nozzle size and see how it goes.