What about the "shoulder"? The distance between the last thread and the start of the slope of the cone? I would imagine that would play a factor too cause even if you angle is the same but the the shoulder is longer you'd deform the button head.... Just a thought...

question what fuel you guys using in this mill need to finish a 10 min final without a pit stop, i am using o'donnelll 30% in my picco evo 2 at the moment runs real good but carnt get ten mins out of a tank if i lean it any more it starts flaming outreally looking forward to running the GRP would like to no what would be the best fuel/mileage thanks

Are others getting over 10min run times at your track? Runtime has a lot to with track conditions and how you drive.

yes thats the problem yesterday missed the bump up by 10 sec the first 5 guys all did the 10 mins without the fuel stop thats what cost me,saw the DRAKE get 13/14 mins pit stops in the final at neo 08 last month thats what made me get this mill would like to know what the best fuel is before start running in thanks

I've tested quite a few fuels and found that Werks 30% fuel seems to get me the best run times so far. I'm sure others will say something else is the best. Also wheel spin is the biggest waist of fuel! Drake gets those 11+min run times by making it a point to reduce wheel spin everywhere he can. I race against Drake often and have been trying to learn from him and other pro's how the fuel game goes. Its all about reducing wheel spin, restrictors, and the right plug for the atmospheric conditions.

I did some measuring today at work. I have the Grp .21 and I'm running the OSp3. The engine comes with the grp6 turbo plug. So, I measured the two and compared them. The angle is 30 degrees on both of them. To me, that's the critical thing. If the lock up angle is correct, no damage will occur. However, I did find a slight difference in the end diameter of the plugs. The OS plug is slightly smaller on the tip. What this means is, the OS plug protrudes slightly further into the cylinder than the stock plug. But only by .003 on an inch. I measured this with my Mitutoyo digital drop indicator. I then used Dykem blue dye to test the fit of each plug into the button. This gives evidence of the contact surfaces of the plug and button. The dye showed that there is a perfect seal with both plugs.
Conclusion: I've been measuring steel as a tool and die maker for twenty years now. I believe that these two manufactures of plugs are interchangable. But an engine expert, I am not. With the tests I've done, I believe you cannot damage your button by using OS plugs in your Grp button because the angle is correct. But the question is the .003 of depth between the two plugs. Will this make a difference? Personally, I don't think it will matter, because the surface area of the glow plug that is inside the cylinder is VERY small. I've had no problems using the p3 in mine and will continue to do so.
Notice the blue dye in the angle which shows the contact between the os plug and grp button is perfect.

The grp plug depth from the bottom of the button to the face of the plug is .116

The os depth is .113

wicked work....but I still have seen numerous GRP built motors pissing fuel out the button with a OS plug......tighten the plug all you want and it still leaks........Same thing with using a OS in a Picco.......

Nice work!



[QUOTE=Geo Y-Rock;4398158]I did some measuring today at work. I have the Grp .21 and I'm running the OSp3. The engine comes with the grp6 turbo plug. So, I measured the two and compared them. The angle is 30 degrees on both of them. To me, that's the critical thing. If the lock up angle is correct, no damage will occur. However, I did find a slight difference in the end diameter of the plugs. The OS plug is slightly smaller on the tip. What this means is, the OS plug protrudes slightly further into the cylinder than the stock plug. But only by .003 on an inch. I measured this with my Mitutoyo digital drop indicator. I then used Dykem blue dye to test the fit of each plug into the button. This gives evidence of the contact surfaces of the plug and button. The dye showed that there is a perfect seal with both plugs.
Conclusion: I've been measuring steel as a tool and die maker for twenty years now. I believe that these two manufactures of plugs are interchangable. But an engine expert, I am not. With the tests I've done, I believe you cannot damage your button by using OS plugs in your Grp button because the angle is correct. But the question is the .003 of depth between the two plugs. Will this make a difference? Personally, I don't think it will matter, because the surface area of the glow plug that is inside the cylinder is VERY small. I've had no problems using the p3 in mine and will continue to do so.
Notice the blue dye in the angle which shows the contact between the os plug and grp button is perfect.
[snip]

OK, so it appears you only get a hair more compression with OS plug. At least the angle is the same.

wow thats research!!! lol

The only thing, if the OS plug protrudes into the combustion chamber and not flush and level, it defeats the purpose of running a turbo plug in the first place. You would be running your engine as if it had a standard glowplug head.

Isn't the purpose of the turbo plug the perfect seal of the angle? IMO it's all about the angle.

.

Yes the .003 is mimimal. If it sat in the button further, it would change the affects of using a turbo button in he first place, as with standard buttons, the glowplugs sits uneven to the top of dome, and you cannot shape the top of combustion chamber as tight with a standard glowplugs as you could with a Turbo. That why the turbo head button and glowplugs are supposed to produce more power, they run a tighter closer combustion chamber due to the small taper on the end of the plug.

Hmmm... am I wrong in the understanding that a "hotter" plug is actually longer for more compression, (igniting the mixture sooner) and a "colder" plug shorter? (related to how far into the combustion chamber it protrudes?) That was always my understanding of how that works... but maybe I'm mistaken? IF that is correct, then the next colder OS plug probably protrudes the same amount as the GRP??? Just food for thought.