 Compression Ratio, Will I be able to tell the difference? |
|
|
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
|
| sdoolin |
 Feb 7 2025, 04:42 PM
Post
#1
|
|
Member  Group: Members Posts: 414 Joined: 1-May 14 From: LouKY Member No.: 17,299 Region Association: None  |
Rebuilding(ish) my 2056. On my first build I was able to achieve a compression ratio of very nearly 9.0:1. With this build, I am having to add .020 spacers below the jugs to get any measurable deck height in the jugs. I am calculating a compression ratio of 8.6:1.
Will I notice the loss in compression ratio? |
   |
 
|
  |
Replies
| sdoolin |
Feb 9 2025, 05:03 PM
Post
#2
|
|
Member Group: Members Posts: 414 Joined: 1-May 14 From: LouKY Member No.: 17,299 Region Association: None |
Measured valve lift a bunch of times today. Worst case I am losing .036" of lift at the exhaust valves, and .018" of lift at the intake valves. Best case I am achieving slightly greater than advertised lift on this cam (.435). So I am good with it and am not going to bother measuring for new pushrods. The geometry at half lift looks really really good, things are lined up well.
Will proceed with final assembly. I will have questions about oil pressure verification soon. A pic, because pics help everything (and 914 world autorotates my pics for some reason)...  |
|
|
|
Posts in this topic
sdoolin Compression Ratio Feb 7 2025, 04:42 PM
technicalninja You need AT LEAST .036 with cast and .040+ with fo... Feb 7 2025, 05:38 PM sdoolin Measured deck height in the jug, with an .020 spac... Feb 7 2025, 06:02 PM Superhawk996 Sounds like you are playing with fire.
Without se... Feb 7 2025, 06:21 PM
sdoolin
Sounds like you are playing with fire.
Without s... Feb 7 2025, 07:26 PM Superhawk996
Sounds like you are playing with fire.
Without ... Feb 7 2025, 07:30 PM technicalninja
Measured deck height in the jug, with an .020 spa... Feb 7 2025, 06:57 PM sdoolin Yep, I don't want this help. Y'all go buil... Feb 7 2025, 07:27 PM worn
Yep, I don't want this help. Y'all go bui... Feb 14 2025, 07:12 PM sdoolin
Yep, I don't want this help. Y'all go bu... Feb 15 2025, 08:44 AM sdoolin I especially like the turd bit. Feb 7 2025, 07:29 PM sdoolin Superhawk thank you for your reasonable response. ... Feb 7 2025, 07:33 PM Superhawk996
Superhawk thank you for your reasonable response.... Feb 7 2025, 07:44 PM Jack Standz
Rebuilding(ish) my 2056. On my first build I was ... Feb 8 2025, 03:05 AM sdoolin
Rebuilding(ish) my 2056. On my first build I was... Feb 8 2025, 07:35 AM sdoolin Bolted things up on one side of the engine today a... Feb 8 2025, 12:37 PM Superhawk996 0.100” clearance to the exhaust valve is startin... Feb 8 2025, 01:43 PM Jack Standz
Bolted things up on one side of the engine today ... Feb 8 2025, 03:04 PM sdoolin Thank you both for the thoughtful replies. My orig... Feb 8 2025, 04:32 PM Superhawk996 0.140” - 0.150” clearance to exhaust valves is... Feb 8 2025, 10:28 PM sdoolin I'll likely button this engine up this weekend... Feb 14 2025, 02:27 PM Jack Standz Modified #2.
Bolt transmission to engine. Remove... Feb 14 2025, 04:41 PM sdoolin
Modified #2.
Bolt transmission to engine. Remov... Feb 15 2025, 08:38 AM 930cabman Have you checked crankshaft end play? Feb 14 2025, 04:52 PM sdoolin
Have you checked crankshaft end play?
So I re-c... Feb 16 2025, 04:08 PM Al Meredith Years ago when Len Hoffman was rebuilding heads he... Feb 15 2025, 05:02 PM worn
Years ago when Len Hoffman was rebuilding heads h... Feb 15 2025, 08:49 PM Superhawk996 No discernible crank end play is a no-go.
Redo ... Feb 16 2025, 04:30 PM sdoolin
No discernible crank end play is a no-go.
Redo... Feb 17 2025, 08:09 AM stownsen914 Separate from the crank end play, if you are askin... Feb 17 2025, 08:15 AM sdoolin
Separate from the crank end play, if you are aski... Feb 17 2025, 01:16 PM sdoolin I have measured all of the shims I have on hand (6... Feb 18 2025, 05:25 PM sdoolin So, I re-measured crank end play. Installed flywhe... Feb 22 2025, 01:05 PM Superhawk996
Am I looking for .004" thrust with all thr... Feb 22 2025, 01:16 PM sdoolin Thank you Superhawk. Installed third shim, remeasu... Feb 22 2025, 02:04 PM Superhawk996
Thank you Superhawk. Installed third shim, remeas... Feb 22 2025, 07:09 PM Jack Standz Add a cable from the negative side of the battery ... Feb 22 2025, 02:24 PM Superhawk996 I’m going to ask a question that I’ve assumed ... Feb 22 2025, 07:17 PM sdoolin
I’m going to ask a question that I’ve assumed... Feb 23 2025, 09:20 AM Jack Standz It's a good idea to fill the oil filter with o... Feb 23 2025, 02:51 PM sdoolin I have confused myself. It happens.
Having re-in... Feb 27 2025, 10:37 AM Superhawk996 Follow the Haynes or factory manual to instill the... Feb 27 2025, 12:15 PM sdoolin
Follow the Haynes or factory manual to instill th... Feb 27 2025, 04:02 PM sdoolin Engine went in on Friday. Easy peasy. After I pour... Mar 2 2025, 05:23 PM sdoolin Could this be a faulty oil pressure sending switch... Mar 3 2025, 10:30 AM VaccaRabite
Could this be a faulty oil pressure sending switc... Mar 3 2025, 11:35 AM Superhawk996 If it were me I would not be starting the engine j... Mar 3 2025, 12:53 PM sdoolin Installed my brand new oil pressure test gauge (Ha... Mar 3 2025, 04:20 PM VaccaRabite Your pressure is high because the oil is cold and ... Mar 4 2025, 06:20 AM rfinegan Woohoo
glad you get the pressure...sounds like the... Mar 4 2025, 09:03 AM sdoolin Yep, cold oil and running (expensive) Brad Penn 20... Mar 4 2025, 09:10 AM sdoolin She's alive, and running well(ish). Drove abou... Mar 11 2025, 10:55 AM 930cabman
She's alive, and running well(ish). Drove abo... Mar 11 2025, 12:17 PM friethmiller @sdoolin ,
Congrats! Glad the build was succ... Mar 11 2025, 11:54 AM sdoolin Moving on to some other fiddly projects. Oil press... Mar 11 2025, 02:56 PM |
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 12th March 2025 - 02:12 PM |
Invision Power Board
v9.1.4 © 2025 IPS, Inc.