Compression Ratio's (E7s / Gtps) - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars
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.

LinkBack Thread Tools Display Modes
post #1 of 5 (permalink) Old 09-29-01, 09:48 AM
Posts: n/a
Compression Ratio's (E7s / Gtps)

I need some advise, I am currently home porting a set of Gt-40p's. I am going to fit larger valves 1.94/1.54 (stock 1.85/1.46) and I want to mill the heads to up the compression ratio to a something similar to the 220kW AUII heads. I think the P's are a 59cc chamber, WHAT IS THE E7 CHAMBER CC?? I'd like a compression ratio of 9.45:1, how much would I get milled off around 20thou? I read that the rough estimate for a small block Ford factory type casting is 1cc for each .007" milled?

Sponsored Links
post #2 of 5 (permalink) Old 10-01-01, 09:35 AM
Posts: n/a
Ok i am going to reply to my own post here.
E7 casting are 64cc combustion chambers and I read the GT-40p is 60 (so say factory tolerences 59-60cc).

So not even milling p's would raise compression on my engine no? ANYONE?

post #3 of 5 (permalink) Old 10-01-01, 10:41 AM
Officially Bored with 347
svo347's Avatar
Join Date: Jul 2001
Location: Perth West Oz
Age: 42
Posts: 3,585
well actually milling ya heads will increase the c/r not sure how much to remove my tfs were shaved to obtain 9.9:1..
check out the ford racing catalogue pg 115 its explains how to work out c/r's..
hope this helps, also keep an eye on valve clearances not that i need to tell you about that

svo347 is offline  
post #4 of 5 (permalink) Old 10-03-01, 08:20 PM
Posts: n/a
haha thanks brett.
heres what my mate Sean Meldrum told me,...

the original iron GT-40s from FMS or from a Lightning were 65cc. From a Cobra they'd be milled from the factory. I think the rough estimate for a small block Ford factory type casting is 1cc for each .007" milled. Figure approx. 4.3cc reduction.

A 59 cc chamber would have you at 9.5ish. 60 would be about 9.38ish. The nominal range for a P is 59-61. A .010" cut should shave a bit over 1cc. So I'd say .010-.015" should easily get you to 9.4:1

post #5 of 5 (permalink) Old 10-03-01, 10:54 PM
Posts: n/a
On that subject came up with E7's 030Th = 9:5 about right ??. [+5cc for piston chamber & valve relief's} so 58 cc head c.chambers is what they go for..
Sponsored Links

  Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars > The Garage - Tech Forums > General Tech
Gear in this thread - Powered by O'Reilly Auto Parts

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
XR6-T ... poorly chosen gear/diff ratios T3man F6 Typhoon | XR6 Turbo 44 01-05-04 03:28 AM
Cleveland Enquiries oil pressure, compression pressure RevHeadRon Cleveland Tech 7 10-11-03 06:45 AM
low compression pistons price? OverDose Inline 6 Tech 3 05-08-03 12:17 AM
Diff? Ratios? vbman187 Trans | Driveline 3 11-17-02 11:15 PM
Why don't LPG Falcons run higher compression? Luke Plaizier LPG Tech 1 07-23-01 10:24 PM

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

For the best viewing experience please update your browser to Google Chrome