Any reason I shouldnt run Bosch plugs?
08-20-13, 12:55 AM
#1
Any reason I shouldnt run Bosch plugs?
My new 1980 came with new Bosch w5cc spark plugs. Is there any reason I shouldn't run them? The car seems to run fine. I re-gapped them to .041 as per FSM specs. Ive always run NGK, but if there is no reason to switch I will run these until they foul out.
08-20-13, 11:08 AM
#2
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yeah just wait until they fail, its bosch, failure will be quick
08-20-13, 11:30 AM
#3
I've always discarded Bosch plugs in a new car. As long as there is no common failure of the tips breaking off into the engine or something! If I can get a couple thousand miles out of them I'll be happy. I look forward to installing new BR8s!
08-23-13, 11:33 PM
#7
carb whisperer
Try the gslse plug, BR9EQ-14.
It makes sense to run a slightly colder plug than stock, even if its just a stock port with an exhaust. It helps slightly richen the mixture without actually dumping more fuel into the engine, and is a flat upgrade if youre running smaller jets, or a stock inj. system or carb.
But thats only with the s3 ignition system where its so easy to do. Ive converted 2nd systems to colder plugs and have trouble seeing any benefits at all running the stock coils, and timing. It seems it was predetermined to run the two differing heat ranges by more than just the coils.
The factory's primary reason for running the BR8EQ14 was a mix between the hotter BR7 variant, and the ideal BR9. The BR8 was a slightly more emissions friendly plug, while the BR7 was recommended for "city" driving, where power wasnt as important, and the leaner mix would probably never be noticed; whilst being more "efficient" in terms of the EPA. The GSLSE's tailpipe waste was clean enough with fuel injection to warrant many different changes, one including the step to colder spark plugs.
But seriously, try the SE's plugs. Its an easy performance upgrade if you're running a 12a with a full exhaust. No matter how its inducted, stock carb or aftermarket.
It makes sense to run a slightly colder plug than stock, even if its just a stock port with an exhaust. It helps slightly richen the mixture without actually dumping more fuel into the engine, and is a flat upgrade if youre running smaller jets, or a stock inj. system or carb.
But thats only with the s3 ignition system where its so easy to do. Ive converted 2nd systems to colder plugs and have trouble seeing any benefits at all running the stock coils, and timing. It seems it was predetermined to run the two differing heat ranges by more than just the coils.
The factory's primary reason for running the BR8EQ14 was a mix between the hotter BR7 variant, and the ideal BR9. The BR8 was a slightly more emissions friendly plug, while the BR7 was recommended for "city" driving, where power wasnt as important, and the leaner mix would probably never be noticed; whilst being more "efficient" in terms of the EPA. The GSLSE's tailpipe waste was clean enough with fuel injection to warrant many different changes, one including the step to colder spark plugs.
But seriously, try the SE's plugs. Its an easy performance upgrade if you're running a 12a with a full exhaust. No matter how its inducted, stock carb or aftermarket.
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08-24-13, 10:27 AM
#8
Ive run colder plugs in the past and they dont seem to last as long before they foul out. Ive even tried BR7eix and BR9eix, but the single electrode can't hold up to daily driving. Compared to BR8eq14 and BUR7EQP they just dont last worth a crap. I've had over 120,000 miles of seat time in my RX7s too.
However, when I get my direct fire wired in I may run BUR7EQP Leading and BR9eq14 Trailing.
However, when I get my direct fire wired in I may run BUR7EQP Leading and BR9eq14 Trailing.
08-24-13, 11:42 AM
#9
carb whisperer
I drove my last set for 2 years! One year in my SE, then i pulled them out and put them in my 12A one day when the holley flooded. Meant to replace them and forgot :P
08-24-13, 12:09 PM
#10
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Try the gslse plug, BR9EQ-14.
It makes sense to run a slightly colder plug than stock, even if its just a stock port with an exhaust. It helps slightly richen the mixture without actually dumping more fuel into the engine, and is a flat upgrade if youre running smaller jets, or a stock inj. system or carb..
It makes sense to run a slightly colder plug than stock, even if its just a stock port with an exhaust. It helps slightly richen the mixture without actually dumping more fuel into the engine, and is a flat upgrade if youre running smaller jets, or a stock inj. system or carb..
so it has nothing to do with the mixture. it may allow a leaner mixture, as it won't be hot enough to preignite anything, but in and of itself doesn't do a thing.
i also like the GSL-SE plugs, if its a "for fun" car you're probably going to be driving it harder, and in that case its nice to have a colder plug
08-24-13, 02:19 PM
#12
Single electrode. I was worried about breakage. It runs fine with them, but I have never seen Bosch in a rotary. NGK and Denso is all I've ever found in the 8 RX7s I've owned. As well as the 5-6 spare engines I've owned. One had a set of Autolights. I plan on doing direct fire soon so I will run BUR7EQP/BR9EQ14.
The car came from a Euro shop so maybe hes partial to German parts. He specializes in Mercedes and Porsche. I have removed Bosch plugs in every car I've ever owned, even my Mercedes.
The car came from a Euro shop so maybe hes partial to German parts. He specializes in Mercedes and Porsche. I have removed Bosch plugs in every car I've ever owned, even my Mercedes.
08-24-13, 02:30 PM
#14
carb whisperer
the temperature range of the spark plug is literally referring to the temperature of the spark plug, a colder spark plug will literally run colder than a hot plug.
so it has nothing to do with the mixture. it may allow a leaner mixture, as it won't be hot enough to preignite anything, but in and of itself doesn't do a thing.
i also like the GSL-SE plugs, if its a "for fun" car you're probably going to be driving it harder, and in that case its nice to have a colder plug
so it has nothing to do with the mixture. it may allow a leaner mixture, as it won't be hot enough to preignite anything, but in and of itself doesn't do a thing.
i also like the GSL-SE plugs, if its a "for fun" car you're probably going to be driving it harder, and in that case its nice to have a colder plug
In fact, just changing from the stock BR8EQ-14's to BR9EQ-14 on all of my carb'd cars let me lean out the idle mixture at least a half turn with no adverse effects.
Theres something to it, swear to god lol
08-24-13, 09:26 PM
#16
carb whisperer
Mine does 
One of my 12a's I was testing with a stock nikki for a rebuild was fine and ran great totally stock. Then I installed the Rb dual exhaust and it still ran good, but according to the AFR gauge it was a little leaner than before with the new exhaust. THEN i ported the intake mani a little bit when I removed the shutter vlave and filled in the anti afterburn port and EGR ports. After everything was reinstalled, no vacuum leaks or anything and it was a bit leaner still. Maybe just 5 jet sizes lean from the stock 92 in the nikki. But before I jetted it I tried going to a set of SE plugs with it as I always did my holley's before dyno tuning, and without touching *anything* at all the mix was richer with the nikki. I mean richer everywhere, like decel, accel, warmup, idle, power, etc. It became overall a bit richer just like the older engines I played with with aftermarket carbs.
So I kept the smallish jetting since the plug change yielded me pretty close to where I wanted to be AFR-wise. Still a tiny bit lean, but I like it that way.
So long story short, YES in my experience those plugs require less fuel to burn. Same effect with a v8, or any of the other engines ive tuned over the years or built a carb for. It was always standard practice to read spark plugs and go a step colder on a naturally lean engine set-up just to help fatten it up.
One of my 12a's I was testing with a stock nikki for a rebuild was fine and ran great totally stock. Then I installed the Rb dual exhaust and it still ran good, but according to the AFR gauge it was a little leaner than before with the new exhaust. THEN i ported the intake mani a little bit when I removed the shutter vlave and filled in the anti afterburn port and EGR ports. After everything was reinstalled, no vacuum leaks or anything and it was a bit leaner still. Maybe just 5 jet sizes lean from the stock 92 in the nikki. But before I jetted it I tried going to a set of SE plugs with it as I always did my holley's before dyno tuning, and without touching *anything* at all the mix was richer with the nikki. I mean richer everywhere, like decel, accel, warmup, idle, power, etc. It became overall a bit richer just like the older engines I played with with aftermarket carbs.
So I kept the smallish jetting since the plug change yielded me pretty close to where I wanted to be AFR-wise. Still a tiny bit lean, but I like it that way.
So long story short, YES in my experience those plugs require less fuel to burn. Same effect with a v8, or any of the other engines ive tuned over the years or built a carb for. It was always standard practice to read spark plugs and go a step colder on a naturally lean engine set-up just to help fatten it up.
08-25-13, 12:36 AM
#17
So you have a California model? I'm sure removing the emissions on it really changed the performance and reliability. I know any time I've swapped a stock exhaust for a Racing Beat exhaust the idle naturally raised to 1400 RPM due to increased flow and leaner mixture. After you drop it back down to 750-800 RPM its much more solid than stock.
08-25-13, 01:58 AM
#18
carb whisperer
Yup, you should have similar emissions crap if its not already removed. My 85 is outfitted almost exactly like your red 79, with the rota RB's, big louvers, and RB strut brace, and breather, etc...
08-25-13, 10:30 AM
#19
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Changing from BR8's to BR9's always yields me a slightly richer mix according to my AFR gauge. And thats doing something to make an actual tangible difference to a sensor like that, one you can read on a gauge. And as Id said before, without changing jetting or anything like that.
In fact, just changing from the stock BR8EQ-14's to BR9EQ-14 on all of my carb'd cars let me lean out the idle mixture at least a half turn with no adverse effects.
Theres something to it, swear to god lol
Theres something to it, swear to god lol
08-26-13, 05:07 PM
#20
The hotter plugs keep the plugs cleaner and they burn fuel better all other aspects of the plug comparison being equal (same design, just different heat range). So the opposite is true with colder plugs. Which is why colder foul quicker.
And yeah, when I run a MSD I always get 1 more MPG.
And yeah, when I run a MSD I always get 1 more MPG.
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