dcrasta

Those cranks look sweet, but the counterweights look a little thick. Im not sure why they are that thick, but they definately are bullnosed to hell. I agree with you on the 'old tech' .. Maybe the next generation crank has more of a knife edging or slimmer profile on the counterweights.

One question I have. What about teflon or other coatings on the counterweights to promote oil 'release' from the surfaces of the counterweights? I know piston coating is popular with some builders, (I have wiseco' pistons in my turbo car that have coated skirts), .
What are you thoughts on that?

BC

Hmmm. I guess my point is that with a fuel that is almost knock free, that the engines is simply not being abused as much at ANY power level as when it undergoes knocks on regular fuel.

Cheburator

Greg,

All I did was question your statement that stock cranks and bearings are **** and that they would fail within a season...

I could not care less what Porsche did with the Cup Cars. GM probably did the same with their LS7 derived lumps when they found their dry sumps are not that good in the real world...

The point is - your product is great, and I would be knocking on your door for a set of custom crank, rods and pistons (limited to 6.2ltrs) when the time comes....

But please, spare us the doom and gloom, we are not idiots. And maybe we have been racing them for a short period of time, but we happen to know and talk to someone who actually raced the thing in 1980, in a Porsche backed car...

GregBBRD

The actual "thickness" of counterweight is determined by the distance from the main bearing to the rod bearing...which is determined by the original engine designers. I don't have the ability to change that, without designing a completely new engine.

It is possible to "undercut" the counterweights, to reduce some of the mass....it's just time and money.

It is also possible to put a multitude of different coatings onto a crankshaft, for various reasons....that is also just time and money.

It is also possible to make each crankshaft cost over 10K. Many of the crankshafts that are made, where these are made, cost that much. Many crankshafts are over 20K.

Design has to reflect the "cost point".

This is a very nice "current technology" crankshaft at an excellent price. No excuses. No apologies. I've spend hours and hours designing this crank, with people helping me that know more about crankshafts than I'll ever know. I suspect that the "next batch" of cranks will look exactly like this, unless there's a huge demand for more expensive crankshafts for our engines.

As I've said, I had to build many crankshafts to get the price this low. And the profit margin is very, very low, for me. I just don't see 928 people buying crankshafts that cost 5,000 or 6,000 dollars. If I thought they would, I'd build the same exact crankshaft and change the price to make it more profitable....

brutus

Let's see...Kim Crumb former PCA 928 tech guru blew up his GT twice , his 85 "Project 928" car from Pano the first event after he sold it. David Lloyd a few, Stan Shaw a couple, Constantine's car , Doc in Texas , Anderson and Fan, the old Tilo car on multiple occasions, 86 racer out of San Diego couple times while he had it couple more for the next owner. That is without really thinking about it.
So I have a hard time believing there are no problems tracking a 928. But a few have gotten away with it for longer than others but many more have not !

GregBBRD

And I'm not trying to be pissy. I'm just trying to address your thoughts, logically. And I'm certainly not saying that you are an idiot.

Sorry you are taking our exchange of ideas, that way!

All I can do is learn from what I personally see, and make changes to reflect any of the problems that I see. I've seen all the 928 engines that I ever need to see, with "pounded" rods bearings. Actually, way more than I need to see.

I'd completely agree that the "early" engines are much more durable that the later engines. The entire "lower end" of the engines are much less loaded, since the "early" engines make far less power, yet use the exact same bearings. They don't suffer from the same oiling problems as the later engines...because the volume of oil that can "hide" in the cam carriers is far, far less.

I'm not a "doom and gloom" kind of guy...but I am realistic. And I've seen a boat load of these engines fail, from the "soft" rod bearings. There's no point in me telling everyone this isn't a problem...when it is. Hell, we switched to harder "Chevy" rod bearings, in these engines 15 years ago!

Think of it like this:

If you take a 9mm handgun and "bore it out" to shoot 40 caliper bullets out of it, weaknesses that are not present with the 9mm might show up with the 40. That's what Porsche did when they went from 4.5 liters to 5.0.

Now take that same 9mm handgun and bore it out to shoot 45 caliper bullets. Certainly you'd expect it to have weaknesses, however, this is what Porsche did when they went from 4.5 to 5.4 liters. They built vehicles that frequently had bearing failures when they simply got run "hard" on the Autobaun, much less were raced!

Then, individuals (not Porsche) took that same 9mm handgun and bored it out to shoot 500 Smith and Wesson rounds. A few lucky guns might work, for short periods of time, but the majority are going to "explode" in the owner's hands.

That's what happens with stock 928 rod bearings in a 6.5 or even a 6.0 liter race engine.

Boom.

Cheburator

Ok, how many of them had dry sumps?

Anderson? The one of his that failed looked like I had designed it.

No disrespect, but our 4 cars that had dry sumps designed and built by PACE Products are still going OK. I guess having the know-how from working on F1 and Le Mans dry sump instalations helps when it comes to designing a viable solution for our low-tech and old school engines.

brutus

Two advantages to being dry sumped are the much greater oil capacity so you can fill up the heads and still have some oil left over for the bearings and venting the blow by back to the tank and NOT into the intake which greatly reduces the tendency to detonate.
Off hand I am not sure how many of the ones I mentioned were drysumped engines but am sure it was few. Several did use an accusump however.

IcemanG17

Finally a Doc reference I can actually UNDERSTAND..... its like a very dim, near dead light bulb in my head finally went off.....

there is one thing I DO understand....if you want a "race" stroker....you call Doc....it worked for Mark Anderson and Joe Fan YEARS ago...their 928's still run...Doc's work is not cheap, like many 928's are nowdays.....

you want state of the art performance, at a 15 year old car price....its just not gonna happen... Time to quote the immortal Mark Anderson "what part did you think was cheap...the racing part or the Porsche part"

I am proud to have a relatively cheap race car that turns relatively fast laps vs $$$$ spents....

SeanR

Some that I know, including myself, have just stopped putting our 928's on the track so we can actually enjoy driving them. Just not worth the pain and suffering when they go down. Pain being the check written and the suffering the pain the wife gives us.

Black Sea RD

My 928 racer was accusumped, had just been converted to a 5 speed and I was using Mobil One oil before it blew up with Mark A. at the wheel at the PCA 48 Hours of Sebring races.

I had replaced the con rod bearings a few thousand miles before and it never missed a beat when I was driving it at PCA DE days in automatic transmission form.

But having a Pro racer pushing it harder than it probably had ever been before, being able to hold RPMs unlike the automatic in multiple gears with an over 120K mile stock engine and brand new Hoosier road race tires was really pushing it's luck.

No regrets however.

Cheers,

brutus

Big difference between fast for some and really fast for very experienced and well qualified drivers. Big sticky tires, High G corners, running it up to redline all adds up. Hard to compare the level of competion in different areas of the country or world especially since most ALL drivers think they are driving their 928 as fast as anyone possibly could.

cold_beer839

Greg,

Once again just awesome work!! Do you ever sleep?

928mac

A question for Greg.
Concerning oil filling the cam covers

Dose it need all that oil flow to the cams or the pressure.

It seems to me that the bottom end is only half the issue.
If the cam journals spill to much oil I would ask why.
Or is it a matter of just poor return

Thats it, just 1 and a half questions at a time

brutus

I bet , He sleeps but dreams about 928 engines all night long. Wakes up with solutions to problems that have needed fixing for years.