gtsum---thanx for the info. I'm in the market for an engine for my truggy. I keep looking at the GRP's mostly because they are the freshest design. I have been hoping to read about some feedback from the racers.

Thanx

the new gold head GRP is internally the same as the MR tuned Ninja's....the silver headed GRP's are the same as the regular Ninja's inside........ The cases are different, but the sleeves,pistons and cranks are identical........ Yes the Ninja also had a domed piston as well !

they are just a very nice running .21, with the best fit,finish and bling in the industry... They definitely aren't superman, but they are at least IMHO the fanciest show in town !

No offense, but pictures and basing it off of pictures can be inaccurate becuase of angle, distance, etc...

I would like to see the numbers on a set of calipers, actual measurements...

Dude, run what you want to. If it floats your boat to run OS plugs, do so. It you bought a GRP engine, you should run GRP or Ninja plugs that fit correctly, end of story.

I LOVE my GRP(Ninja) 21, ran about a gallon through it practicing today, did a bit of performance tuning...and WHOA, this thing puts out some SERIOUS power.
I need to reglue all my tires, the GRP power has torn them off of teh rims :tire:

Well, I whipped out the digital calipers and a bunch of plugs....

O.S. Turbo, GRP Turbo (C6), Mugen Turbo, and O'Donnell Turbo

Now rather than post my actual numbers, I'll post my findings. Reason being, calibration of digital calipers will vary so numbers may vary. The key is to use the same digital calipers for all the measurements, apples to apples comparison...

I measured total length from where the plugs sits on the button head to the end of the cone.

Length of the cone itself, from the shoulder to the tip or end.
Diameter at the end of the plug (filament end)
Diameter at the shoulder (Where the threads end, and just before cone starts)
Length of plug from where it sits to where the threads end....

In summary; I found the Mugen and GRP to be basically identical (no real surprise).

The O'Donnell was very close to the GRP that I'd have no fear of running it in my GRP. The differences I found were in the .001 range which I can attribute to my error....

The biggest difference was between the O.S. Turbo and the GRP C6...

The two big differences were in the (outside) diameter of the tip/end where the filament is. The O.S. measured .197, the GRP .202. The next biggest difference was in the diameter of the "shoulder". The O.S. measured .256 and the GRP .271

So, the O.S. is smaller by some. Other than that observation, I don't know what that really means....

I'd sure like to hear what others mic'ed out...

My suggestion is, it you ran an OS plug in the head button, use OS plugs for that button. If you want to use a GRP/Ninja plug, get a button for that glowplug. I have seen them leak, not just this brand, but all others when you switch up glowplug brands. I have heard people tried the OS plug and went back to the GRP glowplugs and said they didn't feel as good as the OS, but this could be because the taper is now not sealing properly.

I have been hearing the GRP is closer to the Picco taper than any other plug, but I would still say stick to GRP plugs unless you are certain you have no leakage issues with another brand.

Come on man,... you can see the freakin difference... geesh! My point here is Novarossi plugs wont work no matter what the caliper say's! LOOK! The angle and distance is the same as they are laying right next to each other...! The taper does not match, the pictures are not lying....!

The reason to actually figure this out is:

10 GRP plugs @ $11.50 x 10 = $115.00
10 Odonnel plugs $6.99 x 10 = $69.90

What plug would you rather run if they both fit and perform well?

Oh... I see you said no offense... sorry! Anyways, good job on measuring. No need for me to take close ups now. Cool. :o

Ninja, GRP, or Odo plugs got it!..

Thanks.

My understanding is there are 3 options
Ninja plugs
GRP plugs
O'Donnell 97 plugs< exact same taper, I run these

got to race my GRP mill this weekend and it's a winner. Plenty of power throughout the powerband and it was delivered really linear. I'm happy with it:p I was running a P3 plug as well;)

I asked Mike Truhe if I could run an O.S P3 with no problem in the GRP engine this is what he told me.justindyer: yeah that will fit just fine

One thing, does the stock GRP plug suck? I'm trying to figure out why everyone runs a P3 plug instead of what it comes with.

The one it comes with is a cold plug I think a GRP 6 mine died after breakin.

I ran the P3 with very good results. P3's are cheaper and easier to find. Plus they idle for 1/2 with P3s.

Yes, the grp6 is a medium plug. the grp5 is the hotter of their selection. I emailed Mr. Drake and he told me to run the 5. I'm a tool and die mold maker. I have the precision tools to get some hard facts about the plug dimensions. I will measure a grp and an os. I work second shift so, I will post my findings in the early hours Tuesday morning when I get home from my Monday. The difference of the end diameter from .197 to 200 isn't as important as the angle. If the angle is different, that's when damage will occur. I will get the bottom of this.

Truhe told me to run the 4.But told me the OS would work fine no problems.

Ive been running boss & ninja # 6 plugs with 25% with great results and i can get them alot cheaper here in Australia than the grp plugs. #6 plug seems to be ideal for Australian daytime conditions.

The problem is if you are looking for the "hot" plug (GRP), just about every place is out of it. I can't find it anywhere in stock. So I believe people are looking for alternatives until those are available OR a less expensive alternative...

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...

fuel
 

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 out:flaming:really 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

Fuel
 

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. :tire::tire::tire::tire::tire::tire:

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.
http://pic20.picturetrail.com/VOL146.../315240201.jpg
The grp plug depth from the bottom of the button to the face of the plug is .116
http://pic20.picturetrail.com/VOL146.../315240196.jpg
The os depth is .113
http://pic20.picturetrail.com/VOL146.../315234981.jpg

http://pic20.picturetrail.com/VOL146.../315234983.jpg

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:smile:. 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.

Man,... I'm glad I got this plug thing started. You guys all kick butt! Thanks for taking the time to really use your skills and figure this out for us.:tire:

I'm feeling better about trying another brand. I do think the recommendation of continuing to use the same plug, or what ever you settle on would be a smart thing. Its nice to know you could use the OS plug, as they are cheaper and more readily available. As for the .003 well I just shimmed my GRP up for 30% and that shim measurement is much much larger than the .003.

:):)

You guys ROCK!!

Glowplug temp is detemined by the size or thickness of the wire. The hot glowplugs have thinner wires, so they glow very easily, as where the cold plugs have a thicker wire, that requires more compression, heat or lean mixture to get them going. Thats why the cold plugs idle erratic, but come on hard on the mid to topend, due to the RPM's keeping the heat going on the wire.

Novarossi changed up the system with hot and cold in the same heat range. This is the length of the glowplug body, not the wire size. The difference is how quickly it dissipates heat, but will have the same wire thickness in the same heat range.

So what is the verdict on glow plugs? I just ordered a GRP .21 only to find out that GRP plugs are no where to be found (in stock)... Will the Mugen plugs work? IM guessing so as the motors are close to identical, but at 11 dollars a plug, I don't want to order a bunch and find out that the MR plugs are a no go?

They are considered to be Losi parts:

http://www.amainhobbies.com/index.php/cPath/1_68_880

OD97T work great