Denso plugs

[usgecko]

Another dumb question from a newbie here - I see a lot of you have Denso plugs as mods.
I got 3 q's for you:

1)What are the advantages here ?
2)How easy are they to change ?
3)Would their installation upset factory warranty ?

[MM03MOK]

Originally posted by usgecko
1)What are the advantages here ?
Dennis said so!!

[RF Overlord]

1) Although they add a few HP by themselves, they're really part of a "package" with the chip (or re-flashed ECM) and a cooler thermostat, that allow Dennis's programming to work at its best...

2) They are VERY easy to change.

3) ANYTHING you do to this car "may" void the warranty, if your dealer chooses to pursue that line...but the dealer would be more likely to void it for having a chip than for having the plugs...this is a very gray area; for instance, some dealers will happily install the 4.10 gears and honor the warranty, but some absolutely refuse (like mine :rolleyes: )...

[studio460]

I just ordered a set of Denso IT-22s from Reinhart Automotive (two steps colder--Dennis said that it'll be fine for my N/A Marauder) instead of the IT-20s since I plan on getting a supercharger later this year anyway. I'll be getting the Densos and the 180° thermostat next week to complement my recent dynotune from Jerry. I just have two questions . . .

1. Are the Densos pre-gapped? If not, what gap?
2. What is the torque ft.lb. spec for wrenching the plugs?

Thanks.

[studio460]

Hello . . . Anyone?

[MarauderMike]

I think everyone must be in Hershey:D

[chapel1]

I put my denso's in just before my powertune.Make sure you use alittle antiseize on the threads,just alittle.They come pregapped.I put my old one back into the Denso boxes.You'll know when you remove the old ones how much force you"ll need to put the new ones in.Make sure your spark plug socket is secure to your extension you won't believe how far in the plugs are or how long the spark plug boot is.
PS You don't heed alot of force just make sure you hand start them and don't be in a hurry.

[Petrograde]

Torque?,... I asked Dennis this question when I bought them. He said "just snug them down."

[studio460]

Thanks, guys.

I finally found an old post from Bunny, and she said it's "11 ft.lbs." The Denso box says a "1/16 turn" after it's tight for "taper-seat" plugs, which apparently these are. Someone else posted a Ford-recommended gap spec of 0.052"-0.056" for non-Denso, Motorcraft factory plugs. Due to the significant design difference between the two makes of plugs, that spec may not necessarily be directly applicable to the Densos, I'm guessing. But I know you're really not supposed to gap them manually because you run the risk of damaging the electrode. Dennis Reinhart made an explicit post NOT to gap the Densos. After visual inspection with a gap gauge, the Densos I received from Dennis looked very close to 0.050" as delivered, and I'm leaving them that way.

Thanks, chapel1, for the tip about using anti-seize. Got some Permatex anti-seize and will use very sparingly. I found an old thread about the "dangers" of using anti-seize--the thread was split whether you should use it or not. I'm still going to use it--but an extremely light application.

So, to summarize [edited to include RF's Denso information]:

Spark Plug Gap and Torque Specs for Denso Iridium Plugs:

Denso IT-20 [1-step "colder" for normally aspirated engines]
Denso IT-22 [2-steps "colder" for supercharged engines]

Torque: 11 ft.lbs. (1/16 turn for taper-seat or 7-15 ft.lbs., according to Denso. I found 11 ft.lbs. to "feel" just right).
Gap: Denso recommends 0.050" gap; Ford 4.6L spec. for factory Motorcraft plugs 0.052"-0.056"; however, although Dennis Reinhart does not recommend regapping the Densos--it's your decision to regap or not (although, if I were to do it again, I would attempt to CAREFULLY regap to Denso's spec of 0.050").
Anti-seize: No definitive recommendation (anti-seize not applied to factory plugs). Personally, I did apply anti-seize.
Electrolyctic grease: applied to insulator and inside of boot as indicated by Permatex directions (electrolyctic grease is present on factory boots).

Just re-editing this post after installation. Factory plugs' gap were dead on at about 0.052" upon inspection after removal. The Denso IT-22s appeared to be much tighter than that, at perhaps, 0.040" but I still left them as is, and did not attempt to readjust the gap simply because I just knew I'd ****** up at least one of the plugs!

[RF Overlord]

'Shooter:

I think you've summarised it pretty well...

LML: maybe that should be in the FAQ...?

[BillyGman]

gapped them to Ford spec.....didn't brake nuthin.....and the car runs great......and ya don't need any torque spec. Ya just turn em til ya feel em stop.

[studio460]

Well, I need a torque spec, since the last time I torqued a spark plug in an aluminum engine was 1978! I have NO IDEA how much is too much!

[BillyGman]

but you don't need to overthink this one. it's a piece of cake. I do fully agree w/the recommendation to use the anti-seize compound on the sparkplug threads. That's needed because of the metal of the plugs being steel, while the cylinder heads that the plugs are being threaded into are aluminum. I'm an aircraft mechanic, and at my workplace whenever we install any hardware that is of a different metal than the parent material that it's being installed into, we use a zinc chromate type primer on the threads to prevent corrosion. When dissimilar metals stay in contact w/eachother for awhile, there's a tendency for a chemical reaction to take place that will cause corrosion.

[studio460]

None taken! It was your post on the other Denso thread that I stole the gap spec from! Although I actually agree with your post on the other thread, I hesitated to regap because I'd thought maybe the gap spec may be slightly different for the Densos than the one specified by Ford for the Motorcraft plugs due to the differences in design. I had planned to regap to 0.052" just like you said in your post, but I just knew my clumsy hands would've ******ed up the darn electrode! Good to know about your use of anti-seize compounds on aircraft applications.

[BillyGman]

I can get pretty fussy while working on my cars. The times when I've worked w/my brother on these car projects, I drive him nuts because I tend to be very methodical too. But in my efforts to pay attention to detail, my experience w/working on Helicopters (I work at Sikorsky Aircraft) sometimes comes in handy since any aircraft has to be built more carefully and w/tighter quality control than a car does. And incase the reason for that isn't obvious, then I'll state that if there's a mechanical failure due to workmanship on a car which effects driveability or causes the engine to misfire or shut down, then the end result would usually be no worse than the driver of the car in question to be stranded on the road and have to walk home. But if it's an aircraft and there's a similar mechanical failure, the pilot and passengers will die.

[Ross]

I haven't changed the plugs on my MM, but I have a question about gapping the Denso's. We all know that a proper gap is critical on any plug, and we all know that some mechanical parts can be different from others, either because of accidents at the factory or other factors. I know that in the past I have sometimes bought a set of plain old AC or Champion plugs, and they had different gaps from the factory. Are Denso's made with such perfect quality control that we can blindly put them in without at least checking the gap to make sure that they are all just right? What if one is banged around in shipment or dropped and the gap changes? It seems like a small step to take, and an important one, to know what the Denso gap should be, and to check it before putting it in, then correcting it if necessary. Maybe I'm wrong on this, and my ancient technology is way out of date, so please correct me.

[Lidio]

I know this is probably going to disappoint a few people and maybe even upset a lot of you toward me. But I've always based what we do at our facilities for 13 years now on honest performance upgrades that work and are realistic. I've said this to many, many people for over a decade now that they're aren't any miracles in spark plugs!!

We recently had a Marauder on our chassis dyno and made four solid clean stable runs with it and it averaged 239 at the rear wheels.
While it was still strapped to the dyno, we installed the proper Denzo's and changed nothing else. It proceeded to make an average of about 239RWHP still. Sorry for raining on some your parades but the only time I've seen plugs make a worth while difference is when the vehicle was way over due for a plug change or tune-up.

Colder plugs and messing with heat ranges can play a role in other aspects of tuning on some applications but the only argument and point I want to make is that the plugs them selves seem to do nothing when replacing a perfectly good plug.
Most Dyno operators who will claim small bolt-ons like this make big differences typically come up with inconclusive dyno results because they didn't wait for the engine to fully stabilize before making a full pull. And some people will make a change to a car and re-dyno it on a different day. I've seen just different tie down tension's for the car on the dyno and tire pressures show different numbers at the rear wheels.

Sorry for stating facts I've seen and proved up close. I can post all the dyno sheets if needed.


Thanks

[prchrman]

thanks Lidio...I do believe you...no rain here...just happy someone told the truth...if all mods got their supposed HP gains it would take nothing to get a 400hp motor...but it just don't happen in the real world...again thanks and no flames here...willie

[BillyGman]

something that hasn't been covered here w/this gap thing, my line of thinking on this is that if these Denso plugs were so much different that they actually required a different gap, then I'm sure that the manufacture would clearly state that on each plug box. It's the engine that the plugs go into that is the biggest factor that dictates the gap. Especially the ingnition system of the engine in question. The reason that the automobile manufacture lists a gap spec in their shop manuals as well as in the generic manuals that can be found in any auto parts store is because that gap spec will be the same regardless of the brand of plug used. If you ever changed the ignition system to an aftermarket one that was intended by the manufacture to be an improvement over the stock ignition, you would notice that the ignition manufacture lists in the instruction manual the recommended gap which will be a different setting than the car manufacture listed for the stock configuration(ie the stock ignition). And it doesn't list what brand of plug to use since the brand of plug isn't very important in the way of the gap setting. Really, this is becoming more of an issue here than it needs to be. When I bought the Denso plugs from Dennis, I checked the gap on all 8 of them, and four of them were .010" different than the other four. So if the gap was supposed to be different than the car manufacture calls out for, then how would I know which four were correct since there isn't a gap spec listed by Denso? So again, I'll state that the plug gap needed is .052-.056"(the Ford spec.). I'm through w/this subject unless Dennis jumps in here w/something profound which I highly doubt since this really isn't a big issue.

[RF Overlord]

Originally posted by Ross
What if one is banged around in shipment or dropped and the gap changes? It seems like a small step to take, and an important one, to know what the Denso gap should be, and to check it before putting it in, then correcting it if necessary. Maybe I'm wrong on this, and my ancient technology is way out of date, so please correct me.

Ross:

The Denso plugs come with a plastic collar that protects the electrodes in shipment...the reason for not re-gapping is that iridium is a very hard, but very brittle metal, and with the centre electrode being so tiny, it is much easier to damage it with conventional gapping tools...if you are very careful, and use the right tool, they CAN be re-gapped successfully, it's just that Dennis has determined it's not necessary for our application, therefore it's not worth the risk...

[Ross]

Those posts were exactly what I was getting at. If the plugs are shipped with special packaging to prevent damage like Overlord said, that could help minimize one of the gap problems I was talking about. On the other hand, like Billy said, no quality control program is perfect, and he has found different out of the box gaps on his Denso plugs. Therefore, some of the plugs will have to be regapped, whether you want to or not. You're certainly not going to install 4 plugs with one gap and 4 plugs with a different gap, right?

[TripleTransAm]

I agree about the 'no miracles' part of the thread, but only among new spark plugs. The fact remains that different spark plugs will wear differently... example, the stock A/C plugs on LS1s tend to burn away the platinum pucks rather quickly, and that renders them out of spec due to the ensuing silly plug gap that remains (they're already huge at 0.060). I know this is just another example of older plugs needing replacing, but my point is that some plugs get to that stage sooner than others.

And that discrepancy mentioned by Gman as far as plug gaps... yikes. Count me as one of the guys who WILL be checking the gaps once I get those plugs. I see big differences in some engines with plug gap changes, my LS1 being one of them. I'll be gapping my MM's plugs on the short side of the range.

[SergntMac]

I am inclined to agree, and disagree, with Lidio.

I agree that there are no "miracle" mods. I disagree that the Denso plugs do not make power.

My experience with the Denso plugs (IT20) on my first MM showed clear and defining dyno results. Not specatular differences, mind you, only 4 HP and 3 LBs TQ, but a difference nonetheless.

The car remained strapped down on the dyno for the change in plugs and stat. The engine was allowed to cool down between pulls. The stat was changed to the 180, and the cooling system refilled and warmed up to operating temps before the test pull.

Adding things up back then, the bang for the buck was present in terms of a small fine tune that added power that could be seen on the test machine. Moreover, these mods provided flawless operation on the street.

There is a concept and process of fine tuning our MMs for premium performance, and this is one of those mods. Reinhart stated back then that bringing down engine temps and adding a cooler spark optimizes the combustion process, and I was able to prove he was right. Adding up all the small fine tunes contributes to the overall performance of the car, and when you're wanting to lower those ETs, every step helps.

I've done dyno testing with other mods, in fact I tested everything in Stage I and II to prove (or disprove) Reinhart's claims. I came to test the Stallion Torque Converter (single plate) and got zero performance on the dyno. Anyone want to challenge that mod's performance, or, value on the street? My first MM made 271 RWHP and 301 RWTQ, and ran consistent at 14.2x when I sold her. The first 30 or so HP and TQ gains were big mods, like the Reinhart chip and a "Jerry tune." The rest were small fine tunes that collected together in the end result. Had I passed on making those mods because they were insignificant by themselves, as prechman suggests, where would I be today?

Not everything shows on the dyno, it's just a test tool. The proof is on the time slip from the other test tool, agreed?

prchrman...I'm disappointed to read your opinion, I hope I misunderstand your position. These expressions here are our opinions and thoughts, hopefully based on our actual experience. I respect Lidio's views, but I would expect him to differ in perspective and results due to the nature of his collective experience. I've spent as much time under the hood of one MM as he has under the hoods of many MMs. To say that one tells the truth, implies that others are not truthful, and that is simply not the case. Build your car, Willie, add your mods, see what you have to say then?

[RF Overlord]

The Denso web site specifies 7-15 ft/lbs for 14mm taper-seat plugs in aluminium heads, and a .050" gap for the Marauder...

[chapel1]

Do not paint the anti seize on your threads.If you get the anti seize on thinly on only a couple threads you will have a enough.
At are dyno tune my stock Marauder pulled more HP and Torque then the other stock Marauder's.

[Smokie]

I believe Lidio and I also believe the Sarge, the difference or lack of difference that "only plugs" make on a dyno can truthfully fall in either direction. I don't have a "very powerful" Marauder and perhaps that is why I "did" notice a difference in the throttle response and idle smoothness of my car. Dennis told me no gapping was needed and I installed them as they arrived. I have no numbers or specs to prove or disprove anything, and since the plugs had to only satisfy (or not satisfy) me, my judgement was all that mattered. In a highly modified very powerful Marauder the change of plugs probably would go totally unnoticed, it helped my car; does anything else really matter ? :)

[RF Overlord]

Smokie, you hit the nail on the head...the only thing that should matter is whether one feels good about one's own car... :D

[studio460]

Good job, RF! Thanks for doing the legwork on this one! By the way, I changed to the colder Densos because I am experiencing some minor detonation at low idle, under throttle after my recent dynotune. Changed the plugs last night. Problem still remains. Haven't gotten a chance to install the 180° thermostat yet. Jerry is sending a new file to a tuner north of Los Angeles to re-flash my EEC.

By the way, I think Lidio's post was refreshing, thanks Lidio! Actually, I think everyone on this thread has made valid points--thanks for everyone's input!

P.S. Oh, and another thing . . . 11 ft.lbs. "felt" just right on my torque wrench, and resulted in anywhere from a 1/8 to 1/4 turn past finger tight (the box says 1/16 turn).

[studio460]

Okay, I re-edited the summary post earlier in this thread to reflect RF's contributions on Denso's specs. By the way, BillyGman, I DON'T think you're being too fussy at all! I believe the plugs should be gapped to Denso's specs, spot on!

[SergntMac]

Originally posted by NBC Shooter
I changed to the colder Densos because I am experiencing some minor detonation at low idle, under throttle after my recent dynotune. Changed the plugs last night. Problem still remains. Haven't gotten a chance to install the 180° thermostat yet.

Ypu may want to give Dennis a call on this, but as I recall his instructions, he said NOT to use the Denso plugs WITHOUT the 180 stat in place. You may be causing your own detonation problems. Just a thought...

[TripleTransAm]

Originally posted by NBC Shooter
Oh, and another thing . . . 11 ft.lbs. "felt" just right on my torque wrench,


You must be a real whiz with the ladies, NBC... women love sensitive fingers.

:lol:

[Ross]

TTA, please don't encourage NBC...:nono:

[studio460]

Originally posted by SergntMac
Ypu may want to give Dennis a call on this, but as I recall his instructions, he said NOT to use the Denso plugs WITHOUT the 180 stat in place. You may be causing your own detonation problems. Just a thought...

Thanks, Sarge. But the detonation issues occured immediately after the dynotune when my Marauder was 100% stock (except for the Steeda underdrives added that day). I added the Densos as a stop-gap. Ran out of time to change the stat too. Plan on changing stat ASAP. I am in contact with SCT and they are trying to resolve this remotely.