New Crankshafts
02-17-2012, 02:29 AM
#92
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Thread Starter
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.
This is what has made "fixing" the 928 bearing problem so difficult. There's more than one problem. You fix one and the other one bites your ***. You fix two problems and then a third bites you. Even the very patient can get "past" the third one....most simply find another hobby.
This new crank isn't going to fix the supply problems...no crank can live without oil. It isn't going to fix the problem of the oil packing into the cylinder heads at high rpms, either.
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
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.
This is what has made "fixing" the 928 bearing problem so difficult. There's more than one problem. You fix one and the other one bites your ***. You fix two problems and then a third bites you. Even the very patient can get "past" the third one....most simply find another hobby.
This new crank isn't going to fix the supply problems...no crank can live without oil. It isn't going to fix the problem of the oil packing into the cylinder heads at high rpms, either.
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
It really bothers me that the only engine that Porsche decided to reduce the pressure/volume of oil to the cam area (944S) has a terrible history of "snatching" the chain tensioner off of the head, ruining virtually everything under the cam cover. I really don't see why those engines do this, and yet our engines never do this. Makes no sense, to me. So, I choose to not limit the oil, but remove it, instead.
Worth noting, Porsche certainly had the ability to "limit" the amount of oil that went to the heads in the street 928s, but decided not to do this. They had the part from the 944S and had certainly run the 928 engines enough to know about the oil problem to the heads, but chose to not do this.
Also worth noting is the fact that the 944S has relatively "short" gears and is a complete "dog" until it gets up into the rpm range....so to be able to drive it, it needs to be "spinning" at higher rpms. This would certainly deliver way more oil to the valve area, than an automatic 928 that tries to find "high gear" before it can get across an intersection.
I do now believe that the factory gave up on trying to keep the crankcase from getting positive pressure, by the time they made the GTS models. That tiny vent in the filler neck isn't big enough for a vent....it's more like a place that the engine can use to 'burp". I think they decided that they couldn't keep the heads from filling up, so they decided that all they needed to do is give the engine a place to "burp". Drilling oil return holes into the pistons in a "positive" pressure crankcase would have "pushed" the oil from the crankcase onto the cylinder walls....so they decided to leave the holes "out". It all makes sense, now.
02-17-2012, 02:47 AM
#93
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Thread Starter
The people that are building the cranks are way smarter than me and they have never even "blinked" at my requirements for these cranks. These cranks are virtually "truck" cranks compared to some of the cranks that they make. (A long stroke, small journal pro stock crankshaft is an example of this. Virtually no crank pin overlap, very light, undercut counter weights, huge holes drilled through the rod journals, etc.)
02-17-2012, 03:10 AM
#94
Former Sponsor
Thread Starter
I do get bored easily....and I like to constantly improve things.
Every high performance engine I build has something "new" inside that I dream up, fabricate or have built, and test. This tends to "slow" down how quickly engines get done...and people do get impatient....but the wait is always worth it.
Absolutely no two engines have ever been the same. It's a constantly "evolving" thing. The customers don't ever pay for this "new" technology....they pay for the "old" technology that the last guy got for free!
02-17-2012, 04:09 AM
#95
Rennlist Member
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. 
Once again, great work Greg. And on reflection, very, very reasonably priced.
One thing though and you never answered the question asked on this thread by a fellow lister - with the higher rpm and better power outputs which would come along from your new product, is it nigh time you turn your attention to the transaxle? You mention that you want to shift the powerband higher up - sort of BMW ///M engines of old , which is a solution, but ultimately more of a band aid for our cars...
If you can make such great engine products, rise to the challenge and make the 5spd better too
02-17-2012, 04:31 AM
#96
Nordschleife Master
Shifting up the power band makes more HP, but not more torque. HP makes you go fast, torque breaks parts, with the caveat that everything needs to be ok with the higher rpm.
02-17-2012, 07:40 AM
#97
Rennlist Member
true, but look at the v10 in my m5 - makes 507bhp at 7750rpm, and 520Nm of torque at 6100rpm... I very much doubt that you can just move the hp up and leave peak torque low down...
02-17-2012, 11:40 AM
#98
Drifting
with the stroker that I recently drive , I am planning on moving the devek crossover from off the headers back about 17 inches and by calculation this should move some torque up the rpm ladder so I can quite shredding rear tires as bad... I am uncertain what percentage this moves the torque though(kinda of what louie did with his)
02-17-2012, 11:46 AM
#99
Archive Gatekeeper
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Yeah, I HATE all that tire shredding torque, having to feather the pedal- really sucks! 
02-17-2012, 12:09 PM
#100
Not the sharpest tool in the shed
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Greg, forget about the requests to strengthen the 5spd, that only helps half of the owners. What about redesigned heads? Now that is something we can all use and therefore a better investment in your time versus return.
Some may disagree with this but certainly not I (S4-or-die) or that other fine gentleman driver, Roger.
Some may disagree with this but certainly not I (S4-or-die) or that other fine gentleman driver, Roger.
02-17-2012, 12:33 PM
#101
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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....
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....
02-17-2012, 12:47 PM
#102
Rennlist Member
with the stroker that I recently drive , I am planning on moving the devek crossover from off the headers back about 17 inches and by calculation this should move some torque up the rpm ladder so I can quite shredding rear tires as bad... I am uncertain what percentage this moves the torque though(kinda of what louie did with his)
Why on earth would you want to change anything torque delivery wise? The manual tranny cars do this to protect ripping the box apart but not the auto's.
I presume you have some respectably wide rubber on your mount? A decent more or less stock GT/GTS motor likes 295 on the rear- with a motor like yours you probably need something in the 330 range if you are to have a fighting chance of hooking up. Surely you did not lay out what you did to convert the beast into a bar of soap? Remember you now have one heck of a motor under your hooves now!
Louie's car has some pretty decent rubber keeping it all in check.
As for Greg's cranks- yes please!
Regards
Fred
02-17-2012, 12:53 PM
#103
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Greg, forget about the requests to strengthen the 5spd, that only helps half of the owners. What about redesigned heads? Now that is something we can all use and therefore a better investment in your time versus return.
Some may disagree with this but certainly not I (S4-or-die) or that other fine gentleman driver, Roger.
Some may disagree with this but certainly not I (S4-or-die) or that other fine gentleman driver, Roger.
02-17-2012, 01:00 PM
#104
Inventor
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02-17-2012, 01:08 PM
#105
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Huh- very cool, except if I'm reading the 'how does it work' correctly, it assumes that one has sequential injection, as it blocks injector pulses 1 cylinder at a time (?)
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