The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > Racing and high performance (trucks haulin more than hay)

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 11-08-2010, 10:55 PM   #1
Yellow76
Registered User
 
Yellow76's Avatar
 
Join Date: Jul 2009
Location: Tulare,CA
Posts: 87
Would this compression work?

Number of Cylinders :8
Bore in Inches :4.030
Stroke in Inches :3.48
Rod Length in Inches :5.7
Static Compression Ratio : 9.98
Inlet Valve Closes ABDC : 39.5º
Boost Pressure in PSI : 0
Target Altitude 200


This gives me 9.19 dynamic compression with a .040 head gasket. Would this set up run pump gas (91)?
Yellow76 is offline   Reply With Quote
Old 11-08-2010, 10:56 PM   #2
Yellow76
Registered User
 
Yellow76's Avatar
 
Join Date: Jul 2009
Location: Tulare,CA
Posts: 87
Re: Would this compression work?

With this cam http://www.lunatipower.com/Product.aspx?id=1984&gid=287
Yellow76 is offline   Reply With Quote
Old 11-09-2010, 02:05 AM   #3
Super73
Registered User
 
Super73's Avatar
 
Join Date: Nov 2007
Location: Bay Area, Ca
Posts: 2,841
Re: Would this compression work?

Curious how you are coming up with that static compression of 9.98 and DCR of 9.19..

To get a SCR of 9.98 with the info you gave you would need a total of 75 cc's IE 71cc heads and -4 cc pistons for a total of 75cc.. Could be 68cc heads and 7cc pistons but either way is that right?

I think you are using the .050 number to get 39.5* IVC.. With 268* duration at .006 and installed on a intake center of 106, I get 8.23 DCR. DCR needs to be measured when the valve is closed. I did not see an intake centerline on the cam card you provided so I guessed on a 106icl. A 108 would net 8.12 and a 104 would net 8.35.. All of those "should" be acceptable with pump gas.

Anything over 8.5 is questionable and anything over 8.7 I would really suggest not running 91 with.
__________________
------Motor---------------Bottle
60'---1.53---------------1.41
1/8---6.58 @ 105.92----5.87 @ 118.41
1/4---10.38 @ 126.97----9.24 @ 142.49
Super73 is offline   Reply With Quote
Reply

Bookmarks

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

Forum Jump


All times are GMT -4. The time now is 12:35 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com