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Ultimate Fuel Economy Early 22R/20R Build Recipe

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Old 03-07-2012, 09:23 PM   #1
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Ultimate Fuel Economy Early 22R/20R Build Recipe

I am looking for experience and advice as to how to build the ULTIMATE FUEL EFFICIENT 22R/20R Engine.

what I have been able to find, and what is correct, versus mis-information:

1975-1980 20R has 89 mm stroke, 88.5 mm bore, domed piston, hemi head, smallest valves. round intake, round exhaust. stock double row timing chain. Compression height is same as early 22R

1981-1984 22R/22REC has 89 mm stroke, 92 mm bore, dished-dome piston, larger valves. earlier has stock double row chain, later has stock single row chain. compression height is same as 20R.

1985-1994 22R/RE/REC/RTEC has 89 mm stroke, 92 mm bore, flat or dished pistons, flat head. block is not 2 mm shorter; it is closer to 1/4" or 5 mm.
20R Head WILL NOT WORK ON THIS BLOCK WITHOUT HIGH DOLLAR MACHINING. domed pistons will protrude from block ~ 1/4", flat pistons will loose compression, resulting in very low ratio from increased head chamber without piston dome. head will require MASSIVE AMMOUNTS OF MACHINING TO GET CAM CENTERLINE RIGHT. Compression height is different from earlier block (20R, 22R)

Connecting Rods and Crankshaft is the same for all years. pistons differ in compression height, crown geometry (flat dome for 20R, dished dome for early 22R, 'full crown type' for early 22REC, flat w/ small valve notch for late 22R/22RE, Dished for 22RTE.
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Old 03-07-2012, 09:55 PM   #2
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Re: Ultimate Fuel Economy 20R / 22R Build

I am considering a Hybrid Early Block (1981-1984 22R Block, 1975-1980 20R Head) with the early 20R/22R Double Row Timing Chain.


Stock 20R valves should help with intake velocity, exhaust valves matched to intake valves. 20R oversized valves would be less restrictive, what effect on torque? 22R valves can be installed by a good machine shop. My goal is for a good, high-inertia intake 'ram effect'. any experience on hybrid motors with big versus medium or small valves?


Stock 22R pistons (9.0:1 factory, est. 9.4:1 with reduced 20R head chamber and same gasket thickness) or stock 22REC celica pistons (unknown piston dome or compression ratio.)
High Compression to about 10.5:1 for high-altitude 85 octane pump gas (above 4000 feet), higher compression to ~ 18:1 for e85 (~ 106 octane)

Fuel Induction:

A.) 4 small side-draft (28mm venturi) carburetors direct to each cylinder; intake manifold similar to 22RE lower intake manifold. Intake tuned for resonnance at ~ 2500 - 3500 rpm.

B.) stock or small side-draft carburetors, mounted stock or remote from intake manifold.

Split exhaust, cylinders 1 & 4 into one pipe, 2 & 3 into the other. twin exhaust pipes.

And the the HIGHLY EXPERIMENTAL MODS which have been built in the past by others in the field

a.) ethanol vapor induction @ 173 degrees + with or without water induction for anti-knock
b.) gasoline vapor induction @ 350 degrees + (but less than ~ 525 degrees) with or without water induction, with or without extensive pre-mix and/or ~ 1 psi heated boost, similar to smokey yunik's designs,
c.) ambient gasoline vapor induction, with air-fuel mix being drawn vaccum-style through a series of evaporation/mixing chambers.
d.) critical heated liquid fuel injection (think hot radiator cap geiser when you remove the radiator cap and the coolant instantly boils up all over you)

D.) exhaust turbine for charging system

E.) exhaust heat capture and re-purpose for up-stream application for fuel preparation, or for other utilization

my goal is, quite simply a 50 mpg (or better) 22R daily driver.
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Old 03-12-2012, 05:54 AM   #3
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I'm not sure what's driving you to do this but if I wanted to get 50mpg I wouldn't try it with a 22R pickup. It seems to me that you are looking at a ton of work, money and frustration to pull this off...or try to. I want to save on gas money but I want to do so without driving myself insane so I'm just going to switch one of Toy 4x4's to propane and see what the actual savings is. I will keep track of this thread. I would like to know if you can do it but I already have a headache. Good luck
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Old 03-12-2012, 06:07 AM   #4
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Slam your head in a door and snap out of it.

You'll come out cheaper.

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Old 03-12-2012, 06:22 AM   #5
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How are you coming up with this 50 MPG figure? I think you would have to more than double the fuel economy on this motor with a carb. I think that would be very hard to do, given no electronic monitering on the A/F signal from an AFM/MAF and an O2 sensor.

I wish you all the luck in the world, but if it was that easy everyone would be doing it. Keep this thread updated and hopefully this is not some fly by night type of theory / thinking.
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Old 03-12-2012, 06:35 AM   #6
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in before the end

i'm gonna watch how this plays out. seems interesting
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Old 03-12-2012, 07:14 AM   #7
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..... but you're going to use CARBS?
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Old 03-12-2012, 07:15 AM   #8
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I wish you luck but....
Truck Aerodynamics, and no fuel injection... i don't see how you are going to even get to 30mpg.
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Old 03-12-2012, 10:05 AM   #9
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Scribed for kicks.
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Old 03-12-2012, 11:53 AM   #10
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I get 50mpg when I'm out of gas....

Sounds like your trying to restrict the motor to lower power and raise mpg in a sense right?

Wouldn't that yield the same effects as using less throttle? An easier mod would be to stick a piece of 2X4 under the gas pedal so you can only push it 1/4 way. Uhhh....
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Old 03-12-2012, 08:55 PM   #11
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thanks for the replys.

Stage 1.) Build the engine for maximum conventional fuel-economy with standard carburation. general trend is high compression, balance crank, low-restriction exhaust, etc. this also makes some power. more power, less lead-foot required.

Stage 2.) tune the intake for airflow velocity, high-vaccuum, ram-air effects to key in at the low-end for peak 'grunt' torque to pull tall gear ratios at freeway speeds (ie, crusing down the interstate @ 80 mph with a tach reading ~ 1500 - 2500 rpm.)

What can someone get with applied intake tuning, anyone??

Stage 3.) select carburetion for maximum tunability. lots of choices here -

tiny one barrel for high vacuum, low-end torque;

staged 2-barrel (primary/secondary,

twinned 2-barrel,

spread-bore small 4-bbl, (1.2L rx-7 would be about right for cfm, factoring in the fact that rotarys are really about twice their advertised displacement),

twin 1 bbls,

or quad 1 bbls. google for triumph spitfire carb choices.

I haven't run any non-stock carburetors, though I have been researching options. What information is not out there is real-world daily driver data for different configurations aimed at streetability and affordable fuel consumption.

Most everyone knows that to get gobs of power you port the heads like crazy, get huge valves, get a huge cam, and then slap a million cfm carb on top of it all. then, when you get 6 mpg and 278 horses, shrug it off, because you are after the horses, not the mpg's.

It requires a lot of weeding to find out what doesn't work to try to figure out what *might* work. If you make power while sucking fuel, you've got power.

If you make power while sipping fuel, (though maybe more than stock) you've got power, and efficiency over the guy who just has power.

Figure the efficiecy factors, then you know how to build a daily driver that can knock the socks off of anything stock, for affordability.

I figure that a GOOD mechanic KNOWS what to do to get results in whatever direction he/she is aiming for, not just the herd direction. That is the difference between making informed decisions, and between 'follow the leader'.

If I can figure a decent 'recipe',
it might push the stock 2wd mileage from 17mpg/24 mpg to, maybe, 19 mpg/38 mpg.

Not unheard of, in terms of comparable sized vehicles with comparable drivetrains.



stage 4.) this is the clincher. read: fish carburetor, tom oggle, smokey yunik, etc. most of the famed '100mpg carburetors' dealt with the gasoline in VAPOR phase, not in LIQUID phase. gasses mix beter with gases, and only the VAPOR burns. Dynamically speaking, the atomization results in droplets. more droplets produce more surface area, and more evaporation. cylinder compresses, heat encourages vaporization, pressure discourages vaporization. ignition occurs, VAPOR Burns, heat boils off outer layers of remaining droplets, piston finishes stroke, burning fireballs get spit out into exhaust pipe.

Do you really believe that ALL of the fuel burns in the cylinder? something is burning in the exhaust manifold, and also in the Catalytic converter.

Hence, get rid of the non-burning liquid, then you get a more complete burn of what fuel is there, and are not throwing away 1/3 of your fuel btu's, power stroke heat, and power stroke pressure (before the inevetible heat engine losses) to the exhaust pipe.

Vapor stochiometric is different than liquid stochiometric, as well. lean to kill your valves is somthing like 15:1 air:fuel; just right for vapor is probably more like 22:1; but nobody knows because nobody runs vapor mixing equipment except for CNG or Propane, which get comparable fuel economy per volume even though there are less BTU's in the same volume..

Then again, if a knowlegable, self-taught mechanic, could take a 1984 pontiac fiero with a 151 cid (iron duke) 4 cylinder, set up a low-boost 1 psi draw-through CARBURETED PREHEATED charge into a HEATED mixing - optimized turbo-charger (which he called a homoginzer), and send the air-fuel mix into the cylinders at around 450 degrees farenheight, and he also DID NOT GET KNOCK, DID GET 250 HP at about 5000 rpm, and got very close to 50 mpg doing it, all in the early 1980's,

I think the same thing could also be done NOW with toyota's 150-ish cid 4 banger.

Probably a lot easier than geting a 70's mercury V-8 boat to get 90+ mpg (which is claimed to have been done with a different approach of the same theory of


Then again, theory doesn't mean beans until it is proven correct, or disproven so something better can come along. but, if no-one does the experimenting, then the theory dies in the coffe shops and the taverns still-born on the table.
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Old 03-13-2012, 04:03 AM   #12
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i like that you have a plan, just be sure to post updates and pictures. i'm interested to see if you can actually make your goal.
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Old 03-13-2012, 06:12 AM   #13
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I say go for it. Your only down side is getting 30 MPG insted of 50 MPG. I don't think you will blow anything up...
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Old 03-14-2012, 09:47 PM   #14
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I've got a few rigs. first got into the yotas for the micro-min RV's. (they are the GEO METRO of motorhomes, and have a reputation for being able to go forever.

Currently, I have two early 22R 21' RVs, one I've tested @ 18 MPG highway/13 MPG city, (parked)

the other got ~ 20 MPG on the 4th of july a couple of years ago. (RV's sit a lot) (parked)

the third rig is a customized 6 wheel (tandem axle) Loong-bed flat-bed (14') with a 20R. it gets ~ 17mpg in town, ~ 21 mpg on the road. 3 piece driveline, 2 diffs (one is an idler), 4 spd manual. (parked for the winter 2010, robbed ignition/regulator parts for the 3/4 ton)

4th rig is an 80 3/4 ton longbed, 20R, 4 spd manual, 4.11:1 ratio 8" diff, stock daily driver. gets ~ 17mpg - ~22 mpg (i've got slightly oversized tires, 205-75R14 versus 205-95R14). Odometer croaked recently, so loging is on hold.
I plan to build a short-block 22R and drop in, and transfer the head/carb/22R split manifold (I replaced the stock 20R manifold with the split tri-Y plumbed 22R setup).

5th rig is an 83 1/2 ton longbed 2wd, 22R, 4 spd manual, 2 piece driveline, 3:42 ratio 7.5" diff. new project daily driver. lot's of miles on the (now stopped) clock (odometer is dead @ 172K, how I got it), 125#-135# compression, on at least second (somewhat sloppy) single row chain (got a double roller chain to go in when I'm ready to get greasy). Planning on going to a mild hybrid motor on this, stock 22R internals, 20R Head w/ original valves, 22R alumunum rocker/cam, double row chain. also planning on dropping in a 5 spd manual.

Parts pile has a couple of 20R heads with stock valves, 20R intakes, 3 20R Carb rebuilder cores, mazda rx-7 nikki ~ 225 cfm 4bbl carbs, honda Keihin 28 mm Carburetor setup, and some other bits and pieces.

Might be setting up for casting a custom intake for the 20R, 4 straight runners with a knob near the front for the thermostat mount and coolant passage, with carb-clamp hose nipples for side-draft carbs. that should be a simple casting, and a simple pattern to make from flat wood and round wood stock. Then port for the coolant passageway to the thermostat, and use the
original water outlet.

Either that, or cut the runners off of an original and weld pipes to the mounting flange, if I want to get crazy on the intake. dont' have aluminum welding stuff, though.

Lower 22RE intake manifold would make a good start there, too. 4 runners, factory water outlet, some years will fit the early 22R head (though not the 20R)

I've got a bit of prejudice against the laser block (85-94 with the peanut on the side and the lower deck height, with the flat pistons and flat head) - don't care for the lack of a bolt-on oem double roller chain and metal guides, and the wear-through-the-timing-cover archiles heel shared by all of the 20R/21R/22R engines.

I'd like to find a set of pistons from an 83-84 toyota celica 22REC (early block, full crown type, hemispherical head), but there isn't a whole lot of info out there about those. Haven't even seen a picture of what they look like.
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Old 03-14-2012, 10:07 PM   #15
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This is cool... but why not just swap in a newer motor that gets better mileage? also changing your gear ratios, transmission from auto to manual (you prob already have a manual), or if possible the gears inside the trans for a taller od would gain alot imho. By the way, if you don't already know about it or have one, you should check out a Mpguino. They are technically only for fuel injected motors. But I don't see why it wouldnt be possible to rig up some sort of flow meter and get it to work with a carb.
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Old 03-15-2012, 03:43 AM   #16
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i'm going to pull the "pics" card...

pics please!

sounds like an impressive collection, but i think everyone here would like to see pictures

(if you need to know how to upload pics, here's a link)
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Old 03-15-2012, 08:14 AM   #17
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in for fun...

50mpg if I still drove my CRX...
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Old 03-16-2012, 08:17 PM   #18
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re: pics of my most custom rig (and passenger)

I've attached a pic of my most customized rig with a passenger sitting on-board. I had a bit of fun putting that together - custom springs, custom spring hangers, custom drive-line center section, frame extension, custom bed fabrication, wiring harness fabrication, etc. Daily driver until winter hit - then I parked it in favor of another rig. (it got stuck reaaally easy, on level wet grass!) something to do with tandem axle, and not being twin-screw. hope I dont offend any jeep people out there. (it's another project I had, 1.3L Mazda Rotary (Wankel) in a Jeep XJ Cherokee, anyone?) it came with a locked up amc 2.5 L. cut my losses when I sold the nearly new tires and aloy wheels. They got the Jeep Shell, too. Still need to plumb in hydraulics and install a winch. Yay - more fun.
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Ultimate Fuel Economy Early 22R/20R Build Recipe-apr18_002.jpg  

Last edited by troyjmueller; 03-16-2012 at 08:32 PM.
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Old 03-17-2012, 05:32 AM   #19
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all right... looks good. thanks for that
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Old 03-18-2012, 07:32 AM   #20
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Re: mileage build-up

Got started on phase 0.5 last night. 1983 2wd long bed half-ton. 22R, stock carb, assumed stock cam, 195 75 R 14 tires, wheels, 4 spd manual, 3.42 ratio.

Repairs Pending: Replace timing chain; tensioner had given up the gost. went with 81 - 82 timing set, oil pump drive from a 20R, guide bolts from my bucket of metric bolts. this is at final re-assembly stage.

Repairs needed: Instrament Cluster (Odometer is dead @ 172,399k). Otherwise, no way to track the mileage.

Specs: Stock Early 22R, Fed emissions (no smog pump), nominal 9.0:1 compression. No A/C, No P/S. 4 spd manual transmission. 2 piece factory driveline with center bushing & 3 u-joints.
3.42 Axle ratio (checked & agrees with the model plate)

Simple things to be done:

Clean out frame rail dust. (weight is a bad thing) and dirt accumulation in the frame weighs a bit

Install aftermarket guages (oil, amp, water, vaccuum)

Maybe wire in factory tachometer (I have an SR-5 Cluster.) all that needs to be done is to re-wire the terminals of the wireing harness. then a wire can be run from the coil to the terminal on the plug that feeds the cluster the tach signal.

Planned upgrades:

2wd 5 spd manual trans ( I have a couple in my stockpile)

20R head (I will probably use a later ~1980 with fuel pump & P/S boss)
pending checking of valves, guides, and warp. I plan to leave the valves & ports stock, hoping to encourage air velocity / lower end torque.
20R intake manifold, Carburetor (pending overhaul of a locked-up core carb)

cosmetic stuff
- front bumper end-caps
- brush guard
- maybe building a custom bed, something along the lines of a flat-bed or utility bed with sadle-bag style storage boxes.
- maybe duallys (not in line with fuel economy, I know.)
- Rectangular Box Steel Rear Bumper (the stock bumper is all tweaked)
- twined exhaust stacks on driver side of vehicle (sort of cool, dual is easy to do with the stock split upper pipe, just cut the pipes before the third Y, extend and plumb. the trick is to find 1 1/2" mufflers. Motorcycle mufflers might be a good bet. this might help on the back-pressure due to the split nature of the plumbing - 1 & 4 share a pipe, 2 & 3 share a pipe. 360 degrees engine rotation between exhaust pulses, phased 180 degrees apart. I hear that combo makes a decent 'sound'.
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1984, 20r, 22r, 22rec, cid, compression, difference, early, economy, engine, fuel, head, high, intake, pistons

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