John Veninger

Here is the chart:

Doug Hillary

Hi John,

great stuff - this is the data I originally sought when putting a small racing oils list together here many months ago. This type a realtime-regularised data acquisition is very valuable to us all

I am more and more convinced that a synthetic oil with a HTHS viscosity beyond 4 and nearer 5+ may be better for these engines when being tracked

What oil (brand/type/viscosity)were you using in this run?

Do you plan to eventually capture the oil's temperature too?

Great stuff - thank you again

Regards

Fastest928

If you are racing, and you have the racing accusump setup with check valve, the actual engine oil pressure is only measurable at the input to the engine..or at the accusump output, as they will now be thesame!

If you run two gauges, like I have in the past, then you will see the difference in oil pressure....the stock oil gauge measures the output at the oil pump, and if the accsump is plumbed correctly the stock gauge will read the pump failing to pick up oil.....

Marc
DEVEK

Fastest928

.....as your engine is being fed by the output of the accusump!

Marc

John Veninger

Syntec 5w50
I might consider running a different oil, but can justify the cost between the "other" oils and the deal I get on Syntec unless I can measure the difference. The good thing is now I can!

Sure do. I need to hook up the sensor. I have the ability to capture 4 sensor inputs above and beyond the RPM, speed G force, and unit temperature (inside the car)





I'm going to add another pressure gauge to the accusump line. This way I can compare the stock sender to the accusump sender and plot both channels from the AIM unit. Maybe I can get this in before I return to LRP on the 30th

Nathan Valles

Facinating stuff!!!!

One question, Is your G-meter hard bolted to the frame or does it have some rubber and foam insulators. It seems that some vibration isolation or a good numerical smoothing function might be in order to minimize the chatter and smooth the curves a bit. (engineer and math nerd showing through)

Still it is really great having this kind of data available. One thing I would suggest when you go again is to take the same turn at 3 or 4 different speeds to generate 3 or 4 different curves as opposed to just flat out. say if you take the turn normally 80mph, then also run at 75, 70, and 60 mph. look at the data and see where the pressure fails to drop. If there is no pressure drop at 60mph then on your next run before the end of the session, turn the accusump off and run a 60mph turn to verify that the accusump really does help out.

There is likely much more to be learned here just by having some actual data to analyze.

Bye the way, What data acquisition package are you using?

mark kibort

That could be the issue right there. I just cant be that lucky, can i??
Ive run either redline or Amzoil in both of my race cars, and both have had no issues and pressures ALLWAYS measured by the stock guage at 5 bar when on the track. 20-50 is the weight as well.

I think most of all our oiling issues are oil brand related. But thats just my educated guess.

try a oil change with amzoil and let me know what happens!

Ive also seen temps as high as 280f with my last part euro engine, and when I removed the block, that had over 170,000miles and 40,000 race miles and commuting to the races, the bearings were almost perfect. nothing out of the ordinary on #2/6 bearings.


Mark
no accusump,
stock oil cooler
Amzoil, always on the full mark
Holbert 928 race car (S4)
going on 3 full racing seasons!

Doug Hillary

Hi John,

thank you for the info I requested. You are using a most suitable oil and while I do not have the High Temperature High Shear (HTHS) viscosity of that oil I suspect it will be about 5 and I believe this is a good figure. Synthetic oils are mostly better at the extremes - all else being equal (viscosity etc.) "Exotic" Brands are sometimes just that - exotic!

There is no doubt that using the correct oil viscosity when "tracking" is very important. The most critical of all aspects when under high load is the High HTHS viscosity which is mearured at 150C

Until some really accurate date is obtained, engine bearings typically operate at up to 180C and this makes the HTHS viscosity a good indicator of the oil's performance in this area

Too high a HTHS viscosity robs power and may affect turbo spinup, lifter efficiency etc so an effective balance is needed. I believe for tracked 928s the HTHS rating of ANY oil used should be 4.1> at the minimum and 5+ preferred

Mark;

It is inlikely that the BRAND of oil is really an issue. The type may be but as we discussed before, if you use an unsuitable viscosity of ANY oil you will have a problem under high load and especially so under HTHS

The now obsolete Mobil 1 TriSynthetic 10w-30 had a HTHS viscosity of about 3. The obsolete M1 15w-50 version of this oil had a HTHS of near 5! The DIFFERENCE in FILM STRENGTH between these two M1 oils at high temperature IS ENORMOUS !!! The 10w-30 oil was almost destined to fail in your application as many other Brands of oil would have too!

The new M1 SuperSyn range is a much better and more robust "total" formulation - a different product. I would still not race the 10w-30 version however! I do NOT use M1 in any of my vehicles. I do use Mobil's Delvac 1 5w-40 - it has a HTHS viscosity of 4.2

The "Racing Engine Oils - "Short List" " thread on here in November 2003 covered some of this. As examples note the following HTHS viscosities;

Castrol's "R" synthetic 10w-60 = 5.4
Shell Helix Ultra synthetic 15w-50 = 4.8
Motul's V300 Competition/LeMans oils = expected at 5.2>
Amsoil's (some) = to 5.9
Mobil M1 (some) = to 5.4

As stated above "I believe for tracked 928s the HTHS rating of ANY oil used should be 4.1> at the minimum and 5+ preferred"
This would then put the preferred "published" viscosities in the 10w to 20w-40 to 50 range ( eg 15w-40, 20w-50 and etc)

The oil's Brand and type or if it is a mineral or synthetic product probably matters little - however, there is a safety margin with a synthetic at the extremes!

It would be well worthwhile to check the HTHS viscosity of the oil you are using - it may save your engine!

John's oil temperature data acquisition may narrow the HTHS down to even tighter parameters than about 4.1> - 5>!

John, this data is simply excellent and similar to that we have used since about 1996 in heavy diesel engine real time monitoring. This has enabled better driver education, enhanced fuel economy and longer engine life in Heavy Trucks!

Thanks again for sharing your data with us all

Regards

John Veninger

Sorry, but thats not going to happening

My unit is mounted to the tunnel near the front on some had rubber mounts. My car is way to stiff to smooth out the spikes. I can down load the data and use Excel to smooth it out, but haven't done so yet.

I can get that information
I hope to get more data points with temperatures and also run at different tracks which will produce different G force vs. rpm situations. I'll share as new data becomes available.

Doug, you do realize that oil is like religion to some people

Doug Hillary

Hi John,

I do, I do. It simply isn't for me - I'm too much of a realist I suppose

Cost effectiveness is my game - ExxonMobil and Detroit Diesel are at this moment doing a funded "tear down/measure up" on one of my engines with 1m kms on it. Oil changes have been done at 100kkms and the average oil useage rate from new has been 1ltr/6k from. That's good economics for me if the wear rates confirm what the oil analysis has told us for the last four years

If it doesn't stack up I don't buy it! The Brand doesn't matter much - availability and performance is the trick!!

Please keep up the good work and posting the HTHS viscosity of "the good oil" (Castrol) you are using will help us all

Regards

mark kibort

interesting stuff. Sure, Im really not that hooked on the brand, but the type and weight of the oil. film strength is very important and ive heard debates on the importance of shear qualities.

could the wide range of weight (ie 5-50) be a problem?

Im not so much concerned with results of 100000000mile tear downs, as I am with racing mile tear downs at extreme temps.

Im no expert, but I have some emperical data with my 3 engines and the use of good synthetic and keeping the revs under 6200rpm and monitoring the oil temps. and keeping it clean. (changed every 3 races with amzoil, and with the old dyno oil like kendal 20-50,used on my old 4.7, i changed it every race)

mk

Doug Hillary

Hi Mark,

yes, you touch on a valid point - the "spread" of an oil's viscosity is sometimes a problem in respect to its eventual HTHS viscosity
Some formulations do enable a wide spread and a higher HTHS number (eg Castrol's R 10w-60 at 5.4). Generally the wider the spread the lessor the HTHS.
But I believe each product's HTHS needs to be known before tracking it in a 928 - and a 5+ HTHS would be my choice

Anything above the HTHS 5 mark is a robust oil but then viscous "drag" tends to start have a negative effect on power output and fuel use
( this is one reason why the CAFE requirement of 0w-20 etc oils produces formulations with a HTHS of only about 2.6>)

Some racing engines will tolerate oils with a HTHS of around the 3.6 mark (Mobil's new M1 R 0w-30 is one)

Why the million mile engine life and the 62k change points are of interest is that in consort with Used Oil Analysis (UOA) it can prove that certain oils do not shear down after hard and prolonged use and give good wear results. Truck diesel's oil temps continuously run at 110C+ and any "mixed fleet" synthetic 5w-40 or 15w-40 mineral oils that survive this for extended periods and still remain in grade are excellent products for use in cars too!

There is also another bearing lubrication effect that needs to be understood too. The "dam" effect in the rotating bearing creates a thinner oil film behind it which is barely greater than the oil's "thickness". Too thin, and critical temporary shear occurs resulting in rapid wear caused by any contaminants present. Clean oil is very important

Thanks Mark - I think your revs limit, and a good quality clean oil has worked for you. You have the results to prove it too!
If you could carry out a UOA after your three race sessions it may tell us some interesting stories too

Regards

mark kibort

Ill save a sample as it will have 3 race weekends and 1000miles of street driving after this next weekend. (still knocking on wood)

the filter looks very clean as of the last few oil changes. the only thing stuck to my magnetic drain plug was that 3rd tooth from the cam sprockets.

(I had to laugh when i saw the last one. the magnet was sooo very clean, not even the usual film, except for that big ole tooth from the cams.

where do you want me to send the sample?


mk

Nathan Valles

John,

Are you sure your Accusump is working??????? It's supposed to provide 3-5 seconds of protection isn't it? According to your graph you only exceeded 0.6g for about 3.5 seconds, 0.9g for 2 seconds, and 1.1g for 1 second before oil pressures started to drop.

Assuming the Accusump provided the minimum 3 seconds of protection means that the oil pickup problem begins at only 0.6g's of force. In comparison, great big SUV's can pull 0.7g's on a skidpad.

Here is an easy way to test the system. Get a few cones and go to a large shopping mall really early on a Sunday morning. Mark out a large u-turn or even better is a 360 degree circle that you can enter and exit. (like a roller coaster loop-the-loop laid on it's side) Drive it at 30, 40, 50, etc., until you notice a repeated minor drop in oil pressure. Then turn on the accusump and see if you can go faster before you get any oil pressure drops. If you have real time readouts then you can get a passenger to monitor the system while you drive.

Feel free to ignore the suggestion, but it doesn't look like your Accusump is giving you an additional 3-5 additional seconds of protection to me. It's either that or the oil pickup issue is far worse than I ever thought it was.

John Veninger

Nathan,
Did you read Marc Thomas comment eariler?
I'll be running two oil presssure senders next time.