How is compression raised? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
Ford Forum Ford Forum

» Auto Insurance
» Featured Product
» Wheel & Tire Center

Go Back   Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > The Garage - Tech Forums > General Tech
Register Home Forum Active Topics Photo Gallery Auto Loans Garage Mark Forums Read Auto Escrow

General Tech Have a question that is not covered by one of the other categories? This is the forum for all other items not specifically covered in other categories.

FordForums.com is the premier Ford Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 01-06-2003, 21:40   #1 (permalink)
Chasing 500rwkw
 
DansEdgli's Avatar
 
Join Date: Apr 2002
Location: Melbourne
Posts: 3,176
How is compression raised?

This is probably a dumb question but how is the compression raised in an engine?
I know you can get aftermarket flat top and domed pistons but is there other ways. Is the block skimmed or is it the head only that gets modified?

Thanks guys.
Dan
DansEdgli is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 01-06-2003, 21:49   #2 (permalink)
Registered User
 
Join Date: Oct 2001
Location: Mt Warrigal, NSW, Australia
Posts: 170
Usually only the head. To skim the block the engine will need to be stripped.
__________________
When cubes aren't enough.
Blow NOS!!!
12.3s @ 110mph so far
blown EF 6 is offline   Reply With Quote
Old 01-06-2003, 21:54   #3 (permalink)
Chasing 500rwkw
 
DansEdgli's Avatar
 
Join Date: Apr 2002
Location: Melbourne
Posts: 3,176
Thanks for that. I wasnt sure. Now i know.

Dan
DansEdgli is offline   Reply With Quote
Old 01-07-2003, 02:02   #4 (permalink)
plarsson
Guest
 
Posts: n/a
There are five interconnected aspects to compression as measured by ratio.

You will increase your compression ratio by doing any or all of the following; Shaving the Deck of your Block, Shaving the face of your Head, Fitting Flat Top or Raised top Pistons and by increasing the stroke of the crank. Another way is to use thinner than standard Headgaskets, or "O" ringing the Head and block.
"O" Ringing is really only used in extreme applications IE Drag Racing.

You can offset the increase in compression ratio by any of the following, Die grind and reshape the Squish area in your cylinder head (must be done precisely and equally in all cylinders), Increase the Cylinder Bore (don't go mad coz theres only so much meat in the walls), Dished pistons or carefully reshaped pop top pistons. The other method is a bit crude though Mercedes used this on their earlier motors, and thats to add additional head gaskets and Decompression plates.

Without trying to confuse the issue, you can gain a marginal improvement in compression by using "Gapless" Piston rings. These are the same as normal piston rings except that they have an opposing step on each end of the ring which mates up to remove the "gap".

Aiming for a compression ratio of more than 9.5:1 on regular unleaded is very optomystic, although many of the current cars run up to 10.5:1, they have engine management systems with knock sensors which retard the ignition to save it from pinging too loudly.

Hope this helps.
  Reply With Quote
Old 01-07-2003, 04:05   #5 (permalink)
Chasing 500rwkw
 
DansEdgli's Avatar
 
Join Date: Apr 2002
Location: Melbourne
Posts: 3,176
Yes that did help thanks.
The Head and Cam combo that im going for is recommended for use with a 9.5 compression ratio. I'm taking my head head off and giving it to them to do so i imagine they would take care of the new compression ratio this way. Ill probably have to run optimax which is alright cos i use it anyway.

Cheers Guys
Dan
DansEdgli is offline   Reply With Quote
Old 01-07-2003, 06:32   #6 (permalink)
Two SC 61's = trouble
 
ebxr8240's Avatar
 
Join Date: Jul 2001
Location: Penrith,nswAus/Morrinville.NZ
Age: 61
Posts: 6,360
Static compresion yes another way is forced induction.. Turbo / Supercharge or chemicaly with Nitrous n2o..
__________________
Don't be afraid to try something new. Remember, amateurs built the Ark...Professionals built the Titanic!
.
Tuned & maintained by "Peppertree Perfmormance". Dart block, Scat 4340 steel crank, Custom C.P pistons.Oliver rods.. Mal Wood twin plate clutch.. Twin SC61/2's,482 rwkw/ 645 rwhp..
Passengers, myocardial infarction material..
R.I.P Possum...
ebxr8240 is offline   Reply With Quote
Old 01-07-2003, 16:17   #7 (permalink)
plarsson
Guest
 
Posts: n/a
ebxr8240, I don't think DansEdgli was looking at more than the basic engineering changes to perk up his motor.

I'm not sure that forced or chemical induction will increase compression, but it certainly makes a difference in the "Fun" equation...

The Silver Bullet is back on the road next week can't wait to take it for a blatt up the F3 ...
  Reply With Quote
Old 01-07-2003, 21:35   #8 (permalink)
Registered User
 
ir33t's Avatar
 
Join Date: Nov 2002
Location: Melbourne
Age: 32
Posts: 341
you can get your pistons ceramic coated by HPC, that will raise it aswell + a few other bonuses
__________________
AU Series 1 I6 Futura, 17" XR Series III Rims, Kings superlow springs and Bilstien shocks, K-MAC adjustable caber kit, xr8 snorkle, BMC Filter, EF a/box lid, custom storm water pipeing, pacemakers, h/flow cat, 2 1/2" zorst mandrel bent, dyno'd @ 117.2kwrw b4 bmc
ir33t is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > The Garage - Tech Forums > General Tech



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Jaguar's Tribute to Style on Rodeo Drive 2002 Raised $750,000 For Entertainment Indus Stacy94PGT Ford Worldwide News 0 09-25-2002 21:22
Will all v8s have raised bonnet 2002 s3 xr8 The Pub 7 09-22-2002 03:05
Low Compression: Do I have a problem? EA S Inline 6 Tech 7 08-15-2001 02:45
Why don't LPG Falcons run higher compression? Luke Plaizier LPG Tech 1 07-23-2001 22:24

Powered by vBadvanced CMPS v3.2.2

All times are GMT -7. The time now is 20:16.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.6.0
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.