Using washers also adjusts the depth the electrode is in the combustion chamber, which also needs to be taken into consideration. The star-point plugs eliminate this for the most part, and don't see to make any measurable power increases on stock, daily drivers. Start wailing in the 7K+ rpm range and some interesting things happen.

 

in stock applications the "star" tpe of plugs you mentioned (I assume your talking about things like the bosch platnum plus 4 types) not only don't show any increase but actually will show a decrease, put a set of those in my wifes 97 F150 4.6 mileage went from 16-17mpg to 12-13 instantly and didn't go back up till I put regular plugs back into the engine. I don't know the physics of why this happened but I gaurentee it does, and did.
Also please not racers don't use these plugs either, and I assume that it's for the same reason cause a nascar team can afford any plug they want to run, and they don't run those.
also the depth a plug is into the combustion chamber doesn't have nearly as much affect on the flame front as the angle of the electrode and the washers aren't that thick to make much of a difference.

 

I have found enough difference between the threads in the head, and the threads on the plugs to get a good index without shims. ideally you want the gap to point right at the intake valve/center of combustion chamber. I'm happy if it is close, and not "blocked" by the electrode.

years ago I tried to shroud every plug to see, and sure enough it lost mileage,I now try to at least be close on my gassers.

 

[QUOTE=whd507]I have found enough difference between the threads in the head, and the threads on the plugs to get a good index without shims. ideally you want the gap to point right at the intake valve/center of combustion chamber. I'm happy if it is close, and not "blocked" by the electrode.
[QUOTE]


It depends on the chamber design, any port work, machining of the chamber surface to remove burrs, bumps, and dimples, etc. Certain engines benefit from putting the spark more towards the exhaust valve - though generally one would need dish pistons too.

Again, on the street, this kind of "detail" provides less benefit than on a full-out race car.

It might be because they don't work, but it might be because they burn up too quickly, and that's one more potential disaster to change mid-race. I'm not saying they're good plugs, just saying your assumption of why nascar doesn't use them, may or may not be correct. Maybe there is a rule against it? I'm not overly familar with nascar rules, personally. Just food for thought.

 

No rules against running them at all, and bieng platinum they don't burn up that fast they have the problem that you mentioned in that they shroud the spark from all directions instead of having it open from any direction. There was some testing by the Roush racing team when they first came out I don't know whether it was just dyno tests or track testing or for sure what the actual results actually were but they decided against them which speaks volumes to me. Also please note I don't know of any race teams of any class that run platinum plugs my understanding is they will actually reduce the spark, and are good for longevity not performance.
BTW this includes me I run autolite AR-3922 racing plugs in my race engine. these are not a split tip, nor are they platinum, but they are a resistor type plug if anyone is interested. They are also a side gap plug which does eliminate some of the benifits of indexing the plugs, or the detriment of not doing it.

 

i read an article of trucks in australia the use straight 8 engines and the last two cylinders are used for air pumps to air up the air suspension and not power the motor.if there was a way to shut down 2,3, or even 4 cylinders while driving at part throttle then good gas mileage would be a possibility.other more real world things to do would be to run synthetic fluids in the transmission,transfer case,motor,and diffs to reduce friction. use lower temp t-stat a little better fuel(premium) good air intake and a good flowing exhaust.lite weight wheels and tires and keep the truck weight down.air pressures high(40psi) tune up the motor, adjust the timing and carb and stay under 55mph.that should do it but then again you could just swap in a smaller motor but what fun would that be.

 

GM aready did this cylinder shut down thing on the Caddy's. They also dropped it after only a couple of years.

 

Crown Vic Police Intercepters did this until the last one rolls off the line.

 

Gm does everything first so they can screw it up and give the rest of the automotive world a bad impression. Lets see, there was the 350 Olds diesel conversion, the V8-6-4, the aluminum block/steel head HT 4100 and a bunch of other smaller displacement disasters. The Japanese watch all of this and then proceed to get it right-the Prius is a good example, but Ford is coming on with their hybrid Escape. It used to be that the Japanese copied us but now it's the other way around. OK Im on a rant I'll shut up now!!

 

You forgot the Vegas POS engine.

 

Yeah well don't forget that GM developed fuel injection in the 50s then decided that it would never work or amount to anything as far as a commercially viable product so they sold the patten to Bosch (and then had to pay Bosch for the rights to use thier own invention)

 

Getting closer to 20 PG here but dont know how close yet. Just did some recurving of the distributor had to weld up the advance slot. Re jeted the carb a bit. Last trip used about as much fuel towing 12K to 14K boat as I did towing my 4K boat. Idle circuit still looks lean on mixture. Might need 2 stage power valve for best tow/ empty economy. Got a lot of projects going truck isnt at the top of my list right now unless it isnt running. Needs front shocks right now then a better muffler. Going with RS 9000. I know with changes so far when towing my big boat millage isnt that far off from friends towing comperable sized boats with current diesels.




EFI heads have screwed up ports.

 

Who makes a good windage tray for the 460?

A GM Service Manager buddy of mine said they were getting 1 mpg with the WT addition on there 454s.

 

Windage tray ... like baffles in the oil pan to reduce 'slosh'? (for lack of a more mechanically correct term) How would this increase efficiency and mileage?

 

windage trays keep the oil from "slapping" against the crank counterweights., and crank scrapers scrape the excess oil off the weights, to increase balance.