Advanced Engineering Tech For the more hardcore LS1TECH residents

How to make torque at higher RPM...

Thread Tools
 
Search this Thread
 
Old 06-23-2006, 02:06 PM
  #161  
TECH Fanatic
 
Old SStroker's Avatar
 
Join Date: Jun 2002
Location: Upstate NY
Posts: 1,979
Likes: 0
Received 3 Likes on 3 Posts

Default

Isn't it much more fun when you figure it out for yourself?

It is to me, anyway.

FWIW, MEPs (I, B or F) are not something you measure, but something you calculate. As mentioned by a few, they relate how much torque (Indicated, Brake or Friction) is associated with each cubic inch (or cc) of displacement.

With good intake & exhaust tuning an engine (like an open Cup engine and perhaps Pro Stock) may have it's highest VE at/near power peak rpm rather than torque peak rpm. It still would most likely have a higher BMEP nearer torque peak because of increasing friction torque (and FMEP) at the very high rpm hp peak.

Keep the fires in you heads burning.
Old 06-23-2006, 02:13 PM
  #162  
TECH Senior Member
 
joecar's Avatar
 
Join Date: Apr 2002
Location: So.Cal.
Posts: 6,077
Likes: 0
Received 12 Likes on 10 Posts

Default

Very interesting, I want more...
Old 06-23-2006, 02:53 PM
  #163  
TECH Resident
 
DavidNJ's Avatar
 
Join Date: Dec 2004
Posts: 881
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by Old SStroker
It still would most likely have a higher BMEP nearer torque peak because of increasing friction torque (and FMEP) at the very high rpm hp peak.
Unless you have variable displacement or are converting from 4-cycle to 2-cycle on the fly, bmep has a constant relationship to torque. Peak bmep always occurs at peak torque.

I was hoping for specific engines where the peak bmep was well below peak VE. I would have thought this is more likely in engines with VEs of 105-115.
Old 06-24-2006, 03:30 AM
  #164  
FormerVendor
 
racer7088's Avatar
 
Join Date: Nov 2001
Location: Houston, Tx.
Posts: 3,065
Likes: 0
Received 5 Likes on 5 Posts

Default

Originally Posted by DavidNJ
Unless you have variable displacement or are converting from 4-cycle to 2-cycle on the fly, bmep has a constant relationship to torque. Peak bmep always occurs at peak torque.

I was hoping for specific engines where the peak bmep was well below peak VE. I would have thought this is more likely in engines with VEs of 105-115.
F1 engines make peak BMEP before peak IMEP all the time. Most super high rpm engines do even in Comp when people are really measuring or calculating. An F1 engine right now can make decent VE at quite a bit higher rpm than they are turning at max power but the FMEP is a very large component up there.
Old 06-24-2006, 03:34 AM
  #165  
FormerVendor
 
racer7088's Avatar
 
Join Date: Nov 2001
Location: Houston, Tx.
Posts: 3,065
Likes: 0
Received 5 Likes on 5 Posts

Thumbs up

Originally Posted by DavidNJ
Peak bmep always occurs at peak torque.
Well Torque is what you actually have left at the end of the crank so it IS in fact BMEP. Just because Tq peaks at the crank doesn't mean that VE peaked at that same point. It all depends on the friction and other curves.
Old 06-24-2006, 08:54 AM
  #166  
TECH Resident
 
DavidNJ's Avatar
 
Join Date: Dec 2004
Posts: 881
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by racer7088
Well Torque is what you actually have left at the end of the crank so it IS in fact BMEP. Just because Tq peaks at the crank doesn't mean that VE peaked at that same point. It all depends on the friction and other curves.
Yes, I know. However, looking at street engine maps it always appears that torque nearly exactly flows VE. I think this is just a factor of the air flow tuning and low torque and power peaks of most street engines. Points at which big, friction not linearly related to speed has reared its head. If the friction was linearly related to speed, than bmep would relate to VE.
Old 06-24-2006, 11:36 AM
  #167  
FormerVendor
 
racer7088's Avatar
 
Join Date: Nov 2001
Location: Houston, Tx.
Posts: 3,065
Likes: 0
Received 5 Likes on 5 Posts

Thumbs up

Originally Posted by DavidNJ
Yes, I know. However, looking at street engine maps it always appears that torque nearly exactly flows VE. I think this is just a factor of the air flow tuning and low torque and power peaks of most street engines. Points at which big, friction not linearly related to speed has reared its head. If the friction was linearly related to speed, than bmep would relate to VE.
Pretty much.



Quick Reply: How to make torque at higher RPM...



All times are GMT -5. The time now is 12:57 PM.