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First Engine Rebuild - Decisions?

Old 11-17-2017, 04:46 PM
  #46  
Humboldtgrin
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I wouldn't go against Dave or Mike's advice. Just change your oil more often. Possibly look into a crank scraper and screen to help with aeration of the oil. And possibly a LR oil pan baffle kit or even an oil cooler for the returning oil from the turbocharger.
https://www.crank-scrapers.com/Porsche_944.html
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Old 11-17-2017, 10:04 PM
  #47  
ekoz
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Originally Posted by Humboldtgrin View Post
I wouldn't go against Dave or Mike's advice. Just change your oil more often. Possibly look into a crank scraper and screen to help with aeration of the oil. And possibly a LR oil pan baffle kit or even an oil cooler for the returning oil from the turbocharger.
https://www.crank-scrapers.com/Porsche_944.html
Thanks for chiming in. They are actually looking at some options for a smaller port....their standard wont work on this block and Mike wasn't opposed, but his standard method would need to be modified. He's going to get back with me. I'm going with the scraper for sure, but curious about the oil cooler from turbocharger. I'll do some searching but haven't seen that.
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Old 11-17-2017, 11:59 PM
  #48  
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You would have to fabricate a cooler setup from the turbocharger. Your not going to find a kit.
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Old 11-18-2017, 12:11 PM
  #49  
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Originally Posted by ekoz View Post
Well LR is advising against windage ports on my block due to sleeves having a deep shelf. Concerns are that it would remove too much material.

Any thoughts on a "small" windage port? LIke drilling a few holes for ports or is that just a waste of time?
keep in mind that the windage is caused by the bottom of the piston moving as much air as the top of the piston, aka 1 cylinder's displacement (625cc on a 2.5L).

a few little holes likely wouldn't accomplish much, the factory ports were fairly large.
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Old 11-18-2017, 01:46 PM
  #50  
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The issue with this motor prior to failure was if it was filled to the top fill line with oil, in a short amount of time it would push quite a bit of oil into the catch can on the track or really any high rpm runs. Once it got down to the 1/2 mark on the dipstick it woudn't move any lower. In fact when I got the car home after throwing the bearing, I checked the oil level and it was right at the 1/2 way mark. This is what has me scratching my head and trying to solve.....absolutely no leaks and little to no smoke out the tail pipe.

One suggestion was knife edging crank to prevent splash affect in pan. And I was thinking windage would really help this. If I can't do windage, want to do as much as I can to try and solve. Not the end of the world if I can't but just seemed like that could be part of the issue.
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Old 11-18-2017, 01:51 PM
  #51  
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knife edging doesn't seem to do anything except make the crank both lighter and weaker (more flexible).

if you look up a recent thread by Neil @ Performance Developments it was brought up - "bull nosing" the crank weights (basically just rounding the leading face and smoothing the corners around to the sides) is sufficient to cut down the crank's aerodynamic effects without sacrificing strength.

if you're feeling frisky and want to do something about windage ports without cutting windows between bays, you could drill thru the SIDES of the block and run external pipes from 1/2 and 3/4....

you have a catch can - i dont recall if it's been discussed but did you drill out the AOS top port?
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Old 11-18-2017, 02:26 PM
  #52  
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If knife edging was a Smart thing, it would have been that way from Porsche. And on all the new bmw m engines.
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Old 11-18-2017, 03:17 PM
  #53  
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Originally Posted by ealoken View Post
If knife edging was a Smart thing, it would have been that way from Porsche. And on all the new bmw m engines.
porsche and bmw are still constrained by "big car company" production issues (cost), but your point makes sense when you look at stuff really made for revving - F458, LFA, GT350R, 997GT3, etc.
all have blunt CWs
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Old 11-18-2017, 03:26 PM
  #54  
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Originally Posted by V2Rocket View Post
knife edging doesn't seem to do anything except make the crank both lighter and weaker (more flexible).

if you look up a recent thread by Neil @ Performance Developments it was brought up - "bull nosing" the crank weights (basically just rounding the leading face and smoothing the corners around to the sides) is sufficient to cut down the crank's aerodynamic effects without sacrificing strength.

if you're feeling frisky and want to do something about windage ports without cutting windows between bays, you could drill thru the SIDES of the block and run external pipes from 1/2 and 3/4....

you have a catch can - i dont recall if it's been discussed but did you drill out the AOS top port?
will look at bull nose options. Understand lighter, really didn't think it would make it weak but looking at photos of knife edge, I agree that there would be some weakening as well. AOS was drilled,

Piping idea is interesting but not sure I'm ready to go down that path.....but that is outside the box thinking.
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Old 11-18-2017, 04:02 PM
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Ok, i might have to eat my words.. this is a shark werks 4.1 L for the 997 G3Rs
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Old 11-18-2017, 04:41 PM
  #56  
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their 4.1 crank is billet though, so presumably optimized in design.
our cranks were forged to be heavy...
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Old 11-19-2017, 09:51 PM
  #57  
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You need to be extremely careful about knife edging crankshafts. It is done to help the counterweights to go through the thick oil in the pan. But in most engines, the oil is not at the bottom where the counter weights swing, but stacked up against the wall of the block and the oil pan..

What you are doing, is removing weight from the counterweights. The weight is there for a reason. It depends on how much % of weight is added in the design of the crankshaft, all is designed into the crank when all the masses are known. This is why we bull nose the counterweights only. Removing weight does not make the crank any less stiff, but it does hurt the rotating balance and the torsional balance even more. Then the aftermarket add lighter rods, and pistons and raises the RPM and the engine torsional balance all goes in the tank. One of the many reasons why the rod bearings fail.

Knife edging is a great sales pitch to get the customer to think they are getting a racy crank but reasons need to be understood, for and against. Unfortunately many of those offering this service don't understand either.
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Old 11-19-2017, 10:01 PM
  #58  
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Also to what I have said, a picture was shown of a GT3 engine with a knife edged crankshaft. I'll leave my opinion of the builder noted to myself, but we designed and have sold over 100 crankshaft dampers for these engines to stop crankshaft, oil pump and camshaft actuator failures.

I heard the other day, after fitting one of our dampers designed for the air cooled 911 engine, a gain of 30 BHP was found in dyno testing. We are of the opinion, if you contain the crank flex at the front of the engine where the cams are driven, you control and hold the designed cam timing positions. Same can be said for the 944 engines. The recent engine we built for Patrick's WTA project included a damper incorporated into the cam drive system.
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Old 11-19-2017, 10:45 PM
  #59  
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We are of the opinion, if you contain the crank flex at the front of the engine where the cams are driven, you control and hold the designed cam timing positions. Same can be said for the 944 engines. The recent engine we built for Patrick's WTA project included a damper incorporated into the cam drive system.[/QUOTE]

A high output 944 3.0 16v turbo build was well documented on here a couple of years ago. It was quite telling the crank specialist involved only polished the crank. Do you think the standard 3.0 S2 damper is adequate for an 8v 3.0 turbo road car?
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Old 11-20-2017, 12:26 AM
  #60  
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Have you considered a simple approach? see http://crank-scrapers.com/Porsche_944.html This will help keep the oil in the pan and reduce windage losses.
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