Why do our engines keep blowing up?

[John Yorke]

Ant - nice to see you on the forum again! [allthough just as cagey as ever!]
Interested on the spark plug thing, is there such a thing as a compromise - ie: fitting say 9\'s in the trailing and 11 / 11.5 in the leading - my thinking being, having the colder plugs for heavy duty and not so cold plugs for easy starting - a bit like having 7 & 9\'s as standard.

[db2boy]

John,
   Im still in this game, people know how to find me Cagey? Me? Oh pahlease! Ask Carl, Im not cagey

I personally noticed no difference when I experimented with say 11.5/11 and 11/10.5 combos. Either in smoothness, seat of the pants power, idle, EGT, etc

I have also never had any starting problems due to running colder plugs, yes idle and warm up are rougher but none of these myth start up issues.

Want to mod to big power, u need colder ranges of plugs.

Rgds

Ant

[20B_boy]

Originally posted by db2boy
I have also never had any starting problems due to running colder plugs, yes idle and warm up are rougher but none of these myth start up issues.

"myth start up issues"??

Dude, how much daily driving did you do, and how many cold mornings did you try and start your FD with 11\'s? Not many \'cause you used the Honda for work...?

My experience of using an FD with 11\'s as a daily driver for 12 months was that it failed to start and required in a couple of instances quite major deflooding during the cold months. Changed to 7s and 9s - never failed to start after a second of cranking....

[20B_boy]

I totally agree about big power = colder plugs though of course. My car was not the same at WOT with warmer plugs, used to misfire, splutter and cough some times at peak torque which was very unnerving. The sound was as I imagined detonation would sound but as the motor lived to tell the tale and on more than one occassion I guess it wasnt!

[db2boy]

As always, in my expierence! No the FD never was a daily driver, but yes I would sometimes take it to customers or to work and yes it did have early morning/late night cold starts. Being a daily driver instead of a stop/start car would surely help it with starts anyway?!?!

Heck that was even with the stupid matchbox battery before I swamped it out to a large Bosch one! In 2 years of running 11 and 11.5\'s I never once had a starting problem or flood problem.

Again though tuning tuning tuning, think about the whole system and process of starting, ignition, fuel, air density, air temp and not just the plug ratings............

Rgds

Ant

[Carl]

Originally posted by John Yorke
Ant - nice to see you on the forum again! [allthough just as cagey as ever!]
Interested on the spark plug thing, is there such a thing as a compromise - ie: fitting say 9\'s in the trailing and 11 / 11.5 in the leading - my thinking being, having the colder plugs for heavy duty and not so cold plugs for easy starting - a bit like having 7 & 9\'s as standard.

Hi John,
I could not help noticing that you were considering putting 9s in the trailing and 11\'s in the leading.
DO NOT PUT THEM THIS WAY ROUND!!It could blow your engine up!
The colder plug MUST go in the trailing,ie the 11\'s should be in the trailing plug holes.
If anyone is fitting 7\'s and 9\'s then fit 7\'s in leading and 9\'s in trailing.
Kind regards
Carl

[g11ary]

I have several daily drivers, theres a contrdiction, but I do drive a RX daily and never have I had a starting problem unless the engine was on its way out and once I stupidly was in a rush and moved a car turned her straight off. All cars are in diff states of mod and all run dif plugs. Cant see plugs being much of an issue unless serious power for drag or circuit racing if just for daily or weekend driving.

[20B_boy]

Originally posted by db2boy
As always, in my expierence!
"myth start up issues" sounded more like a sweeping statement to me which is why I bothered answering!

No the FD never was a daily driver, but yes I would sometimes take it to customers or to work and yes it did have early morning/late night cold starts.
Yes, "some times" started it in the cold - which I was comparing to EVERY DAY, starting first thing, again after sitting for 9 hours in the cold, then again after sitting for a couple of hours and once more at midnight-1am...

Being a daily driver instead of a stop/start car would surely help it with starts anyway?!?!
You reckon?? I thought it would be the opposite; switch on, sit in traffic, stop, repeat cycle? would this not foul the plugs if any thing?

Heck that was even with the stupid matchbox battery before I swamped it out to a large Bosch one!
I think mine was slightly larger than yours, but not much?

In 2 years of running 11 and 11.5\'s I never once had a starting problem or flood problem.
In about 18 months (inc 2 winters) and 25,000 miles I only ever had cold start and/or flooding probs when running 11s...

Again though tuning tuning tuning, think about the whole system and process of starting, ignition, fuel, air density, air temp and not just the plug ratings.............
Dont get me wrong Ant, I hold your rotary tuning skills in the greatest regard (and I love you man!); this is all just MY opinion based upon MY own personal experience!

R.

[bill shurvinton]

thing is. If you have a \'serious\' engine, you won\'t worry about keeping several sets of plugs for it and driving to the track on \'street\' plugs then changing to \'race\' plugs is no great problem.

[maximtaylor]

WI should remove the need for such cold plugs, should it not?

Appreciate what you are saying about looking at the whole process and the the importance of good tuning Ant.

Debate rages about what is good tuning as well, just look at the datalogit discussions about split timing for one classic!

Regards

Max

[db2boy]

Rich - you are such a twat - love you too man ;-) So how about the ECU start up fuelling being too rich/lean and the start up timing being too adv/rtd for a given plug range - reckon that would affect different plug ranges??

As for the split discussion, a subject in my mind, thoughts and ECU for about a year now - personally I favour split.

Carl, I found T1 = 9, T2 = 11, L1 = 11, L2 = 9 stopped rotor tip chatter.

Rgds

Weeman

[maximtaylor]

mmmmm.... same as Carl then Ant, thats 2-0 so far on split....

I tried 8 for a while, my bottom and ears said engine felt more perky than Mazda\'s 14 or 15, but then again I like to experiment a bit.

How much at boost? 12,10,8 . Someone please sacrifice an engine on a dyno to try different split........anyone??? hello??

Regards

Max

[bill shurvinton]

Max,

WI will reduce heat, but in terms of the plug I would not say that it will allow you to run much cooler, as once you have a safety margin you\'ll only end up increasing boost/timing.

I must pull my finger out on the ion sensing, then we can solve the split issue for once and for all.

Bill

[John Yorke]

Thanks for the advice Carl - trust me to get it back to front! if mixing the plugs has no real effect I will have to learn how to swap out hot plugs:D
What benifits could you expect from fitting an ignition amplifier?

[Carl]

Hi John,
There is a lot of views on this but I think it is only really needed on really high output engines.
Kind regards
Carl