Well yeah, there have been heaps of older 4.0L and 4.2L supercharged Jags running water/meth.

Not so many 5.0L, although the worlds fastest F-Type is running water/meth, amongst other things LOL https://www.jaguarforums.com/forum/f...r-meth-176656/ talk to Philly Single

 

Thanks Cambo, thats great info to know! I will most probably give that a try after installing my water/meth kit, already have about 22K miles on the stock plugs, so Im thinking that having them out and taking a look at them is a good tell as well.

 

Never heard of 'colder' plugs before. Out of curiosity, are they:
1. Lower resistance, to produce less heat.
2. Higher thermal conductivity, to get rid of heat better.
3. Something else?

Thanks - inquiring minds want to know.

 

From NGK site: "When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, keeping the firing tip cooler. *A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter."


Hot tips are more likely to allow detonation. Cold plugs will make for more difficult cold weather starting. In my racing days, I would need to use a hot set of plugs to start and warm the engine on cold days. I would then switch to cold plugs for track time to avoid grenading the engine that was running at 14.5:1 compression.

 

To quote Sean, who works at JLR in the engine calibration dept. at JLR;

"Hot plugs do not cause detonation, they cause pre ignition. Which is very hard to detect, and very destructive. The standard tune on 4.2 SC's (and the NA's for that matter) is tuned to not get the spark plugs to hot. There is an area of the ignition map that is deliberately retarded for this, it is set by using instrumented spark plugs. And in this area the plugs will get hot enough to cause engine failure levels of pre ignition way before any spark induced detonation occurs.
Obviously, anybody trying to tune one of these engines in the after market will not be able to measure this. So fitting colder plugs is absolutely the right way to go."

He was talking about the 4.2L, but i'm sure the same will apply to the 5.0L/3.0L as well.

 

Thanks for the correction, Cambo. This is indeed the case. I get them confused occasionally.

 

So if I'm doing the VAP tune, upper pulley and sport cats I should also change the plugs? How big of a job is that?

 

At what point did VAP recommend colder plugs? I purchased the "power pack" (upper pulley, tune, sport cats, springs) from Stuart and he never mentioned needing colder plugs.

 

Lower pulley is larger than the upper pulley. Its not necessarily a requirement at this point, but we're trying to make more power safely.

Plugs appear to be as big of a job as the pulley. I'll be trying to tackle that this weekend.

 

For those of you thinking about plugs, I will tell you it sucks pretty bad on this car. Access, specifically on the driver's side, is very tight, and requires something similar to this remove the coils on the entire driver's side bank:





Also, if anyone has the torque spec on these plugs, that would be appreciated!

 

20Nm / 15lb-ft

 

Thank you sir. WhiteTardis also provided me the service procedure; which was probably the least detailed thing I've ever seen. Probably took me about 4 hours.

Mostly because of this screw. Terrible placement, only about 2 inches of space when tightened.



Also this rubber insulation piece was a huge pain in the *** to remove. I'm not looking forward to reinstalling it in the morning.



And lastly, I was amused to see a 508 PS label on the engine. That one doesn't make any sense at all to me.

 

The service manual reckons to renew the spark plugs you should disconnect and move out the way the two intercooler hoses (over to left in the pic, towards the front of the car), same on the other side. Apparently this makes it much easier to remove and then replace the rubber insulation pieces.

 

Also, 508PS seems to be the designation for the Range Rover 5.0 SC motor, so maybe the F-Type R motor is simply the same motor as the Range Rover version but tuned to 550PS instead.

 

I did disconnect those. It was still a huge pain on the drive side. Passenger side wasn't too bad. I was able to snake that by without disconnecting the coolant hoses at all.

 

Lots of good info here. I am now about to either upgrade the intercooler or going with a spray kit (Since winter is on the way, I am leaning towards the spray kit). Either way, it seems that it is prudent to run cooler plugs. Currently running VAP tune + crank pulley. I notice you mentioned that you did your plugs recently. Have you done any dyno runs or datalogs to see the difference?

Also, if possible can you send or post the service manual steps? I have an ALLData subscription and it does not provide an R&R for the plugs...just gives me gap and torque numbers

 

I don't have a dyno anywhere near me to check this on. I have been running the car down the strip, but due to some unfortunate engine issues haven't had a chance to take it since installing the plugs. I had to return to stock while everything was sorted out. Don't expect to have new results until next spring.

As for the install instructions, they are so poor, its not even worth uploading.