Mr Cox

Yes, perhaps the undercut for the thread on the plug and the loose fitting copper gasket is the real problem. The threads themselves should not give that much extra volume but they would provide a channel to the unused volume around the gasket...

I've been making "turbo heads" for my small engines ever since AndyW showed how relatively easy it is. Especially on engines that use a clamp ring it is fairly easy to make new heads even on a very small hobby lathe.

aspeed

Yes, the lathe is very handy. I have a little Taig lathe, but mostly use my Hardinge Chucker turret lathe because it can take a bigger cut and is a bit more accurate with collets. The Hardinge is in the outside shop, so I don't like to hang around for long in the winter.

lfinney

My Feedback: (44)

why would anyone use a idlebar plug in these small engines? my experience has been ugly with idlebar plugs in half A engines

rc lifer

Have any of you guys tried the Norvel .074Turbo head and adapter that can be had from the NV engines site?

rcguy59

My Feedback: (8)

I saw it on there a few days ago. The website just runs me around in circles and it won't go to "checkout".

rc lifer

rcguy, Yep it did the same to me. I went through the registration process twice last night and still couldn't order it. Today I got an email from NV, that had me go to a web address to complete the regisitration. I did that, then was able to sign in at the NV site and able to make an order for the Turbo head and some gaskets. It will be interesting to see how long it takes for it to get to me. Anyway, I was just wondering if any body out there had used one yet.

aspeed

They are not an idle bar plug, but more of a racing plug like the Nelson plug. There is a taper on the bottom surface that seals much better than a regular plug giving better performance that especially shows up on .15 and smaller engines. There are different heat ranges too. The car guys use them a lot in the Picco, Novarossi high performance motors. http://www.ebay.ca/itm/NEW-O-S-P3-Tu...s&hash=item5ae

hllywdb

I ordered one and expect it in soon. I will let you know how it works out. Shipping times? About the same as Tower. And Tower is closer to me.

hllywdb

Actually it came in the mail today. It includes the head clamp. It is threaded for the OS style turbo plug like valentine did with his. I'm not sure you would have room for a nelson on the 074. In any event the OS style makes more sense as they are available everywhere in lots of heat rangesand should be produced for a long time. With the plug installed chamber looks identical to the factory button so I would expect the same performance.

Andrew

That was pretty quick --- where was it shipped from? Waiting to see how it performs. I certainly agree with you that the turbo adapter is probably the best option, particularly since the plugs should be around for some time to come.

hllywdb

Andrew it shipped from California. I ordered it between Christmas and new year's. They've always had outstanding shipping. Not sure why you had issues registering, I've ordered from both my laptop and my phone.

rc lifer

hllywdb-Sometimes the websites have an attitude, or perhaps I did something wrong. Its all good now. I am now a registered NV- Norvel website online customer. Have you bought from NV Engines before?

hllywdb

Yes, many times.

hllywdb

OK, I finally got a chance to stop by the LHS and pick up the correct OS turbo plug (P6). I had a P3 (Scorching Hot) a P7 (Cold) and a P8 (Ice cold). Figures.
Comparing the new turbo head to the factory head a few things are apparent. First is that the chambers both appear close in size and shape. Second is that the insert for the turbo head is a bit thicker on the seating surface. Lastly the turbo head clamp is taller, has an additional cooling fin, and the area that you lock the wrench in to gives almost twice the area for the wrench to bite on.

Anyway I pulled an 074 out of the bin and bolted it to the stand. This one isn't quite fully broken in yet so it isn't fully on pipe yet. But it won because it was already bolted to an engine mount. Hey I'm lazy. Plus I figured since I was testing the head, not the motor it realy didn't matter as I needed to see how it performed against the stock plug. I made sure it was shimmed right and ran some numbers using a MA 7x3 and an APC 6.3x4. The WOT numbers are still low on this one as it's early, so your actual milage may vary.

On the factory head I got 15,200 with the 7x3 and 15,300 with the 6.3x4. Low idle was 2880 and 2940 respectively. I bolted on the new turbo head with the 7x3 and got 14,300. This seemed a bit low so I removed one head shim. The next run gave me 15,300 and an idle of 2700. I next switched to the 6.3x4 and got 15,300 and an idle of 2900.

So it seems the turbo head will give identical performance and perhaps a little better idle, you just need to remove one shim over what you are using on the stock plug. I can't tell if it is a slight difference in chamber or if the cavity in the OS plug is a bit larger. What I find even more interesting is the additional cooling area. I think this, combined with the ability to run a slightly hoter plug (P5) might let you run a bit more prop, perhaps even adding another shim, a bit more Texaco style.

aspeed

That is good to know. I suppose another test would be a 1/4" - 32 plug test on the same props. I made up an insert like that a couple of weeks ago, but it is just too cold to run it now. It didn't even want to turn over. Florida would be nice now. I think the extra fin is just there because you can. The turbo plugs are usually much taller than a standard. If the motor idles good without cooling off too much then it is probably a good thing.

hllywdb

People have used the regular plug adapter that NV makes and have said the loss is no where as bad as the ones for the cox 049's. These heads have zero loss and with the OS plug availability we should keep them flying for quite some time. I may pick up a few more just for piece of mind.

aspeed

I got 2 or 3 of the 3 pack Merlin plugs. They are ok too, a bit cheaper. The Turbo conversion allows hotter or colder plugs for special apps I guess.

Andrew

Thanks for the report --- it's always good to get an unbiased evaluation of a new product. I'll have to dust off the credit card and get a couple of heads.

Mr Cox

I think that the later head clamps from Norvel also have four fins, but I'm not sure, will have to dig one out to check.

I actually prefer the OS P3 and P4 to the colder ones, but I'm also running 10% nitro as my standard fuel. What fuel was used in the test?

hllywdb

I used Sig 25%. I used the P6 as that is the same heat range as the stock plug as well as the Nelson plugs I use on the 1/2a turbo heads. I figured I'd keep things apples to apples.

Mr Cox

Okey, the higher Nitro level might explain it then. Not sure how to compare the heat range of the Turbo to the regular ones, but on other RC engines I'm using mostly the OS P3 and P4 as well.

Checked a few Norvel .074 engines that I have and it seems they are both with three or four cooling fins, and the four might be the latest version. Makes more sense if they simply make a Turbo insert and kept the head clamp as before.

hllywdb

Could be that all the new ones have ben superceeded to the 4 fin head clamps.

All the turbo plugs I use are light load high rpm applications so a medium or medium/hot is all I need. My gas cars are on-road so they use the medium plugs too. The only engine I use the P3 in is the GX40 from NV. I suspect a P5 may help with a bigger prop, but not sure they have the port timing to go too big. That's more a job for the Enya 09, which will putter around with an 8x4 and not complain too much. The Enya is such a nice motor it's too bad it weighs so much.

aspeed

When I made my turbo head, I noticed that there was not much meat left to get the thread in. Maybe the clamp is bored out a bit for the new insert. Mine is just over 9mm bore, and it is an 8mm thread on the plug. I have the three fin clamp. Normally the cooler plugs are better with high nitro. Not sure what numbers they use.