Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Technical BBS > 1- Porsche Technical Forums > 911 Engine Rebuilding Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Try not, Do or Do not
 
Henry Schmidt's Avatar
 
Join Date: Apr 2004
Location: Fallbrook, Ca. 92028
Posts: 5,918
Garage
All good information.
We use JE pistons with limitations.
The issues we see with JE is with the 95 & 98 mm pistons. When limited to 7200 RPMs with standard (not light weight) wrist pins we see no issue. Above 7300 RPMs we limit engines to 50 hr.
We use JEs without limitation in all other sizes.
One tip: The high compression JE piston design offers a challenge to cylinder flow dynamics so we modify them by simply massaging the dome to allows for better flow at overlap.
On a small diameter bore w/ 2.0 heads this offers a 3-5 hp increase.
No secrets here, just a lot of trial and error.
We match the 81 mm JE piston with our 906 Nikasil cylinder for one of the best combinations available @ any price. Our street pistons run @ .0015 and the race pistons run @ .003 piston to cylinder clearance.
Note the 906 cooling tin.


__________________
Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net
Old 09-23-2007, 01:30 PM
  Pelican Parts Technical Article Directory    Reply With Quote #21 (permalink)
Try not, Do or Do not
 
Henry Schmidt's Avatar
 
Join Date: Apr 2004
Location: Fallbrook, Ca. 92028
Posts: 5,918
Garage
Our special piston design had both compression and light weight as priorities.
We built 4 different pistons for our 81 mm 906 cylinders.
10.5:1 and 11.5:1 for 69"S" heads
10.5:1 and 11.5:1 for 2.2-2.7 heads.
The special design of our 906 Nikasil cylinders allows for the installation of 2.2 heads on a 2.0 cylinder. 2.2-2.7 heads have bigger valves, better valve angle and advance hemi shaped combustion chamber.



__________________
Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net
Old 09-23-2007, 02:26 PM
  Pelican Parts Technical Article Directory    Reply With Quote #22 (permalink)
Registered User
 
Join Date: Jan 2003
Location: Burlington, Wisconsin
Posts: 9,035
I have used zero oil on mine(with exception of turbo oil drain. with je's and have 1100 miles on them so far with no slap running .0028 P-C clearance.. John yours looks great
__________________
Ben

Current project 73 914-6 Gt project rusteration 2.4
Reproduction 914-6 oil tanks, 1-5/8" 914-6 heat exchangers source call 2623647426 or email mbconsulting21 @gmail.com
Old 09-23-2007, 04:57 PM
  Pelican Parts Technical Article Directory    Reply With Quote #23 (permalink)
Registered User
 
Join Date: Jul 2000
Location: So. Calif.
Posts: 18,078
Quote:
Originally Posted by john_cramer View Post
Thanks Gents. Olivier, beautiful stuff. Those look like 906 pistons, what is the CR?

Sherwood, cross-hatch has to do with break-in and the angle is also attributed to oil retention on the cylinder wall and the rate of ring rotation AND friction. Most of the ring manufacturers mention this in their catalogs and claim that the correct hatch is around 20-25 degrees.

Here is a good paper on the subject from MIT. http://dspace.mit.edu/bitstream/1721.1/32371/1/61516071.pdf
John,
I tried to find some ring (ring pack) rotation data in the 104 page document. Great info, but I couldn't find anything related to ring rotation. If piston rings rotate due to the honing pattern on the cylinder (or whatever reason), why do manufacturers recommend staggering the ring end gaps (not aligned)? If they rotate, the relative end gap positions wouldn't maintain the original spread and surely not in synchronization.

Sherwood
Old 09-23-2007, 08:46 PM
  Pelican Parts Technical Article Directory    Reply With Quote #24 (permalink)
Moderator
 
304065's Avatar
 
Join Date: Dec 2001
Posts: 9,443
Sherwood, here are a couple of shorter references, sorry about that.

http://www.automotiverebuilder.com/ar/eb010642.htm

And another good short one.

http://www.engine-builder.com/Cylinder%20Bores.pdf

Some good microphotography of cross-hatch:
http://www.autospeed.com/cms/A_109105/article.html

The reason you have to stagger the gaps is because the rings DO move around and you want to give yourself a fighting chance of good compression AND not melting down a piston until the engine breaks in. Expressed another way, by installing the gaps 120 degrees apart (and NOT over an oil return hole) you increase the likelihood that the ring gaps won't line up at some point. Of course their rotation rate isn't exactly the same, which is why when you tear an engine down the rings aren't still at 120 degrees after 100,000 miles.

This phenomenon was described by Harry Pellow, the "Maestro," in his inimitable style.

http://www.hcpresearch.com/ring_gap.html
__________________
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 09-24-2007, 05:41 AM
  Pelican Parts Technical Article Directory    Reply With Quote #25 (permalink)
Moderator
 
304065's Avatar
 
Join Date: Dec 2001
Posts: 9,443
Quote:
Originally Posted by Henry Schmidt View Post
All good information.
One tip: The high compression JE piston design offers a challenge to cylinder flow dynamics so we modify them by simply massaging the dome to allows for better flow at overlap.
On a small diameter bore w/ 2.0 heads this offers a 3-5 hp increase.
No secrets here, just a lot of trial and error.
Henry, I have seen you mention a couple times that "radiusing the sharp edge between the valve pockets" will help.

Is it simply a matter of breaking the sharp edge with some light abrasive? Or do you mill the piston crown?

I have one of those stand-mounted polishers that does a fine job on stuff (except when it grabs an eleven blade fan and throws it into the back yard) and the width of the buff is approximately equal to the ridge between valve reliefs.
__________________
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 09-24-2007, 02:31 PM
  Pelican Parts Technical Article Directory    Reply With Quote #26 (permalink)
 
Now Available for Ordering:   101 Projects For Your BMW 3 Series 1982-2000  [more info]
Registered User
 
efhughes3's Avatar
 
Join Date: Aug 2002
Location: Bend, OR
Posts: 7,082
Garage
Quote:
Originally Posted by john_cramer View Post
I have one of those stand-mounted polishers that does a fine job on stuff (except when it grabs an eleven blade fan and throws it into the back yard) and the width of the buff is approximately equal to the ridge between valve reliefs.
I'm sorry, but that made me laugh-it gave me an image of Ninja's throwing around 11 pt. stars at each other.
__________________
Ed Hughes
1995 993 Coupe "Sapphire"
Old 09-24-2007, 02:39 PM
  Pelican Parts Technical Article Directory    Reply With Quote #27 (permalink)
Try not, Do or Do not
 
Henry Schmidt's Avatar
 
Join Date: Apr 2004
Location: Fallbrook, Ca. 92028
Posts: 5,918
Garage
The issue is flow accross the piston top during overlap. All you need to do is massage the sharp edges between valve pockets. A gentle radious. We use a die grinder with a blue Scotch Brite pad.
Then polish the dome using a cloth wheel with medium ruge. ( Brown Tripoli Buffing Compound)
__________________
Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net
Old 09-24-2007, 02:53 PM
  Pelican Parts Technical Article Directory    Reply With Quote #28 (permalink)
Moderator
 
304065's Avatar
 
Join Date: Dec 2001
Posts: 9,443
Quote:
Originally Posted by Henry Schmidt View Post
The issue is flow accross the piston top during overlap. All you need to do is massage the sharp edges between valve pockets. A gentle radious. We use a die grinder with a blue Scotch Brite pad.
Then polish the dome using a cloth wheel with medium ruge. ( Brown Tripoli Buffing Compound)
Thanks for that advice, Henry.

I need to knock down the sharp edges where the valve reliefs were milled so I'll work on the crown at the same time. Probably going to put a plastic bag under the skirt up to where the dome starts and wrap it with a layer of duct tape to minimize any abrasive getting into the ring lands or oil return holes. And will obviously clean them thoroughly when done.
__________________
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 09-24-2007, 03:01 PM
  Pelican Parts Technical Article Directory    Reply With Quote #29 (permalink)
Try not, Do or Do not
 
Henry Schmidt's Avatar
 
Join Date: Apr 2004
Location: Fallbrook, Ca. 92028
Posts: 5,918
Garage
My pleasure, I am always willing to help.
__________________
Henry Schmidt
SUPERTEC PERFORMANCE
Ph: 760-728-3062
Email: supertec1@earthlink.net
Old 09-24-2007, 03:46 PM
  Pelican Parts Technical Article Directory    Reply With Quote #30 (permalink)
Registered User
 
Join Date: Oct 2001
Location: Momence, IL 60954
Posts: 1,823
Send a message via AIM to cnavarro
I'm thinking about using this company to process pistons, which may at the bleeding edge help with deterring issues arising from internal stresses due to the machining and forging processes. Coupled with cryogenic treatment and I don't think you can go wrong.

http://wpctreatment.com/

BTW, I had a researcher working on this same technology independently and I was very surprised to find that this technology already somewhat exists, although were looking at doing it with selective chemical etching just microns deep.
__________________
Charles Navarro, LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

'99 Boxster powered by Flat 6 Innovations; '10 Cayman S (DFI testbed)
Old 09-26-2007, 06:36 AM
  Pelican Parts Technical Article Directory    Reply With Quote #31 (permalink)
abit off center
 
cgarr's Avatar
 
Join Date: Feb 2002
Location: At the Airport Kentwood, MI
Posts: 6,995
Garage
Send a message via Yahoo to cgarr
Sounds like an enhanced shot peen process maybe?
__________________
______________________
Craig
G2Performance
Twinplug, head work, case savers, rockers arms, etc.
Old 09-26-2007, 06:47 AM
  Pelican Parts Technical Article Directory    Reply With Quote #32 (permalink)
what? me worry?
 
TimT's Avatar
 
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 6,792
Charles, thats another interesting surface treatment it sort of looks like a microshotpeen. I had a similar process do on the internals of my transmission. The R&P, input, shaft, gear sets, sliders, and spiders were REM treated.

Evans Performance

REM Chemicals
__________________
who are those guys? <<< ( Butch Cassidy and the Sundance Kid)
Rent a GT3RS from us!! Call or e-mail.
Transportation and Track support
Rudtners Racing

'69 911 GT-5
'75 914 GT-3
Authorised Haltech seller and installer
Authorised Unichip installer
BBS wheels
Fikse wheels
Redline motors oils
Swepco
1500 hp chassis dyno
Old 09-26-2007, 10:23 AM
  Pelican Parts Technical Article Directory    Reply With Quote #33 (permalink)
Registered User
 
Join Date: Oct 2001
Location: Momence, IL 60954
Posts: 1,823
Send a message via AIM to cnavarro
The WPC process is different that the REM process in some respects, but gets the same net effect. I've never seen anyone use the REM process on pistons though. I've used it on rockers and other parts that could use the stress relieving and due to the mirror finish, reduce windage and improve oil shedding. I've been having parts REM microfinished for a few years now, can't say it's hurt anything. The kind of clientel I get for the type 4 / Porsche 914, allows us to try out all kinds of expensive coatings and processes, as these guys don't blink an eye at spending $20-35k on their four cylinders at the high end.
__________________
Charles Navarro, LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

'99 Boxster powered by Flat 6 Innovations; '10 Cayman S (DFI testbed)
Old 09-26-2007, 11:34 AM
  Pelican Parts Technical Article Directory    Reply With Quote #34 (permalink)
abit off center
 
cgarr's Avatar
 
Join Date: Feb 2002
Location: At the Airport Kentwood, MI
Posts: 6,995
Garage
Send a message via Yahoo to cgarr
I love you guys! (not in a foot tapping way) Now I want to tear down my new engine and do it all over again....
__________________
______________________
Craig
G2Performance
Twinplug, head work, case savers, rockers arms, etc.
Old 09-26-2007, 12:06 PM
  Pelican Parts Technical Article Directory    Reply With Quote #35 (permalink)
Registered User
 
Join Date: Feb 2004
Location: UK
Posts: 2,231
Surely the REM process apart from super finishing is a surface conversion technique that effectivley produces a phosphate layer and is incomaparable to any peening process.

I can believe that REM does help slightly with fatigue strength as it will help to remove micoscopic surface defects that can act as fatigue crack initiation sites in a simlilar way to polishing.

Polishing can also produce some surface compressive residual stress that does inhibit the formation of fatigue cracks but some care is needed as incorrect techinques on soft metals can cause a flow pattern on the surface that creates a residual tensile stress that has just the opposite effect.

Shot peening is great, it can produce significant surface compressive stresses and it does tend to remove surface defects. I am convinced that it is more effective that polishing but again some caution is needed. The type of shot and the screening system used to remove broken particles is essential and it is very important to use the correct angle between the shot and the wory piece. Perpendicular is always good. Peening needs to be carried out in easy steps or the surface compression produced can cause bending to occur and this would clearly be disastarous.

(I have used peening to straighten long drive shafts that have bent during heat treatment and that are too hard to risk putting in a press)

If the shot is apllied parallel to the work piece then surface tensile stresses can be produced which again reduce fatigue life.

I would always tend to use an FAA/CAA apporved contractor such as Metal Imporvements as they have well controlled and proven systems and here in UK I pay around $150 to peen a set of rods.

WPC looks interesting but I awlays worry about technical descriptions that show a complete lack of understanding of some of the basics of metallurgy.

I just cut this from a site promoting WPC

WPC achieves this process by firing ultra fine particles towards the surface of a product at very high speeds. The resulting thermal discharge permanently changes the surface, strengthening the ionic structure and creating a harder more durable final product.

I really fail to understand some of these comments.

Metals just don't have an Ionic structure. They are crystals and have an atomic structure The whole concept of the metallic bond differs considerably from ionic bonding as any half decent scientist understands.

I also don't get how microscopic particles can generate sufficient heat to cause thermal hardening.

Steels can be locally hardened using induction heating and even flame techniques but to obtain the transformation of crystal structure needed to aloow hardening a minium of 850 degC is needed and temperature must be held for reasonabe lengths of time to allow carbon atoms to diffuse through the structure and move to differnt locations within the crystal. I just don't believe that there is sufficient energy available to allow this to happen.

As regards thermally processing the surface of Aluminium or Copper Alloys to produce local hardening it just ain't going to work, Aluminium alloys don't harden in the same manner as steels and heating followed by quenching just won't make the hard, just the opposite and if we all remeber or old single cylinder motorcycle days when engine had a Copper sealing ring we used to anneal them by heating to cherry red an quenching.

Aluminium Alloys can only be hardened by either cold working or by precipitation hardnening.

I can believe that WPC can offer benefits due to surface finish, oil retention etc but hardening !!! I would need to see some really good metallurgical justification before I believed.

Sorry to bang on but as a grumpy old man I don't like 'snake oil'

Last edited by chris_seven; 09-26-2007 at 12:16 PM..
Old 09-26-2007, 12:13 PM
  Pelican Parts Technical Article Directory    Reply With Quote #36 (permalink)
3 restos WIP = psycho
 
kenikh's Avatar
 
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,716
Simple question: what does "M" forging denote?
__________________

- 1965 911
- 1969 911S
- 1980 911SC Targa
- 1979 930
Old 09-26-2007, 12:42 PM
  Pelican Parts Technical Article Directory    Reply With Quote #37 (permalink)
Moderator
 
304065's Avatar
 
Join Date: Dec 2001
Posts: 9,443
"M" is the forging type from JE, compared to their "P" forging.

From another thread, posted by Mike Bruns,

Quote:
Walt, we have seen some of the problems you describe, some have alot of hours on them and have some cracks developing in them at the skirt/pin boss area, depending on what type of wrist pin they have some of the lighter pins ie.. tapered wall design or thin wall JE has some thoughts of pin flex having an effect on the piston, but we also have seen cracks coming out of the pin oiling holes in the pin bore, and have changed ours to broached style oiling, also the type of forging, the M has a better strength at the pin boss than the P forging and if it has an offset pin it can get thin on one side as well. the type of forging can be seen under the dome unless its had under crown milling. The forging is seen as example on a 95mm bore with a P forging "96P" or "96M"
Piston failure
__________________
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 09-26-2007, 01:15 PM
  Pelican Parts Technical Article Directory    Reply With Quote #38 (permalink)
Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,270
Garage
Quote:
Originally Posted by john_cramer View Post
The reason you have to stagger the gaps is because the rings DO move around and you want to give yourself a fighting chance of good compression AND not melting down a piston until the engine breaks in. Expressed another way, by installing the gaps 120 degrees apart (and NOT over an oil return hole) you increase the likelihood that the ring gaps won't line up at some point. Of course their rotation rate isn't exactly the same, which is why when you tear an engine down the rings aren't still at 120 degrees after 100,000 miles.

This phenomenon was described by Harry Pellow, the "Maestro," in his inimitable style.

http://www.hcpresearch.com/ring_gap.html
John,
Didn't the factory 993 pistons have a protrusion in the ring land that kept the rings from rotating? Couldn't the same feature be added to the JE's?
__________________
Dave
'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 09-27-2007, 07:37 AM
  Pelican Parts Technical Article Directory    Reply With Quote #39 (permalink)
Moderator
 
304065's Avatar
 
Join Date: Dec 2001
Posts: 9,443
__________________
'66 911 #304065 Irischgruen
Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13)
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)
Old 10-23-2007, 12:24 PM
  Pelican Parts Technical Article Directory    Reply With Quote #40 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 

Tags
901/05 , jcrebuild , john cramer rebuild


All times are GMT -8. The time now is 04:35 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2017 Pelican Parts LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.