tr55 or tr6 for my application?

[Robmnrd]

(Cliffs at bottom for those that don't feel like reading my novel. lol)

Hey guys, I'm planning to do a plug swap today/tomorrow (fun labor day activity? lol) but I'm having trouble deciding which plug is correct for my application. Based on the searching I've been doing it sounds like my car is a 'right in the middle' kind of build and something like a tr55-6 would be perfect...if it existed.

It would seem the most important factors when deciding what plug to get are N/A vs. FI, CR, power production, ignition system, and to a lesser extent things like underhood temp. My research has more or less brought me to the conclusion that anywhere from a stock car to a cam only+bolt ons type car will be perfectly fine with the tr55 and may actually perform worse with the tr6. I have also concluded that cars with H/C/I+bigger bumps in compression, or FI cars, high hp cars etc. need the colder tr6.

My problem is that while my car is a H/C/I+higher (than stock) compression build, it's not an all-out high hp type build like all the examples I found while searching seemed to be. My CR is just over 11:1; not exactly pushing it and not a huge jump from stock. I've never had it dynoed but Lloyd specced the build to be ~360-375 to the wheels; pretty far from what is possible out of a H/C/I build and hardly "pushing it". So I'm having trouble figuring out which plug I should go with since it seems like the tr55 might be too hot but the tr6 might be too cold (is there a goldilocks plug for me? ) I guess I'm hoping someone on here has already experimented with the two and a somewhat similar build to mine and can chime in.

Cliffs:

Mild H/C/I build (~11:1 CR, ~365 rwhp)
Stock ignition system
Seems like tr55 might be too hot, but tr6 might be too cold
Which one do I get?

Hope to get some answers, I wanna get this started soon! lol

Edit: One last question, stock gap is .05 but it looks like I might want to close that a little. Any input from you guys? .045 maybe? Or maybe all the way to .04?

[Nocooler]

TR6's are half a step colder than TR55's

Either will work honestly and I doubt you'll notice much difference between the 2.

If you daily drive it - I'd stick with the TR55's, if you race it the 6's will probably be better.

[Robmnrd]

TR6's are half a step colder than TR55's

Either will work honestly and I doubt you'll notice much difference between the 2.

If you daily drive it - I'd stick with the TR55's, if you race it the 6's will probably be better.

Hey thanks for the reply!

I ended up going with Autolite 104s, because I was smart and pulled one out to see what I put in waaaaaay back when I did the H/C/I originally (should have thought about that to begin with lol). They are what LE recommended back then so I feel fine about using them again. I think they are equivalent to the tr55, more or less, and it is a daily driver like you were saying.

I couldn't get a decisive answer on gapping them though so after doing a bit more research I concluded that I'd probably be fine anywhere in the 35-40 range, so I am gapping them at ~37. I don't think anything about my build would necessitate closing the gap more than that, but worst case scenario I just pull them back out in a couple hundred miles if things aren't 100% right.

So if anybody has a similar build to mine and wants to know about spark plugs, this thread is for you!

[1BADAIR]

tr5= heat 5 .040 gap
tr55 = heat 5 .058 gap
tr6= heat 6 .40 gap
either should work without issue

[Robmnrd]

Ugh, pulling them again already. >.< Finished the swap yesterday and started it up, seemed like everything was okay but I was blocked in with my brother changing brake pads on his car behind mine so I didn't take it for a drive to be sure. Went to class this morning and there's definitely a problem. About 90% of the time one (or more) cylinders isn't firing or isn't adequately firing, and then the other 10% of the time you get a nice kick in the butt as you get full power. Checked wires after class, all of them are on tight and I made sure to move them as far from the headers as possible in case they are arcing (They're further from them now than before the swap...) and still not running right.

Right now my two guesses are that the plugs are gapped incorrectly or one (or more) are cracked/broken. I e-mailed Lloyd and asked him for his recommendation for gapping the plugs and he confirmed that I should be using 104s but gap them to .035, and I was gapping them probably to about .04. I'm not sure if the .005 difference is enough to cause this issue but I'm gonna fix it anyway. While swapping passenger side plugs, two of the new ones were dropped but they seemed like "soft" drops so I gambled and used them anyway - I'm betting with my luck that one or both of them has a hairline crack that I couldn't see before I put them in. So while my car cools down I'm gonna go buy another 4 plugs and replace the two that I dropped as well as have a couple extras "just in case". Regap them all to .035, make sure the wires are tucked far away from the headers...and hope for the best.

Wish me luck! lol

[JoeliusZ28]

My car definitely prefers the TR6 i have a cam only build with 11.5:1. Id go tr6s personally, use a conservative gap to keep the opti happy.

[Robmnrd]

My car definitely prefers the TR6 i have a cam only build with 11.5:1. Id go tr6s personally, use a conservative gap to keep the opti happy.

Yeah, it seems like my buildmight be juuuuuuust enough that at a minimum keeping the gap tight is in order. If after this round of gapping/installing things still aren't quite right I'm probably just gonna do a full plug/wire swap and go with the tr6s and a nice set of wires. Not that I advocate randomly buying parts to try to fix a problem, but I have no idea how old the wires are so who knows...maybe I coincidentally damaged one/caused one to be damaged at the same time I did my plugs lol

[Robmnrd]

Mystery partially solved?

So I pulled one of the ones I dropped yesterday and I think it's safe to say there was a problem with it (picture included of what I found...lol.)

SP2.jpg

I don't think it's supposed to look like that...especially since my engine actually runs pretty clean considering it's a pcmforless tune - all the old ones I pulled looked basically spot-on where you'd want them to be.

Well after seeing this I replaced it with a new plug gapped at .035 and decided I might as well give it a shot and she started up and idled better than before. However (there's always a however) when I took her for a test drive things still weren't quite right. Under light throttle/load and while cruising there is more bucking and lunging than before I began my plug swap this weekend; she just runs a little rougher than before overall I guess. The strange part though is that under high throttle/rpms she feels like she has more power than before the plug swap.

I can't explain that part since it seems somewhat counter-intuitive. So I've decided once she cools back down again I'm gonna start "randomly" pulling plugs and seeing what they look like, and then putting them back in gapped at .035. If they're looking good overall then I'm gonna start looking for gremlins in my plug wires.

If anyone has any input on why a plug swap would result in worse normal-driving manners but better high throttle/WOT pull I'm all ears as it's a new one in my book. lol.

[1BADAIR]

is the wire good? if youn pulled on the wire and not the boot the wire is probably torn. .05 shouldnt cause an issue. WOt takes more amperage so the coils will put out more to couteract a bad plug or wire

[Robmnrd]

is the wire good? if youn pulled on the wire and not the boot the wire is probably torn. .05 shouldnt cause an issue. WOt takes more amperage so the coils will put out more to couteract a bad plug or wire

I always do my best to pull against the boot of the wire, but I'm not going to say "no I guarantee I didn't pull the wire" since it's definitely possible that I did that on accident. I'm going to pull a couple plugs from the drivers side and whichever one I think will be easiest on the passenger side tonight and see how they look, regap them and put them back in. Assuming the three more I do tonight all look good then I'm going to move on and assume that you are right and there is a problem with a wire.

Is it still possible to get the packard-produced oem wires still? I heard that for an otherwise stock ignition system they are a lot better than most aftermarket wires. Any input on that?

[JoeliusZ28]

Sounds like wires to me too, especially if the bucking is heavy throttle down low

[Robmnrd]

Sounds like wires to me too, especially if the bucking is heavy throttle down low

Well I have an update. I pulled all four from the driver side (I'm getting good at it! Had them all out, regapped and back in in 60 mins flat! lol) and they all looked good which was a relief. I then pulled one from the passenger side and it also looked good. Regapped it and put it back in. Decided I would take another test drive and it was definitely running smoother than the earlier test drive. A lot smoother. It still doesn't seem 100% like pre-plug-swap but the overall improvement suggests to me that if I pull the other two plugs from the passenger side that I haven't done yet, and regap them correctly, then it'll probably basically be fixed.

So my plan for tomorrow when I have daylight is:

Pull the two plugs I haven't pulled yet and regap them.
Put them back in.
Pull the one I posted the picture of to see if it's black again or looking normal.
If it's black, I think it's safe to say I have a wire issue.
If it's good then it was just the combination of incorrect-gapping and a bad plug that caused my issues.

I'm feeling confident that it'll be sorted out by the last two plugs, but even if it isn't I've requested a (potentially early) birthday present of high quality cut-to-length spark plug wires, so if I have a wire problem it'll be fixed about as well as possible.

As a side-note thing, what do you guys know about how long it takes the pcm to re-learn everything when the battery has been disconnected for multiple hours? For whatever reason I decided it would be smart to do that when I did the first swap as well as the first plug check I did earlier today - could my pcm re-learning everything be a portion of my issue? I know in the past when I would have the battery disconnected for a few hours the first start and first few minutes of idling would be kinda tough, but would everything be basically fixed after about 5 mins of driving?

Edit:

Good God I need to work on not writing novels for posts....sorry guys lol

[JoeliusZ28]

(I'm getting good at it! Had them all out, regapped and back in in 60 mins flat! lol)

Your new goal is to match my time of all 8 plugs and wires in an hour and a half

Also, what kind of headers do you have? I had bad luck with cut to length stuff. My first set of taylors arced horribly. My next set of wires were MSDs which I think were fine, but the opti boots fit so snugly it was impossible to get them on after the crimp without destroying the wire after so the end result was the same. A nice set of factory AC Delco wires solved all my issues, and thats the only thing I will put on my car anymore. I dont have any clearance issues with my pacesetter headers, and I didnt even use the factory looms, just zip ties to hold them away from the primaries.

[Robmnrd]

Your new goal is to match my time of all 8 plugs and wires in an hour and a half

Also, what kind of headers do you have? I had bad luck with cut to length stuff. My first set of taylors arced horribly. My next set of wires were MSDs which I think were fine, but the opti boots fit so snugly it was impossible to get them on after the crimp without destroying the wire after so the end result was the same. A nice set of factory AC Delco wires solved all my issues, and thats the only thing I will put on my car anymore. I dont have any clearance issues with my pacesetter headers, and I didnt even use the factory looms, just zip ties to hold them away from the primaries.

I can see getting good enough to do all 8 plugs in 1-1.5 hours...but wires too? That makes me go

I've got LPPs, the first batch not the revised ones. The driver's side is really pretty easy to work around; I could probably time-attack that side and get the plugs out and back in somewhere around the 45 min mark. Passenger side not so much...theyre a fairly large header with thick flanges and 1-3/4 stepped to 1-7/8 primaries so even just getting the plug threaded is a pain on that side. >.< I'm a pretty big dude with big hands too so it's a real tight squeeze. lol.

Yeah I've heard from more than one source that unless you've got a pretty impressively modded ignition system the stock wires are the way to go under most circumstances. Thanks for the tip on the cut-to-length ones; I'll save some birthday cash!

[JoeliusZ28]

ah, you will have a harder time with those headers, i couldnt do it in 1.5 hours either Good luck!