Crank drilling modifications for better oiling ?
 

Guys,

I have a crank that I am looking to modify to help with oiling. This is on an 88 na race car that has lost its share of rod bearings. (not the same motor)

I am looking to understand some of the stuff I see on a crank from Lindsey that my buddy has.

It is a knife edged crank. It has perpendicular drilling on all of the rod journals, it has an extra hole added (so a total of 3 holes) in the man journal, and it has the plugs enlarged and drill and tapped.

I have heard before about perpendicular drilling the #2 and #3 journal. This one has all 4 drilled.

I have never heard about adding an extra hole to the main journals. Since the mains never have problems, I assume it is to balance out the flow between the rods and the mains now that there are extra holes in the rods?

Any insight would be appreciated.

Thanks

Ed

knife edging is a wast of time and money i have done 2 of my 944 motor with the crank getting knife edged . they make no more hp or tork . the cross drilling and chamfering does help . and yes you can spin the mains too but your right it is rear . don't think that cross drilling is a cure for the spinning of the #2 rod baring . 3 weeks ago i loaned out my 944 spec car to a friend and he gave me my car back with a motor thats totaled . there is nothing that can be saved but the water pump . that motor was crossed drilled and knife edged . 9k and only 3 races on the motor . the rod went throw the block so hard it bent the balance shaft and broke the balance shaft cover in two .

wow, a real shame.
John

Knife edging isn't intended to make power, it's to reduce the rotating mass and therefore allow for faster rev-up.

it give less rotating mass to keep the rev up in road racing its not a plus .you can cut the flywheel . it also remove the square edge that has to push its way throw the oil so yes on some motors it is a power adder but not the 944 motors . becouse the counter balances are only 24 mm wide on the 944 motors to say the 2.0 vw motor thats 8 mm fatter .

I believe it also helps with reducing (but not eliminating) windage. I wouldn't call it a waste of money at all. Serious engine builders do this all the time along with lightening the flywheel, rods/pistons to the extent possible, etc. Anything you can do that will keep rotating mass weight down helps (assuming you don't sacrifice strength).

porsche-o-phile +1 on windage for knife edge-ing, it really helps alot and makes a difference on high rpm motors in general in conjunction with a scraper and a windage tray. the first thing to do though is baffle the oil pan . anything you can do to keep oil at the pickup is the key and good clearances with good clean oil. I like redline 20w50 race oil or even the regular redline 20w50 . If you step into the realm of dry sump, thats another tier up for high rpm RACE motors . Everyone has their own oppinions, these are simply mine. i too have all rod/main journals cross drilled.

OK,

so, has anyone ever heard of adding more holes to the main journals.

Thanks

Ed

yes , my crank has both main and rod journals cross drilled

yes you can cross drill mains too . my motor thats now shot it was done to that motor . any serious engine builder will tell you to do a dry sump for road racing like on 2 of my cars 962 and ITS 944 !

I have a full dry sump system that came off another car, but I would rather sell it than use it.

Ed

the 944 motors don't have a problem with windage . the conter weights are not that fat and the sumps are deap with a windage tray from porsche .

if your racing, and turning rpms with more power, its better imho

The only problem 944/951 have are the owners that neglect basic maintenance then sell for a project

Whether they are good racing engines or not has been determined since porsche did build the car to race and their engine isnt that far from the ones we own. Im pretty sure its a stout engine when built correctly.

To the guy who burn up his engine what oil did you have in it?

why do you need to know what oil i use ???

Porsche machine shop in L.A. ?
 

I've been considering cross-drilling and adding a remote cooler (read about that on an older post here or on Rennlist). I'm looking for a decent machine shop in the South Bay area of L.A. My motor is stripped down and I would like to have the head rebuilt, also may need some work on the cylinders.

Any recommendations?

Thanks

oh wait i thought you spun a bearing. I now read you put the piston through the block. I guess thats just bad luck

it was my friend not me ! he cased the oil pan on the ripple strips or turtle backs what ever you want to call them . cracked the oil pan lost most of the oil and then it went to a catastrophic failure . we have built 17 944 motors to date not one has spin a baring yet ! we don't use any add on oil coolers even with the 2 944's we run in the enduro series ( 6, 12 , and 24 hour races ) the oil temps and pressure are right were they should be even on the hottest days . we tend to use 10/40 oils most of the time changing the oil before every event . they are all NA cars if we run a turbo car i may think about adding an oil cooler ?

For those of you claiming that the 944 counter weights are not that wide, think again. look at the weights on the 944 crank compared to the weights on this 4.6 liter crank. I would contend that knife edging on the 944 crank would be beneficial.
http://forums.pelicanparts.com/uploa...1284853234.jpg

http://forums.pelicanparts.com/uploa...1284853273.jpg

-def need to add an oil cooler for turbo, there is simply more heat created with pressure. Also , you ultimatley should run oil weight in conjunction with bearing clearances . tighter clearance = lower weight oil . and vise versa. I know alot of guys running 15w40 instead of 20w50 on enduro motors, but again, they run slightly tighter clearances to prevent scavenging from prolonged high rpms. But start with baffling the pan IMHO for saving the bearings. if your building a street car, you dont need knife edging or add scrapers, just baffle the oil pan and keep oil where it belongs and change it more than often. using zddp helps the cam and lifters alot. and yes the counter weights are fat as hell on stock 944/951 cranks. The cheapest solution for reducing oil drag is adding a better windage tray in the oil pan.

there is no reason to think again !i too can post some photos of cranks with fat and thin conter weights its point less ! there not that fat ! 24mm is about average for most conter weights . there is no big plus to knife edging the 944 crank !it will not give you more hp or make the motor last any longer .there is no big problem with windage with the 944 motors . the cost don't out weigh the plus fo doing it . if you want to spend the money to do so than do it . i have on some of my motors and there is no plus to it .the 944 motor max rpm is about 6200 the shift point is about 6000 not a rev happy motor . the first # in oil is cold cranking weight 20w winter 20 weight and so on . we only use a 50 weight oil on every hot days . day that are over 100 degrees . other than that we use 40 weight in all 6 of the teams 944's . our fealing is that the 50 weight only is to thick to get proper flow throw the oil passages . it was the teams choose 3 years ago to start using 40 weight most of the time after a run of spinning barings . we feal it was the right move becouse we have not spon a baring sence then . one of the enduro 944's has 3 years of racing on it 5 24 hour races 3 12 hour races and 6 6 hour races on it along with a hand full of sprint races . other than timimg belts and oil changes we just keep running it .

962.... sounds like that guy owes you an engine.

no its called racing ! its just apart of racing i don't like ! he's a long time friend . he is doing all the work on the car my shop will pay for the parts to rebuild an other short block .

Windage is an issue with ANY engine.

A 944 engine is less suceptable to it than many, but it is certainly not immune to it. Anything that one can do to eliminate or reduce it is free horsepower and free minimization of (many) other potential problems.

windage is only a issue if it gives you a issue ! and its not with a low reving 944 motors . but like i stated before if you want to spend 1000 to 1500 dollars to get at most 1/2 hp go for it ! i did with 2 of my motors . one of the motors we did a knife edge and rebalance on it only turned 1/2 more hp on the motor dino . and a motor that turns at most 6200 rpms oil cavition is not an issue !