ESE's works engine tuner

[TZ350]

I have been told about carbon fiber pistons with ceramic tops being used in factoryTZ's and without any other changes they picked up another 1,000 rpm of reliability, could be a myth, but its an interesting idea.

Something I scraped from the net:-

"Internal-combustion engines would be constructed with cylinders and ringless pistons made of lightweight carbon/carbon composite materials, according to a proposal. This proposal is a logical extension of previous research that showed that engines that contain carbon/carbon pistons with conventional metal piston rings running in conventional metal cylinders perform better than do engines with conventional aluminum-alloy pistons. The observed performance improvement (measured as increased piston life during high-performance operation) can be attributed mainly to the low thermal expansion of the carbon-carbon composite. Carbon-carbon pistons can continue to operate under thermal loads that cause aluminum pistons to seize or sustain scuffing damage due to excessive thermal growth and thermal distortion." http://www.techbriefs.com/component/...t/article/2258

Makes you think......... no piston rings = the possibility of much wider exhaust ports for better blow down time area.

[TZ350]

Carbon fiber cylinder barrel, and fiber conductivity better than copper, this gets better all the time:-

"this configuration could likely be chosen to maintain the close-tolerance piston/cylinder clearance because it would exploit two features of carbon fibers that are very attractive in this application: high lengthwise thermal conductivity (for some fibers, greater than that of copper) and nearly zero lengthwise thermal expansion. This configuration would minimize thermal expansion of the cylinder bore while maximizing the outward conduction of heat through the cylinder barrel" http://www.techbriefs.com/component/...e/2258?start=1

[kel]

It would be great if it is, but I suspect that if one already has 27hp it will be easer to lose a few than add two or three more.......but fingers crossed.

Come on give yourself some credit here, you made 27hp through considered study and implementation, 30hp is certainly on the cards with the reworked cylinder.

[TZ350]

30hp is certainly on the cards with the reworked cylinder.

Hopefully know by the end of the week.

[koba]

That carbon stuff all looks pretty damn cool.

I'd read about the Britten team experimenting with carbon fibre conrods and other stuff.

[wobbly]

No one has managed to get "ringless" pistons to work in a normal sized bore on petrol, but a company I work for has a patent on a trapped piston ring that allows a T port with no bridge.
See
http://www.wipo.int/pctdb/en/wo.jsp?WO=2005121608

[speedpro]

Sort of like an inside out Dykes ring. Fitting it will be the trick. Winding it in through a slot leading to the ring groove and then pegging it to stop it rotating it's way out could be a possibility. Making the slot would be a mission for the machinist but I can't see a piston that's screwed together staying together at revs. Interesting idea though, if I've got it right.

[TZ350]

.

Trapped Ring, thats a clever idea.........



Instead of a screwed together piston, there may be other ways of retaining the ring, like using another ring with an OD smaller than the ring land and that clips above the inverted dykes ring.



With the retaining ring bottoming on the ring land and not free to move it would not add anything to the mass of the captivated compression ring and compression pressure would still be able to get past the retaining ring to seal the compression ring.

[speedpro]

The screwon piston crown could be useful. Squish could be adjusted by adding shims and screwing it together. Or if you had problems with detonation you just screw in another crown.

[kel]

I've been reading some more from Jan Thiel and Frits Overmars musing on the development of the Aprilia RSA, thought Id share this one from Jan Thiel on expansion chamber development -

"We once had an exhaust design software on loan from a very well known company, the results were useless! It was mostly cut and try"

Seems even the very best subscripe to the cut and try method.

[gatch]

The screwon piston crown could be useful. Squish could be adjusted by adding shims and screwing it together. Or if you had problems with detonation you just screw in another crown.

Using this method you could just about fabricate your own pistons from scratch.

Bore some heavy ally tube. Drill a hole larger than the gudgeon right through. TIG in some bosses. Turn the outside, the ring groove and thread the bore for the screw on crown. Finish the hole for the gudgeon. Mill in whatever skirt shape you like.

Turn an external thread to suit. Then using either the finished piston or a fixture, turn the top of the piston crown. To get the deck height perfect you could either machine some off the crown or piston, or shim to suit.

Might even work with a little experimentation..

[kel]

Quote Originally Posted by F5 Dave - Sub port very close to the transfer tops.

I am not sure what a good separation here looks like, but these do look a bit close.

Should be OK, here's a picture of the RSW125 ports for comparison.

[wobbly]

The software Thiel tried was from Ricardo, and yes its useless at close comparisons of pipe geometry.
In an SAE paper that they did on how fabulous the sofware was they showed the sim bmep curves for 4 different pipes on a TZ250 cylinder.
A pair of pipes were identical except for the header length.The sim showed no difference, the dyno showed a 2Hp change.
I Emailed them about the statement that the sim could predict small changes but failed to see a "huge" 2Hp difference in the results they published.
Anyway it all got nasty in the end when I suggested they spend more time on perfecting the code and less time spouting how good it was in SAE papers when clearly it didnt work.
The code I now use has proven to be very accurate, as its updated almost weekly,but as with all high end stuff like this it depends upon having alot of emperical background knowledge to begin with.
For example, twin angle headers that show up a result in the sim very easily, show exactly the same trends on the dyno, but the thing that does take time to suss is the length of each section and can only be seen by watching the pressure traces in real time on the screen to see what each engine config really "likes".
Kev and I used to spend hours doing this with the old Dynamation 4T when he first got it - and we learned a huge amount from even that old code simulator, and were able to for example design a much better cam/pipe combo for the Britten.

[richban]

Found one of the charts from the new engine. The exhaust gas analyzer was giving a different reading on almost every run I think it was on its way out. Anyway crank is being fixed this week so can't wait to get this thing up and running again. I think it has lots more potential. It really wants to rev to the moon just not sure how much it could take and last.

[wobbly]

Dont be a big girls blouse - the FXR with 48.8 stroke should be at 13000 all day, its well under 4500 ft/min and the pressure fed big ends are way less prone to cage skidding causing failure..
Christ the 450 singles are reliable to 12500, after that it gets horrible real fast.