I have seen it mentioned on here that 3rd gen RX-7 plugs can be used on our cars.

But I havn't seen much concrete information on it. Considering the huge difference in price I'm curious, do they work without issue?

 

Rotary God Says they do Thread
So long as you don't leave them in for 100,000 miles I see no reason not to use the RX-7 plugs but change them every 30,000 miles or sooner. I guess the thing to think about is a 9,000 RPM Renesis harder on plugs than a twin turbo FD?? I think the FD was harder on the plugs so FD plugs should work fine.

 

Your avatar makes me trust you.

 

Also, I read something about the trailing plug being a different length...and insight on that?

 

The RX-7 plugs work fine. There are many people running them in RX-8's. The plugs are physically the same length. The only difference I can think of would be the length of the ceramic element due to the heat range differences between the 7's and 9's.

 

Mazsport sells RX-7 NGK Platinum plugs for the RX-8, with shims on the trailing plugs to make the plug closer to OEM spec.
These are the plugs i'm running now... and they are working just fine.

-hS

 

sweet, if I were to go to the parts store, what part numbers should I ask for?

Nevermind, I found them. RX-7 platinum plugs for $6 a piece, in stock. I shall get those today.

I'm assuming the shim is not necessary? It will just sit a bit further in without it right? Woohoo! Higher compression here I come!!(kidding).

 

What are the benefits? TIA

 

Platinum RX-7 plugs are $6 a pop.

The cheapest I've ever seen a RX-8 plug is $20 a pop.

So a full set for $24 instead of $80 sounds good to me.

I've "heard" that the RX-8 plugs are better at preventing flooding, but the RX-7 plugs have also been redesigned for that as well. Regardless, as long as you're not an asshat and flood your car you'll be fine.

 

Duh, I didn't pick up on the $6 tidbit in your other post... Too late for me since I just spent well over $100 at the dealer at my recent service... But there will be a next time.

 

What are the benefits of the RX-7 plugs? The biggest benefit is that they save your wallet tons of money. I can't see any performance benefits or downsides. They're just cheaper. That's good enough for me.

 

Just got back from the parts store, once the motor cools down I'll throw them in.

 

well, i think the biggest difference would be the metal that makes up the center electrode. the platinum plugs use platinum (duh), and the stock rx8 plugs use iridium.

here's a pic i found on sparkplugs.com (complete with horrid jpeg artifacting), it shows the different properties of the different metals used in spark plugs.


now, what do all these number mean? i think the short of it would be, the platinum plugs won't last as long as the iridium plugs...but i'm not a metalurgist, nor do i play one on tv, so i may be way off.

 

Well at $24 for a set I don't mind replacing them sooner.

On a good note they are in and the car starts, idles and drives very smooth.

But I'm still feeling like I'm lacking some top end. Sometimes I get taht 7500rpm kicks, other times it's just flat up top.

I guess I'll have to take it into the dealer, I just don't want them to replace the spark plugs I just bought. Oh well.

 

well, if you take it to the dealer, and they replace your $24 plugs with $120 (dealer pricing) plugs, then you come out the winnar...unless they charge you for the plugs.

 

Interesting turn of events. I took the car back out to go get some groceries and upon leaving my apartments I hit the gas like I normally do except now the car had more pull to it.

It was raining so I didn't got full throttle, but now the car feels 100% different than when I had first installed the new plugs. It's a good deal better. Hopefully when I take it out after it rains and go WOT the 7500rpm kick will be back, and stay for good.

Maybe somehow the computer had to adjust for new plugs?? The a/f readings could be different now due to a more complete burn and it had to re learn it?? Would make sense seeing as how the plugs I removed were cruddy, looked like they had been through a few floods and just plain nasty.

I bought it from CARMAX less than a month ago and they kept going on about how each car gets a full tune up and an eleventy billion point inspection. My ***. These spark plugs looked like they had seen every single one of those 15,000 miles it had on the clock. I'm very surprised they were not changed during the "full tune up" it was supposed to have gotten before hitting the lot. I mean, these things were horrible. No wonder I had a miss at idle. Now my idle is sikly smooth. Thanks FD spark plugs!!

 

But, Iridium is so cool!!

http://www.theodoregray.com/Periodic.../index.s7.html

 

If you're asking me, I have no clue.

I'm not that up on differen't heat ranges and their benefits and such. If I could benefit from running all leading or all trailing I'd love to know as well.

 

I run 7's in leading and 9's on trailing. The only people that I know who run 9's all the way around are turbo 3rd gens that get driven hard at the track. The type of driving you do will affect this. If you do mostly stop and go city driving, you'll need a different heat range than if you drive on the freeway all the time. The good news is that plugs are cheap so you can pull them out after a while and see what they look like. Then you can try the others for comparison.

 

Rather then start a new thread.......

I bought a new 05 about a month ago.

Having a 100 mile daily commute (other way of traffic) I run 70-80 mph. Once a day on the way home getting on the freeway (about 3 miles from work so its warm) in 3rd gear at 3000 RPM I blast it to about 7500. I know not very exciting. OK sometimes I buzz 8000. There is a bump and just past it I punch it. Just as I pass a lightpole it's hitting 7500. Getting 21-22 MPG since the second tank.

Then I get a notice "Urgent recall". The dealer says all they want to do is check the charging system and I'll get a free oil change. With 3000 miles I take it in.

On picking up the car they tell me they put in new plugs (hotter due to cold weather fouling) and my ECM was "reset". I live in Texas where below 70° is considered "cold". It was 96° on the way home today, typical cool June day.

The last 3 tanks of the same driving have been in the 18 MPG range. Idle is just barely a bit rougher, and letting out the clutch in first takes a wee bit more go pedal.

At 7200 there is a hestiation that wasn't there before.

The lightpole where I was getting 7500 RPM - it now only gets 6600 RPM. BIG difference.

I get the impression the hotter plugs are doind exactly what hotter plugs do - and probably giving just a wee-bit of pre-ignition that the ECM sees as detonation and retarding the timing.

What is the correct heat range of plugs for this car? I don't care if they are platinum, iridium, or even unobtaium, I want the car to run like it did before.

Anyone have good info on this?

 

Start with the RX-7 plugs. Use the 7's in the leading and the 9's in the trailing. Only use NGK. You can get them at O'Reilly. They will say either leading or trailing and the 7's actually have a little "L" on them and the 9's have a little "T". They are only a few bucks a piece so this isn't a bank breaker to try out. If that doesn't work out for you, try the 9's in the leading also. One of those 2 combinations works from naturally aspirated to all but the most extreme turbo RX-7's. This is more effort than money as even 6 plugs total will no only run you less than $30 total. These are not the platinums. Those have to be ordered and are about $2 more each. Try this out and see what happens. It's the cheapest experiment you can do.

 

I found Platinum RX-7 plugs at the local Advance Auto Parts, in stock. In fact the computer showed they had around 40 of each.

After driving for a bit, the new plugs made a world of difference.

 

but see all that money is weight and so in spending more money your car goes faster cause your wallet weighs less

 

After reading this I decided to change mine.

I had about 21k in miles on my car. I went to advance auto parts and picked up the RX7 plugs. They only had the standard, non-platinum plugs so I used those.

I jacked up the car, took the front wheel off and starting taking the old ones off. They were on there TIGHT. I had to use my breaker bar to get two of them off.

I was use to use anti seize so this won't be a problem next time.

My plugs also looked like they could be replaced. Maybe next oil change I will do that.

The car seems to idle smoother, but that could just be the placebo affect. Hopefully I will be getting some better gas mileage next tank.

Here is what my old ones looked like.

 

the car didnt run better because of the platinum plugs. it ran better because you changed bad plugs with good plugs.