There was a thread a couple days ago that mentioned a turbos ability to actually increase gas mileage. This does not make sense to me because it is my understanding that all a turbo does is compress more air into the cylinder, and more air = more gas, which results in less mileage. Is there something I missed about turbos, is it something in the tune? Thanks for the help.

 

i SUPPOSE u COULD get better gas milage, but ud have to keep it under 3000 RPMs. The whole concept of a turbo is using wasted exhaust to spin the turbine......so i mean it should be easier for the motor to suck in air. but then again the FMU is feeding the engine more gas.

 

its all based on volumetric efficiency. power is made by pumping air. the more air you pump, the more power you make. if you can make a 1.8l engine ingest 1.8l of air in one full cycle, then you are hitting 100% VE. but thats harder than it sounds because there is a (usually) small amount of burnt air (that cannot make any more power) left in the cylinders after the exhaust stroke has finished, so you cant fit 1.8l of fresh air and fuel in to burn on the next cycle. but with a turbo(or any power adder to a point) you can raise the efficiency of the engine enough that it makes the same amount of power while working less. with FI you can actually get the VE over 100%, and thats where the mileage comes from. but the problem is that your more efficient engine also makes more power, and we like to use that extra power to accelerate faster. if 2 properly tuned cars were put side by side, and one had 100hp, and the other had 200hp, and they were accelerated to 100mph(i.e) at EXACTLY the same rate, the one with 200 horses didnt have to work as hard to get there in that amount of time, so it will use less fuel.




it made sense to me, but i was typing it, i hope it makes sense to you and doesnt just sound like im rambling.[8D]

 

Yeah, like pcupo said, the turbo uses otherwise wasted exhaust gasses to force more air into the engine. This can increase your gas mileage to a certain point, until you start using tons of gas to make tons of power. If you have a fairly decent tune, and you are running lower boost, and you don't drive agressively, you will get better gas mileage. There's a guy on turbod16 that claims he gets close to 40 mpg on the highway.

 

I feel like I'm on the verge of understanding. Everything you guys said makes sense, but I'm not quite getting it. Is there a good book or site on turbos that explains how they work in great detail? Maybe that would help me out.

 

http://search.barnesandnoble.com/boo...37601606&itm=1

and

http://search.barnesandnoble.com/boo...=9780760308370

both are awesome books.

 

check it...

https://www.hondacivicforum.com/m_51477/tm.htm

 

^^Haha sacs said tit in that post.

But yeah that site is good too.

 

i was gunna say that...but decided it wouldnt fit me being helpful for once :P

 

where?