spark plugs for modified 2.2
 

I'm getting ready for my annual on my 911 and would like some comments on spark plugs. My engine is a 2.2 with E cams and S pistons & cylinders, and webers. The plugs currently in use are Bosch WR5 DC+. The car is for street use only, although I do occasionally run it over 7,000 an love it. Is the Bosch plug a good choice, or should I consider an NGK?

Thanks in advance,

Rob

They are basically the same design, just different heat ranges available. If the plugs you are using now are right then leave it as is.

If you are changing elevation, fuel, or fiddling with your timing and fuel mix then you may want to consider a different plug.

If you are taking your car up to 7000 and lovin it I would think your plugs are probably the right ones.

If however you are having some negative symptoms then please let us no what those symptoms are.

Shane

I went to Iridium and love them, never foul. And my car is a 2.5L 10:1 comp, so I was used to fouling, alot.

i dial in fuel mix first then find a plug that burns clean

the only gig is that our engines may need 10 miles to blow off carb starting carbon for a clearer pic

I only go NGK's. I have a similar set up (2.2T, E cams, webers) and use BPRE6S (I think that is it), but you would need to consider the temperature range for where you are and the type of driving you do. i.e. if you are lucky enough to be next to an autobahn (which I see you probably arent) then lower plug temps are fine, if you drive in traffic then higher temps are required.

I tried Iridiums recently but was less than impressed, my mech (whose opinion I trust - he has the reputation for been the best in these parts) tells me iridium plugs dont work too well on carb'd cars, at least in his experience. They are much better on EFI cars.

Also if you dont have any problems generating spark then Iridiums are probably not the best way to go because they work at a lower spark voltage whereas the standard ones spark at a much higher voltage.

I would stay away from non resistive plugs if you dont have resistance in your leads, that caused me a lot of trouble.

Without trying to start a Spark Plug War, I am also cautious about Bosch plugs. Bosch make a lot of good stuff but some plugs come from Germany (the good ones) and some from a much cheaper location (again not starting any wars) which are best avoided. No one can tell me how to distinguish between the two. Although I expect platinum plugs would probably...you would hope...be of a high quality.

My father actually snapped a Bosch plug in the engine block many years ago, that was not easy to get out.

Out of interest, how much horse power does your car make at the wheels?

Here's some info I left out. The temps here are very mild, rarely freezes and rarely over 85. No stop and go traffic. Most touring type driving. Gas is typical crappy California.

Adelaide901, as to your question about rw horsepower, I don't know 'cus I've never had it on a dyno. Based on the parts used, I'd guess it to be somewhere between an E and an S. I do know that its power band starts to really push at about 4,000 rpm and it will rev easily to over 7,000.



Rob

the correct heat range is the result of timing, compression ratio and air/fuel mixture. the spark plug REMOVES heat from the combustion chamber. so the more HP the engine makes, the colder the plug.

wr5 is a fairly cold plug but probably works for you because of the compression ratio you have. if you are not having any fouling problems, stay with it. you want to run as cold a plug as you can.

WR5 is about the same as the NGK BPR7. stay with the copper plugs and either the ngk or bosch will work fine.

the trick to tuning an engine is trying to figure out if AF ratio is causing the plug to look bad, or the timing or is it just the heat range of the plug.

i have tried W4's to W6 in my car, lower compression than yours im sure. i ended up with W6's, but dont let that influence you, you just have to experement. the W4 did not foul even though it is very cold, the W5 looked better but i ended up with the W6, well BPR6. i have CIS not carbs.

356robo, you might want to ask Craig, father of Clint Smith of Rebel Racing Parts. He works on 356s (even has a 4-cammer) and 911s and has lots of great knowledge from experience. I would just visit him rather than trying to call Clint, since he does not return calls very quickly. ContactUs They are just over in Morro Bay.

Max,

I know Craig. He did some work on my 356's a few years ago. I'd ask him to do some work on my 911 if it were beyond my knowledge. I like to do as much as I can. Craig's a great guy and he's very knowledgeable.

I just meant ask for his suggestion on type of spark plugs, not that you could not change them yourself. :)

if you are not having problems with them, i would stay with the hat range you are at. if you wish to try the NGk, BPR7 = WR5

Wait
Are you guys really running E cams on otherwise stock 2.2Ts? I thought you couldn't do that with T pistons? What's the gain? What dizzy do you run..

Hmmmm....

/thread hijack

Max,

No offense taken. I was only saying that I've had Craig do some work on my cars and he's really good.

Rob

Dan,

I've got S pistons and cylinders (9.8 compression) along with the E cams. When I bought the car with this engine, it had a T distributor. When I changed to an E distributor, the difference was really noticeable. I chose an E distributor because it was available and the curve is the same for E's and S's.

Rob

I think Craig uses Bosch, btw.

Dan - I dont know is the short answer.
The engine was rebuilt by PO. I have seen the receipts and believe it has e cams and I assume (and dont know otherwise) that it has T P&C's.
As for the dizzy - how can you tell?
The car has a lot of go (for its age) - on the dyno my car produces 150HP at the fly wheel. I think this is E territory, no? (also any dyno result should have a big asterix next to it).

Just checked the dizzy, from the part number on the side it is an S model ( I hope the missus cant hear me banging around in the garage at 12:30 in the morning :)