Projected or non with blowers?
 

There are alot of guys on here, that say you should not run projected tip plugs with power adders, and or, at all with marine applications. Some on here, myself included have run them for several years without problems. IMO, with a projected tip plug you can run a colder plug without fouling, reduce timing, and have the benefit of having the spark at a better position in the cylinder for combustion. So, my question to all is this; If the tune on the motor is right, why not run them? The spark plug has two jobs, first is to light the flame, second is to remove heat from the chamber. So, with a projected tip, you initiate the flame front closer to the center of the combustion chamber, which has the affect similar to advancing the timing. Whereas, overall timing can be reduced, decreasing the chance of detonation. Also, being able to run a colder plug extended into the cylinder, would it not transfer heat into the cooling system better? If I am wrong, I would rather replace three sets of plugs, then pistons . LOL

If you take a brand new cylinder head put a plug in it flip the head over and look where the plug is its like WTF! The plug is no where near the combustion chamber. It's way up in the threads. Well, there is a reason for that... They are trying to keep the hot spark plug away from the already lit fuel mixture. This is what works the best it makes make power. With a projected tip plug you are defeating the purpose of the cylinder head design. I can really remember the last type I saw a projected tip plug in any type of all out race motor and I'm around alot of different motors.

I was always told it was a no no in supercharged engines, nitrous engines, etc. Told by some engine builders, spark plug company resources, supercharger installation manuals, etc that projected tips were not to be used.

Obviously they are working for some guys just fine though.

Bawana how much total timing are you running on your setup?

I always thought a projected tip was a band aid to a poorly designed combustion chamber. Most modern bbc cylinder heads that i know of from AFR, Dart, Brodix, do not spec a projected tip that i know of. I believe the edelbrocks do though.

Good question for the pros.

MT.. I run 30* locked.. was thinking of going to non projected, and 32*. But the thing runs so good now & idles great. But with the way gas is.... a little extra insurance is always good. I have Brodix BB1 heads

is this what your referring to

Yup

Wonder if thats the ticket as far as things not getting hurt. For years my blower motors have been at 32, 34, and even 35 deg. Idle great, never fouled a plug, never hurt a piston or valve. Been running non projected #8 heat range NGK plugs or AR134 autolites.

I wonder what would happen if u tried to run 35 deg of lead with a projected tip? My guess it would wreck pistons ?

I cant see 30* with a projected tip being safer or further from detonation then say a std tip with a couple more degrees?

Kinda like when chevy came out with the fast burn chambers. While 34 deg of timing might be just fine on a bbc open chamber dart head, you wouldnt want to run that much timing with the fast burn style vortec chamber.

Icdedppl had the opposite in his engines. Someone by mistake installed a .460 reach plug in his head that called for a .750 reach. The engines were kinda hard to start and lacked acceleration with the 32 deg of lead. After talking with his cylinder head guy and bob m, the byproduct of that scenerio, was basically retarded timing in the combustion process. Of course the plugs were always black as they were set way to far back. After installing the right plugs the engines now light off with a flip of the key and spring to life. With the short plugs, they kinda chugged like blub blub blub blub blub until they caught. The cylinder head guy felt that if the engines had been dynoed with those short plugs, he said he woukdnt have been surprised if the engine wanted like 38-40 deg of timing advance

i know a few people who are running them in supercharged engines and getting away with it,also know a guy who lost 2 engines partially because of projected tip plugs.no real reason to run them but thousands of reasons not to just my opinion.

I have run them both (15 years ago) in blown engines with NOS, aluminum heads timing base at 11* all in at 3800 rpm total advance 35* never had any damage with the extended tips but EGTs were a bit higher then ideal. I had better throttle response with the non projected and kept them in. I do not recommend them with power adders or if you like to run 5500 rpms and above for extended periods of time. Note I'm old school and like to run my engines a bit fat on the big end! that could have helped also.

What afr did you considering fat in blown applications? I think fat as in the 10s as IMO I like 11.7 :1 or a little south of that @ WOT.