|
|
|
|
| Author |
|
|
Registered
Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
|
cross dilled crank
has anyone had their crank cross drilled.
someone mentioned this to me the other day then said I probably don't need it with the oil pump in the 930. what about valve springs, should I replace them all
__________________
86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold Last edited by T77911S; 09-20-2019 at 04:10 AM.. |
||
09-20-2019, 04:07 AM
|
|
|
Registered
|
My crank is cross drilled and case & main bearing modded to supply oil to crank at both ends and now the center. Changed cams and springs long time ago.
__________________
3.3 ltr, stock compression, efi, twin turbo - no intercooler. |
||
|
09-20-2019, 05:14 AM
|
|
|
I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
|
Stock build its not needed. Making changes? Maybe.
I help build a lot of non-stock applications and usually suggest to cross-drill anything that will spend significant time at high rpm and especially over 7k rpm. The 930 pump will supply enough oil to keep those extra holes in the case and crank supplied. Think of it as insurance for the oil film on the #2 and #5 rod bearings.
__________________
Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
||
|
09-20-2019, 06:53 AM
|
|
|
Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
|
I think all motors need it and it was a design flaw from the factory.
Valvesprings can be checked. If in spec, no need to change.
__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
||
|
09-20-2019, 07:20 AM
|
|
|
Registered
Join Date: Mar 2008
Posts: 1,082
|
Pull the plugs, cross drill the crank, drill the case, drill and groove the main bearing. Sleep well.
|
||
|
09-20-2019, 07:34 AM
|
|
|
Registered
Join Date: May 2005
Location: Loxahatchee, florida
Posts: 2,894
|
yes and polished and knife edged
 
__________________
88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's. 2019 Silverado 6.2L |
||
|
09-21-2019, 03:52 PM
|
|
|
|
Registered
Join Date: Sep 2015
Location: Costa Rica and Pennsylvania U.S.
Posts: 3,301
|
cross drill crank
But of course.It just helps to make it more bulletproof and not much cost.2 & 5 rods are the last to be fed oil.If you rev your motor before the oil is warm # 3 rod bearing fails due to thick oil that backs up and overheats the bearing at the surface.Ciao Fred
|
||
|
09-21-2019, 04:48 PM
|
|
|
Registered
Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
|
whats the cost of this.
does the case have to be drilled also
__________________
86 930 94kmiles [_ _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
||
|
09-23-2019, 03:34 AM
|
|
|
Registered
|
I have crossed drilled both my 930 motors. There is nothing like driving and hearing the fail happen. I don't recall what it costs as it was all while the crank was being machined. I want to say around $300-$400 for the extra work. The machinist told me it will be good to over $8k which is more than my valve train will take.
One of the cranks has a failure with the PO and he didn't have the crank modified and it failed a few years later on me. Given my experience, I think it is a must do while it is out considering the cost of the rebuild. It is getting harder and harder to find a good crank. Also, go with ARP hardware also. I have always been told build the strongest bottom end you can afford as this is the foundation for longevity. Or I may have read this on a stone tablet.
__________________
John- 78 Slick Top 930 "Illegitimi non carborundum" Last edited by sundevil64; 09-23-2019 at 04:41 AM.. |
||
|
09-23-2019, 04:36 AM
|
|
|
Registered
Join Date: Mar 2008
Posts: 1,082
|
Quote:
Yes, and the bearing. Plus you either groove the crank or the bearing. Have the case plug holes threaded too. Oil enters the crank at the number 1 and number 8 bearings. When you drill the crank you intersect the main oil galley with the #2 and #5 rod oil galleys so those two rods are now being fed from the center and not the last to be fed oil as the oil in the crank is traveling from the outside in so to speak. Stock build or not. It would be silly not to. Last edited by nocarrier; 09-23-2019 at 07:05 AM.. |
||
|
09-23-2019, 06:55 AM
|
|
Twin turbo 935
Carrera
Speedster
