spark plugs for FI 16v

Which 20vt engine codes plugs will best suit a 16v turbo engine?

thnks again.

Get the plugs of the S2. Bosch F5DPOR

Any ideas what will last longer in an G60 turbo? Still on standard G60 plugs.

im using 20vt plugs from golf 1.8t. they are platinum so have a longer service life like the g plugs

JNLRacing wrote:Get the plugs of the S2. Bosch F5DPOR

Would I be right in thinking these will have a larger spark gap than a normal NA plug?

No.

Spark plugs work in two ways heat rating and gap.

The larger the gap the bigger the spark, the bigger the spark the more efficient burn and the more torque you make and ultimatelly hp. Make the gap too big and the spark blows out not igniting the fuel properly. As you raise compression or add nitrous or add turbo/charger the charge in the combustion chamber is a lot denser, so you need more oooomph to bridge the gap by using a high powered coil. Alternativelly you may have to make the gap smaller to compensate if you have a lesser powered coil.

The next stage is heat rating make the plug too hot and your engine will carry on dieseling from self ignition from the ceramic/tip of the plug. Make the plug too cold and the fuel won't ignite properly as there is not enough heat. Running a forced induction car that's highly tuned during the summer some can potentially benefit from going one heatrange colder for example to avoid detonation.

Getting the correct heat rating and gap can lead to some significant extra ponies. When I used to tune up the old carburetted v8's down the quarter we used to go three sets of spark plugs of varying heatranges first we'd try each set once down the quarter and chose the set that gave the best trap speed (using identical gaps) as it gave a good indication which was burning fuel the best. Then we would do 2 passes at 2thou gap increments starting large and working down, if the times got slower as we went down we would make the gap bigger instead. At a certain point you would find a gap size that if you went either side you go slower. So you'd settle at the setting in the middle. You make a note for the future that when the weather climate is like that day of testing you'd use those plug settings. Obviously you repeat for different times of the year.

The bit that was most surprising was that quarter mile times could change by as much as 0.3sec on setting plugs up correctly. Which mathematically 10hp = 0.1sec on the quarter (at the times we were running) equated to a 30hp gain on a 400-450hp motor using the correct plugs.

As for changing plugs on your motor to long life ones they will always be a compromise to optimum performance. Plugs are one of the most important links in the combustion chain manufacturers have spend a long time working out which electrode ground strap configuration works best for your engine. Very rarely will you benefit from changing them to a different type unless there is a problem with them due to a high state of tune.

JNLRacing wrote:Get the plugs of the S2. Bosch F5DPOR

I use / used those in my VR6T and they work well.

I prefer the NGK V power plugs though. R5671A or some such, can't remember the p/n off the top of my head. Cheap as chips too, couple of bucks each.

many thanks gents.
very helpful as always.

Thats really interesting reading.... So I have standard plugs which are recommended for the standard G60 engine in mine at the moment. Given the amount of work I've done to my engine, it may well be that these are no longer suitable (plus they are now 5 years old) rfom what I've read. Other than the 'run it up and down the quarter mile' or 'run it on the dyno' is there anything I can do to check this?

most people run the g40 plugs on the g60 when they are highly tuned.

Flusted wrote:most people run the g40 plugs on the g60 when they are highly tuned.

So why is that?

someone give me ngk part numbers for both (bosch will do but I understand the numbering/coding on ngk better) then I'll see what the differences are.

JNLRacing wrote:someone give me ngk part numbers for both (bosch will do but I understand the numbering/coding on ngk better) then I'll see what the differences are.

A commendable attitude.
Someone help the man out please.

Yes, that is a commendable attitude .

I've managed to find this (shameless lifted from Matey Matey website on tuning G60's)....

"The spark plugs are meant to last about 40k but it is worth checking them for condition. They should only be replaced with the appropriate platinum tipped Bosch plugs. For a standard or modestly tuned G60 you want W6DPO plugs and for a highly tuned lump use W5DPO (as fitted to the G40) as they run slightly cooler than the 6s."

Sorry for such a numpty question, but why do cooler running plugs suit the more highly tuned G60's?

EDIT - also found some NGK numbers. W5DPO corresponds to NGK BP7ET, while W6DPO does not have a direct comparison. The nearest one is W6DP which is BP6ES if that helps.

OK that's jogged my memory I knew there was something the opposite to do with the Bosch plugs.

As a future reference point NGK R plugs like the BP7ET are what you would find in a small 1.4 or even a 5.7ltr chevy lump running nitrous. They are considered to be a cold plug. The smaller the number the hotter. The number referring to the amount of ceramic exposed etc...

A Bosch spark plug number works the other way round the higher the number the hotter the plug. The more tuned a motor becomes the hotter the combustion cycle and the colder the plug it needs to run to prevent detonation. As a rule of thumb small capacity engines run higher combustion temperatures than larger cc engines of the same tune this in turn means that they require a cooler running plug to prevent detonation hence the G40 plug number being 1 stage cooler than that of the G60.

Now NGK spark plugs don't get any cooler than the 7 rating so the fact that the G60 Bosch spark plug cross references to a 7 will explain why the colder G40 plug doesn't cross reference to an NGK plug as you can't get an 8 in that range.

Long and short though the G40 plug will indeed be suited to running on a highly tuned G60.

Hmmm, very interesting. So especially with me going down the nitrous route, when it comes to changing the plugs, I'll be better going for then G40 ones then.

Another daft question - does changing the plugs affect the mapping at all? I.e. would I need my current map tweaking. Can't think why it would (unless the time for the spark to form varies) but thankfully I'm not afraid of looking daft to ask the question .

You'll find that it is potentially possible to run more advance timing = more power. Depending who has done the map would determine whether you may benefit from a remap. Alternativelly you may find the fact that the knock sensor is no longer sensing knock at WOT you are not having to go into the ignition compensation map which in itself will yield better performance much like running super unleaded vs leaded.