Greg, ive run faster for longer at laguna than Anderson on the same tires. Remember, Anderson running 1:40 at laguna on DOTs with 420rwhp . Ive run 1:36.1 on DOTs with 372rwhp. (dont forget much smaller brakes, less wing, more weight, cheapo suspension, smaller tires, narrower track, etc etc ) He has run 1:34 on DOTs with 520hp..... I did 1:36. on DOTs with 370 hp. NOW, WHO HAS MORE CORNERING FORCES??

Greg, your a smart guy, it lets us all down when you say nonsense like this!

Now, when anderson was burning up a set a day, we changed his aligment to not have as much camber and suddenly his tires were not cording out! but of course, you werent there to see this.
Oh, and i almost forgot... Anderson burns up tires at a real fast rate when he runs 1:31 at laguna on slicks! now, this is big time speed...... Oh, but then there are guys that run for a few hours on slicks at 1:24 too. (aka ALMS GT2, GRAND AM GT, PIRELLI WCGT, Porsche Supercup)

Again, you seem to live in your very sheltered world. Willow springs kills tires around turn 8-9, becuase its high g-loading, for a long time . Im not contradicting myself here, but the g-loadinig is the same for the engine as any other track BUT, because the car is going near 135-145mph, the forces ONLY on the tires are HUGE.

SO, to answer your erron claim about tire wear and my efforts, yes, i to have corded a set of DOTs in a half a day at Willow Springs. and guess what, they were a brand new set of Hoosiers, and only runninig 1:34.

any more anectodal evidence Greg????



Oh and by the way Greg, just because you are burning up tires, it doesnt mean you are pulling a lot of cornering forces. Now, i have the world of respect and admiration for mark as a driver, but anyone can get a little sloppy and over drive the tires, due too many reasons. (i.e. set up, adrenelin, race battle, etc) this doesnt mean you are faster, just because you are abusing the set up. Simularlly, if you blow engines, it too doesnt mean you are faster.
If i had a dollar for every time i heard this at the track from cars 4 seconds slower a lap, i would be a weathly guy:
"Im boiling my brake fluid because this track is so hard on brakes."
"I need the bigger brakes. these 14" brembos are too small "
"Im cording my tires becuase the track is so hard on them here."
and my favorite, just yesterday..... " laguna is hard on wheel bearings"
RACERS are hilarious..... this kind of material just doesnt stop!

 

 

Well a little data has come in...it threw #6 rod...& #2 was really close...but I can't upload the pictures.......its not pretty

 

I have disassembled cradles, and old and new pans and picks ups.
I'd be happy to assemble these and take some pics of a tilt test if anyone would be interested.
Any particular protocol to follow?

 

That would actually be pretty handy Adam.

 

Hmm, Geared engine stand, mount up a girdle with oil pickup, pan +/-petals, measure the angle with an inclinometer app on the iPad, and GoPro it all.

How many quarts of water in the pan?

 

Big difference folks...... which one would YOU want in your race car??


Here is brian's engine pic too!

 

YES... that just about sums it up!! But, dont try and tell greg anything. He seems to pride himself on people that break things.

In racing, smooth is fast! always has , always will!

 

Wait....wait....I know the answer to this....

Neither.

A cross drill crank works well to about 6500 rpms, when the centrifugal force and the oil pressure start interfering with each other and the rod ends up without much oil. My opinion which I have no desire to debate, since there is no "right answer". There's literally volumes of information written on this subject.....and one engine builder does one thing and another builder does another thing.

 

Excuse my lack of knowledge of the subject, but are any of the stock 928 cranks cross drilled? does anyone besides mark anderson run higher than 6500rpm (besides my frequent shifts at 6590rpm all day long)? (and i have a cross drilled crank in my stroker, but there was not one in the holbert 5 liter, nor in scots engines, or in any of my prior engines)

and, why would you want to go over 6500rpm anyway, unless your engine was built for it , and as far as i know, none of the road racers around here have engines built for it or tuned to optimize for beyond that RPM limit.

The poiint is, and i think you would agree. the 4.5L cranks with the small oil holes are probably not racing material. the 4.7 and later cranks are. cross drilled or not.

here is a nice modex cross drilled crank

 

Funny, Days of Thunder clip check out @ 1:11 and notice the "burnout" they forgot the spool !

 

MK -- All 928 cranks are "cross drilled" as far as I know. The stroker crank you show in your picture is not cross drilled, it has a "straight shot" oiling passage. Not that anyone cares, I've come to the conclusion that these crank drillings don't matter that much once the oil pressure is regulated to the appropriate pressure level which is somewhat higher for a cross-drilled crank. Mazda Miatas are regularly raced with cross-drilled crankshafts to 8,000 rpm, for example. If you can get a continuous supply of oil to the mains at the correct pressure, I believe the 928 engine can take a lot abuse. Best, Tuomo

 

Hmmm, pardon me for barging in but as I recall F = ma and if the centrifugal force(a) increases at higher RPM, would then not the F go up as well? There-by producing greater oil pressure in the rod journal? I'm failing to see why an increase in RPM would reduce the oiling at the rod journal due to higher centrifugal force. Of course, the same forces operate on the rod/piston as well, but that has nothing to do with the force of the oil in the passage with increasing RPM. It's just that those forces may outweigh the increased force applied by the oil film. I don't know, and will not be calculating the force vectors for the various components.

 

The issue is that at some point the oil in the passage, at a point closest to the crank centerline, will reach caviation pressure. Let's say oil cavitates at 0 psi absolute. At that point, the centrifugal force pulls a vacuum in the oil passage with oil moving back towards the main surface and, separately, forward towards the rod journal. The oiling stops.

If oil would be a steel wire, the (net) centrifugal force would pull the steel wire out the passage. But oil is not a steel wire, it's a fluid, and there oil molecules aren't bound together. You can't "pull" a fluid, you can just reduce the push on one side and let the push from the other side push the fluid.

Am I explaining myself clearly here? Realistically, probably not.

Once the oil has been accelerated to the surface speed of the main, the required oil pressure to push the oil to the rods is proportional to the square of the main journal radius minus the square of the minimum radius of the oil passage. Cross drilling of 928 cranks makes the second term zero. A straight shot oiling passage doesn't go thru the centerline, and the second term is negative.

 

The cranks are not mine.....the ugly engine pic is mine