timmmy

HI all,

So I suffered an engine failure recently while on the dyno.

here's the short story, I can fill in the gaps if needed.

The car id 'Judas' my 2003 Audi Rs6, LS swap, AWD, 383 stroker with dual rear mouth Precision 6266's

We made 800WHP on 93 pump on a dyno dynamics hub dyno a run or two prior ti losing oil pressure dow to 5psi at hot idle.

Upon teardown we found evidence of lack of oil. 2 out of 4 main bearings were hammered flat and worn hard, 4 out of 8 big ends worn and overheated.\

Motor spec:

LS1
383 scat stroker crank & HB rods
Custom Mahle pistons 9:5.1 with skirt and crown swain tech coatings, pro seal rings
Calico coated race bearings
Melling high pressure pump
Canton drift pan
AFR 230 Heads
custom grind Comp cam, comp push ros 1.75:1 comp roller rockers
Fast 92 intake ans 102mm throttle body
1000cc injectors

I suspect we ran out of oil volume at 15psi boost on long dyno pulls and this caused the bearing hammering.

So the questions are;

1) Better high volume/ high pressure pumps? Whats out there
2) I think revving the stroker to 7200 was a big cause, destroy back to 5.7 or go LSA?

Thanks for your input, This car WILL make 1000 AWHP on 93 pump gas!

H

p.s Ill post pics later

Old Geezer

iTrader: (3)

"Upon teardown we found evidence of lack of oil. 2 out of 4 main bearings were hammered flat and worn hard, 4 out of 8 big ends worn and overheated."

"Hammered flat"... Sounds like detonation, to me.
What do you see on the data log[s]?
What do the plugs look like?
Piston tops?

bjankuski

I agree with the detonation comment.

timmmy

I would agree but I cant see any signs of detonation, no erosion on the pistons or in the head and the plugs look good.

We have been chasing what we thought was a slight misfire at 6600rpm for a while, which improved with adding coil dwell. This may have been detonation but the knock sensors were not picking anything up.

RockinWs6

How much oil pressure did you have? Are the bearings towards the frt of the engine worn the worst? Did you experience lifter noise because 1st signs of oil starvation would be lifter noise. Post up some pictures but from here it sounds like a detonation problem. It can eat things up quickly at high HP.

timmmy

Prior to pressure loss we had 30psi at hot idle and 55-60 at hot load high rpm.

We did a pull on the dyno and at about 6.5K rpm got a big puff of smoke from both exhaust pipes (turbos), finished the pull and went back to idle. Still smoking, and that's when we noticed alarm on oil pressure and only had 5psi at hot idle. Engine sounded perfect, idled for about 10 seconds then shut it down and began investigating.

Iniital suspicion was that low oil pressure at high boost killed the turbos, hence the smoke. we pulled the plugs and they were clean, we expected to see fouling but there wasn't any. Hot compression check was 185-195 on all cylinders. no oil in exhaust until right before the turbos. Drained the oil and found lots of copper. Cut the filters and found A LOT of copper, so that's when we pulled the motor.

I will be picking up the engine and bringing it back to my shop tonight to begin a real deep dive look at the parts, Ill post pics in the next day or so for review.

Thx again for all your input.

RockinWs6

Are the turbo bearings damaged?

Paul Bell

iTrader: (9)

I'd think that something in the oil pump went bad. You had good pressure for the first pulls then it went away.

Are you using the 15-276 pan?

Gray86hatch

iTrader: (83)

For that much power I would want to see more oil pressure.

75-80 minimum

Tim

timmmy

I think it happened semi gradually over 4-5 pulls

The pan # I cant recall, it is a canton drift pan for an S14 nissan LS swap (front sump, trapdoored)

timmmy

I would like to see that too Tim, any recommendations on a pump?

timmmy

The bearnigs feel fine, I suspect there are two separate problems here. i.e. engine oil pressure loss is not related to turbo smoke. I have only a single scavenge pump T'd on the turbos, I think it started to suck air past the seals in one, which caused an oil backup. I think aI need a pump per turbo next time round

timmmy

Smoke was absolutely from turbos, no oil anywhere in exhaust tract until turbos.

No detonation or lean condition according to all the catalogs.

No spikes anywhere in spark logs

timmmy

Pics and more info here on FB

https://www.facebook.com/pages/HT-Mo..._type=bookmark

https://www.facebook.com/pages/HT-Mo...=photos_stream

timmmy

video of pull prior
https://www.facebook.com/photo.php?v...type=2&theater

Old Geezer

iTrader: (3)

In looking at the pics of the bearings:
The smeared part looks like loss of oil film.
The parts of the material being gone off the shell, looks to be detonation..
Can't tell from the pic of the block, but is there evidence of cap walk?

Paul Bell

iTrader: (9)

Thanks for the pictures.

Have you opened up and inspected the oil pump?

I'm starting to think that the crank and/or rod bearings had too much clearance and as the oil got out faster than normal, wear occurred causing more oil to come out thus reducing the pressure and increasing the wear.

This could also occur with cap walk like Geezer said.

A motor making the power you want should have forged and doweled main caps.

Although I doubt it was the cause, at this power goal, I'd want a US forged crank.

Paul Bell

iTrader: (9)

What harmonic damper are you using?

timmmy

Morning all,

Again thanks for the input.

It definately suffered accelerated oil film loss as it degraded, the question is what started it. more investigation today/tomorrow.

The crank pulley is a new GM unit from a FWD LS4.

Here are the two build galleries (in reverse chronological order) for a bit more background. The second link is the latest stuff.

https://plus.google.com/photos/11767...521?banner=pwa

https://plus.google.com/photos/11767...105?banner=pwa

Q: What does 'cap walk' look like? I presume some rubbing or deformation on the block at the cap interface?

Old Geezer

iTrader: (3)

"Q: What does 'cap walk' look like? I presume some rubbing or deformation on the block at the cap interface?"
Rub marks, and in some serious cases, material being transferred from one face to the other.
[Looks like craters and mounds.]