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I've heard the theory that with ceramic cats the honeycomb isn't welded inside it is just held in place by the case, this over time causes them to move slightly, then slightly more, then rattle and crack and hence collapse, where as with metal cats they are welded in place and this cannot happen.

Perhaps this is the reason that whilst ceramic is more robust, they fail easier and earlier than metal ones.

Ok little update:

This is our very first 5 axis machined comp wheel. It is based on the older 56T 71mm casted model.

71mmcomp.JPG

The material we've machined out of an block billet alloy (pan caked). Which we can remove more materials of the hub leaving greater suction area, and run longer blades. Since more materials are removed the wheel is noticeably lighter in weight, longer blades with additional suction area would result in greater induction volume based on the same shaft speed.

71mmvs.JPG

I'll be expecting a very slightly increase as in boost response as in terms of when it starts to spool, and incensement in top/mid range power. I will be testing this with our current ceramic ball bearing CHRA assembly once my engine head is reconditioned. I'm looking forward to see any difference in comparison to current results.

I've heard the theory that with ceramic cats the honeycomb isn't welded inside it is just held in place by the case, this over time causes them to move slightly, then slightly more, then rattle and crack and hence collapse, where as with metal cats they are welded in place and this cannot happen.

Perhaps this is the reason that whilst ceramic is more robust, they fail easier and earlier than metal ones.

QFT.

My old cat did this.

Hey mate i still havent heard from u about my turbo Sa smooth garage what is going on with it plz email me at [email protected] i need the turbo back urgently

  • 2 weeks later...

Just finished my 3" metal intake pipe with return ports for both the bov and the pcv. I guesstimated the wrong location for the pcv port and just joined it anyway even though I could have blocked it off and put a new one in.

Car runs a lot smoother with everything connected.

post-29432-0-07757400-1292287452_thumb.jpg

Few little updates:

springs.jpg

Engine head finally came back together with new valves and stronger valve springs.

head1.jpg

head2.jpg

head3.jpg

head4.jpg

I will still be using stock cams and cam gears at this stage, for further experimenting.

Refer to this S1 Rb25det (Not sure if apples to Neo heads):

My Engine builder recommended stronger valve springs that has at least 80Lbs (stock is 60LBS) set pressure for any thing that is rated 500HP+ fly wheel. Valve floating will chew out valves, and seats over time.

Noticing when valves are worn: Irrational / rough idle (RB25det should be smooth as). Hard to cold start, and noticeable deteriation in performance over time after having high powered upgrades.

Unsealed valves results in lag, lose of power, and makes the car feels power less specially pre-boost.

I've experienced all of above. Valve springs should be noticed when building an forgied engine or pumping muscles out of stock build engine.

More to read about valve floating:

Quickie Vocab:

"Valve float" is the layman's term for loss of separation control within the valvetrain, usually over the nose of the cam. In other words, when separation occurs within the valvetrain while the valve is open, it's called valve float.

"Valve lash" is the clearance between valvetrain components, measured at the valve side of the rocker arm, when the system is at rest with the follower on the cam base circle and the valve closed.

A "Valve line" is the chain of components between a single cam lobe and its valve (inclusive).

There are a number of possible outcomes:

* If the separation is occuring on an exhaust valve line, then the piston will be on its way up while the valve is open. Usually the piston chases right behind the valve as the valve is closing, so if the valve stays open for too long, there could be an impact. Such an impact is not necessarily catastrophic; it's not altogether uncommon to tear down a hi-perf engine and find clear evidence of piston-valve contact. It would be preferred if this contact did not occur, and if the contact is too severe, it could definitely result in engine damage. In general, you need quite a bit of "float" before you'll have such impacts.

* When valves begin to "float," valve seating velocities increase substantially. This isn't good for the seat or the valve, and can cause damage over time.

* When valves begin to "float," it is often the case that this will be accompanied by an undesirable increase in the duration of the lift event, resulting in degraded engine performance. Sometimes a little bit of "float" is designed into a hi-perf valvetrain intentionally, and performance is actually improved (this is the exception).

Some Common Causes:

* As was mentioned previously, excessive engine speed leads to excessive valvetrain acceleration, and the valve springs may not be able to maintain contact between all the components. If you know the peak acceleration rate of your cam, and you know the force vs displacement profile for your valve spring, and you know the mass & inertia of your valvetrain components, you can calculate a kinematic separation cover factor that will tell you how fast you can run the engine without the mass x acceleration overcoming the spring force. This answer will always be wrong in real life, because...

* All of the valvetrain components, such as the pushrods, rockers, springs, etc., are flexible, and they will vibrate. Valvetrain vibration compounds the above, and significantly increases the required spring force to maintain contact between the valvetrain components.

* The valve springs themselves may resonate (vibrate quite a bit). This is called spring surge. Picture what happens if you hold a slinky outstreched, pinch some coils together, then release them. The compressional wave travels up and down the slinky. Spring surge is very similar. It increases stresses within the spring, and it reduces (periodically) the amount of force that the spring applies to the seat and retainer.

* Excessive valve lash compounds the above problems. Too little valve lash is worse, but for a different reason.

Some Remedies:

Valvetrain vibration:

* Lower mass valvetrain components

* Increased specific stiffness of valvetrain components

* Increased spring stiffness (add a helper spring if needed)

* Increased spring preload (add a helper spring if needed)

* Use a different cam profile (to excite less vibration)

* Reduce valve lash (to reduce impacts & excitation of vibes)

* Increase damping within the system

Spring surge:

* Replace the spring with a spring that has a higher surge frequency

* Use a different cam profile (to excite less vibration)

* Use concentric valve springs that rub against each other. The rubbing will remove energy and attenuate the spring surge. (this isn't the same thing as "cancelling the resonant frequency," because it reduces the vibratory magnitude at all frequencies vs the same spring pack without rubbing)

* Reduce the solid clearance of the valve spring, to increase coil clashing. Coil clashing removes energy and reduces the magnitude of the spring vibrations

* Add damping coils to the valve spring. Damping coils are coils that change the spring rate suddenly during a few mm of lift near the fitted length. Sometimes the damping coils are completely closed at the spring fitted length. The sudden change in spring rate breaks up the spring resonance as surge sets in.

How valve floats are shown on dyno:

problem.JPG

problem2.JPG

Further update:

chra.jpg

This is the very first new serie of ATR43 Gen3 Alfa, in Duel Ceramic ball bearing and Billet comp wheel setup in .82 turbine and .70 comp. This is one estimated around 560HP in a bolton form. Hopefully I can get some testing and evaluations done before end of this year.

comp.jpg

comp2.jpg

comp3.jpg

In comparison to stock turbo:

vsstock.jpg

vsstockrear.jpg

There will be 4 different Alfa versions. Results and Updates will be posted.

And this is the Gen Alfa 2 CHRA (Duel ceramic BB, Machined Billet 71mm comp wheel). Made for stock turbo high flowing. This should be very interesting.

Getting the test car's engine back together at this stage. looking to do one test for the differences of having billet comp wheel before xmas if car runs ok. Will post some results if every thing goes according to plan.

The new generation of turbos will go through further evaluation and testing. I want this generation to produce the best possible results and hopefully still be affordable to most high performance enthusiastic.

Small update:

This a customized Billet comp wheeled ATR43G3 with sleeve bearing setup in .82 turbine and .70 comp. Clutch blew up (run ended early) at 325rwkws @ 21psi. Internally gated on RON 98 with full stock setup.

I'm hopping to get 370rwkws on it at 30psi on RON98 using a twin plate clutch next year. Might be installing a 6 boost manifold as stock manifold is restrictive at this point.

atr43g3billet325rwkw.jpg

Looks like some good potential Stao...

Thought of making one of those with an external gate rear housing?

All the Hypergear turbos seem to make a huge wack of torque but can't hold it through the rev range which is a pitty :(

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