Automotive Forums .com - the leading automotive community online! Automotive Forums .com - the leading automotive community online!
Automotive Forums .com - the leading automotive community online! 
-
Latest | 0 Rplys
Go Back   Automotive Forums .com Car Chat > Engineering/Technical
Register FAQ Community Arcade Calendar
Engineering/Technical Ask technical questions about cars. Do you know how a car engine works?
Reply Show Printable Version Show Printable Version | Email this Page Email this Page | Subscription Subscribe to this Thread
 
Thread Tools
Old 12-27-2007, 01:53 PM   #1
jayjack
AF Newbie
 
Join Date: Aug 2007
Location: mayfield, Ohio
Posts: 95
Thanks: 0
Thanked 0 Times in 0 Posts
Rotary enginess

so rotary engines... i was thinkin the rx-8 gets pretty bad mpg(i think like 15/20) and it only has like 230 hp. why? doesn't it have like 12 power strokes per 2 turns of the flywheel, that accounts for the mpg but why so low on power. is thats how its engineered? i mean doesn't an rx-8 have the same number of powerstrokes as as a v12 per 2 turns of the flywheel, shouldn't it have more than 230 hp with all that potential?
and i was thinkin to improve mpg could you just turn off like 2/3rds of the injections while like on the freeway or idling, i mean like not spray any gas on two of the three power strokes. i guess it would take some engineering but didn't cadillac do it on one of their v8s? is it feasible to do that?
jayjack is offline   Reply With Quote
Old 12-27-2007, 07:57 PM   #2
drdisque
AF Enthusiast
 
drdisque's Avatar
 
Join Date: Jun 2002
Location: Chicago, Illinois
Posts: 3,476
Thanks: 0
Thanked 7 Times in 7 Posts
Send a message via AIM to drdisque
Re: Rotary enginess

Each power stroke doesn't produce much power because rotary engines don't have very high compression and don't have a long power stroke.
__________________
Dr. Disque -
Current cars:
2008 BMW 135i M-Sport
2011 Mazda2 Touring

Past cars:
2007 Mazda 6S 5-door MT
1999 Ford Taurus SE Duratec
drdisque is offline   Reply With Quote
Old 12-28-2007, 03:38 AM   #3
KiwiBacon
AF Enthusiast
 
Join Date: Jul 2006
Location: Otago
Posts: 849
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Rotary enginess

The rotaries are IMO the lowest form of engine. Sure they can rev out okay to give reasonable power numbers, but their efficiency is terrible.

As DrDisque said they have low compression which hurts efficiency, but they also have a poorly shaped combustion chamber which has a lot of exposed wall area to lose heat into which should be expanding air for the power stroke.

I know Mazda worked very hard to make the RX8 hit emissions targets, it's possible they already cut fuel and spark on some of the strokes. The extra air is needed to burn the unburnt fuel that makes it through to the cats.
KiwiBacon is offline   Reply With Quote
Old 12-29-2007, 07:39 PM   #4
Steel
AF Fanatic
 
Steel's Avatar
 
Join Date: Aug 2001
Location: Tucson, Arizona
Posts: 4,027
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Rotary enginess

However you guys forget that they are easily the coolest engines out there, and by that sheer fact make them better than anything. And RX-7's better than anything. In fact, i'll share some of its sheer awesomeness with you.

http://www.youtube.com/watch?v=K1BWv7iPFUg
http://www.youtube.com/watch?v=13FsSGvhI-k

Bow and pray that the rotary gods dont smite you for your INSOLENCE!
__________________
Steel is offline   Reply With Quote
Old 12-29-2007, 08:39 PM   #5
KiwiBacon
AF Enthusiast
 
Join Date: Jul 2006
Location: Otago
Posts: 849
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Rotary enginess

Quote:
Originally Posted by Steel
However you guys forget that they are easily the coolest engines out there, and by that sheer fact make them better than anything. And RX-7's better than anything. In fact, i'll share some of its sheer awesomeness with you.

http://www.youtube.com/watch?v=K1BWv7iPFUg
http://www.youtube.com/watch?v=13FsSGvhI-k

Bow and pray that the rotary gods dont smite you for your INSOLENCE!
Meh, the Audi R10 would spank that easily.

Don't forget the high quality women too. The slappers with rotor tattoos on their backs.
KiwiBacon is offline   Reply With Quote
Old 12-30-2007, 01:19 AM   #6
beef_bourito
AF Enthusiast
 
beef_bourito's Avatar
 
Join Date: Nov 2003
Location: Ottawa
Posts: 3,191
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Rotary enginess

the r10 is in a different class so it would obviously beat that thing.
__________________
Mr. T doesn't pity anyone who likes the Black Eyed Peas. He just kills them.

Mr. T speaks only when necessary. His main form of communication is folding his arms and slowly shaking his head. And regardless of the situation, he is always understood.

On the A-team, Face , Haniabal, and Murdoch were all masters of disguise. Mr T didn't have to wear a disguise. The bad guys didn't recognize him out of fear.
beef_bourito is offline   Reply With Quote
 
Reply

POST REPLY TO THIS THREAD

Go Back   Automotive Forums .com Car Chat > Engineering/Technical


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



All times are GMT -5. The time now is 10:23 AM.

Community Participation Guidelines | How to use your User Control Panel

Powered by: vBulletin | Copyright Jelsoft Enterprises Ltd.
 
 
no new posts