Spark Plugs...Help with the best for my engine

[leso]

OK guys and girls, i need some help with what kind of sparkplug to buy for my engine. I dont think the stocko bp6es plugs will be suitable for my engine combo..
I am prepared to buy the expensive new fandangled ones if they will work better..!! However my main concern is the heat range, the plugs are for a 18RGU...it has the 253 head that normally runs with 8.7 comp pistons, but i have fitted some 9.7 comp pistons and to confuse the issue even more i have fitted some wade 137 regrinds...believe them to have 298 duration..have twin 40mm webers..and i will only be running bp ultimate or similar....maybe with some octane booster or a mix (need help there as well ) i wont be useing this car for a daily, just for weekend cruises and a bit of track stuff. Hope that is enough info for you helpfull people to provide me with, at least an informed choice..

Looking forward to your replies...regards Leso

[30psi 4agte]

I think The 6 range is the go with that comp.
Some of the N/A guys should beable to give you some better feed back as to what they think from experience.

I use the same plugs in my car up till about 20 psi then go up to 8's.

NGK do some good racing plugs for that engine.

[oldcorollas]

the compression is not so high, and the cam is very big, which reduces your dynamic compression, so you may not need any octane booster (which works minimally anyway), just fresh fuel (not optimax )
sure stock is 6 and not 5? 7 is pretty cold and usually used for warm turbo motors... i'd go with the 6's to start and see how they go...

or.. go with 7's, see if the foul or don7t clean themselves.. and then go back to 6's if needed.

got good spark?

edit: K series motor, 10.2:1, 275/285 cam, rev to 8K. BP6ES or BP6EY.. change them when they get dirty instead of cleaning

[30psi 4agte]

ha ha stu
Looks like i finally beat you to a post

[oldcorollas]

i should just leave you to answer things in future.. you know more than me anyway
i need to spread the rep before dosing it again

[leso]

Thanks for the great information guys...will put some BP6ES in to start with and monitor there condition and if it seems to be the right heat range i will buy some of the ngk racing plugs to suit...great tip about the dynamic compression, i never thought of that. Forgot to mention that i will be running the 21r electronic ign upgrade. Will be trying lots of things ie different fuel/plugs ....good excuse to go to willowbank for the test and tune nights..

cheers Leso

[The Witzl]

I run BPR6EY or BPR6ES in my 18R-GE.

Stock is recommended BPR5ES, but i think these are too hot for the 9.7:1 compression pistons... Never had a problem with the BPR6ES plugs, and i've been using the same for ages.

Like Stu said - change plugs instead of cleaning them. It's only $12/set anyway!