Dr. Destructo blows a rocker apart

[Dipstik-sportech]

Originally Posted by sw20kosh

So he floated a valve and caused damage to his engine at 12 psi on pump gas running 300-330 wp? All these damaged motors is making me think this engine isn't as strong as people initially thought.

I mean if you float your valves on ANY interference engine you're gonna have a bad day, it's not indicative of a weak engine you just need to be mindful of the rpms that's all.

[sw20kosh]

Originally Posted by Dipstik-sportech

I mean if you float your valves on ANY interference engine you're gonna have a bad day, it's not indicative of a weak engine you just need to be mindful of the rpms that's all.

He wasn't even loading the engine up when it went bye bye.

A friend of mine just had a rocker fly out on a stock vehicle on track... followed by catastrophic damage.

[FirestormFRS]

Originally Posted by Element Tuning

I know my dealer has seen broken valve springs and then broken valves which can spit the rocker out. I can see a case if using a factory valvetrain that you could float a vakve at 9k rpm and spit the rocker.

In my case the pin the roller rides on physically walked out. Our spring seat pressure really isn't very high in terms of a high performance engine so this isn't a case of too much of a good thing. Oiling was also good and no signs of galling or excessive heat.

Purely a case of a factory part fail in a high performance application. We'll address this on any new builds from here on regardless of this possibly being an isolated insident.

Thanks,
Phil Grabow

I've seen rockers get thrown at higher than factory rpm, not on this engine though. Could the rocker have been spit and the force knocked the pin out? That's not uncommon in over revved engines.

[Element Tuning]

Originally Posted by FirestormFRS

I've seen rockers get thrown at higher than factory rpm, not on this engine though. Could the rocker have been spit and the force knocked the pin out? That's not uncommon in over revved engines.

Not likely based on how the pin edge looks. I didn't give you guys a close up shot of that but it definitely walked out.

Now a property built motor and all these shortcomings dealt with is how to make it realiable. We have really worked hard to come up with a solution to the low oil pressure and now we'll have a solution for this "cheap" part. In something like our Pro Comp motor spitting a shim would not be common since appropriate valve springs and valve lash are used. The surprise is the component failure itself.

I just break stuff, it's what I do. You just don't always know the failure point of the parts until you break them and find out. There are no pointing fingers when your engine building, car building, ecu development, tuning, and race driver are all in house. You just get on with it an engineer it better ir you fess up to the mistake (as a driver I have taken a few motors out totally due to my mistakes). It is very frustrating and it does scare people but when we start winning championships and breaking track records people can at least feel confident in our motors. I share the failures and the accomplishments equally so people can see the effort and R&D that goes into what we do.

[Element Tuning]

Originally Posted by SmsAlSuwaidi

Yup, funny that the car was barely on any load when it happened. The car is now being shipped overseas though and is getting a 2j or lsx. While the one that is still in the states I'm going to give the fa20 another shot

I bet under full load the valve shim dropped first and that gave enough room for the rocker to fall out without much load or RPM.

So far I'm lucky as we've accounted for all pieces except the roller which I suspect shot out the valve cover. We have the rocker, pin, and the valve shim luckily (none of those parts are beat up either).

From some of posts and PMs I've received the pins are failing so mine is not an isolated incident and it's even happening on totally stock cars (no engine or power mods).

We'll look at all my current rockers to see if there are signs of any others walking out. We have a race coming up next weekend so we will likely chance things and if all looks OK just drop a new rocker in for now. We don't have time to tear into things too deeply at this point.

[xwd]

Originally Posted by sw20kosh

So he floated a valve and caused damage to his engine at 12 psi on pump gas running 300-330 wp? All these damaged motors is making me think this engine isn't as strong as people initially thought.

The pistons seem pretty good unlike some of the other Subaru engines, but you are always going to find the weak points. I never expected it to be all that strong, companies don't overbuild engines now like they used to especially in $25K cars, and Subaru has never been known for stout engines.

[gramicci101]

Originally Posted by dwx

The pistons seem pretty good unlike some of the other Subaru engines, but you are always going to find the weak points. I never expected it to be all that strong, companies don't overbuild engines now like they used to especially in $25K cars, and Subaru has never been known for stout engines.

Their sand-cast, full closed deck STi blocks of old were incredibly sturdy. Like you said though, they don't overbuild things anymore because it costs more money.

[Element Tuning]

OMG I got lucky for once! Less than 4% leak down on all 4 cylinders. While that's higher than normal for our engines it's right in line with how we built this particular one (looser than normal).

There is some cam lobe damage from the roller likely getting stuck and a couple dings where the roller exited the valve cover. Not sure what I'll do to make this next race in terms of these cams. Clean up up or replace them.

The other rockers on this bank of cylinders looks OK meaning no obvious signs one if failing.

[Turdinator]

What will you guys do moving forward from here? Find a fix for the factory rocker or develop a replacement part?

[brn12345]

Check out my two posts on this thread on page 4. Could be useful.

http://www.ft86club.com/forums/showt...t=56181&page=4

[Element Tuning]

Uh look at the manufacturing inconsistency here! These are the two new rockers I purchased to be modified and tested.



I can see why one could fail more easily than another given how the secure the ends without uniformity! It's a roll of the dice really!

[Calum]

For the love of all that is holy, when you make a run of new billet rocker arms, sell a top end kit with rockers and springs. I know you guys mainly do in-house builds, but god damn that has me terrified.

Can the valve covers be pulled with the engine in the car? I'm seriously debating on pulling mine on the weekend to inspect.

Originally Posted by Element Tuning

Uh look at the manufacturing inconsistency here! These are the two new rockers I purchased to be modified and tested.


I can see why one could fail more easily than another given how the secure the ends without uniformity! It's a roll of the dice really!

[Element Tuning]

Yeah these are horrible but the one that failed wasn't even as bad from what I remember. We will not be making new rockers as that's an engine part that really should be designed by a company that has been producing them for a long time. We have modified the oem rocker and will test that our modification remains reliable and doesn't cause any other issues.

Hopefully we can make the Trans Am and Whelen USTT race this weekend at Limerock. The engine is buttoned up already build not back in th car. I did mock up the dry sump/external oil pump mount today but I don't think we can finish that in time. I still have a few lingering gremlins from the fire (no ABS) that I want to fix.

We were able to pull the valve cover in the car so we knew what broke. We did not attempt to replace the rocker with the engine in the car and I honestly don't see it being possible/worth it. Somehow Steve replaced the rocker with the cams in but I don't know how he did it as he told me to leave him alone. LOL!

[Calum]

Originally Posted by Element Tuning

Yeah these are horrible but the one that failed wasn't even as bad from what I remember. We will not be making new rockers as that's an engine part that really should be designed by a company that has been producing them for a long time. We have modified the oem rocker and will test that our modification remains reliable and doesn't cause any other issues.

Hopefully we can make the Trans Am and Whelen USTT race this weekend at Limerock. The engine is buttoned up already build not back in th car. I did mock up the dry sump/external oil pump mount today but I don't think we can finish that in time. I still have a few lingering gremlins from the fire (no ABS) that I want to fix.

We were able to pull the valve cover in the car so we knew what broke. We did not attempt to replace the rocker with the engine in the car and I honestly don't see it being possible/worth it. Somehow Steve replaced the rocker with the cams in but I don't know how he did it as he told me to leave him alone. LOL!

Loosen the lash adjustment, remove rocker arm. He'd need to adjust the lash with the new arms anyway. Wait, shims... WTF? Did he manage to compress the valves with the heads on? I know you've said you don't run much seat pressure, but damn.