Thoughts on the "slant plug head"

[Pablo]

Now back to the subject of my thread. After I got the head back on, and sealed up - so far no leaks. With the clutch set in "grip" mode, the bike runs great and does have more torque than the regular head. I may just change heads back and forth over the summer. For $22, if you can dial the other items in - it's worth it just for fun.

Is the cc shape ideal? NO way. The only thing the slant head adds is a higher CR and some very marginal squish zones. For $22? You decide.

 

[Ghost0]

Sorry Pablo to get a little off topic on this thread again but I want to clear up this powerband thing. As was stated, all engines have what is described as a powerband. An engines powerband is nothing more than the rpm range that the engine produces its maximum power. The attached graph shows a graphic representation of a stock Chinese 2 stroke vs a modified, tuned pipe equipped 2 stroke. Note the stock one has a wider but lower poweband. This is a pretty "flat" powerband and as Jim suggested has no real peak but a more gradual curve but it still has a powerband. Then note the modified engines powerband. It is much narrower and "peaky". Yes it produces more horsepower but in a much narrower rpm range.

 

[Creative Engineering]

Yeah,

Technically you guys are right!

I just have an "old school" definition of a powerband stuck in my head: especiallly when talking about 2-cycle engines. If I can't feel it...it ain't there.

Hey for $22.00 and a quick install that offers more torque...how could a guy go wrong.

Jim

 

[Pablo]

Hey for $22.00 and a quick install that offers more torque...how could a guy go wrong.

Jim

Well it could blow the bottom end out!! I'm sure it doesn't help "longevity".....not that I would ever use that word with a HT engine.

 

[POPS]

I read some where that some one put the slant head on backwards(Plug pointing to the rear). He said something about better flow and cooling ?? Any thoughts guys ? Maybe give that a try Pablo and let us know if there is any noticable difference ?...POPS

 

[Pablo]

I honestly don't think it would change much. I put my spark plug pointing forward for one simple reason. My plug wire would not have reached the plug!

Frankly leaning back puts the plug mighty close to the carb. Also, does it really cool better to have the fins first...?

 

[POPS]

I just read who did this. It is Goat Herder in the other slant head thred below this one...POPS

 

[Creative Engineering]

Floridaboy has been to the shop for two installs of sprocket adapters and engine mounts.

He has the Grubee 48's...both had the head mounted, (backwards), with the plug angled towards the intake side. Actually the plug is "angled" towards the exhaust which Brendan power says is a typical arrangement for final tuning a very hot 2-cycle engine. In our callaborative build-up of the new engine, he said not to bother with fixturing the head for an angled plug as there is no way this engine will ever be able to take advantage of it.

I think it is done to help with a tight installation.

Jim

 

[Goat Herder]

Floridaboy has been to the shop for two installs of sprocket adapters and engine mounts.

He has the Grubee 48's...both had the head mounted, (backwards), with the plug angled towards the intake side. Actually the plug is "angled" towards the exhaust which Brendan power says is a typical arrangement for final tuning a very hot 2-cycle engine. In our callaborative build-up of the new engine, he said not to bother with fixturing the head for an angled plug as there is no way this engine will ever be able to take advantage of it.

I think it is done to help with a tight installation.

Jim

That sounds confusing to me please clarify . Sorry Goat?

 

[Goat Herder]

This angle head thing has got my curiosity . Why don't someone offer us a truly spect out head they would become famous Immediately . Uh Well they would sell a lot of heads!!! I have a new head on hand it is stock. Never been permiated with oil. Had not been used yet. Going to find a welder perhaps even weld it myself . Then find a lath perhaps yes myself too! LOL The angled head was one extreme to the other too much compression. Gonna have to do like the three little bears story and find my favorite bowl of pourage.?

 

[Goat Herder]

Can these heads even be welded on? There has to be some hidden reason why no one has tried this?

 

[Norman]

I've used aluminum solder on them with no ill effects to reattach a broken fin or to build a broken off fin on the head and cylinder. I use an oxygen/ acetylene welding torch a propane can't get it hot enough quickly for me.
I can try to do the inside of the head haven't yet the solder melts a just a few degrees less than the aluminum so I guess it will work?. Try it at your own risk heck it might come loose then it would not be pretty inside. Bang! Bang! SCREEEECH! @$$%*&(*$%$%$?!!!!! If you know that I mean!
Norman

 

[Creative Engineering]

That sounds confusing to me please clarify . Sorry Goat?

Goat,

I don't know either.

I saw the other slant head post, and asked my neighbor at the shop, (He builds high performance 2-cycle engines), if it would make a difference as I'm going to re-work a China girl.

He said they do angle the plugs, but it is used as a final tuning procedure for a highly modified engine.

He said this engine would not be affected either way, and that I should not go to the trouble of making my cylinder heads with the plug at an angle.

I always figured the plug was put in at an angle, so that the engine would fit a tight frame.

Jim

 

[Goat Herder]

Yeah my fascination was never ever for the angle jig!

 

[Pablo]

I'm pretty sure (and I've stated it at least once) - if you had the exact stock head (hemi), but with the squish band and CR of the "slant head", the hemi head would be better than the angled head.

IF the angled head is for engine in frame fit issues, why did they make the CR so high?

 

[Goat Herder]

The new head I spoke of is not of angle design. There lies my interest that has had my curiosity! Its one of those heads with the bogus squish bands on them. How about that magical welded bead on the inside! Than with care cut to size?

 

[Creative Engineering]

I made some Billet 6061-T6 cylinder heads for the race car that had to have the plug holes at a compound angle. It was the last operation before cleaning up the ports. It was a tense moment pulling the first one off of the compound rotary table to see if the holes came into the chamber at the correct location. I already had a lot of hours into making them. Fortunately the math worked out right!

I made a set of billet valve covers just for the WOW factor! They were O-ring sealed which makes it quick and easy to do a valve adjustment, but other than that; it was just Bling.

We picked up about 1/2 second in the 1/8 mile, so I was happy with the outcome.

Jim

 

[Norman]

VW heads!???!!! That is what they look like to me monster ports, fuel system must be buckets just pour it in! Pro Stock? drag racing? Did I get it right?
Hey Jim you ought to check in with Steve Bennett he owns and operates great plains airplane engines in Nebraska. They do home built airplane engines, VW based you could drill the heads for dual spark plugs and machine the case for the front bearings. Modify the crankshaft for the huge bearing that we use on the front and the front bearing its made out of aluminum lots of parts that need machining you can tell Steve I sent you may not help but Steve and I go way back in the home built airplane building thing. Might be able to get some work from him! You can also put an add in the home built airplane mag for machine work lots of people in Fl that fly. I have more flying time in my homebuilt that any other airplane close to 1600 hrs and all on the same engine it has never let me down even over the Atlantic ocean I got worried looking down at the big shadows in the water that seemed to be following me lost sight of land I then decided to turn around and boogie for home.
Norman
I need to say the heads are a piece of ART!

 

[bmc_az]

How about doing a chamber insert. If I remember correctly didn't someone build a "mule" motor for testing diffrent chamber shapes?

BMC

 

[Creative Engineering]

VW heads!???!!! That is what they look like to me monster ports, fuel system must be buckets just pour it in! Pro Stock? drag racing? Did I get it right?
Hey Jim you ought to check in with Steve Bennett he owns and operates great plains airplane engines in Nebraska. They do home built airplane engines, VW based you could drill the heads for dual spark plugs and machine the case for the front bearings. Modify the crankshaft for the huge bearing that we use on the front and the front bearing its made out of aluminum lots of parts that need machining you can tell Steve I sent you may not help but Steve and I go way back in the home built airplane building thing. Might be able to get some work from him! You can also put an add in the home built airplane mag for machine work lots of people in Fl that fly. I have more flying time in my homebuilt that any other airplane close to 1600 hrs and all on the same engine it has never let me down even over the Atlantic ocean I got worried looking down at the big shadows in the water that seemed to be following me lost sight of land I then decided to turn around and boogie for home.
Norman
I need to say the heads are a piece of ART!

Thanks Norman!

Both Don Pauter, (Pauter machine, in California) & Roger tannenbaum, (B.R.E. in Florida) have made Horizontally opposed 4's that are loosely based on the VW. I've made heads for both the Pauter and the B.R.E engines. The cast heads were a weak point for both engines.

I'll give Steve a call...I'll have to check on the homebuilt plane mag too. My industrial customers are all in a holding pattern...I haven't had any commercial or military work since Mid-December.

Jim