G

gmjeric

I'm New Here
has anybody used different rings such as those from total seal that have antifriction coatings.....overlaping designs.....or thinner profiles
 
also has anybody used custom pistons with the ring pack and pin moved as high on the piston as possible
 
I know the F-1 guys will use automotive gapless rings in the little O-200's, but they are also usually running plain steel barels, overbored to the limit of the rules. Once you start dealing with the big bore Lycoming cylinders, it is tough to even find "off the shelf" to fit. Add to that the requirements driven by chrome or nitrated cylinders, and it's even tougher to find compatable rings from the automotive world.

Not saying it cant be done, but I've not heard of such on a Lycoming. Perhaps someone else knows different?
 
I have a set of ECI 2nd rings I had TotalSeal modify to be gapless.

I have a friend running the same rings in an IO-360 on a Mustang 2 and last I talked to him his compressions were 80/80.
 
Last edited:
rings

In the 70's and 80's the total seal rings were quite popular in 0 360. No sure about compatability withm nitride cylinders but I know they are still available for Lycoming steel cylinders.
 
Mike S said:
This will lower the compression....................
Click to expand...

no we make up for it in rod length....when building from scratch get the smallest combustion chamber to leave plenty of quench..design piston as compact and flat as possible....then determine stroke and get the rod last....


the deeper the rings are on the piston and the wider the gap from piston to wall the less efficient you become...this all becomes dead volume that must be filled burned exhausted but doesnt burn in time to add push.....im still looking to encapsulate the spark plug but leave electrode bare so that maybe we could get two pads for quench area......ill dig it up but if you look at harley heads they are in the same boat...then go look at a eldelbrock harley head and you see the quench areas...then go look at a nitro prostock billet harley head and youll see the refinement im after
 
gmjeric said:
also has anybody used custom pistons with the ring pack and pin moved as high on the piston as possible
Click to expand...

gmjeric said:
no we make up for it in rod length....when building from scratch get the smallest combustion chamber to leave plenty of quench..design piston as compact and flat as possible....then determine stroke and get the rod last....
Click to expand...

My response was to your original post------nothing mentioned about rod length etc.

I stand by the comment that raising the pin height will lower compression, given the info in your original post. Your second post seems to be relating to a clean sheet design..........

What are you looking to accomplish with these design changes anyway???

Rod length is usually adjusted to accommodate stroke changes, or to lower piston skirt friction by lowering the rod angle----which is probably a negligible issue in our low RPM engines.

Your comment about needing to fill the volume above the rings is spot on, specially with our big bore engines.

A Dykes ring can actually be installed with virtually zero volume lost above the ring.

images


Dont forget cooling...................
 
Sorry i was making the assumption of gaining rod length to accommodate the piston pin change...

Im looking to maximize the efficiency of an o200...

as for the heat....add thermal coatings to ports, combustion chamber, valves and pistons.....keep the heat in the cylinder then keep it moving out the exhaust....also laying the valve seat from 45 to a 30 degree cut


with as low of a piston speed that we have im really concentrating on port velocities...we get about 3% increase from compression bump but when you match a cam profile to fit the compression increase your 3% can go to almost 10%

yes i could get all the power from an 320 or 360 but not fan of the extra weight....etc
 
gmjeric said:
exhaust....also laying the valve seat from 45 to a 30 degree cut
Click to expand...

Why would you do that on the exhaust valve. Most engines have a 45 cut on both valves but a Lycoming or any aircraft engine for the matter is slow turning so it was found that there were better port numbers at low lift on the intake with a 30 degree cut.
 
Good...

gmjeric said:
with as low of a piston speed that we have im really concentrating on port velocities...
Click to expand...

Good that you understand the value of this often overlooked, and misunderstood factor-----

A good 4 into 1 exhaust can help, and the total intake runner from mouth of the intake to the valve are quite important here also.

One thing I have noticed in these engines is how poorly matched the passages are at the mating surfaces ------- carb/servo to sump/manifold for instance.

Cold air sump will keep intake charge density up-----good thing.

Do not forget the use of ram air------I am getting over an inch of MP just by pulling a knob after take off :D

Here is a link to a thread on my ram air setup on my RV 10.

http://www.vansairforce.com/community/showthread.php?t=40855&highlight=ram+air&page=4
 
rocketbob said:
Why would you do that on the exhaust valve. Most engines have a 45 cut on both valves but a Lycoming or any aircraft engine for the matter is slow turning so it was found that there were better port numbers at low lift on the intake with a 30 degree cut.
Click to expand...

the exhaust would also benefit as you are looking at the rate of area open to flow...at low lift the area on a 30* degree cut is a hair larger than that of a 45*..

i am trying to get as much air flowing as quickly as possible
 
gmjeric said:
the exhaust would also benefit as you are looking at the rate of area open to flow...at low lift the area on a 30* degree cut is a hair larger than that of a 45*..

i am trying to get as much air flowing as quickly as possible
Click to expand...

I would talk to the guys at Lycon and get their opinion, because its going to be a trade-off between low-lift port velocities and wide open. They use a Serdi to cut 3-way and I suspect there's not much benefit. Especially considering the intake with its sharp corners and protrusions, that's an area that some porting work will benefit along with porting the cylinders. In other words I don't think you'll gain much changing the valve angle. There are other tulip shaped valves used on turbo engines you can try to get the port velocities up.
 
I plan on porting...just by feel there seems that the port cross section grows and that the top of the port could be filled some...this was justa quick feel of the finger though....

yep lots of sharp edges that need smoothed ...inside radius was much better than i expected though
 
gmjeric said:
has anybody used different rings such as those from total seal that have antifriction coatings.....overlaping designs.....or thinner profiles
Click to expand...

Over the years, I've used Total Seal rings (with varying success) , moly filled rings (with varying success) and plain 'ol chrome faced rings (with excellent success) .

In air cooled, aircraft engines, the rings transfer quite a bit of piston heat to the cylinder walls. When unusual ring configurations are chosen, it's not uncommon to experience heat transfer problems, ring overheating, and loss of ring tension.

In particular, Total Seal's seem to be hit or miss.

One thing to consider, the compression number (80/80) does not equate to HP, as even somewhat poorly sealing rings will make rated HP. And oil consumption rates often have no bearing on engine life. In fact, it's rumored that zero oil consumption results in rapid cylinder wear.
 
rocketbob said:
I would talk to the guys at Lycon and get their opinion, because its going to be a trade-off between low-lift port velocities and wide open. They use a Serdi to cut 3-way and I suspect there's not much benefit...
Click to expand...

This conflicts with the info fed to all the hod rodders back when I started into cars back in the 80's. The multi angle valve seat was MOST beneficial at low lift.

I guess I'd be mostly concerned with the reduced contact area on the exhaust valve seat, but Lycoming moves much of the heat through the stem anyway, so perhaps it's not an issue.
 
You must log in or register to reply here.