Another DASC/FI spark plug...

[lpcapital]

The NGK BKR7E appears to be the plug of choice for the DASC. It looks like everything started from Shawn, the only one that actually looked into using different spark plugs. I decided to do my own due-diligence and for the sake of it, trying something different.

My choice is for some Bosch plugs, part number is F6DSR. Here's a description.

The plugs are a heat range colder than stock (stock Bosch HR is 7), they have a silver core (best thermal & electrical conductor), no suppression, closer gap than stock at 0.7mm or .027" (stock is 1.016mm or .032"). It has a thing called "burn-off resistor" inside: speaking to the Bosch tech he said it helps holding the spark longer (we're talking milliseconds). I think this is because the gap is closer so you need a lower voltage to fire the spark.

It's used in several Saab, WW, and Audi, all using FI...

I wanna go check at the auto parts stores around and see if they have any in stock before ordering them online.

[lpcapital]

PS: they are available on Amazon for $6.50 each and they qualify for the free shipping...

[Danny318]

you get them first, and if they are good I'll get em too

[lpcapital]

Theyl be in Friday. I'm doing one thing at a time so I can see how each one affect it. I got Magnecor KV85 wires as well, but they will go on in a couple weeks.

I'll let you know how they perform. I wish I had an ELM reader so I could compare timing at WOT and actually have data...

[blowin 4]

i think ill try them out ...

[lpcapital]

I shopped around a little and Amazon has the best deal. I order them this morning and I'll get them Friday with free shipping. However, just for the sake of it, let me install them and try them out. At least if they are no good only one of us waste the munny...

[lpcapital]

Got a call back from Autolite today.

Stock plugs are numbered 3923: the last digit (3) is the heat range and for Autolite the lower, the colder.

1 heat range colder would be 3922 available only in copper core and resistor type (the resistor reduce EFI but also interfear with the spark. If quality wires are used EFI is not a problem).

2 heat range colder would be 3911

If you need an even colder plug you can get the the 3910. It's their coldest plug.

[Danny318]

Why are we getting colder plugs again?

[lpcapital]

Originally Posted by Danny318

Why are we getting colder plugs again?

The heat range is a comparative measure of how well (or how bad) a plug transfers heat away form the tip. When you go FI the heat generated in the combustion chamber is much higher. And a plug which is too hot could be the source of pre-ignition. Here's a nice read on the subject.

[Danny318]

okay just making sure.

[Criswell]

Originally Posted by lpcapital

The heat range is a comparative measure of how well (or how bad) a plug transfers heat away form the tip. When you go FI the heat generated in the combustion chamber is much higher. And a plug which is too hot could be the source of pre-ignition. Here's a nice read on the subject.

Keep in mind, if you have any deposits on your plugs, that a colder plug will collect deposits/foul even faster, because you dont have that extra heat to burn it off. Thank god youre on the right track though, most people seem to think that colder plugs are gonna net them some kind of monster horsepower , because a friend of a friend of a friend or the infamous "they" use them in their racecar.

By the imfamous "They" im referring to when people say "they say if i (name mod here) ill get an extra 20 horsepower". The most common "they" reccomendation was flipping the carb spacer upside down on a small block chevy. /Sigh. After years of customers referring to this elusive "they" i began asking who "they" are. Mysteriously , no one was able to give me an answer.

[halcrontech]

Seriously, I would avoid silver electrode plugs. It doesn't last as long compared to Iridium or platinum. I have used Brisk Premium LGS plugs. It doesn't last long. It starts misfire after ~20K miles. Thats sucks considering they cost 3x the price of NGKs.

[lpcapital]

I end up buying the Bosch F6DSR and I've been driving the car for about a week now and they are fantastic. The other day it was about 80 outside and the car didn't pull timing once. When under boost the car is very smooth throughout the whole rev band. I haven't had any problem with misfiring when the engine is cold or while sitting in traffic so the heat rang is spot on.
The best deal I could find for them was Amazon selling them for $6.50 each and a set of 4 will have free S&H so it's a good deal.
As far as expected life, silver has a density very similar to copper, so you should expect the same change interval.

Bottom line: if you have a DASC I would highly recommend them.

PS: If you have a stock M44, these are not for you

[performanceisland]

i just replaced my original oem spark plugs at 49K miles, which by the way looked fine, with the 4503 PLATINUM IR FUSION Do not gap style spark plugs, and car runs good with one exception, i have the DASC installed on my 1999 ti. I dont know if anyone had tried these at all, the only problem i have after my DASC kit install is the car doesnt want to start nice in the winter -30 degree weather, evrything was fine before install of DASC, and battery is fully charged, i have to hit the gas pedal and give it gas and rev it a little for it to stay running at first, even idling, i might try changing to my stock sprak plugs just for a day or so to see if maybe its my plugs.

[Danny318]

See to me, this plus your losing a pound of boost problem makes me think you have a leak somewhere. You should check all the vacume lines, check all your surfaces to make sure everythign is sealed. Make sure the intake boot after the maf doesnt have a crack in it, etc.