register gallery
 

Go Back   Mazdaspeed Forums >
MAZDASPEED SECTION
>
Mazdaspeed 3/6 MZR Gen1 Forums (2006-2009)
> Mazdaspeed3/6 General Discussion


Welcome to Mazdaspeed Forums .

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

*When you join MSF as a registered user, there will be No Ads.

*Registered Members get access to the Off Topic Area of the Forum

*Registered Members have an opportunity to upgrade their accounts to VIP, which brings a host of goddies for supporting MSF such as Raffles, Additional Forum Access, More PM Storage, The ability to upload more Images and many other enhancements.

*Registered members also get access to the live chat box!
Reply
 
Bookmark and Share LinkBack Thread Tools Search this Thread Display Modes
 Old 09-18-2008, 02:39 PM   #1
 
bombdotcom's Avatar
 
Join Date: Mar 2008
Location: ft bliss, TX
Posts: 816   (View Stats)
iTrader: (2)
Rep Power: 0
bombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the world
Thanks: 221
Thanked 111 Times in 73 Posts
Groans: 18
Groaned at 40 Times in 20 Posts
(Thread Starter)
Not Ranked  0 score     
Default engine compression?

whats the deal with it? i wanna build my engine soon and i have no idea what all the numbers mean and so on?....
__________________
(RIP) 08' MS3---MODS:COBB AP- COBB SRI AND TIP- COBB RSB- COBB KNOB- CP-E TMIC- LIMITED EDITION HKS BOV- CORKSPORT DP AND TP- TRZ REARMOUNT- MD OCC- PTP IM COOLER KIT- COSWORTH BSD- EIBACH PROKIT- TWM SHIFTER BUSHINGS- JBR SHORT SHIFT KIT-

13' CWP MS3
bombdotcom is offline   Reply With Quote
 Old 09-18-2008, 02:52 PM   #2
Jackal
 
Breakdown81's Avatar
 
Join Date: Jun 2008
Location: Los Angeles Westside
Posts: 869   (View Stats)
iTrader: (0)
Rep Power: 3044
Breakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the worldBreakdown81 is the leader of the world
Thanks: 1,754
Thanked 5,871 Times in 285 Posts
Groans: 56
Groaned at 14 Times in 13 Posts
Not Ranked  0 score     
Default

general rule of thumb for compression ratios:

for turbo cars lower compression is better, it allows you to feed more boost.
high compression is bad.


suggest you get a copy of corky bells books, specifically maximum boost. also start searching around this forum on the turbo induction section and the engine sections, get knowledgeable then build with confidence.
Breakdown81 is offline   Reply With Quote
 Old 09-18-2008, 04:18 PM   #3
 
bombdotcom's Avatar
 
Join Date: Mar 2008
Location: ft bliss, TX
Posts: 816   (View Stats)
iTrader: (2)
Rep Power: 0
bombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the world
Thanks: 221
Thanked 111 Times in 73 Posts
Groans: 18
Groaned at 40 Times in 20 Posts
(Thread Starter)
Not Ranked  0 score     
Default

ya i needa pick up a book. can i get it at barnes and nobles?
__________________
(RIP) 08' MS3---MODS:COBB AP- COBB SRI AND TIP- COBB RSB- COBB KNOB- CP-E TMIC- LIMITED EDITION HKS BOV- CORKSPORT DP AND TP- TRZ REARMOUNT- MD OCC- PTP IM COOLER KIT- COSWORTH BSD- EIBACH PROKIT- TWM SHIFTER BUSHINGS- JBR SHORT SHIFT KIT-

13' CWP MS3
bombdotcom is offline   Reply With Quote
 Old 09-18-2008, 05:10 PM   #4
 
MTuning's Avatar
 
Join Date: Jul 2008
Location: PA
Posts: 362   (View Stats)
iTrader: (1)
Rep Power: 0
MTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond reputeMTuning has a reputation beyond repute
Thanks: 30
Thanked 42 Times in 34 Posts
Groans: 16
Groaned at 16 Times in 8 Posts
Not Ranked  0 score     
Default

lower compression allow more of a safety factor to prevent detonation, in relation to timing.
MTuning is offline   Reply With Quote
 Old 09-18-2008, 08:59 PM   #5
MSF Punished Member
 
FWD=WWD's Avatar
 
Join Date: Sep 2008
Location: WPB
Posts: 200   (View Stats)
iTrader: (0)
Rep Power: 0
FWD=WWD is a name known to allFWD=WWD is a name known to allFWD=WWD is a name known to allFWD=WWD is a name known to allFWD=WWD is a name known to allFWD=WWD is a name known to all
Thanks: 3
Thanked 11 Times in 10 Posts
Groans: 4
Groaned at 2 Times in 2 Posts
Not Ranked  0 score     
Default

high compression isnt always bad. its good in N/A cars because it alows more power due to the higher compression in the cylinders pushing back on the pistions and rids harder...

But in turbo setups, thats the turbo's job... to ram the air into the cylinder to do the same thing... if they both did it, it would be too much and every thing just goes kaboom. lol.


Turbo = Low compression ... usually around 8.5:1 is a general lowest.. besides the extremists.

N/A = tough call... ive seen as high as 14:1 in big block v8's... maybe 12:1 in hondas.. and my bimmer was 11.5:1...
FWD=WWD is offline   Reply With Quote
The Following User Says Thank You to FWD=WWD For This Useful Post:
Breakdown81 (09-23-2008)
 Old 09-19-2008, 06:56 AM   #6

 
Ziggo's Avatar
 
Join Date: Mar 2008
Location: Melissa, TX
Posts: 3,843   (View Stats)
iTrader: (6)
Rep Power: 5301
Ziggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the worldZiggo is the leader of the world
Thanks: 27,149
Thanked 10,240 Times in 2,732 Posts
Groans: 6
Groaned at 16 Times in 15 Posts
Not Ranked  0 score     
Default

14:1 is generally the limit. 600cc Sportbike engines will tend to 15:1, but they are very oversquare and run such high rpms that knock really dosn't have time to develop.
Ziggo is offline   Reply With Quote
 Old 09-19-2008, 07:02 AM   #7
 
Awddsm97's Avatar
 
Join Date: Aug 2008
Posts: 37   (View Stats)
iTrader: (0)
Rep Power: 0
Awddsm97 is a glorious beacon of lightAwddsm97 is a glorious beacon of lightAwddsm97 is a glorious beacon of lightAwddsm97 is a glorious beacon of lightAwddsm97 is a glorious beacon of light
Thanks: 0
Thanked 9 Times in 9 Posts
Groans: 0
Groaned at 0 Times in 0 Posts
Not Ranked  0 score     
Default

In turbo applications I've run everything from 8:1 to 10:1 compression. Lower compression will allow for more boost on pump gas. Higher compression will put you closer to the limit at a lower boost level. However in a race motor application high compression and big boost make big power. For street cars I usually stay under 9:1.
Awddsm97 is offline   Reply With Quote
 Old 09-19-2008, 08:41 AM   #8
 
mexicant's Avatar
 
Join Date: Mar 2008
Location: abc
Posts: 867   (View Stats)
iTrader: (0)
Rep Power: 0
mexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the worldmexicant is the leader of the world
Thanks: 1,081
Thanked 533 Times in 154 Posts
Groans: 147
Groaned at 34 Times in 29 Posts
Not Ranked  0 score     
Default

If you go with a lower compression, your bottom end power and spoolup time will suffer. My DSM has a 7.8:1 compression ratio, the big upgrade is to use the 8.5:1 compression ratio pistons, it makes a world of a difference in spooltime and initial "hit" of boost.
__________________
"08, I hate to break it to you, but if it gives kevin a boner, its porn"

NATOR PERFORMANCE
Nylon washer sponsered
mexicant is offline   Reply With Quote
 Old 09-19-2008, 09:53 AM   #9
Banned
 
phailerider's Avatar
 
Join Date: Mar 2008
Posts: 4,639   (View Stats)
iTrader: (11)
Rep Power: 0
phailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the worldphailerider is the leader of the world
Thanks: 761
Thanked 2,323 Times in 966 Posts
Groans: 49
Groaned at 179 Times in 125 Posts
Not Ranked  0 score     
Default

all the big vag turbo builds kept stock compression with their setups... that was enough for me to keep the stock 9.5:1 compression in place on my build. If our motors werent DI, i may have dropped it, but for a di motor, we felt that we would have lost too much of the advantage of the motor to go lower.

maybe were wrong... but im excited to see 24 psi, with a gt30 on 9.5:1. Quick spool big power, and meth to cool it.
phailerider is offline   Reply With Quote
The Following User Says Thank You to phailerider For This Useful Post:
Breakdown81 (09-23-2008)
 Old 09-20-2008, 02:58 AM   #10
 
Demi's Avatar
 
Join Date: May 2008
Posts: 1,107   (View Stats)
iTrader: (2)
Rep Power: 0
Demi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the world
Thanks: 935
Thanked 4,122 Times in 219 Posts
Groans: 61
Groaned at 16 Times in 11 Posts
Not Ranked  0 score     
Default

Ken and I were talking about this. My thinking is that were are gonna see higher numbers with lower compression on this car, Randy had his reasons for his compression choices and is having great success with it. Once we get the fuel figured out a little better I think we are gonna hit another wall that only lower compression or higher octane fuel will take care of.
__________________
************************
Beginners guide to turbos<- New to this? Give it a look!

-And for the rest of you, if it comes from Autozone and doesnt replace something that broke off your car or make your cabin smell like Coco Butter, its fucking rice.

Demi is offline   Reply With Quote
 Old 09-22-2008, 02:54 PM   #11
 
bombdotcom's Avatar
 
Join Date: Mar 2008
Location: ft bliss, TX
Posts: 816   (View Stats)
iTrader: (2)
Rep Power: 0
bombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the world
Thanks: 221
Thanked 111 Times in 73 Posts
Groans: 18
Groaned at 40 Times in 20 Posts
(Thread Starter)
Not Ranked  0 score     
Default

so what exactly do the numbers mean? air to fuel?
__________________
(RIP) 08' MS3---MODS:COBB AP- COBB SRI AND TIP- COBB RSB- COBB KNOB- CP-E TMIC- LIMITED EDITION HKS BOV- CORKSPORT DP AND TP- TRZ REARMOUNT- MD OCC- PTP IM COOLER KIT- COSWORTH BSD- EIBACH PROKIT- TWM SHIFTER BUSHINGS- JBR SHORT SHIFT KIT-

13' CWP MS3
bombdotcom is offline   Reply With Quote
 Old 09-22-2008, 07:32 PM   #12
 
Demi's Avatar
 
Join Date: May 2008
Posts: 1,107   (View Stats)
iTrader: (2)
Rep Power: 0
Demi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the worldDemi is the leader of the world
Thanks: 935
Thanked 4,122 Times in 219 Posts
Groans: 61
Groaned at 16 Times in 11 Posts
Not Ranked  0 score     
Default

Air to fuel ratios represent the mixture of air and fuel in the combustion chamber. I believe 14.7 is quote unquote "perfect" or stoichiometric mix. This is in reference to the amount of air to fuel. So 14.7 is 14.7 parts air to 1 part fuel. The lower the number the richer (more fuel) the mix is. The higher the number the leaner it is (more air). Most of the danger lies in too lean a mixture, but it should be noted that extremely rich can be dangerous to an engine as well.

But thats not what these guys are talking about. The compression ratio represents the amount the piston stroke and bore will compress the air fuel mixture. The higher number (in this case 9.5) is when the pistion is bottom dead center. When the piston drives to top dead center it compresses the 9.5 to 1. As in 9.5:1. So some thing like 10:1 would be more compression and 8.5:1 would be lower. Higher compression can lead to higher horse power numbers in properly outfitted engines (naturally aspirated cars do well with it). But lower compression setups lend themselves to larger amounts of forced induction. Typically lower compression produces less heat and there for less chance for detonation.

This is the simple explanation. Here are some good links that explain it better than i can.
HowStuffWorks "Producing More Engine Power"
HowStuffWorks "Diesel Engines vs. Gasoline Engines"
HowStuffWorks "How Gasoline Works"
HowStuffWorks "Other Horsepower Increasing Methods"
__________________
************************
Beginners guide to turbos<- New to this? Give it a look!

-And for the rest of you, if it comes from Autozone and doesnt replace something that broke off your car or make your cabin smell like Coco Butter, its fucking rice.


Last edited by Demi; 09-23-2008 at 10:27 AM.
Demi is offline   Reply With Quote
The Following User Says Thank You to Demi For This Useful Post:
Breakdown81 (09-23-2008)
 Old 09-23-2008, 03:06 AM   #13
 
bombdotcom's Avatar
 
Join Date: Mar 2008
Location: ft bliss, TX
Posts: 816   (View Stats)
iTrader: (2)
Rep Power: 0
bombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the worldbombdotcom is the leader of the world
Thanks: 221
Thanked 111 Times in 73 Posts
Groans: 18
Groaned at 40 Times in 20 Posts
(Thread Starter)
Not Ranked  0 score     
Default

thanks alot
__________________
(RIP) 08' MS3---MODS:COBB AP- COBB SRI AND TIP- COBB RSB- COBB KNOB- CP-E TMIC- LIMITED EDITION HKS BOV- CORKSPORT DP AND TP- TRZ REARMOUNT- MD OCC- PTP IM COOLER KIT- COSWORTH BSD- EIBACH PROKIT- TWM SHIFTER BUSHINGS- JBR SHORT SHIFT KIT-

13' CWP MS3
bombdotcom is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pulsar Spark Plug Replacement, Pinging Engine, Jeep Liberty Engine Stalls, Windows Are Stuck, Blower Motor Runs On Low O Haltech Automotive News 1 04-13-2012 08:13 PM
Pulsar Spark Plug Replacement, Pinging Engine, Jeep Liberty Engine Stalls, Windows Are Stuck, Blower Motor Runs On Low O Haltech Automotive News 0 07-10-2008 10:10 AM
So, anything out there you'd like to strap a jet engine to? Haltech Automotive News 0 05-19-2008 07:40 AM
So, anything out there you'd like to strap a jet engine to? Haltech Automotive News 0 05-17-2008 09:17 AM


All times are GMT -7. The time now is 02:55 AM.
Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
SEO by vBSEO ©2011, Crawlability, Inc.
vB.Sponsors
Template-Modifications by TMS
©Copyright 2008 ; 2014 Cymru Internet Services LLC | FYHN™ Autosports HQ
Ad Management plugin by RedTyger
Page generated in 0.69433 seconds with 28 queries