Spark plug heat range???

[dac69er]

I have been sent some heat range 8 plugs. I feel these are too cold for my application.

I only use the car in the summer (UK), it will be a forged engine running 1.4bar boost. It is a street car, not for track.
I don't hoon it constantly either.

Are the 8s fine, or should I send them back and get 7s

 

[Jay]

For street you should get away with 7's but you could try running the 8's and monitor them for fouling. If you start seeing deposits you can swap them out.

It's hard to gauge exactly as compression, timing, AFR's and driving style all play a part.

 

[gorganl2000]

i've run both 7s and 8s.
i currently use 8s with no issues...i'm mildly modified and only use my car on the odd weekend, but its fine being driven daily if i wanted to

 

[SKINY]

RS Turbo Fiesta plugs I use, think they are 7 never gave me any issues

 

[dac69er]

For street you should get away with 7's but you could try running the 8's and monitor them for fouling. If you start seeing deposits you can swap them out.

It's hard to gauge exactly as compression, timing, AFR's and driving style all play a part.

I'm running relatively high CR compared to most people as I'm not going silly with boost.

I've always felt 7s are even too much for anything 160-170bhp or less.

I've been fobbed off with something I haven't asked for, but equally I don't want to make a big thing of it if it's not really an issue!?

 

[gorganl2000]

For street you should get away with 7's but you could try running the 8's and monitor them for fouling. If you start seeing deposits you can swap them out.

It's hard to gauge exactly as compression, timing, AFR's and driving style all play a part.

Jay raises some good points...it really depends on the specific variables
i'd also suggest that you discuss it with your tuner

i had no trouble with the 7s, but we decided to go with 8s and be on the side of caution given the hot climate, low gas quality, knock potential, power/boost targets, engine set up, etc.

 

[dac69er]

Any other opinions? What are others using with forged setups on the street?

 

[gorganl2000]

oh, just to add, i've used TRD iridium, NGK iridium and NGK copper plugs in the 7 and 8 heat ranges over the years...i saw no difference in operation/performance...so i stuck with the much cheaper NGK copper plugs and i'll replace them as required, which will be long before the end of their service life anyways.

the more expensive iridium plugs will last longer, but not worth it in my specific case