Turbo Engine Faliure

[c928jon]

Hi

I have a "fairly" heavilly prepared 944 turbo as a track day toy, my intention was to work on braking and suspension before turning to the engine...but...

It looks like I had an oil problem at Bedford and have spun up the bottom end bearings on cylinders 2 and 3.

I'm stuck over which option to go for, second hand engine or rebuild. It is really only a bit of fun and as such can't really spare huge funds at the moment. Any ideas?

If anyone knows of a used engine kicking about, let me know

 

[John Sims]

Tricky question, and no doubt why you asked it. []

A 2nd hand engine may well be long in the tooth and due to detonate its self but will certainly be cheaper. The best route might be go the cheap option with the second hand lump and then rebuild the original as time and funds become available. You can then flog off the replacement engine once your original is ready to go back in.

 

[c928jon]

I agree, its a bit of a catch 22.

Does anyone have an opinion on 225 or 250hp for track use, is the k26/6 more responsive for track use, or go for the 250?

I've found a 250hp engine with all the bits to do the swap, and think we are going this way initially (i use "we" as its 50-50 ownership with a friend, not the royal we []) I'm also hunting the parts to rebuild our old engine, maybee with upgraded parts to handle a bit more boost pressure.

Is there anything else worth doing whilst I have an empty engine bay?

 

[edh]

Have you worked out what your oil pressure problem was?

- Oil too hot? Slipping drive to oil pump?? Oil pump failure? Cracked pickup?

This may be self-evident but you need to build in something to stop it happening again. Better oil cooling & reinforced pickup (much easier to do with an engine out, as is the RMS and sump gasket, and belts, waterpump etc..)

Presumably you have your current turbo, so the cheapest route is to keep it - the engines are the same, just the turbos and the chips are different. I would always go for the 250 just because there's more potential, and you should be able to keep it on boost on most corners of most tracks. The real answer is a hybrid BB turbo from Simon Peckham [] but that's probably out of your range right now. MarkK is doing pretty well with 26/8 at the moment []

 

[edh]

Might also be worth emailing Darkvisorman on here - he had my old turbo & has replaced the engine with something a bit interesting. It was a 170k motor but with very clean bores & a fairly recent headgasket / belts etc..

 

[Diver944]

The bearing on #2 cylinder is the one that normally goes on a hard used track car. Lot's of forum chatter seems to point the finger at an oil level less than the maximum being the main cause, and during hard cornering you get less pick up which leads to a thinner film on the bearing.

I know with my old engine that I could easily use 100ml of oil in a single 20 minute track session and you can go from Max to Min in a morning on track so you have to get into the habit of topping it up after every session. Actually leave it to cool down and top up just before you go back out to get a better reading.

Normal road use would see that same engine use less than a litre between 6000 mile services, its the full on boost track use that consumes the oil.

Good luck with the replacement or rebuild, I would stick with the K26/8 turbo as at the track you are never off boost long enough to make the K26/6 worthwhile

 

[John Sims]

Oil surge can be an issue - Lindsey Racing do a baffled sump kit which could be worth a look.

I (probably) get an oil light going round Luffield. I say probably as I only notice the big red light out of the corner of my eye as I have other things on my mind at the time and can't look to see what it relates to. It goes out again.

 

[edh]

I don't think Andrew S has ever had any oil starvation problems - and he would be about the most extreme / fastest trackday driver i could think of in a 944. Running on slicks as he did is going to exaggerate any potential oil surges

 

[John Sims]

While you have an empty engine bay I have always hankered after a Lindsey Racing 3 piece cross member. That way you can remove the sump pan with the engine in situ.

 

[Diver944]

ORIGINAL: edh

I don't think Andrew S has ever had any oil starvation problems

Very true and I've never seen anyone drive the socks off a 944 as much as he did [8D], but I would bet that Andrew topped up the oil very regularly

 

[edh]

come on c928jon - spill the beans & settle this discussion (I won't call it an argument because we're all far too pleasant to argue [])

 

[Hilux]

ORIGINAL: edh

I don't think Andrew S has ever had any oil starvation problems - and he would be about the most extreme / fastest trackday driver i could think of in a 944. Running on slicks as he did is going to exaggerate any potential oil surges

Agree completely.

If you look at the 944 sump it is quite well baffled but any sump can be improved.

I would suggest a low oil level or cracked pick up pipe however I have read on a certain track in America a particular quick manouevre followed by a huge boosted acceleration while leaning the other way exiting a corner can cause this but it is quite a particular manouevre and not a general problem.

The pick up pipe is a long pipe with a weighty end so it vibrates and stress fractures above the oil thereby sucking in aire so toasted engines ensue. A simple stay (or collar) solves the problem.

 

[c928jon]

Well just to let those worried about why it failed.........

A combination of wear, human error and over enthusiasm.

It was the hottest day of the year, 32deg at bedford, which is a long fast and hard circuit on the car.

We ran fairly hard all morning and checking the oil regularly.

We had a problem with the oil pressure in the car for a while, which was checked with a gauge and pointed towards the sender, which was leaking oil. Occasionally it would flicker for no reason.

Well, the oil had got that thin by the afternoon and it was difficult to check the level (my excuse and sticking to it)

So basically, we ran out of oil and ignored the warning light due to it's errant behaviour.

rattle rattle bang bang.....

No 3 is a mess, top shell slid under the bottom shell.

I should pick up the replacement engine this week, at which point the pounds will undoubtedly teach me another lesson

 

[c928jon]

I might go on dragons den with an oil sender triggered engine cut out device

 

[c928jon]

oops, and thanks all for the v useful comments[]

 

[Hilux]

It was the hottest day of the year, 32deg at bedford, which is a long fast and hard circuit on the car.

Depends which circuit and how long you stay out for.

The water temp gauge on a 944 is obscured by the lozenge wheel also which is also a telltale.

Bad luck but I`d be very interested to know if it wasnt a 15 or 10-40?

 

[c928jon]

It was the gt circuit, all four little ones joined together, we were doing out-5hot-in.

The oil was the closest racing spec to 20-50, I think it was 15-50 but i'm trying to repress the whole thing.

We run a race-technology dash, set up with the temp in large, engine temp/oil temps were ok, upper limits but ok.

We have a data logger that recorded all the sorry details Two previous corners oil pressure dipped, the last corner of death it dropped low and by the end of the corner the damage was done.