new car surprise gas saver - Page 3 - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 11-06-2009, 11:16 AM   #21
Registered Member
 
Join Date: Dec 2007
Posts: 618
Country: United States
Quote:
Originally Posted by BEEF View Post
so what are the major contributing factors to turbo lag?

he has the smaller turbo which is supposed to spool up faster (and he wants to keep it that way) so I guess the size of the turbo matters but what else?

I have thought about a boosted car at some point and am kind of curious about this as well.

he also pointed out that it would be quite a job to relocate his intercooler since it is mounted right to the turbo and cutting would be required. I think that's right but I haven't looked at that aspect. it is right after the turbo and right before the intake so the entire distance is all of a foot at most.
http://en.wikipedia.org/wiki/Turbocharger
__________________

__________________
John
'09 Saturn Aura 2.4L
'94 Chevy Camaro Z28 (5.7L 6sp)
'96 Chevy C1500 (5.0L 5sp)
'08 Kawasaki Vulcan 900 Custom
'01 KTM Duke 2
Project84 is offline   Reply With Quote
Old 11-06-2009, 11:27 AM   #22
Registered Member
 
Join Date: Dec 2007
Posts: 618
Country: United States
Quote:
Originally Posted by theholycow View Post
Sounds wasteful...energy goes into spinning it up, creating backpressure, and is then discarded out the wastegate.
In a naturally aspirated engine what do you call exhaust?

Waste.

So if you are able to use that waste to create an increase in horsepower, it's sorta like a win-win. To relate it to FE, think biodiesel or methane. Using something that is typically a byproduce to recreate a productive process.
__________________

__________________
John
'09 Saturn Aura 2.4L
'94 Chevy Camaro Z28 (5.7L 6sp)
'96 Chevy C1500 (5.0L 5sp)
'08 Kawasaki Vulcan 900 Custom
'01 KTM Duke 2
Project84 is offline   Reply With Quote
Old 11-06-2009, 02:55 PM   #23
Registered Member
 
theholycow's Avatar
 
Join Date: Apr 2008
Posts: 6,624
Country: United States
Send a message via ICQ to theholycow Send a message via AIM to theholycow Send a message via MSN to theholycow Send a message via Yahoo to theholycow
Quote:
Originally Posted by Project84 View Post
In a naturally aspirated engine what do you call exhaust?

Waste.

So if you are able to use that waste to create an increase in horsepower, it's sorta like a win-win. To relate it to FE, think biodiesel or methane. Using something that is typically a byproduce to recreate a productive process.
Exhaust isn't as wasted as you think; and a turbocharger doesn't reclaim it as usable energy. Turbo takes the movement of the exhaust and uses it to shove more air and fuel into the engine (and as a side-effect it makes backpressure which consumes energy). Without a turbo, exhaust gas velocity's scavenging effect is an important part of making torque (which I can visualize but don't understand well enough to explain to someone else).

Anyway, my issue was not with the general idea of using a turbo; it was with spending energy on spinning up a turbo more than you're going to use it and then dumping that energy by spewing pressure out the wastegate.
__________________
This sig may return, some day.
theholycow is offline   Reply With Quote
Old 11-06-2009, 04:01 PM   #24
Registered Member
 
bowtieguy's Avatar
 
Join Date: Oct 2008
Posts: 1,873
Country: United States
Location: orlando, florida
Quote:
Originally Posted by Project84 View Post
In a naturally aspirated engine what do you call exhaust?
in a domestic V8 w/ a high flow/performance system it's called...music
bowtieguy is offline   Reply With Quote
Old 11-06-2009, 04:23 PM   #25
Senior Member
 
Join Date: Mar 2011
Posts: 446
Country: United States
Location: Charlotte nc
Na engines benefit from well tuned exhaust. A well tuned exhaust will use the mass of the sound wave to create a small vacuum at the port sucking in more air/fuel at cam crossover. a turbo engine works using a pressure differential across the turbo this is why high performance turbo cars have huge exhausts. the major issue with a turbo is they do create backpressure. This will cause a certain ammount reversion of exhaust into the cylinders. Most of the time a turbo pushes enough air to overcome the backpressure. at light load a turbo can be beneficial acting as a pumping loss reducer by pushing air in rather than relying on purely vacuum.


To answer the question about what makes this car a "race" car it was bought with a long history of autocrossing and HPDE's. I am currently using it as an autocross car and plan to take it to a few HPDE events. this car will end up with a roll cage and 5 point harnesses. This is every inch a real race car.
Philip1 is offline   Reply With Quote
Old 11-08-2009, 07:33 PM   #26
Registered Member
 
Join Date: Jun 2008
Posts: 48
Country: United States
Quote:
Originally Posted by theholycow View Post
and a turbocharger doesn't reclaim it as usable energy
The claim is that the turbocharger takes advantage of already expanding gas in the exhaust thus it doesn't waste power. Like you I think that's a bunch of malarkey and a turbo is an energy wasting tube fan for the power hungry. That said the Dodge turbo models got almost the same mileage as the non turbos.

Besides, if your engine has expanding gases beyond the exhaust valve then I say it needs a tune up.
severach is offline   Reply With Quote
Old 11-09-2009, 01:37 PM   #27
Registered Member
 
ma4t's Avatar
 
Join Date: Jun 2007
Posts: 175
Country: United States
Because it's cool to know how stuff works.
http://auto.howstuffworks.com/turbo.htm
__________________
ma4t is offline   Reply With Quote
Old 11-09-2009, 02:59 PM   #28
Registered Member
 
Join Date: Nov 2007
Posts: 1,111
Country: United States
Send a message via AIM to dkjones96
It isn't all free if that's what some of you are thinking. Yes, it is taking advantage of exhaust energy but it also places an additional load on the engine. Turbines create back pressure which is never a good thing for fuel economy or power but a turbocharged engine can shove enough through the intake to overcome it.

Your gains come from the increase in thermal efficiency. The more air and fuel you can cram into the same size cylinder the more heat is generated. Absorption through the cylinder walls and combustion chamber is relatively constant so you lose less of a percentage of that heat as a result.
__________________
- Kyle
dkjones96 is offline   Reply With Quote
Old 11-10-2009, 12:03 AM   #29
Registered Member
 
fowljesse's Avatar
 
Join Date: Mar 2008
Posts: 188
Country: United States
That's cool that your race car gets good mileage, too!
I have a Mazda MX-3 that has about 200 wheel horsepower (short- stroke V6) that gets 34mpg, but I have done extensive modding, including an Engine management system. The car is also a daily driver, so it has a 10 speaker stereo, leather seats, etc... so it weighs about 2,500 lbs.
__________________

fowljesse is offline   Reply With Quote
Reply

Thread Tools
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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Ford claims 81.5 mpg in Fusion hybrid ericgrau Hybrid Vehicles 4 04-30-2009 08:46 AM
What is this stat? cavale Fuelly Web Support and Community News 1 09-03-2008 08:23 AM
Mph Caps billynjoanna General Fuel Topics 2 06-10-2007 12:38 PM
DIY: Wire Tuck!!! SVOboy Experiments, Modifications and DIY 11 09-21-2006 05:17 AM
MID/VSS issue SVOboy General Fuel Topics 16 05-17-2006 05:16 AM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 08:07 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.