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 / 930 Turbo & Super Charging Forum

Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Wo ist die Rennstrecke?
 
DonE's Avatar
 
Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
....what is a boat-tailed piston?

Anyone?
Old 12-04-2007, 06:13 PM
  Pelican Parts Technical Article Directory    Reply With Quote #21 (permalink)
Registered User
 
wmunchovie's Avatar
 
Join Date: Nov 2007
Posts: 58
I like to think that what type of performance one wants should dictate what kind of grind they would be seeking; that is to say, what type of driving situation as a whole one would want out of the engine.... street able, all of the torque crammed to the top, more torque at the bottom end, etc.

I am running webcam no. 40 grind ( 964 sort of ) and it's just killer in the turbo; as with any cam; change timing a degree or two to alter get low/high response. ( please watch out for piston tops ). Also, make sure you have enough spring load to curtail valve float; whomever provides the cam should provide the specs for everything you need to know. Tighter valve springs will close valves quicker but it's tougher on rockers, cam, etc.

I took me for ever to get the cams dialed in properly but that was me; not the cams. Get a big degree wheel and/or mag base dial indicator and a piston stop - throw the clock out the back door

munchovie.
__________________
Is 13 lucky or unlucky ?
Old 12-04-2007, 08:05 PM
  Pelican Parts Technical Article Directory    Reply With Quote #22 (permalink)
Registered User
 
930gt-40r's Avatar
 
Join Date: Jan 2007
Location: Boca Raton, FL
Posts: 2,063
Im for boat tailing (Case and cylinders), dowel pinning, twin plugging, 964/993 crank, stock pistons with C2 cylinders, and a set of stronger rods- I got Pauters that took 900+ in Jimmy Ks drag car. First- make sure that the heads are in good condition then maybe a little porting and polishing could be considered as well. This is probley a 6 grand bill, but defenatly do the dowel pins, twin plug, and freshen the heads- or thats what I would do.
Oh yea- cams too...
__________________
Kris @ Tech9
86' 930/GT-40R Sold
94' Rustang GT daily (long gone)
2008 C6/Z51 Corvette
Old 12-04-2007, 08:35 PM
  Pelican Parts Technical Article Directory    Reply With Quote #23 (permalink)
Forced Induction Junkie
 
WERK I's Avatar
 
Join Date: Jan 2003
Location: Wisconsin
Posts: 3,267
Garage
Quote:
Originally Posted by DonE View Post
....what is a boat-tailed piston?

Anyone?
Never heard of it, Don. Got to be a misquote.
__________________
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 12-05-2007, 07:44 AM
  Pelican Parts Technical Article Directory    Reply With Quote #24 (permalink)
Registered User
 
2369488's Avatar
 
Join Date: Jan 2007
Location: Wichita
Posts: 81
I'll post some pictures of the pistons this afternoon. I am going by the description of the car when I bought it a year ago. So perhaps the boat tail pistons description is incorrect.
Old 12-05-2007, 08:23 AM
  Pelican Parts Technical Article Directory    Reply With Quote #25 (permalink)
Registered User
 
2369488's Avatar
 
Join Date: Jan 2007
Location: Wichita
Posts: 81
Here are some pictures of what is suppose to be "boattail pistons"? They are flat top pistons. Any information would be appreciated.
Old 12-05-2007, 11:30 AM
  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]
A fellow Pelacanite
 
NathanUK's Avatar
 
Join Date: Nov 2006
Location: UK
Posts: 2,002
Garage
They are the cylinders.
__________________
1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG.
Fitting - New service kit.
Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head.

1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods.
Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit.

http://www.danasoft.com/sig/Iamnotanumber.jpg
Old 12-05-2007, 03:34 PM
  Pelican Parts Technical Article Directory    Reply With Quote #27 (permalink)
E-85 sippin drunk
 
turbobrat930's Avatar
 
Join Date: Jan 2002
Location: Warner Robins, GA
Posts: 1,483
To the original poster... While your motor is apart, I would HIGHLY recommend that you look into doing the center oil mod to your crank and bearing.... cheap insurance while its apart....
__________________
Brad...930 gt-1 racecar, increased displacement to 3.6L, JB racing Cylinders, JE 8 to1 pistons, stroked crank, Carrillo rods, extrudehoned 3.2L intake, full bay Bell I/C, GT-2 EVO cams, Rarly8 headers, GTX-35RS turbo, twin plug, P&P heads, Link G4 EFi system, G-50/50 with LTD slip and oil squirters/oil cooler, zork tube, full race coilover system, with carbon fiber body, full cage, E-85 sippin drunk
Old 12-05-2007, 03:44 PM
  Pelican Parts Technical Article Directory    Reply With Quote #28 (permalink)
Registered User
 
2369488's Avatar
 
Join Date: Jan 2007
Location: Wichita
Posts: 81
Thanks turbobrate930 - I will add the center oil mod to the crank bearing.
Old 12-05-2007, 04:23 PM
  Pelican Parts Technical Article Directory    Reply With Quote #29 (permalink)
Registered User
 
2369488's Avatar
 
Join Date: Jan 2007
Location: Wichita
Posts: 81
the pictures are of the pistons and are in the cylinders. The first one is of the piston skirt sticking out of the cylinder.
Old 12-05-2007, 04:25 PM
  Pelican Parts Technical Article Directory    Reply With Quote #30 (permalink)
Me like track days
 
Craig 930 RS's Avatar
 
Join Date: Sep 2003
Location: Kirkland, WA
Posts: 10,190
I've seen modified pistons where the skirts are cut down a bit.


If it hasn't been done yet, and in general, edging the crank and boat tailing the case are a absolute waste of money in a non-high rpm turbo motor.

Springs and ti retainers are a must.
Fully finned cylinders are a good idea for more extensive/hot track use
Flame ringing the heads and cylinders is recommended for track use/and or higher boost levels
964 or SC cams
SC heads are nice - MUCH bigger ports
Rod bolts, baby
Stock rods are perfectly fine for your application
__________________
- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 12-05-2007, 04:58 PM
  Pelican Parts Technical Article Directory    Reply With Quote #31 (permalink)
Wo ist die Rennstrecke?
 
DonE's Avatar
 
Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
And I would add shuffle pinning a street motor is a waste too. Even if it produces +500hp.
Old 12-05-2007, 05:47 PM
  Pelican Parts Technical Article Directory    Reply With Quote #32 (permalink)
Me like track days
 
Craig 930 RS's Avatar
 
Join Date: Sep 2003
Location: Kirkland, WA
Posts: 10,190
Agreed. I missed that one -
__________________
- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 12-05-2007, 06:05 PM
  Pelican Parts Technical Article Directory    Reply With Quote #33 (permalink)
Registered User
 
Join Date: Nov 2007
Posts: 14
i heard something about non turbo heads being made of a different alloy , thus having different metalurgy and not being good for high temp situations?

i hope this isnt true because siiting there and porting turbo heads sucks and takes HOURS!
Old 12-05-2007, 07:48 PM
  Pelican Parts Technical Article Directory    Reply With Quote #34 (permalink)
Me like track days
 
Craig 930 RS's Avatar
 
Join Date: Sep 2003
Location: Kirkland, WA
Posts: 10,190
Yep.

But practical experience has shown this to be of no concern - bank on it.
__________________
- Craig 3.4L, SC heads, 964 cams, B&B headers, K27 HF ZC turbo, Ruf IC. WUR & RPM switch, IA fuel head, Zork, G50/50 5 speed. 438 RWHP / 413 RWTQ -
"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno
Old 12-05-2007, 09:10 PM
  Pelican Parts Technical Article Directory    Reply With Quote #35 (permalink)
Registered User
 
wmunchovie's Avatar
 
Join Date: Nov 2007
Posts: 58
Quote:
Originally Posted by 2369488 View Post
Thanks turbobrate930 - I will add the center oil mod to the crank bearing.
any link to the mod in question ?

thanks, munchovie
__________________
Is 13 lucky or unlucky ?
Old 12-05-2007, 09:25 PM
  Pelican Parts Technical Article Directory    Reply With Quote #36 (permalink)
E-85 sippin drunk
 
turbobrat930's Avatar
 
Join Date: Jan 2002
Location: Warner Robins, GA
Posts: 1,483
Quote:
Originally Posted by wmunchovie View Post
any link to the mod in question ?

thanks, munchovie
There is not a link that I know of to post. What it is....is a mod to one of the center bearings...and the corresponding journal on the crankshaft. Basically, the main bearings are fed oil from both sides of the crank....and in doing so, the number 2 & 5 rod bearings are usually the first to go, as they are the last to get oil... The mod lets the rod bearings get the oil from both ends, plus the center of the crank as well.... usually elliminating any lack of oil problems...any good machine shop such as JB Racing, Ollies, Performance Developments, CCR, etc can do this mod.... It is usually under 100 bucks to mod the center main bearing...and i cant recall what I paid for my mod to the Crank, as I also had mine stroked as well... but it was not much. It is a good mod to do, and a good "do it while you are in there" mod...as well as the piece of mind...
__________________
Brad...930 gt-1 racecar, increased displacement to 3.6L, JB racing Cylinders, JE 8 to1 pistons, stroked crank, Carrillo rods, extrudehoned 3.2L intake, full bay Bell I/C, GT-2 EVO cams, Rarly8 headers, GTX-35RS turbo, twin plug, P&P heads, Link G4 EFi system, G-50/50 with LTD slip and oil squirters/oil cooler, zork tube, full race coilover system, with carbon fiber body, full cage, E-85 sippin drunk
Old 12-05-2007, 09:40 PM
  Pelican Parts Technical Article Directory    Reply With Quote #37 (permalink)
what? me worry?
 
TimT's Avatar
 
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 6,790
We do the cross-drill/bearing mod in all the high output, high revving engines we build.

Cross-drilled crank/modified bearing

__________________
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 12-05-2007, 09:51 PM
  Pelican Parts Technical Article Directory    Reply With Quote #38 (permalink)
E-85 sippin drunk
 
turbobrat930's Avatar
 
Join Date: Jan 2002
Location: Warner Robins, GA
Posts: 1,483
Yep, Tim, That was exactly what I was looking for.... thanks for posting it....
__________________
Brad...930 gt-1 racecar, increased displacement to 3.6L, JB racing Cylinders, JE 8 to1 pistons, stroked crank, Carrillo rods, extrudehoned 3.2L intake, full bay Bell I/C, GT-2 EVO cams, Rarly8 headers, GTX-35RS turbo, twin plug, P&P heads, Link G4 EFi system, G-50/50 with LTD slip and oil squirters/oil cooler, zork tube, full race coilover system, with carbon fiber body, full cage, E-85 sippin drunk
Old 12-05-2007, 09:54 PM
  Pelican Parts Technical Article Directory    Reply With Quote #39 (permalink)
Registered User
 
WydRyd's Avatar
 
Join Date: Mar 2002
Posts: 3,563
FWIW, I run 993 GT2-EVO CAMs in my blown Carrera and I love them. They "come on" at around 3.5-4K RPM, when the turbo has reached max boost of ~1.25bar and they pull like nothing. They truely are an awesome CAM for an EFI setup.

I have no experience with the CIS stuff, so I can't really comment to be honest, but with EFI it's a no brainer.

I'm soon going with a TT configuration, so it'll be interesting to see how they perform in such a configuration
__________________
Merv
'89 911 Turbo Cab
Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition
Old 12-06-2007, 01:01 AM
  Pelican Parts Technical Article Directory    Reply With Quote #40 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 10:53 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2016 Pelican Parts - 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.