Accusump; foggettaboudit or hellayeah cuz?

My last motor blew up - I'm not sure what the order of the failures were and have no empirical evidence to lead me to a conclusion - but, my belief is that the turbo was over-spinning due to a boost hose (feeding the recirc valve) popping off undetected...eventually the ceramic cage and ball bearings of the turbo disintegrated and fell through the drain into the oil pan - subsequently, I believe, metal was sucked into the oil pump and got wedged into the pressure relief piston causing low pressure.

I think as a guttural reaction I thought I would put in an Accusump as in, "...that'll fix ya.." - but the more I think about this, the more it seems like a complete waste of resources;

a) MAYBE on jumps and on tarmac there are enough g-forces to cause a momentary absence of oil - and from talking to a few folks, if the turbo is spinning fast, that momentary absence is sufficient to blow the bearings - (True or Fantasy?)

b) I'm worried about rally conditions, where you can easily have a stall scenario, either on stage or not where the accumulator would empty its contents and now you have 2-3 qts extra in the oil pan. I believe this can be avoided by using an electric valve.

c) Audisport - I've seen some indication that the S1 ran a dry sump system (too much $ for my budget), so potentially oiling might have been a problem -

d) in a catastrophic scenario - you only get a stay of execution.

What are your thoughts on installing an Accusump style accumulator for Rally conditions?

Audisport sure as hell did run a dry sump, although my gut feeling is this is partially because the standard pump sucks, and the rest of it so they could run a huge oil cooler out in the trunk lid.

I've seen plenty of people kill Subaru engines from oiling problems at rallycross, no reason to think you won't run into problems on gravel roads.

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

I installed a big orange 20 psi oil pressure light in my rally car. Ive only seen it flash at a stop light at idle for a while. My thought was if I hit a rock and broke the oil pan I would have a better shot at saving the engine.

I would install a $15 light if it never turns on then worry about other things to go faster. Seems that turbo subies with wrx or older 2.5 rs oil pans suck air if there at all low on oil. New guys at first rally cross didnt realize they used more oil then driving to work. Boom!

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First rally 2013
Rally car type AWD subaru
Total rallies as driver 6
Total rally cars built 2
Total rally cars caged 3
Total rally cars repaired from offs 4
Total years racing exp other then rally 19 yrs
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Accusump systems are great for road racing, where you have very high and sustained cornering g's. I think with rally you won't see 2+ seconds of sustained high g cornering.

I'm a fan of the big idiot light at a lower pressure. Good indicator and should require much thinking on the driver or navigators part.
A well baffled oil pan can do wonders for oil starvation.

As far as nuking a snail due to momentary loss of oil, I'm not so sure. Granted, my street volvo has a plain bearing instead of ball bearings. In quick uphill lefts while accelerating, my oil light comes on, sometimes for a second or two. The turbo has 160k miles on it and it's never protested (yet).

In my experience, the biggest killer for high speed bearings (and engines) is oil break down due to extreme heat.

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Reamer
Seems that turbo subies with wrx or older 2.5 rs oil pans suck air if there at all low on oil. New guys at first rally cross didnt realize they used more oil then driving to work. Boom!

The 2.5RS I co-drove at nationals one year would randomly eat a half quart of oil during a run. We were checking it after every run. I think it was getting stuck up in one of the heads and getting sucked through the PCV. Maybe.

Now, on the other hand, this isn't a Subaru, this is an Audi engine, with a crankcase breather system that sucks rocks and tends to blow the oil out of the block breather, and the head has poor drainback since it's hard for the oil to go down past all the blowby going up...

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Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

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vbares
My last motor blew up - I'm not sure what the order of the failures were and have no empirical evidence to lead me to a conclusion - but, my belief is that the turbo was over-spinning due to a boost hose (feeding the recirc valve) popping off undetected...eventually the ceramic cage and ball bearings of the turbo disintegrated and fell through the drain into the oil pan - subsequently, I believe, metal was sucked into the oil pump and got wedged into the pressure relief piston causing low pressure.

I think as a guttural reaction I thought I would put in an Accusump as in, "...that'll fix ya.." - but the more I think about this, the more it seems like a complete waste of resources;

What are your thoughts on installing an Accusump style accumulator for Rally conditions?

Soooo OP you blew it up. Here's a cookie.

You don't indicate in your post that the engine is torn down for a proper inspection of what happened.

Unless it is out and apart to see for a fact what went wrong we are doing little more than 'Wanking on the Internet.'

For many to most people working on their cars.... And sadly for too many repair shops.... Installing an Accu-Sump thing is doing little more than adding several sources of leaks + introducing ick into the engine when they don't clean up well enough inside of lines or the engine itself.
As for Z-OMG! You just have to have one! How many other Audis are being saved on rally stages by using this? If you can't come up with a dozen people who are solving a problem by using this... Then the answer is a resounding 'No.'

Blew a hose off the intake?
What are you using for clamps? T-Bolt clamps done right are the END of hoses jumping off and they don't cut up the hoses.

Blew up a turbo? Size it right with some headroom and they last...

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JohnLane

Overkill is consistently more fun

An accusump can only compensate for a momentary drop or loss of oil pressure. The accumulator then needs to be recharged by the oil pump. If the pump is weak or there is an ongoing pressure leak the system really isn't going to solve anything.

The accusump is good for two things: as a pre oiler and as a band aid for poor oil pick up design problems.

A proper failure analysis is your first step towards a solution!

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

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JohnLane
How many other Audis are being saved on rally stages by using this? If you can't come up with a dozen people who are solving a problem by using this... Then the answer is a resounding 'No.'

Did more research and apparently the Group B cars were running dry sump and the Group A cars were running wet sump w/baffled pan.

With all due respect, the intro talks about the analysis - specifically low oil pressure due to fragments in the oil pump pressure piston - what we don't know and have no way of knowing is if the turbo blew up first, and if so, specifically why. Also in the description is included the fact that it was a hose going to the recirc valve - its a 1/4 inch hose that may have been left unplugged after a service.

The motor has been torn down by a machine shop, cleaned, new crank provided, new pistons/rods - blah blah blah...

I think the best advice has been to install a big orange light - thanks.

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JohnLane
Blew a hose off the intake?
What are you using for clamps? T-Bolt clamps done right are the END of hoses jumping off and they don't cut up the hoses.

Also, as a lesson I learned from the Huebbes (who are super anal about prep and treat the bug like an airplane) put safety wire on all the intake hose clamps after tightening it. I used to have issues where the hoses going to the intercooler on my Legacy (actually all Subarus) would loosen up over time. Safety wire on the hoses I never touch and I haven't had any issues at all. Nice and cheap tool at HF and some 0.041 gauge wire and good to go!

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vbares

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JohnLane
How many other Audis are being saved on rally stages by using this? If you can't come up with a dozen people who are solving a problem by using this... Then the answer is a resounding 'No.'

Did more research and apparently the Group B cars were running dry sump and the Group A cars were running wet sump w/baffled pan.

With all due respect, the intro talks about the analysis - specifically low oil pressure due to fragments in the oil pump pressure piston - what we don't know and have no way of knowing is if the turbo blew up first, and if so, specifically why. Also in the description is included the fact that it was a hose going to the recirc valve - its a 1/4 inch hose that may have been left unplugged after a service.

The motor has been torn down by a machine shop, cleaned, new crank provided, new pistons/rods - blah blah blah...

I think the best advice has been to install a big orange light - thanks.

Muchachito, one thing about relief valves is that they progressively open up and blow off excess pressure...a jammed up pressure RELIEF valve valve might lead to excess pressure---and you see that sometimes in bulging oil filters.....

And you're right...it's lots of fun to talk about all kinds of reasons for theoretical engine failures but that doesn't help you analyze YOUR specific failure..

Personally I am confused cause that thing is in essence a VW watercooled engine and not particularly waay bad-ed out. Ought to be a very reliable motor package.
What have you done wrong?

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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vbares
Did more research and apparently the Group B cars were running dry sump and the Group A cars were running wet sump w/baffled pan.

With or without Accu-Sump toy? My bet is without. You trying even 50% as hard as did Audi back in the day?

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vbares
With all due respect, the intro talks about the analysis - specifically low oil pressure due to fragments in the oil pump pressure piston - what we don't know and have no way of knowing is if the turbo blew up first, and if so, specifically why. Also in the description is included the fact that it was a hose going to the recirc valve - its a 1/4 inch hose that may have been left unplugged after a service.

The motor has been torn down by a machine shop, cleaned, new crank provided, new pistons/rods - blah blah blah...

In your first post you say nothing of it being torn down....
With all due respect....

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vbares
I think the best advice has been to install a big orange light - thanks.

Agreed. Most of the time the easiest solution is the best. Though this tends to not be how we roll.

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JohnLane

Overkill is consistently more fun

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john vanlandingham
What have you done wrong?

The story is long, went testing one day - and found the motor was having heat issues - when we got her home, I noticed the exhaust manifold was cracked - bits were missing from the turbo flange - no evidence of where those bits might have gone - turbine looked intact.

Replaced the EM, and road tested - no longer having a heat problem - good boost, everything seemed good. I believe in the re-assembly the hose (1/4" that goes from the pressure side to the recirc valve was not re-installed - 2 days later, off to Charlevoix.

Shakedown - all good, Recce in the race car - all good. 1st and 2nd stage - in-town, tarmac - all good, although I do remember hearing the turbo whistling much louder than usual - on transit to stage 3, the engine balked once and momentarily - but I did get out to see if I could see if anything was amiss - didn't find anything.

Start of stage was great - absolutely flying - then half way through, no boost whatsoever so figured something let loose - looked in my mirrors to see if I was smoking real bad - but, nothing - so I continued, no boost, pig mode - towards the end of the stage, about 1k from the end - I started noticing some smoke - figured I'd look at it during transit...oil pressure at that point was not great, but there was some (light did not come on as far as I know - if it did, I didn't see it).

On transit, shut it down and started looking for what I imagined would be a big boost hose that had popped off - everything was tight, except I did find a 1/4" hose on the pressure side that feeds the recirc valve was disconneted - reconnected, re-started and sure enough - big plume of smoke from the tail pipe...

So my thoughts are that we overspun the turbo for quite some time during road testing, shakedown, recce and the first 2 stages - at some point it gave up the ghost - could it have been a momentary loss of oil pressure, while it was overspinning due to a jump (there were several - and a couple sideways) ? I dunno - the folks I've spoken to have indicated a dip in oil pressure while overspinning could have grenaded the CHRA -

In any case, the evidence was a grenaded turbo, bearings and cage material in the oil pan, oil pump pressure relief piston jammed due to a piece of shrapnel.

if the detonation could have been avoided by keeping constant oil pressure - perhaps we could have made it through...

...and on further analysis - I think the main points are:
1. How many other rally teams use an accusump? not many...
2. The real problem was overspinning the turbo due to a boost leak? make sure all hoses are installed.
3. did the factory ever use such a device in rally applications? No.
4. Is there clear evidence that a momentary loss of oil pressure lead to detonation? No.

In conclusion and to answer the quoted question; a bigger brighter oil light, and a 20psi switch might be the better option - Audi does have 1.8Bar switches - I was using the gauge sender that would only light my light at effectively zero (bad)...

We have an Accusump that I'll be installing in the Civic after we put the new motor in.

A couple of reasons why:

1) We had a couple of spun bearings on the integra--both on road courses (one at Portland, one at Pacific Raceways).
2) Also we've had the oil pan dent to where the pickup was partially obstructed. Oil pressure was high enough to not damage anything, but too low to activate the VTEC solenoid.

I think this is pretty specific to high-revving VTEC Honda motors. I think if you were never going to be on a road course, probably wouldn't be worth it.

Rebuilding the motors is expensive and time consuming--for us the extra bit of insurance is worth a shot. I'll keep you posted if it appears to solve the problem (will never know for sure).

Wouldn't the lack or recirc valve be basically causing shock/backspinning to turbo not overspinning. Wastegate should have still operated.

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Grant Hughes

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NoCoast
Wouldn't the lack or recirc valve be basically causing shock/backspinning to turbo not overspinning. Wastegate should have still operated.

hmm - yes - that's pretty aggressive on the bearings eh...good thought.

Wastegate worked fine.