Projected tip plugs more prone to detonation?

Are projected tip plugs more prone to detonation, as compared to the equivalent non-projected tip plug?

Probably depends on the combustion chamber design. I use the extra projected, extra wide gap plugs on my pump gas engines. Same part number that the factory puts into the modern engines.

Not if you get the heat range and timing correct for that motor
I like and always use them on all my N/A motors
you should always strive to get the spark as close to the center of the piston as possible

I use this type in my 512, they work great. the spark is not shrouded by the ground strap.

Thanks for the feedback. Anyone see value to iridium plugs? I know the OEMs use them for longevity, but the fine tip seems to produce a well concentrated spark. Would that be beneficial to power production?

those are interesting. whats the part number on those?

bkr6ek & a step hotter bkr5ek NGK I run the 5 in my 9.5to1 512 street car. 4000 miles on them & some track passes, no missfires & they still look great. no signs of detonation.

Regular NGKs at $20 a set.Especially when you reading plugs!

Ill check those out. Thanks

In NGK's, the higher the number the COLDER the plug unless that weird sukka is different...........

yep,they follow the same as all NGK.

An NGK "5" would scare me. I'm not sure I'd use anything hotter than a "7" even for a regular street car, but a lot of that is based on my experience with too-hot heat ranges used in motorcycles.

x2, especially with BB Mopar heads that have the plug sitting almost back to the cylinder wall.

I'm sure I've posted this picture before but here are three plugs I tested in my 470 with the Trick Flow heads. These are all the same heat range and the same brand. Standard, projected and super projected. I use the super projected just because it seems like it should be better but I did not notice any difference on the dyno between the three plugs.

Went 9.79 @ 135+ several years ago first pass ever w/the new combo and a # 7 and my carb was lean as in the 14's up top and saw a tiny bit of peppering so now I run 8's at 12.1.1 comp.........

I think CR plays a big factor. I was using regular tip NGK -7 plugs in my 10.3:1 470 street car, and have been having an issue keeping them clean and would have sporadic misfires driving around town. I changed to some used Autolite 3923 (projected tip) and the plugs look better and I don't notice misfires now. I need to get new plugs and have been pondering what to get. Given my recent tests, I plan on going with -6 but still need to decide exactly which type to get. The "super projected tip" plugs look interesting. Also thinking about trying the fine tip iridiums as an experiment.

Sure would like to see a comparative timing strap read on those three plugs after a good pull. Sure seems that the projected plugs would be risky in a power adder situation.

I run the NGK BKR6E in my 505 , same plug in my 440 . 505 is 11:1.
Never any issues . Under 10:1 NA I would run -5
These are projected plugs.
Only thing with NGK's is they hate being over fuelled .

Tex

That's good info and I like the fact that you race it and get real world tested info which is helpful for some of us in a similar scenario.......Dyno stuff for sure has it's place especially a chassis dyno in a real world load zone simulating going down the street or track but, I still have tried adding more fuel, timing air pressure and launch/suspension settings to get more out of my car and a few others along the way............

Maate !
I am only a slowpoke compared with most on here .

Tex

Not about that, if your hard testing can reveal real world results of course in your racing atmosphere/conditions, then we all learn some cool stuff and can pass it on.............

Here's an NGK non projected -7 in a 505 with 11-1 on 93 pump gas

here is my projected tip -5 ngk, has some carbon on it , but I would expect that, they have been in there since day one, 4000 miles, mostly street , seven 1/4 mile passes in the heat of summer & no detonation. like I said 512,9.5 comp , small solid.

What's w/those ashy deposits.........

the camera made them look lighter, its black carbon build up,a lot of tuning & the AFR was rich at different times.

I had a REAL hard time getting the transfer slots, cruise AFR to lean out, I should have asked you for help its all good now.

They developed that twin ground plug to combat misfires to save cat converters. I started seeing them in Tacoma pick-up trucks with the 3.4 engine. I am currently running Denso iridium plugs for a Toyota Tundra in my 10.9 compression 493 with Indy EZ heads and they run perfect all year long.
I have considered using the twin ground plugs but it runs so well with the iridium plugs why change

Gus

What type of plug did you run prior to the iridiums? Did you notice anything on the change?

All else being equal, Yes!

OK, this is the first voice with a clear contrary position. Can you share your thoughts on this? Do you think the projected tip is hotter than a standard plug and can act like a hot spot (that was my original thought)?

I'll say this, I do NOT shoot for lean cruise afr's cos we are not efi we have carbs and WET manifolds so richer mixture work/run way better for me and many others I build for. Now I don't mean cruising in the 11's or low 12's but cams w/duration and overlap need to be richer and if I want mileage, I cruise my Ranger..........

No matter what the heat range numbers say for a particular plug ( or comparing different brands of plugs), the farther the porcelain and tip is from the plug housing, the hotter it is going to run. The hotter it runs, the more prone to detonation it is going to be. Just because you can't hear it or see aluminum flecks on stuff, or melted ground straps, etc, doesn't mean your engine isn't running in some degree of detonation. Long before there were knock sensors on engines, I worked in a knock lab ( late 60's ) for a large oil company. An eye opener regarding engine detonation. I wouldn't be surprised if over half the build claims I see on this sight ( running outrageous CR's on pump gas )are running in some degree of detonation. It's just not enough to see / hear or to break stuff - but can be enough to negatively affect performance - and definitely enough to shorten engine life. Hence, knock sensors on all late model performance cars from the factory. KNOCK KNOCK, WHO'S THERE -----------. Hey Thumper, how's tricks?

I understand all that, BUT my Charger is the only car I have to drive, so my AFR is on the edge of lean.

I know of another guy in SO CA that worked in a knock lab also, he lead me to use the projected tip spark plugs in iron headed B and RB motors as well as all of the Mopar hemi motors for drag racing and street use
Same information, different conclusions
I had low compression(true 8.5 to 1) pump gas 350 Chevy boat motor that pinged, knocked, on regular pump gas with a Champion J12Y and quit knocking with a Champion J11Y
I worked in service stations a long time ago before they became gas stations only and I have seen many stock motors that needed the spark plugs heat range changed for the driver
Around town only grandma drive differently than there hot rodder grand kids did
Colder is always safer than a tiny bit to hot when it comes to gasoline and different driving conditions and fuel used

Ran the iridium plugs since the first fire and never tried anything else I've been a tech for close to 35 years and I know how to read my plugs and they have a nice perfect burn on them and I have not heard any detonation even on 90* days with pump 93.
Gus

I ran Bosch platinums with good results years ago, but Chuck Senatore at Muscle Motors said he'd seen detonation problems when they were used with multi-strike ignitions. When I switched to a Crane HI-6, I stopped using them because of his comment.

FWIW, Autolite Racing series plugs have worked very well for me since then. Some are available w/ projected tips and all of them have the ground strap cut back to expose the electrode better.

Who's tricks...........I missed something.......

So because of this thread, I pulled the RN12Y plugs out of my 340 6 pack, and went back to the RN9Y. I could hear some detonation on light acceleration. I have been running octane booster. Plugs I took out have a red tint on them. Can anyone explain?

Red tint is most likely from the octane booster.

So should I cut back on the octane booster or just see how the RN9Ys look after some road time?

I prefer the C series but if the 13/16 hex isn't a nightmare than I it's ok.

Don't know your combo but I run a 12 Champion on 11:1 pump gas.

That was sort of what I was thinking but then I realized I didn't know the details of the heat rating of a plug. Does it represent the temperature at the electrode? If so, then equivalent plugs would have the same temperature (although it would be located in a different spot in the chamber). If the rating represents the temperature at the porcelain at the body of the plug (where the actual control point is) then the tips would clearly be different temperatures. Any one know what portion of the plug the heat rating is based on?

I agree colder is always safer when balanced against the negative of too cold. Can you explain more on the "same information, different conclusions"? Are you indicated that your source also felt projected tip were more prone to detonation but had some other benefit that outweighed it? Or that the standard plug was more prone?

I guess it comes down to a balance of many factors, like most things. I am still not sure what type of plug to get, but at least they are not too expensive in the grand scheme!

Juat sayin Hi Thumper. To Cab; I'm not sayin don't run extended core plugs. Just sayin they will run hotter, all else being equal. Ran them in my wedge motors all the time back in the day. They helped to solve a lot of problems such as poor intake runner and combustion chamber design, poor fuel distribution, weak ignitions, etc. A lot of them lived due to high octane leaded fuel. If you can run them and don't end up with the attached pic, by all means, run them. BTY, the pic is the result of running a way wrong heat range plug - and running a little lean.

Same piston exposed to detonation. BTW, never heard it until the damage was done.

You had the same experience that a lot of racers and hot rodders have, they don't hear it until the motor quits or starts smoking
I learned to look at the plugs frequently until I knew the tune up was safe
On my stock 415 HP M.W. on the old 100+ octane high lead pump fuel in 1971 to 1973, it liked the stock J11Y, not the J10y or the hotter J12Y spark plugs. I could hear the difference in idling right away, I could see the differences in on the plugs with one full WOT blast down the street
As far as heat on the plug tip the center porclyn determines what the tip temperature will be, retracted or projected
More porclyn around the center electrode less heat transfer

Just to interject something I know doesn't answer the question. The most detonation resistant plug I've seen with in car, and on dyno experience is an NGK 6061-10. That is against autolite AR series, and champions true race series plugs.

Can't copy the pic, but look at the electrode, and strap arrangement in the link.


http://static.summitracing.com/global/images/prod/large/NGK-5962_w.jpg

Plug electrode heat build up transfers through the porcelain to the plug main body. The farther it is from the main body, the less heat transfer there will be and the hotter the electrode will run. What I was always taught. By 73 high lead content fuel was being phased out as it was killimg convertors - and us of course. Attached is a comparison of 3 plugs that I have run in the past in my SB. Right 2 are NGK's. Left is a Champ. Right plug is by far the coldest (-9) which I run in my blower motor. Left 2 I have run in NA motors and they would not survive in my blower motor. All worked well in the proper environment.

Hi back at ya and are these your blower pistons.......

Yes. I'm a slow learner.

Not apples to apples in a power adder situation and I've been using projected tips forever w/zreo issues as long as the carb/timing are where they need to be.............

True. Can't remember for sure, but with the boost I was running the static CR figured out to be around 17 -18:1. Projected tip plugs don't live there.

I was told by many E85 users to use retracted gap plugs in my E 85 bracket motor, I do
As far as blower motors I was told the same thing on not using projected gap plugs in them, I have found out since then that on blown gas hemi motor the projected gap plugs use under 12.0 lbs. of boost live a long time if the fuel and timing are close to correct

Yep, I did a pair of carbs for a blown 588 BB Chevy in a 25" Eliminator boat and they need the non projected plugs and a bit colder accordingly...........fires right up w/the bump of the key and he lifted at 115 mph at only 5200 rpm stating "It's too fing fast" but would fall on it's face prior...........Power adder stuff is in it's own tuning world imo............

Smokey Yunick invented the projected tip plug--it has been std equip for 40-50 years now?? They are supposed to idle cleaner and better
I have been a hot rod nut and engine guy all my life --I have never had a better plug or better plug company than NGK--quality is unsurpassed--tech line answers phone on first rings and if you give correct info--all ya need is correct compression ratio--fuel type--and the proper thread engagement stuff like always They will put you ON THE MONEY first time if you give correct info Then you order off Ebay with free shipping and no sales tax and get the best for less--I tell this tale again and again but folks fight it and always have other opinions---
Yes Autolite race plugs and Champion race series are good plugs but tech is almost non-existent and price is just stupid compared to NGK on Egay
Just try call NGK tech which you can Google
These are the best quality plugs available Japanese made --superior quality--Amazing tech support--and best price of all the quality units available
Quit fighting City Hall and try em will ya???

I have not been sure what part of plug is used for the heat rating. Found this link this evening:

https://www.ngksparkplugs.com/about-ngk/tech-talk/spark-plug-basics

The description that NGK provides indicates to me that the heat rating does reflect the tip/electrode end of the plug. That should mean that a projected and non-projected tip plug of the same heat rating would have approximately the same temperature at the electrode. That temperature point is placed in a different location in the combustion chamber though.

Now your learning from a good source

Totally agree on the NGK thing

I'd like to see some ACTUAL results from using different brands of the same heat range plugs. I would guess that there wouldn't be much difference to measure. I would have to say yes to the original question. At some point sharp edges and projectile tips will retain more heat in the combustion chamber. Common sense.

- as long as you don't read anything else in to the question - which is NOT SOP for this site - which is ok.

Just ordered a set in a 6. See how those do. I put ngk race 7's in and had an intermittant misfire.

Unless you have a bad plug, connection or ? no reason the 7's should cause a misfire as I've run em w/zero issues at 12.1.1 comp..........

Dont know but definitely had more misfires on the race 7's than the projected tip 5's. Could be that running on the edge of rich may not clean off the 7 like it does the 5's. Gonna leave the 7's awhile and see how they work out.

We run R5671-8 NGK with 13.7:1 on alky perfect!
It is a recessed tip we use an old Vertex magneto run the gap about .018
It lights a 10% nitro alky mix perfectly would run more nitro but have way to much compression--next one is an 11:1 so we can lay the juice to it!
I will call NGK and buy exactly what they say

No experience ever running hotter than maybe a 6 in ngk and that's too hot for most of what I mess with but you are close to 11.1 iirc so not exactly low comp. and if in fact it liked the 5's I'd look real close at the porcelain w/a mag. glass and see how they look but still say #7 if the tunes close............... Just re read that you ran non projected tips in a 7..........Is that correct cos that's not the best plug for you imo, get the 7 projected tip and let tune this thing............

Yes, the non projected tip race plug in a 7. I misunderstood you. Thought thats what i needed. The 5's looked too hot to me as the ground straps are burned white almost to the weld on the shell. I have some 6's with the double strap on the way. Ill try those next.

No biggie but I thought I gave you the stocking # 5030 and plug number BCP7ES but either way, get these and see if they help.............

yes you did, but you also gave me a stock # 7173, which is what i used to run in my small block. no big deal thou. ill try the new 6's when they get here. until then, i will use the 7 race plug. thanks

I would dump the race plug and the 7173's are the projected tip 8's..........You will chase your damn tail if you you don't do it right the first time............

Does the non resistor part cause problems?

I use Ice ignition. They recommend a non resistor plug. resistors work find in it as well.