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Chrenan
Joined: 15 Jan 2003
Posts: 3903
Location: Canada
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 Posted: Fri Sep 07, 2007 3:45 am Post subject: |
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I also noticed in your other thread that you are considering knife edging your crank. That would reduce oil slosh in the pan. You may wany to leave the crank as-is to get the type of oil distribution Smoothie talked about. But based on Nick's experience, it still may not be enough.
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1987 951 - M193 Version for Japan |
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Chrenan
Joined: 15 Jan 2003
Posts: 3903
Location: Canada
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| Posted: Fri Sep 07, 2007 3:49 am Post subject: |
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Of course, the dry sumping you are considering would certainly need to be considered carefully as well if you need the oil slosh to get oil to the cylinder walls. Decisions, decisions. I think I need to build another engine, more ambitious this time, I'm getting excited just thinking about it.
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1987 951 - M193 Version for Japan |
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Fri Sep 07, 2007 3:58 am Post subject: |
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| ideola wrote: | Not one of their off-the-shelf import rods (for high-boost applications) have intrinsic oil squirters designed in, and they felt it was not a concern given the success of their rods on applications...
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I wonder if any of their other import applications included the 924 block and sump arrangement..
From this diagram (angle of the engine and oil level), it looks like there's probably no oil being picked-up and thrown around by the crank, except maybe on hard left turns -
Maybe should bounce that diagram off the rod supplier people and see what they say about the need for squirters in this particular engine (then probably ignore what they say if they still say they're not needed). 
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"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Fri Sep 07, 2007 4:04 am Post subject: |
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| Chrenan wrote: | | If you did, why would Porsche have designed the oiling as such on the low powered normally aspirated 924? |
VW, you mean!
I don't want to imply that any detail of your build is anything less than perfect and genius-level design, Dan, but this makes me a bit nervous. If the supplier could say they had run these in another toofah successfully, that would be one thing, but paying to be a test bed? Scary.
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 07, 2007 4:33 am Post subject: |
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| Rasta Monsta wrote: | | I don't want to imply that any detail of your build is anything less than perfect and genius-level design, Dan |
Beautiful. I'm finally getting my due around here 
I just spoke with Mr. Crower himself. He is faxing me a diagram to show me how to notch the rod in order to duplicate the effect of the squirter. When I get home to the fax machine, I'll scan it and post it. In the meantime, here is a paraphrase of his comments.
The squirters on stock rods are what he called a "24-hour idle squirter", so that if the engine were sitting and idling for 24 hours with absolutely no slosh, they would still provide some lubrication to the cylinder walls. He said that it is a very common OEM design on many imports, including Japanese and German designs. They see it all the time. He said for race applications, most builders prefer to remove the squirters because they're not needed. He also indicated that in addition to slosh, there will be all kinds of oil vapor in the crankcase that provides lubrication. He was adamant that the combination of normal oil flow, slosh, and vapor would provide suitable lubrication. He said rods could be made with squirters at customer request, but he also indicated that notching the rods would achieve the same effect.
-nick, one thing that has me thinking about your post...and I sincerely don't mean to be argumentative...but how do you conclusively know that it was non-functioning squirters that caused the damage? If the bearings were installed incorrectly, isn't it conceivable that something else could have gone wrong that caused the geometry of the rotating assembly to be off? If the rod travel was screwed up because of incorrectly installed bearings, that would necessarily affect how the pistons moved within their bores, and in turn could have caused the damage. Maybe it wasn't the squirters at all. Again, I'm not trying to be argumentative, but I'm just trying to understand how you could conclusively say the damage was caused by non-functioning squirters...there was at least one other variable in play (the incorrectly installed bearings) which might have introduced other variables, which could have led to the piston failure.
I am going to check with some other sources, and assembly is still a ways off, so in any event, this is not a show stopper right now. Best case, I get confirmation that the rods as-is will work, or maybe I need to notch them as a safety pre-caution. Worst case, I either order another set with squirters, or set up a dedicated oil spraying system. Don't get me wrong, I don't want to have to spend the extra money and it would be a set back, no doubt. But it's only time and money and it's not the end of the world.
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erstwhile owner of just about every 924 variant ever made |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Fri Sep 07, 2007 4:35 am Post subject: |
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And there is likely a spray coming out at the rod journals as oil passes through, right?
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 07, 2007 4:38 am Post subject: |
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| Rasta Monsta wrote: | | And there is likely a spray coming out at the rod journals as oil passes through, right? |
Which rod journal? At the wrist pin end, these rods have a chamfered oil pin hole to deliver oil to the wrist pin area...not sure if that's what you mean...
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erstwhile owner of just about every 924 variant ever made |
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Rasta Monsta
Joined: 12 Jul 2006
Posts: 11733
Location: PacNW
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| Posted: Fri Sep 07, 2007 4:40 am Post subject: |
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Oil from the rod bearing. . .
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Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 07, 2007 4:44 am Post subject: |
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| Rasta Monsta wrote: | | Oil from the rod bearing. . . |
One would think so...
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erstwhile owner of just about every 924 variant ever made |
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-nick
Joined: 16 Nov 2002
Posts: 2699
Location: Cambridge, MA
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| Posted: Fri Sep 07, 2007 5:02 am Post subject: |
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Hey Dan,
It's a reasonable question, but the rod bearings are all identical except that four of them have a hole for the squirters, and four don't. I mistakenly put the non-hole bearings on the hole side and vice-versa. After correcting that, and getting a new set of pistons, everything worked with no problem. The pistons literally ground themselves into the walls of the cylinders within minutes at idle when I had the squirters blocked.
Those squirters also cool the pistons. I can't possibly imagine how you can get away without using them. It just seems like a bad idea on every level.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 07, 2007 5:14 am Post subject: |
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| -nick wrote: | Hey Dan,
It's a reasonable question, but the rod bearings are all identical except that four of them have a hole for the squirters, and four don't. I mistakenly put the non-hole bearings on the hole side and vice-versa. After correcting that, and getting a new set of pistons, everything worked with no problem. The pistons literally ground themselves into the walls of the cylinders within minutes at idle when I had the squirters blocked.
Those squirters also cool the pistons. I can't possibly imagine how you can get away without using them. It just seems like a bad idea on every level. |
Fair enough...just had to ask. It will be interesting to see Mr. Crower's diagram when I get home. I'm certainly not going to let them off the hook because they should not have assumed that I didn't want the squirters...we sent them a sample, it clearly had the squirter on the sample, and they should have informed us ahead of time that they were going to omit it. If it turns out they are required, I will press them for a solution.
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erstwhile owner of just about every 924 variant ever made |
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ideola
Joined: 01 Oct 2004
Posts: 15550
Location: Spring Lake MI
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| Posted: Fri Sep 07, 2007 10:58 am Post subject: |
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| Smoothie wrote: | From this diagram (angle of the engine and oil level), it looks like there's probably no oil being picked-up and thrown around by the crank, except maybe on hard left turns -
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OK, so maybe this is a stupid question, but if the crank isn't picking up any oil except on hard left turns, then how in the world would enough oil be delivered to the rod journals in order to create the capillary action necessary for the oil to seep through the bearings and into the squirter hole in the first place???? It seems to me that in order for the squirter to work at all, that the crank must be immersed in oil. And if it's immersed in oil enough to activate the squirters, then certainly it's creating some slosh action. Am I wrong here????
In any event, I did get the diagram from Crower. Unfortunately, my scanner isn't functioning right now. But basically, the concept is to cut a very small notch at 12 o'clock on the vertical face of the rod journal. The fax said that the notch should be .100"-.125" wide, and .030"-.040" deep with NO SHARP EDGES. Presumably, the vertical face of the rod journal matches up to the vertical face of the crank journal in such a way that a small notch such as that described, oriented in a vertical alignment, would essentially create pretty much exactly the same size hole that is present on the stock rod squirter, and in exactly the same orientation, that is, vertically pointing up toward the piston, parallel to the shaft of the rod.
Notwithstanding Nick's unfortunate experience, I'm still a bit skeptical about the function of the squirter...I'm inclined to believe that Mr. Crower knows what he's talking about, and that the squirter is indeed a version of the so-called "24 hour idle squirter". Regardless, cutting a notch as described seems to be a reasonable safety precaution, and one that ultimately ends up being better than the original design, since the main portion of the rod material would not be compromised and potentially weakened by drilling a squirter through it.
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RC
Joined: 25 Mar 2007
Posts: 2637
Location: Australia
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| Posted: Fri Sep 07, 2007 11:21 am Post subject: |
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The oil is under pressure. Fed from the main galleries and through the hole drilled through the crank from the main journals to the big end journals. IIRC the upper main shells are grooved (like most are) to permit positive pressure through at least 180 deg.
I absolutely assume that Porsche or VW engineers designed the big end hole position to provide optimum lubrication at maximum load, ie on the down stroke. You have the engine apart so it is easy to get a practical understanding.
I cant recall if this crank is cross drilled or has an angled orifice but again assume that the German engineers gave considerable thought to the operation and positioning of the oil squirter hole, bearing design and associated factors.
Hope Mr Crower does too! And isn`t just covering his own butt at your expense. 
Roger |
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Fri Sep 07, 2007 1:25 pm Post subject: |
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Yep, the crank's lubed by pressurized oil from the oil pump, not by capillary action. "Squirters" and the Crower-recommended slots both use the pressurized oil from the oil pump that's been routed internally through the crankshaft.
The wrist pins are the only parts in the area that I can think of that rely primarily on capillary action for lubrication.
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"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox
Last edited by Smoothie on Fri Sep 07, 2007 2:03 pm; edited 1 time in total |
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endwrench
Joined: 07 Dec 2002
Posts: 1631
Location: Victor, Montana
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| Posted: Fri Sep 07, 2007 2:03 pm Post subject: |
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RC, the crank is cross drilled from what I remember.
I have always been of the understanding that oil squirters are designed primarily for piston cooling not lubrication. Lubrication is a function of rod bearing clearance and rod side clearance.
Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
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