JDM BP-Z3 you want this motor - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 03-16-2010, 07:44 PM   #21
Elite Member
 
Join Date: Dec 2008
Location: Colorado
Posts: 1,669
Total Cats: 36
Default

Quote:
Originally Posted by JKav View Post
Sparetire, what you and the Hotrod article are referring to is VE.

I have yet to see an engine detonate due to an excessive VE. I have seen it happen with a high DCR.
Sparetire is offline   Reply With Quote
Old 03-16-2010, 07:48 PM   #22
Elite Member
iTrader: (1)
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 4,682
Total Cats: 216
Default

Quote:
Originally Posted by JKav
ZOMG! My cylinders are so full of air and fuel, its gonna [email protected]
*Translated for emphasis of absurdity*
Full_Tilt_Boogie is offline   Reply With Quote
Old 03-17-2010, 03:36 PM   #23
Elite Member
iTrader: (8)
 
Join Date: Sep 2006
Location: Severn, MD
Posts: 1,927
Total Cats: 5
Default

Quote:
Originally Posted by Full_Tilt_Boogie View Post
*Translated for emphasis of absurdity*
I'm pretty sure you don't realize that JKav knows his ****. He worked or works for Garrett and was behind the creation of the Disco Potato you all know and love.

Feel stupid yet?

Frank
fmowry is offline   Reply With Quote
Old 03-17-2010, 03:41 PM   #24
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

Quote:
Originally Posted by Full_Tilt_Boogie View Post
Also, youre retarded and you smoke ****.
Um...whoa there.

I got a pretty damn good grade in Thermodynamics...JKav is right ******* on.
gospeed81 is offline   Reply With Quote
Old 03-17-2010, 03:52 PM   #25
Elite Member
 
Join Date: Dec 2008
Location: Colorado
Posts: 1,669
Total Cats: 36
Default

Then I am confused. I hear engine builders and tuners talk about DCR all the time. How you can get away with a higher static comp if you have a mild DCR. So while you cannot measure DCR like you can SCR, it certanly matters. Just as you cannot measure HP, only TQ and RPM. Technically it does'nt exist, but it matters and is a characteristic of an engine affected by valve timing, SCR, etc. There is a pretty good Wiki on it thats probably better than the link I posted earlier.


Is it essentialy the case that by lowering VE through cam timing at peak TQ (maybe some overlap or something?)you can lower the propensity to knock? And is DCR basically a way to express that as a single easily managed number? Thats what I thought anyway....

Edit: And I got an A in Thermo. Because I am the man.....and because I only had two other engineering courses that semester........

Last edited by Sparetire; 03-17-2010 at 03:53 PM. Reason: And I......
Sparetire is offline   Reply With Quote
Old 03-17-2010, 04:00 PM   #26
meatbag
iTrader: (50)
 
gospeed81's Avatar
 
Join Date: Nov 2008
Location: Houston, TX
Posts: 7,357
Total Cats: 26
Default

DCR is a way for those familiar with motor geometry to approximate one of the many aspects of volumetric efficiency.

It is trying to say that real compression only occurs after the exhaust valves close, when in reality this is just a measure of exhaust cam timing, which affects VE.

Other considerations are scavenging, intake cam timing, intake manifold design (helmholtz), head flow, exhaust, etc.

VE and CR can be used in thermodynamic formulas to describe the power a motor makes.

I'm not sure how you'd do the same with SCR and DCR...
gospeed81 is offline   Reply With Quote
Old 03-17-2010, 04:14 PM   #27
Elite Member
iTrader: (1)
 
Join Date: May 2009
Location: Jacksonville, FL
Posts: 4,682
Total Cats: 216
Default

Sense of humor in this thread = none.
Full_Tilt_Boogie is offline   Reply With Quote
Old 03-17-2010, 04:15 PM   #28
Crumple Zone Tester
iTrader: (7)
 
mgeoffriau's Avatar
 
Join Date: Jul 2009
Location: Jackson, MS
Posts: 7,656
Total Cats: 447
Default

I blame Stephanie Turner.
mgeoffriau is offline   Reply With Quote
Old 03-17-2010, 04:17 PM   #29
Elite Member
iTrader: (3)
 
Join Date: Dec 2004
Location: Houston
Posts: 2,904
Total Cats: 4
Default

I thought the only difference was the intake, cam, and the fact some of them used a different exhaust manifold (4-2-1) than what we used.
Pitlab77 is offline   Reply With Quote
Old 03-18-2010, 12:34 AM   #30
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by Full_Tilt_Boogie View Post
Nothing ******* exists.
The only reason I can hit the keys on my keyboard is because the electrons in my fingers are repelling the electrons in my keys.
Also, youre retarded and you smoke ****.

No, you smoke **** and you r dum. That is "you r" not "your" or "you're". Two out of those three are correct.

Jkav is one of the few authoritative hard-tech engineering members here and we don't need your dumb internet jockey *** chasing him off. Input from members like him are what makes this forum good.
Faeflora is offline   Reply With Quote
Old 03-18-2010, 06:58 AM   #31
Elite Member
 
Join Date: Dec 2008
Location: Colorado
Posts: 1,669
Total Cats: 36
Default

Quote:
Originally Posted by faeflora View Post
No, you smoke **** and you r dum. That is "you r" not "your" or "you're". Two out of those three are correct.

Jkav is one of the few authoritative hard-tech engineering members here and we don't need your dumb internet jockey *** chasing him off. Input from members like him are what makes this forum good.
Stop being a racist *******.
Sparetire is offline   Reply With Quote
Old 03-18-2010, 07:02 AM   #32
Elite Member
 
Join Date: Dec 2008
Location: Colorado
Posts: 1,669
Total Cats: 36
Default

Quote:
Originally Posted by gospeed81 View Post
DCR is a way for those familiar with motor geometry to approximate one of the many aspects of volumetric efficiency.

It is trying to say that real compression only occurs after the exhaust valves close, when in reality this is just a measure of exhaust cam timing, which affects VE.

Other considerations are scavenging, intake cam timing, intake manifold design (helmholtz), head flow, exhaust, etc.

VE and CR can be used in thermodynamic formulas to describe the power a motor makes.

I'm not sure how you'd do the same with SCR and DCR...
Makes sense. But DCR seems pretty useful to me because it does give you a hard number that takes pretty much everything into account and gives you an idea of an engines propensity to spark knock. Its not as theoretically correct as looking at VE and CR etc, but it seems like a pretty expedient little number to me. My guess is that DCR and the results of a compression test would correspond fairly closely compared to SCR and a comp test.
Sparetire is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 58 12-13-2017 10:04 PM
1994 Spec Miata Race Car SM/SM2/SSM For Sale Quinn Cars for sale/trade 6 10-23-2016 08:58 AM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Nuke Mars! Joe Perez Current Events, News, Politics 8 09-30-2015 05:41 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:16 PM.