mark kibort

Im coming from the 928 side of the Porsche fence and as you all much know, racing the 928 at Willow has provided some interesting causalities. the famed "#2/6 bearing" failure is widely talked about and i understand that its a concern in the land of the 944T as well as the land of Willow springs.

What solutions have you guys found to fight your #2 bearing problems if there are the same issues.
If there is issues... what kind of oil are you guys using? what are the oil temps when racing. Any breathers, baffles, scrapers, windage trays, accusumps, etc etc?

who has lost an engine? what are some of the reasons that you folks may have seen failures.

I have some ideas of why some of the 928'ers have seen problems... but they don't want to talk about it. guys running 10-15 seconds slower a lap grenading engines and blaming it on the turn 8-9complex or turn 2 at willow springs.

Ive been racing the platform for 18 years now with no such issues, nor any modifications over the last 8 years (80hours, but using a drilled crank now) and curious to those that haven't seen issues, if they are incorporating the same things i am in my race prep and style.

Interested to hear of all the experiences and theories /solutions here.

Mark

fejjj

Mark,

Michael Mount has a solution that he has posted about.

https://rennlist.com/forums/924-931-...aring-fix.html

harveyf

Mark, I've been following your thread on the 928 forum. Anecdotally, I meet a lot of guys with stock 944's and 951's at DE events that do NOT talk about having had problems with #2 bearings. And although we're not racing per se, I think the cornering forces at a DE can be very comparable. Many guys run R-comp tires so some pretty decent g-loads are generated. I looked at the map of Willow Springs and I'm not seeing anything that isn't duplicated here on the east coast tracks. From the one time I was at Willow Springs, years ago, I remember that segment may be slightly downhill. But so is Hogpen at VIR or the museum turn at Barber or the bridge turn at Road Atlanta. My short answer is that a well maintained engine with clean good quality oil with anti-foaming agents will do the trick. Here is the longer version of why I say this:
http://newhillgarage.com/2013/06/25/...tem-explained/

ddombrowski

Watching some in-car videos from different chumpcar events of other 944 teams, I've noticed a wide variety of oil pressures in cars where I could see the gauges on video.

ONe particularly successful team, Floridiot Motorsports, has run 10+ races on a single engine, and eventually had to replace it when they blew a head gasket. They always run a minimum 4 bar oil pressure and I know they use the turbo 944 oil cooler.

Our engine has a few races on it and seems to be doing well, always holding 4-5 bar at speed and at its very hottest may drop to 3.5 bar at idle.

In comparison, there are some teams racing out there that have 2.5 bar at 4k rpm.

I never hear anyone mention the oil pressures they were running at prior to the engine failing.

Arominus

I would have Mr Mount do the rod mod to run clevites.

harveyf

Good observation about the oil pressure. My car runs at 4 to 5 bar when at speed. I would be really freaking out if it fell below 3 bar, if at speed. Hot idle is always on the low side but you're not stressing the engine at idle.

One of my data acquisition books recommends running an oil pressure channel. The race engineer checks oil pressure as a sign of engine health after every on track event. He gave examples where there were momentary drops in oil pressure at certain corners that the engine was able to survive just fine. You might consider purchasing the relatively inexpensive data acquisition unit that Autosports Labs sells before you go to Willow Springs and set up an oil pressure channel.

Here is a link to an article I did about changing out the rod bearings. From the photos, you can get a rough idea of how the bearings looked. My very ballpark change interval for rod bearings is every other season, which works out to be about every 50 to 75 engine hours. I change my oil every other track weekend.

http://newhillgarage.com/2014/12/29/...g-replacement/

There are so many parameters that could cause a rod bearing failure besides oil starvation. Unless a car is fully instrumented and run to bearing failure as part of a science experiment, not sure if we can ever truly know actual causes. I tend to trust the improvements that Porsche made throughout the model life of the 944 as what the guys who built the engines for a living thought best. Also, oil quality has made great strides since the 80's.

Mark, the rod bearing issue has been the subject of much discussion on our 944 forum. You can get a feel for the vast array of opinions by searching and reading these threads. One thing I am pretty sure the 944 does not suffer from, versus the 928, is the 928's problem with oil return from the heads. That issue alone caused me to back off when contemplating building a 928 track car. I prefer recovering from problems with cheap 944 engines versus the more expensive 928

931guru

Since you are on the west coast, Jon Milledge might be your best resource. Former Firehawk racer, a lot of the 944 racers use his expertise.

odonnell

The Clevite rod bearing that Michael Mount offers is a no brainer. It's also not as expensive as you may think.

Van

And I recommend frequent oil analysis - so you can spot bearing wear and replace them when they become an issue. (Note, this is *not* a Michael Mount Clevite rod bearing conversion.)

disasterman

The bearings you should really worry about are the tiny wheel bearings!

kevin12973

Mark,
I have also done a ton of investigating on the subject. There has been many very expensive and complex measures taken to avoid the #2 problem. The winner for most extreme would be dry sump. But I have read many success stories with just two simple measures. One is quality 20/50 oil, Amsoil, Millers ect. Not Mobile 1. And #2, Add a turbo or larger oil cooler. The point is to have quality oil and keep the oil temps in check, then of course do the oil analysis like Van has mentioned.
Crank scrapers are also reported to be worthwhile.If you can get a 87 or88 oil pan with the matching pick up tube, they have a deeper sump and sort of baffles for windage and crank scraping. Also, do not over fill oil. Under braking oil will run forward in the pan and splash the crankshaft, "blender".This is how oil gets airated(foaming) which is believed to be the cause of lack of oil to #2 rod failure.

944hal

I've lost two engines due to #2 failure. I just rebuilt a motor (not because of a rod bearing, just because). I've installed a crank scraper and the Michael Mount rod bearings. I'm breaking in with Millers mineral oil and am going to run Miller exclusively at the track. I also have a larger oil cooler. The engine I just rebuilt was using Millers. The rod bearings, after about 40+ track hours looked great. I had a head/valve problem and just decided to do the whole motor while I had the opportunity. Hoping for startup this week.

Speeddemon944

I ran Spec944 for 5+ years with a doner motor of 90,000 miles. No scraper or baffle, I only changed the belts and water pump. I think this is a recipe for success -

1. Shift at 6K religiously (not 6100 or 6200) - Dyno has proven that a stock motor really starts to fall off around the 5500 mark
2. 20/50 conventional oil - our tolerances are not that tight (relatively) and you're not running a turbo. I use VR-1. I currently race a 951S are run VR-1 Syn.
3. Oil cooler - I didn't tun one on the spec car but it was on my mod list. The turbo runs a slightly modified LR cooler + the factory cooler in series.
4. Oil changes after 6 track days.
5. Oil temps never above 250* (Cup cars have the warning buzzer for 255* IIRC)
6. Proper warm ups and cool downs

Oil pressure in a race is interesting I see 4-4.5 bar at WOT and 2.5 at idle on the Turbo with Syn oil.

Oh and I do still hold the track record at Miller Motorsports park for SP-1 with that car/motor.

speedjw

#1) Run GOOD 20-50W oil, we run amsoil, and noticed a significant improvement over Mobil 1.

#2) Run an oil cooler, not only will you keep your oil healthy, your water temps will drop by 15deg F.

#3) Shift at 6,000

#4) Change the oil after Every Race!

If you do this, you won't have bearing issues...

333pg333

Remember that the OP doesn't have an i4 motor but a V8. The 6000k limit is possibly close for him anyway. We rev our racemotor to 8000k but it has been built for this. I think cooling is crucial in all this.