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
Registered User
 
Mookster's Avatar
 
Join Date: Jun 2003
Location: Tampa, FL
Posts: 341
Garage
Compression ratio questions

I have Wayne's rebuild book and looking at page 113 on Wayne's engine picks. I am no MIT graduate but just trying to understand some of the fundamentals of gaining hp without breaking the bank when the time comes to rebuild/modify the motor.

I have a 1983SC with a 3.0L USA engine with 9.3:1 CR based on the spec book. The euro version of the same motor has a CR of 9.8:1

First, what do the CR ratio numbers mean?

Hypothetical, if I were to rebuild my motor with euro P&Cs what additional modifications to the motor, ignition, and fuel system would be needed? In this hypothetical can I use my current CIS fuel system, cams and heads effectively.

For kicks and giggles (hypothetical), if the compression ratio were increased to 10.1-10.3:1 either by displacement of 3.2L P&Cs or custom JEs. Would this work using the normal CIS system, cams, heads, 92 octane gas and valves? Mods/parts needed.

The reason I ask these questions is I see some of the parts cost differ for small dollar amounts. If you are going to drop this kind of coin on some of these bolt on parts the logic seems, at least on the surface, seems to upgrade to more displacement or higher C/R. My goal is to make a reliable inspired motor without breaking the bank.

All answeres and explainations are greatly appreciated in advance.
__________________
If it has a skirt or tires, it WILL cost you money!
Old 01-17-2005, 05:06 PM
  Pelican Parts Technical Article Directory    Reply With Quote #1 (permalink)
Registered User
 
dweymer's Avatar
 
Join Date: Nov 2004
Location: Tucson, AZ
Posts: 2,356
Garage
Mook,

I am not a pro by any sense of the imagination but IMHO
CIS does not care about CR, it supplies fuel based on air flow. I would think the ignition timing curve would be the same as current also. I don't know if 92 octane would be enough for 10.3:1, or if there would be any valve clearance issues.
__________________
Donnie

Currently Porsche-less.....
Old 01-17-2005, 06:44 PM
  Pelican Parts Technical Article Directory    Reply With Quote #2 (permalink)
D troop 3/5 CAV ,162 AHC
 
afterburn 549's Avatar
 
Join Date: Jul 2003
Location: Army, Retrograded
Posts: 12,628
Generally with todays gas..as you bump c/r pts. up you move your powerband up as this somewhat helps the ping issue.....and there are a hundred other things too...... a bumpier cam ( more overlap) helps as well as other stuff.
Old 01-17-2005, 07:53 PM
  Pelican Parts Technical Article Directory    Reply With Quote #3 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 11:22 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, 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.