:::RHMT::: Real Home Made Turbo

Please login or register.

Login with username, password and session length
Advanced search  

News:

RHMT DIY Hub Dyno?!?!? check it. (link)

Pages: [1]   Go Down

Author Topic: Thinking about air and fuel stuff...  (Read 5168 times)

danwjmu

  • Guest
Thinking about air and fuel stuff...
« on: August 31, 2009, 09:24:20 AM »

Ok, thinking about air and fuel a little bit lately.  On the mower board I'm involved with they're talking about using a cool can for a car to cool the fuel (gasoline) down to make it denser and therefore cram more fuel into the mower.  Now my problem with the whole idea of cooling fuel (in cars as well, where cool cans are marketed) is that you'll get droplets instead of mist forming.  Thinking about how fog is formed.. cold air is moving across warm air or moist ground.  Even at low relative temps the water evaporates and moves into the air.  Reverse this.. have cold water and warm air and what do you get?  Nothing.  Well, actually you'll get water being pulled out of the air, like a cold glass in hot summer air forming condensation on the outside.  So heat the intake as well (automakers already do this).  It just seems to me that you would actually want to warm the fuel rather than cooling it so you get a better evaporation and mixing with the air and also using a heated intake would help.  Yet cool cans have been used for year and these mower guys are talking about them like they do something positive.  They're also talking about chilling the intake manis too.  What's going on here?
Logged

brine04

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2251
  • B-North
Re: Thinking about air and fuel stuff...
« Reply #1 on: August 31, 2009, 11:34:29 AM »

Not sure what's going on but I have seen a few magazine tests over the years comparing warm and cold fuel. The one that sticks in my mind was a motocross mag. They put the jerry cans in the freezer and all the bikes tested made about an extra hp.
Logged
92GSR - mild interest

Joseph Davis

  • Verbal Assault Technician
  • RHMT Moderator
  • Certified OG
  • *****
  • Offline Offline
  • Posts: 34733
  • Eugenics prevents retards like widebody93
    • TURBO THIS
Re: Thinking about air and fuel stuff...
« Reply #2 on: August 31, 2009, 12:09:46 PM »

Turbo cars, which are generally indifferent to atomisation and some in fact like injectors that shoot narrow streams, typically make best power when the gasoline is at ~80 degrees F.

As with everything, your mileage WILL vary.

speedjunky01

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1015
Re: Thinking about air and fuel stuff...
« Reply #3 on: September 02, 2009, 01:15:33 AM »

didnt honda design a gas "vaporizer" back in the 70 when the gov put in the clean air act as an alternative to a cat?

they were able to run the car very very lean on the order of 30:1 or something like that. . .

dont recall the details . .  . googling now

edit:

its old but turo d and crx front its WIN in all ways

http://videos.streetfire.net/video/4df10546-e7e7-4b43-84fe-993600d36841.htm
« Last Edit: September 02, 2009, 01:28:44 AM by speedjunky01 »
Logged

Joseph Davis

  • Verbal Assault Technician
  • RHMT Moderator
  • Certified OG
  • *****
  • Offline Offline
  • Posts: 34733
  • Eugenics prevents retards like widebody93
    • TURBO THIS
Re: Thinking about air and fuel stuff...
« Reply #4 on: September 02, 2009, 02:05:56 AM »

didnt honda design a gas "vaporizer" back in the 70 when the gov put in the clean air act as an alternative to a cat?

they were able to run the car very very lean on the order of 30:1 or something like that. . .

dont recall the details . .  . googling now

It wasn't that lean.

Search for CVCC, it was a stratified charge method.

sewell94

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2194
  • Border Jumper
Re: Thinking about air and fuel stuff...
« Reply #5 on: September 02, 2009, 12:27:46 PM »

Chilling the fuel works, i've seen it done alot on on v8 stuff.
Logged
My real power is not interweb-based, although it does allow me to come across in the interwebs as a magical being shooting pixie dust and cupcakes out my asshole and such.

Adam Hopkins

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 325
  • Peyton Manning
Re: Thinking about air and fuel stuff...
« Reply #6 on: September 02, 2009, 01:10:07 PM »

But isnt dropping the temp of the fuel have more of an effect on air temperature than density of fuel? Am I correct in thinking this?

I mean if you need more fuel then put in a bigger jet or give it some more injector duty.

I wouldnt rely on the temp of the fuel to control how much is fuel is entering the cylinder.

Logged

Joseph Davis

  • Verbal Assault Technician
  • RHMT Moderator
  • Certified OG
  • *****
  • Offline Offline
  • Posts: 34733
  • Eugenics prevents retards like widebody93
    • TURBO THIS
Re: Thinking about air and fuel stuff...
« Reply #7 on: September 02, 2009, 01:36:55 PM »

Chilling the fuel works, i've seen it done alot on on v8 stuff.

Hendren found that 80-85 degrees is where VP blue (118?) makes best power on the turbo SB2s he builds.  Crazy, wise old man, posts on speedtalk.

Teg2boo

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 4261
Re: Thinking about air and fuel stuff...
« Reply #8 on: September 02, 2009, 02:01:20 PM »

I thought that you want the fuel to be cooler because warmer fuel is easier to vaporise and you don't want gas vapor in the combustion chamber since it is easier to ignite aka detonation. I thought want the gas drop to be as small as possible without reaching the vapor state.

I don't know how I got this idea tho lol
Logged


damn you guys too? its a fucking forum not a court room!
 Its not a forum its a gang.  

Conceptz-X

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2118
Re: Thinking about air and fuel stuff...
« Reply #9 on: September 02, 2009, 07:35:31 PM »

Fuel does not burn as a liquid.  There is far more to the equasion. 

They also sell intake gaskets with a screen in them to break up fuel droplets for carbureted motors.   In my opinion they will affect the ram charging effect in the V engine style manifolds. 
Logged

patsmx5

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 1584
Re: Thinking about air and fuel stuff...
« Reply #10 on: September 02, 2009, 08:31:38 PM »

I wish I could wrap my head around the mechanics of what is happening to the air and fuel as it goes from carb/injectors through the IM into the chamber and then right before ignition.

Read up on it. The info is online. If I find a good link I'll post it.
Logged
Quote: Originally Posted by Adam Hopkins
There is no such thing as too much boost. You could have too little rod, piston, or sleeve. But never too much boost.

Conceptz-X

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2118
Re: Thinking about air and fuel stuff...
« Reply #11 on: September 02, 2009, 08:44:19 PM »

My recipe:   Try to atomize what you can at a low temp, have a swirl or tumble inducing intake design, more quench the better, rod ratio around 1.6 for up to 6500 rpm 1.8 to 9k to  give a lower piston dwell time at TDC for the piston and properly use the quench.
Logged

Conceptz-X

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2118
Re: Thinking about air and fuel stuff...
« Reply #12 on: September 02, 2009, 09:52:41 PM »

yea, thats why I suggested a different ratio for a different max rpm   

It also affects the acceleration/decelleration of the piston from TDC and BDC  if the rate is too high the wrist pin comes under additional stress

Longer rod dwells more at TDC and BDC  it reduces pin stress and piston rock therefore increasing ring seal
« Last Edit: September 02, 2009, 09:54:32 PM by Conceptz-X »
Logged

Conceptz-X

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2118
Re: Thinking about air and fuel stuff...
« Reply #13 on: September 02, 2009, 10:01:08 PM »

most current cup motors are running in the 1.9-2.0 rod ratio

bore is around 4.125 with a short stroke  lots of quench  piston has a dish to match the head quench area
Logged

Conceptz-X

  • Certified OG
  • *****
  • Offline Offline
  • Posts: 2118
Re: Thinking about air and fuel stuff...
« Reply #14 on: September 05, 2009, 01:16:10 PM »

also offset wrist pins may be an option with a low rod ratio engine to reduce piston rock
Logged
Pages: [1]   Go Up