Professor Grimsell's Teachings on Spark Plugs

[3RZ]

I would recommend that you stay with resistor type spark plugs if specified by the manufacturer. It seems that the resistor inside the plug is used as part of the resistance of the driver circuit of the ECU in the newer ECU/EFI vehicles. (It was orginally introduced to suppress radio interference) Using non resistor plugs cause the drivers in the ECU to overheat and get damaged because of the lower resistance. This little lesson cost me R4400 compliments of Renault for a new ECU. I got the wrong alternative spark plug part no of a website and when the spares shop did not have the correct one's in stock used NGK BP6ES's instead of BKR6E or BKR6ES. An expensive mistake I will not make again.

[3RZ]

From the NGK website:

http://www.ngkspark.com.au/bulletin_index.htm

THE INFLUENCE OF LPG

An engine converted from petrol to L.P.G. (liquefied petroleum gas) will cause a change in the spark plug operating conditions. Therefore, some consideration should be made on the type of spark plug being installed.

As L.P.G. has different properties to petrol it influences the spark plug operating temperature and required voltage. The extent of this influence can be seen when comparisons are made on spark plugs which were fitted in an engine using L.P.G. and petrol.

Typical results are as follows :


1. Spark Plug Temperature



Temperatures are higher with L.P.G.
compared to petrol. This occurs due
to L.P.G.'s reduced cooling effect.

2. Spark Plug Required Voltage



Required voltage increases with L.P.G.
because of the difference in the bonding
of gas particles between the two fuels.


Recommendation

To eliminate the influence of L.P.G. and to obtain optimum spark plug performance, NGK recommends:

-The use of a spark plug with one heat range colder (if possible) than that listed in the catalogue: eg, BPR6EFS-13 (L.P.G.) instead of BPR5EFS-13 (petrol) for VN 6 Cylinder Commodore.

AND

-The reduction of the electrode gap by 0.1 mm (which lowers the spark plug required voltage)

[3RZ]

Here is an explanation of the spark plug heat range;

http://www.ngk.com/charglossary.asp?kw=Heat+range

[BenHur]

Willem

How about a list of recommended plugs per engine?

[Cookie Monster]

I second that Bennie 8)

[3RZ]

Ok, which engines are we talking about ?

4Y
22R
2RZ-FE
3RZ-FE
7MGE
7MGTE
2JZGTE
Lexus
1UZFE
2UZFE
3UZFE
4UZFE

Anybody want to add any others to the list ?

[3RZ]

Here is a link to all the spark plug information you will ever need all on one website.

http://www.sparkplugs.com/sparkplug411.asp

[Scorpion]

That would be a good start!

[Family_Dog]

3Y should presumably be the same as the 4Y?


-F_D

[BenHur]

Willem

How about a list of recommended plugs per engine?

So how about it then?

[3RZ]

Bennie I have been looking at this for a while now but there seems to be a lot of variables.

There are different versions and year models for the same engine with different plug specs..
Different countries use different plugs and I am getting conflicting information from different sites for the same engines.

I am a bit hesitant to generalise the spark plug spec for any given engine without having more details for the specific engine now that I have tried.

Still willing to assist anyone if they give me the info for their specific application.

[pietpetoors]

Willem, the plug issue again.
I went to buy plugs today. The shop did not have any NGK's and offered me Champions. Only problem was that they did not have RC9YC which the book suggest, and gave me RC9YC4.
Any idea what the 4 is for? And NO, it only has one electrode.

It looks the same as the old lugs which was the normal RC9YC

I had to take it because down here I will only have plugs on Monday if they have to order it.

[pietpetoors]

Another question:
Why do we have to replace the plugs? The old ones' electrodes are still as long as the new ones'. So I cannot see why one have to replace it. Can anything else go wrong. What will happen if you just reset the gap and put it back in?

I kept the plugs for spares for the next loooong trip. At R26 each one cannot just chuck it in the dustbin?

[pietpetoors]

I could not find much one these Champion plugs but at http://www.championsparkplugs.com/
I saw that at least the prescribed RC9YC and the RC9YC4 I received seems to have the same properties.
Both says: 14mm Thread, 19mm (3/4") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor','2','1')">Resistor, Copper Core, Projected Tip, Heat Range 9

If I look at Willem's original posts it seems like the Resistor and heat range values are important and in this case they are both the same according to above mentioned site. The only question now is "If they have the same properties why two different part numbers?"

[3RZ]

Piet al wat dit vir my lyk is dat gap uit die Fabriek groter is, die kommentaar wat ek ekstra sien op die RC9YC4 us dat dit 'n groter gap moet he om te voldoen aan die California emissions control. Die res is alles dieselfde.

Kyk bietjie hier http://www.championsparkplugs.com/sparkplug411.asp onder "Manufacturer's Numbering System"

Ek dink behalwe vir die fisiese sluitasie op die elektrode wat die tyd saam weg gevreet word gaan dit ook oor die aanpaksel op die porselein isolator wat met die tyd saam kan veroorsaak dat die vonk nie meer oor die gaping spring nie maar teen die porselein gedeelte afhardloop omdat die weerstand daar minder kan wees as oor die gaping.

[pietpetoors]

Dankie Willem
Ek het sommer van die begin af die gaping op 1.2mm gestel soos jy aanbeveel het. Ek weet nou nie of dit die groter gaping is en of dit die ander vonkprop is nie, maar ek kan 'n baie groot verskil voel. Die engin tel sommer vinniger revolusies op en trek baie beter.

Jou veruidelikiing oor hoekom ons dit gereeld moet vervang; ek het nie eintlik aan die aanpaksel gedeelte gedink nie, maar dit maak baie sin.