Go Back   EcoModder Forum > EcoModding > DIY / How-to
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 11-14-2008, 08:54 PM   #1 (permalink)
nut
 
Coyote X's Avatar
 
Join Date: Dec 2007
Location: Southen West Virginia
Posts: 654

Metro XFi - '93 Geo Metro XFi Convertible
90 day: 62.17 mpg (US)

DR650SE - '07 Suzuki DR650SE
90 day: 55.26 mpg (US)
Thanks: 0
Thanked 37 Times in 26 Posts
Send a message via MSN to Coyote X
DIY Throttle Body Spacer

This is an easy mod for most cars. I have been trying to think of stuff I have not done to my car and one thing I came up with was a spacer to put under the TBI. Of course nobody makes anything for a Metro and even if they did it is not worth spending much money on something so easy to make. Spacers can show a couple of mpg improvement on an engine using a carb or TBI injection. On multiport it can be hit or miss whether it works.

So you need two things to make one. A plastic cutting board and a TBI base gasket. I got my cutting board from RiteAid locally, it was a nearby store and it was exactly 1/2 inch thick. It cost 10 bucks.

Start by laying the gasket on the cutting board and drawing out the pattern on the board. Drill holes in the mounting bolt holes and some starter holes in the other areas. Use a dremel or a grinder with a deburring bit so it doesn't clog up. I couldn't find my dremel so I used an air grinder with a deburring bit.



One thing to note. You don't have to cut all the holes out. Some of them are much larger than are actually needed. They are used for vacuum passages and as long as they are big enough to let the vacuum source through they don't need a huge hole. On the main bore I made sure it was nice and smooth and properly sized to the manifold. The other holes I just shaved the plastic down so the vacuum signal could get through but otherwise didn't bother cutting it totally out. You can cut them out but it makes it take way longer and you don't gain anything.

Typical reports are a much better bottom end response and slightly improved mileage. I will find out soon with mine and report back. If I feel like it, I will make a second one and stack them for a one inch spacer. I am not sure what would work best on this setup one inch or a half inch. I might try both ways if I get time and if my mpguino ever comes in.

__________________


  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 11-14-2008, 10:09 PM   #2 (permalink)
Master EcoModder
 
Join Date: Sep 2008
Location: Fort Worth, Texas
Posts: 356

Silver Turtle - '02 Ford Focus Zx3
90 day: 38.83 mpg (US)
Thanks: 4
Thanked 2 Times in 2 Posts
LET ME KNOW!!!

All the Mazda 6 guys claim improved mpg, but for $80 I dont see the return on gas... but If I can make one like you for less than $10 then I will for shure do it...

I have MPFI though
  Reply With Quote
Old 11-14-2008, 10:24 PM   #3 (permalink)
nut
 
Coyote X's Avatar
 
Join Date: Dec 2007
Location: Southen West Virginia
Posts: 654

Metro XFi - '93 Geo Metro XFi Convertible
90 day: 62.17 mpg (US)

DR650SE - '07 Suzuki DR650SE
90 day: 55.26 mpg (US)
Thanks: 0
Thanked 37 Times in 26 Posts
Send a message via MSN to Coyote X
I say go ahead and grab a board from a store or take the one out of your kitchen if you can get away with it If other people have reported increased mileage then you really won't have much to lose by giving it a shot. If nothing else the leftover part can be saved and put to use in your kitchen like it is supposed to be or used for fabricating other parts. The plastic is pretty easy to work with and if you warm it up it seems like it could be formed easily.

It took me probably 30 minutes to make the first one shown in the pictures. I Could probably make one in 5 minutes with a drill press. If I had a hole saw assortment and some routing bits to go along with it.

I am probably going to make one to go in my Astro van sometime or another as well. It will probably give me a more accurate number to show how much of an increase there is from it. The Metro is getting some other stuff done at the same time so I am hoping I can tell what it gives me but it might take a few months to sort out how much it helps that car.
__________________


  Reply With Quote
Old 12-30-2008, 01:23 PM   #4 (permalink)
Reformed racecar mechanic
 
Join Date: Dec 2008
Location: Philadelphia, PA
Posts: 3
Thanks: 0
Thanked 0 Times in 0 Posts
Are you doing this to change the effective length of the intake runner or to make a thermal break for the throttle body?
  Reply With Quote
Old 12-30-2008, 01:39 PM   #5 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
This is the first I've heard of adding a throttle body spacer to improve efficiency - aside from your earlier PM. (Coyote asked if I wanted to do an A-B-A test on it, but unfortunately my cruise control situation hasn't been resolved, so I can't run reliable tests with the Flea.)

It might be worth posting a note about the theory of why this mod may help.
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 12-30-2008, 01:53 PM   #6 (permalink)
Hypermiler
 
PaleMelanesian's Avatar
 
Join Date: Dec 2007
Location: Texas
Posts: 2,321

PaleCivic (retired) - '96 Honda Civic DX Sedan
90 day: 69.2 mpg (US)

PaleFit - '09 Honda Fit Sport
Team Honda
Wagons
90 day: 44.06 mpg (US)
Thanks: 611
Thanked 433 Times in 283 Posts
I think the idea is to lengthen the intake, giving it a lower resonance frequency, and moving the peak power band to a lower rpm. Should be perfect for the way WE drive.
__________________



11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles
  Reply With Quote
Old 12-30-2008, 02:17 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Aug 2008
Location: Maryland
Posts: 92

Taurus - '99 Ford Taurus SE
90 day: 17.89 mpg (US)

Windstar1 - '97 Ford Windstar Cargo
90 day: 16.99 mpg (US)

Vulcan - '97 Kawasaki Vulcan 750
90 day: 45.96 mpg (US)

Suzuki - '09 Suzuki SX4 Technology AWD
90 day: 24.62 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
tb spacer, what about uim spacer?
  Reply With Quote
Old 12-30-2008, 02:25 PM   #8 (permalink)
Dartmouth 2010
 
SVOboy's Avatar
 
Join Date: Nov 2007
Location: Hanover, NH
Posts: 6,447

Vegan Powa! - '91 Honda CRX DX
Team Honda
90 day: 66.52 mpg (US)
Thanks: 92
Thanked 122 Times in 90 Posts
Send a message via AIM to SVOboy Send a message via MSN to SVOboy Send a message via Yahoo to SVOboy
Quote:
Originally Posted by PaleMelanesian View Post
I think the idea is to lengthen the intake, giving it a lower resonance frequency, and moving the peak power band to a lower rpm. Should be perfect for the way WE drive.
Indeed, this design is evident in the length of the runners on the honda crx hf, civic cx, and civic vx. However, because of the overall intake design I think for these cars a tb spacer wouldn't do much since the resonance is along the runners into the plenum and would not change with a tb spacer.
  Reply With Quote
Old 12-30-2008, 04:21 PM   #9 (permalink)
Master EcoModder
 
Join Date: Sep 2008
Location: Fort Worth, Texas
Posts: 356

Silver Turtle - '02 Ford Focus Zx3
90 day: 38.83 mpg (US)
Thanks: 4
Thanked 2 Times in 2 Posts
^ Well in the performance world throttle body spacers DO work to improve hp and torque all accross the rpm band.

So with that in mind, it does change something. How that translates to better fuel efficiency? Well, the engine is making more power because its more efficient and this mod does not add air (turbo/supercharger) or increase air consumption, it simply changes the way the air travels. This should in theory improve mpg's.
  Reply With Quote
Old 12-30-2008, 05:10 PM   #10 (permalink)
Moderate your Moderation.
 
Join Date: Nov 2008
Location: Troy, Pa.
Posts: 8,919

Pasta - '96 Volkswagen Passat TDi
90 day: 45.22 mpg (US)
Thanks: 1,369
Thanked 430 Times in 353 Posts
It also creates a larger plenum area, which means slightly more air available for higher RPM operation.

I'm also pretty sure that lengthening a tube while keeping the same diameter increases air velocity, though I might be wrong on that.

Anyway, if it does increase air velocity, that would mean better atomization, as there would be more turbulence in the air, which might make better power/economy.

AFAIK though, the biggest gains are seen in the higher RPM bands (mid-range torque and higher HP) due to the extra volume of air in the plenum.

As an add-on to this - Using thermal plastic to make an intake manifold will net you better HP and TQ as well, due to the temp differential (thermal plastic allows the incoming air to cool the intake manifold, as opposed to the cylinder head heating it... air temp decreases and you get better throttle response and HP)

__________________
"¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı"

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Honda IACV explained TomO Off-Topic Tech 16 12-21-2015 01:49 AM
The Mechanism Behind Flow Separation LostCause Aerodynamics 46 07-15-2010 07:38 AM
Big Bore throttle body for MPG? cfg83 EcoModding Central 19 12-31-2008 09:44 PM
Archimedes screw throttle ronarprfct EcoModding Central 29 08-27-2008 03:10 PM
Throttle sensitivity Formula413 EcoModding Central 13 05-29-2008 04:55 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com