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That's not the same plug Renntech sold me...ths is it...note the serrated nut
Serrated nut does not fit into the spark plug hole. That has nothing to do with if its a correct fit for the car. They both use 12mm sockets, stock uses the 12 point and these use a hex
On the left is the plug KLR CLS suggested, it has a 0.025 gap out of the box. However it will not fit due to the seat type.
Middle is the stock plug of course. Has a 0.025 gap
Right is the RennTech colder plug which is supposed to have a 23mm reach (according to NGK themselves). However is you look at it, it is about half a mm to 1mm or so taller than stock! And the extra length is actually coming from the area described as "reach" (from the seat/gasket to the ground). So it is a perfect fit for a colder plug for the E63. It does have a 0.030 gap out of the box.
So why do I still say that stock is better???
Because the Renntech colder plug is an extra fine wire plug and from experience with these plugs (Lexus used them quite a bit back in the early 2000s), they are good for about 50-60k miles on a naturally aspirated engine. So on a boosted engine you can easily cut that by half and on a very boosted engine like a Tuned biturbo, you can say 15 to 20k miles. At that point might as well keep the stock plugs and change them out every year (10-15k a year guys).
Besides the cost factor, is there anything wrong with the Bosch Silver Core plugs that Weistec is offering? I recently had a set installed in my AMS tuned car and no complaints so far.
On the left is the plug KLR CLS suggested, it has a 0.025 gap out of the box. However it will not fit due to the seat type.
Middle is the stock plug of course. Has a 0.025 gap
Right is the RennTech colder plug which is supposed to have a 23mm reach (according to NGK themselves). However is you look at it, it is about half a mm to 1mm or so taller than stock! And the extra length is actually coming from the area described as "reach" (from the seat/gasket to the ground). So it is a perfect fit for a colder plug for the E63. It does have a 0.030 gap out of the box.
So why do I still say that stock is better???
Because the Renntech colder plug is an extra fine wire plug and from experience with these plugs (Lexus used them quite a bit back in the early 2000s), they are good for about 50-60k miles on a naturally aspirated engine. So on a boosted engine you can easily cut that by half and on a very boosted engine like a Tuned biturbo, you can say 15 to 20k miles. At that point might as well keep the stock plugs and change them out every year (10-15k a year guys).
And that's why a physical comparison is always best. Great work kponti. Yes looks like Seat type is taper fit on the NGK's I cross referenced. Need a gasket seat type clearly. Based on those three I would also suggest stock, but still doesn't solve the heat range problem. Also the renntechs seem to have an extra projected tip. I would not recommend those for high boost. that overall design is poor at pulling heat out of the quench area and into the head. I still think brisk QR12Ls would be best due to thick silver core center electrode, and 12 heat range ( 8 on NGK scale). @ 15 bucks a plug seems like best overall option.
And that's why a physical comparison is always best. Great work kponti. Yes looks like Seat type is taper fit on the NGK's I cross referenced. Need a gasket seat type clearly. Based on those three I would also suggest stock, but still doesn't solve the heat range problem. Also the renntechs seem to have an extra projected tip. I would not recommend those for high boost. that overall design is poor at pulling heat out of the quench area and into the head. I still think brisk QR12Ls would be best due to thick silver core center electrode, and 12 heat range ( 8 on NGK scale). @ 15 bucks a plug seems like best overall option.
Care to post some more info on the Qr12ls? I cannot find them
About $15-17 a plug depending on where. Though even with those I'd still recommend new plugs every 15-20K on a tuned car. Start at .022 gap, and those should give you most spark energy and heat capacity for at least 15K miles.
MR12S might also be an option in a non projected tip also at an NGK 8 heat range equivilent:
The general Idea is that since the electrode is closer to the thread body on the plug, it has shorter path to pull heat out into the head and less tendency to burn the ground strap off under extreme load situations. The consensus is they are also more difficult to blow out due to being tighter to the body, and seem to take more timing before pinging than projected tip.
For example I was getting spark blow out in my CTS-V with Iridium tr7ix's, and switched to a BR7EF gapped down and problem went away and car ran great. They will foul easier and are more difficult to read since the insulator is down low in the plug body. They also need more warm up time so cold idle may be rougher, but then same reason makes them safer up top too. Just noticed the MR12s and 10s plugs are also a 14 MM hex which may make install easier than the QR12LS( won't need a special thin wall 16mm to install)
Interesting, something new for me to know. I did notice that the MR12s were suggested for blown applications verses the QR12s, seems to jive with what you said about extended vs recessed.
Look like I do need to find another alternative to plugs on my Renntech tuned car. After I had the AMS cooling installed, I started getting more misfires under boost which goes away after a quick restart. I may try the Weistec plugs or the Brisk MR12s.
Current plugs are stock with less than 500miles on them. Codes are random misfire on random cylinders
What did you gap the stock plugs at? I'd give the Mr12s a shot, they will definitely hold up to boost better than stockers. Gap is crucial. I'd set it at .022 and try from there.
hmm. I've never found a full set of plugs to be properly gapped out of the box. Maybe pull the stockers out, close them up to .020 and see if it make a difference. Only thing to lose is a bit of your time.
I have had a set of the Weistec/Bosch Silver core plugs installed in my car for a few weeks now. They are gaped to their recommended 0.024, not problems so far.
I have had a set of the Weistec/Bosch Silver core plugs installed in my car for a few weeks now. They are gaped to their recommended 0.024, not problems so far.
I was told by my supplier Renntech no longer has spark plugs so I'm going with Wesistec plugs after 5,000 miles.Hate to go into limp mode or misfire.
Originally Posted by joseyu
I have had a set of the Weistec/Bosch Silver core plugs installed in my car for a few weeks now. They are gaped to their recommended 0.024, not problems so far.
I still have my old 30k miles plugs (that I never had a misfire with), so I decided to check the gaps. All 8 were between 0.025 and 0.028 after 30k miles (stock boost). Pretty impressive but made me question the whole 0.032 stock gap assumption.
I have to say, gotta agree with KLR that you should check the gaps on even stock plugs and regap them down before installing. I think that will be enough for most stock turbos even with a tune
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