LT1-LT4 Modifications 1993-97 Gen II Small Block V8

help me understand dynamic cranking pressure

Thread Tools
 
Search this Thread
 
Old Oct 7, 2010 | 01:01 PM
  #1  
merim123's Avatar
Thread Starter
TECH Fanatic
20 Year Member
Photogenic
Liked
Loved
iTrader: (11)
 
Joined: Oct 2005
Posts: 1,921
Likes: 25
From: Chitown, IL
Default help me understand dynamic cranking pressure

I used this calculator to calculate DCR:

http://www.wallaceracing.com/dynamic-cr.php

for my 227 crane with 53cc/355 (4.03/3.48/5.7)altitude 660, with a 1074 gasket I'm at 11.4 static and right at 230.xx on dynamic cranking pressure and a DCR of 10.7.

I then input my new cam settings and get 216 dynamic cranking pressure.

However, if I up the compression to 12.0 it comes back to 230.xx dynamic cranking pressure. and a 10.7 DCR. an impala head gasket would put me at 11.75 which would bump up the cranking pressure to 225.

So my question
How should I interpret the dynamic cranking pressure info?
Reply
Old Oct 7, 2010 | 02:54 PM
  #2  
1redta's Avatar
TECH Apprentice
 
Joined: Dec 2004
Posts: 347
Likes: 0
From: fort campbell
Default

try a diff calculator such as the one on kbsilvolite
your DCR numbers are to high for pump gas which should be no higher than 9.0
Reply
Old Oct 7, 2010 | 03:12 PM
  #3  
merim123's Avatar
Thread Starter
TECH Fanatic
20 Year Member
Photogenic
Liked
Loved
iTrader: (11)
 
Joined: Oct 2005
Posts: 1,921
Likes: 25
From: Chitown, IL
Default

with this calculator http://www.kb-silvolite.com/calc.php?action=comp

i get 9.46 and my baby crane was at 10.2.
Reply
Old Oct 7, 2010 | 08:05 PM
  #4  
Wicked94Z's Avatar
10 Second Club
iTrader: (26)
 
Joined: Jul 2005
Posts: 3,725
Likes: 1
From: Spokane, Wa
Default

DCR is really a misnomer... There's nothing "dynamic" about using the IVC to determine the theoretical compression the motor sees, which isn't very accurate. I guarantee I could spec two cams that would give you the same "dynamic" (fixed) compression ratio, or cranking psi, and yet one would ping like there's no tomorrow, and the other woudn't be anywhere close to detonation.
Reply
Old Oct 7, 2010 | 09:28 PM
  #5  
speed_demon24's Avatar
11 Second Club
iTrader: (6)
 
Joined: Dec 2001
Posts: 4,609
Likes: 2
From: Ocala, FL
Default

Originally Posted by Wicked94Z
DCR is really a misnomer... There's nothing "dynamic" about using the IVC to determine the theoretical compression the motor sees, which isn't very accurate. I guarantee I could spec two cams that would give you the same "dynamic" (fixed) compression ratio, or cranking psi, and yet one would ping like there's no tomorrow, and the other woudn't be anywhere close to detonation.
But then how would all the internet experts sell cams?
Reply
Old Oct 7, 2010 | 10:22 PM
  #6  
merim123's Avatar
Thread Starter
TECH Fanatic
20 Year Member
Photogenic
Liked
Loved
iTrader: (11)
 
Joined: Oct 2005
Posts: 1,921
Likes: 25
From: Chitown, IL
Default

i'm just trying to learn in the process, thought I'd ask and see what other people thought since I never saw that # being calculated before or being discussed.
Reply




All times are GMT -5. The time now is 09:51 PM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE