Mad max engine build, big power, fuel economy and no fuel injection

There are people who believe that it is not possible to improve the fuel economy of a vehicle. Yeah just like it's not possible to make a vehicle go faster, go off road better or tow more.
Some gear heads think you can't increase power and fuel economy on a gasoline engine. This is some what true but represents a general lack of imagination and obsolete thinking.

The engine is a big block chevy 454, mark 4 series, it's a smog motor from the 1980s. The vehicle is a 3/4 ton 2wd suburban with a 3 speed non lock up auto and full float axle with 4.11 gears.

First I had to establish a base line, find a sample group to make some realistic expectations.
Base line numbers I could find tell me that 1985 was probably the worst year for this engine. Making as little as 190 horses and 380 torque and had the worst fuel economy of all years. Since it was considered a "heavy duty vehicle" no EPA fuel economy numbers were ever published.
So it had no power and shit fuel economy.
Looking up the next closest thing, a half ton suburban with a smaller 350 engine all indications were it probably wasn't going to be good. Looking up fuel economy on the new suburban that has fuel injection (obviously), a 4 speed lockup transmission, a much smaller engine and aero dynamics. EPA says they get 12 city and 16 highway, problem was people were reporting around 10, usually less in the city and up to 14 highway.
Reading and talking to people I found out quickly not to expect even as little as double digit fuel economy on the highway.

Actual testing which I didn't do a lot of it was getting around 6.6mpg driving it around town.
So I figured I could get the fuel milage up to maybe 8 or 9 in town and maybe 12 on the highway.

So I took a wide ban oxygen sensing meter out of my camaro. This instrument tells you in real time what the engines air fuel ratio is. It was running way to rich.
The obsolete quadajet carburetor had to go. The cast iron intake had to go to too.
I put a edelbrock carb on there which I have had experience tuning and an aluminum edelbrock intake manifold, because the cast iron one sucked and square bore carb wouldn't fit on the original spread bore manifold.

I checked the ignition timing before I pulled the top of the engine off it was pretty close to where it needed to be.
When I got the intake manifold I saw hints that it was starting to develop a leaking cylinder head gasket. The engine would likely need to come out, but later.
I put the new intake and carburetor on and started working on my mad max tune. Lean burning cruise, lean burn idle and fuel dumping wide open throttle, removed the cold air intake so the air cleaner would suck in warm air from the engine bay.
This worked very well for fuel economy, but the warm air intake seemed to reduce full power which I didn't like. In town fuel economy went from 6.6mpg to 9 to 10mpg. Driving like a normal person.
Then I could milk up to 13mpg out of it when I would cut the engine off at stop lights and use the Mexican overdrive which is where you get up to speed, put it in neutral and cut the engine off and roll to your next stop sign or turn.
A Mexican I know told me about Mexican overdrive so it's not racist.

I developed a switchable thermostatic and cold air intake for last winter. This would take scorching hot air off the exhaust manifold and mix it with out side air to maintain a consistent 95°F, then I could switch it to cold air for mad max power. I liked the way this worked.
So now I had greatly improved fuel economy with no sacrifice in power. The holy grail.

I never took the suburban on the highway when it was getting 6.6mpg, so I have no idea what it's original highway fuel economy was. I never have taken it on a long road trip, but I would take it to the next town over which was a 55 mile round trip. I would filler up, drive the round trip and filler up again at the exact same gas pump this would always net between 16 and 18 mpg. Remember I was only expecting 12mpg, new modern 2015+ fuel injected suburbans only get around 14 on the highway.

By this time the cylinder head gasket was starting leak a lot and I was starting to wonder if my lean burn tune was burning the valves.
I pulled a cylinder head, found the leaky head gasket and found the leaky gasket cylinder was very badly tapered, the engine would need a rebore, it had been leaking coolant for a very long time.

So the engine had to come out and it was not going going to be the same when I got done with it.

 

Here is my take on gas engines. We are stuck using 1950's technology when it comes to Big Inch gas engines, even with fuel injection and electronic controls, us that run older engines are sort of stuck in the stone age. How ever, I must share my most recent engine build and hope it inspires to what is possible. I have a 1972 Jeep Wagoneer that is my daily driver and it is also my go to rig for towing my toys and running errands. The Stock Buick 350 was worn out and needed help or replacement. After months of digging around, I discovered a little known trend using a Big Block that can actually get pretty good fuel economy and still make a shit load of power. I started out with a good Cadillac 500 inch from 1971 ( which is the most powerful year of this engine) and I started the build from that. First was a tear down and inspection to make doubl sure the correct parts were present and that there were no hidden surprises. Once that was done, off to the machine shop we went for a complete going through and build. I had the cylinders honed, had the crank journals align honed and the cam journals align honed as well, then had the block decked and every thing blue printed. I ordered new pistons and had the rods re done, and then had the entire rotating assembly balanced both statically and dynamically to insure a long lasting and vibration free engine. I had the heads cleaned and all valves re ground and the seats replaced for unleaded fuel at the same time, I had him do a 3 angle valve job on the intake valves and leave the heads un assembled. I took the heads home and spent 4 nights porting them carefully to blend every thing and to port match them to the intake gasket. I then had them re cleaned and assembled with new seals. I ordered a new cam from Comp Cams ( it's a pretty mild grind, Like an old "R.V." grind) and a new high rise intake manifold. I then port matched the intake to the gasket and assembled the entire engine. After the install and brake in with brand new headers, she was noticeably a hell of a lot more powerful then the old engine. I also found a good Rochester Quadra Jet Carb for it and after rebuilding it and jetting for what I thought would get me close, I installed it with a 1 in Phonolic spacer and let her rip. Stock, this engine was listed at 400 HP and 530 Foot Pounds Of torque. On the Chassis Dyno, I made a best of 518 HP and 677 Pounds of torque!!! AND, I am getting 14 MPH in town and 17+ on the highway, With 3.73 gears and 32 inch tall tires!!! SO, Yes, a big inch big block can make killer power and also deliver really good fuel economy, and I have all ready blown the stock rear end, and have since swapped to 3/4 ton axles narrowed to fit the jeep and all is well. Now to get my 440 inch Hemi Headded Big Block in my 70 Challenger to get more then 7 miles per gallon! LOL, Prolly not!!!
Not for nuffin, but I would seriously look into doing the Caddy 500 swap, just make sure you get the correct ( non Chevy) trans to go with it and you should be a lot better off then any 454 Chevy I have ever heard of.

 

I decided to stick with the 454 because there was a ton of aftermarket for it. But I wanted to make it better faster and stronger because we have the technology. BUT a cost.

To get your carbed hemi to double digit fuel economy do what I did. Cheat. Get your self a tuning kit for your carb and wide band oxygen sensor meter. The O2 meter remove about 95% of the guess work to tuning your carb. The thermostatic intake removes about 90% of the seasonal tuning you might normally do with a cold air intake.
The wide band meter costs $200 to 300 but will quickly pay for its self with improved fuel economy, better throttle responce and maybe fewer spark plug changes.

My first experience with a lean running engine was a fuel injected car I had back around 2000. The engine air intake sensor had malfunctioned and was causing the engine to run lean all the time which gave great fuel mileage but was lacking power and was slowly eroding the exhaust valve's sealing surface. It ran great until the burned exhaust valves lost compression. My theory was that the exhaust valves don't get burned running lean at idle or lean cruise, just at or near full throttle.
I got the carburetor set up and running like it was supposed to be for high altitude. Still I was only getting about 8mpg driving around town and 10 to 12mpg on the highway to the next town over which I thought was awsome. Then I started working on my lean burn tune. This quickly improved the fuel economy by an additional 10 to 20%. But I didn't know if it was sustainable. Was it burning up and eating away at the exhaust valves?
So after about 7 to 8 months of this lean burn operation the engine came out, I pulled the exhaust valves to check them for any sign of what happens to my car engine from years ago and to my relief there was no pitting what so ever on the valve's sealing surface. My mad max lean burn idle and cruise, with fuel dumping wide open throttle tune was safe.
These smog heads were going to the scrap yard anyways.
They weighed about 78 pounds each and could be coaxed to make up to up to about 400hp with a lot of work.
These cast iron smog era boat anchor heads and restrictive heavy cast iron exhaust were not part of my vision.
I wanted to do something resembling the factory engines from the late 1960's early 1970s, where you had aluminum heads, big cam, higher compression. None of these engines got very good fuel milage with carburetors back then probably because the wide band oxygen sensing meter hadn't been invented yet.
GM performances parts sells modern copies of those aluminum cylinder heads and they are not horribly expensive and they are made in the USA. So I got them and to my delight both aluminum cylinder heads weighed a little less than 1 cast iron head.
The divorced style dual plane intake I put on earlier, the aluminium cylinder heads and replacing the cast iron exhaust manifold with tube headers should save about 120 to 130lb.
The "air gap" intake I used is more like a modern fuel injected engines intake where it's made of aluminum and it stays separated from the hot engine until they have to join together. The old design put the bottom of the intake manifold and the top of the hot engine together. Good for making the engine, cheaper more compact, lighter and good for fuel economy and great for carburetor anti icing. But the restrictive design heats up the air and fuel a lot, bad for power.

That carb icing thing i mentioned is a safety concern, for cars it's more of a phenomenon than a constant problem. It's only a constant problem for planes that fly through freezing clouds of water vapor all the time. But I do have some experience with this. I lived in Maine in the mountains so I did encounter freezing clouds of water vapor occasionally. On a fuel injected car I had about 20 years ago when I was young and dumb I had removed the coolant lines going to the throttle body and removed the exhaust gas recirculating system that put a little scorching hot exhaust at the throttle body, mainly for emissions. I was driving along on a few occasions during foggy freezing nights and when I let off the gas the throttle didn't let up, about the time I started to ththink "oh shit" the throttle snapped closed, or slowly closed each time. It was pretty rare. I didn't know what was going on at the time.
So to prevent the carb from icing I got a thermostatic air mixing intake that gives the engine air at a consistent 95°F. It's Russian made so I know it will work about as reliability as an AK47.
And when it gets real cold I found a carburetor heater plate from a 1965 to 68 ford thunderbird that actually fits my carburetor and intake. It's heated with hot engine coolant, I'm going to control coolant flow to it with a valve so it only comes on when I need it, during cold winter weather. This will improve cold weather operation and fuel economy too.
So before I pulled the engine to get rebuilt I pretty much had the intake heating figured out for improving fuel economy with out hurting power during the winter.
I never got to put my thunderbird carburetor heater on before I pulled the engine. It it will go back in next time.

 

Funny thing about the Franken Hemi, I built it with the plans to add fuel injection and a much better ignition system after the initial build, right now it's in the base line set up with the duel 4 barrels and stock size headers. It's making really awesome power, but I can tell it's really being held back. Hemi's by design breath better then any other system man has come up with ( why they are still banned from most competitions) and this one feels like it's choking to get enough air and fuel. It should get double digit numbers on the road with a good free flowing air and fuel system, and with the Aluminum heads and the correct size headers, should make even more power then it currently does. I may also find the cam I have installed is a bit less then the potential, but for now it does pretty good. I am hoping I can take advantage of today's modern tech with advanced engine management and lean burn, so time will tell. As of right now, the big inch hemi is only about 70 hp over the 1958 382 Hemi I built for my old hot rod, The 'Old Girl" cranks out just under 580 hp on a pretty much stock engine, just ported heads and a good dual quad intake and headers, and high volume oil pump. Surprisingly, the Old hemi design is a better design, and it took quite a bit of work on the new heads to get things closer to where they should have been. One thing about all hemi's, they will starve the intake valves of oil if you don't do something about it, and they will also flatten out cams if if you don't run over size thick wall pushrods. Summer time I will be installing the fuel injection and electronic controls and after tuning on the chassis dyno, we should see substantial gains in both power and fuel economy.

 

Good job on that 454 - my Dad had a truck with one and two fuel tanks, he needed both of them! You could actually see the fuel gauge move when the truck was on the highway

 

When I got the engine apart I found one connecting rod had a loose bolt and at some point the crank looked like it was oil starved so it would need to be machined. So that was the perfect excuse to put a stroker crank in it and bump the 7.4L up to a nice even 8L.
Also so in my reading I found that in the 1990s when GM switched from a flat tappet cam to roller cam just that switched netted +1.5mpg and up to 20 more horsepower and 15 torque from idle to max rpm, so it got a comp hydraulic retrofit roller cam set. Just a little 270 grind, nothing too radical. More power when I need it and better fuel economy the rest of the time, exactly the theme of the build how could I not. The roller cam also allows me to run just about any engine oil I want, I don't have to find the much more expensive oil with higher extreme pressure addtive content.

I decided to stick with oval port heads because they supposedly work better at lower RPM. Plus I already bought the oval port intake as my first mod when I did the carb swap.

Did some math and I figure the thin air here effectively lowers the compression by 2 full numbers. So I bumped it to about 11:1 that should be fun.

The suburban has a 40 gallon fuel tank. It should go for a ways if I can get it up to 15mpg on the highway or more, compared to getting 10 or 12. More MPGs would be better.

 

Air pressure has absolutely everything to do with adiabatic compression.
Mechanical compression ratio and adiabatic compression are 2 completely different things.
I am going to use water or water methanol to control knock when I start to really open the throttle. It's either that or buy premium gas all the time, which is 40 to 60 cents more per gallon here. That's a pretty good motion to figure it out.

 

One thing I found with the Water/Meth injection that I recommend doing is to wrap a "Heat Stove" of coiled copper tubing around one of your header pips and plumb your injection line after the pump through that. Effectively converting the water mix to steam! This has several advantages, Steam is more efficient at cooling the intake air then just the water/meth mix alone, it boosts your operating pressure from about 3000 psi to right round 3400 psi, and it actually uses LESS of the mix by about 20%. Power potential goes up because the intake temps go down, and the air density goes up not only because of the cooler air, but because of the "inert" gas nature of the intake charge, and finally, the Alcohol part of the mix actually creates O2 when it is ignited. On my Jeep, I gained close to 60 HP at a mile alt and it sustains that all the way up to the top of Pikes Peak! Where this system really shines is on my Diesel Rigs! My 7.2L Cat gained 70hp and my 4BT 3.9 Cummins gained 64hp , and my Big Cummins gained a whopping 105 hp! AND, these numbers are at 5600 feet alt! I base lined the Cat motor with a "stock" water/meth system and found I could get about 50 hp gains out of it, so I started experimenting with injector pressure and the mixture to see if I could get it any better. I remembered my old science class taught us that steam will flash temps faster then just water, so I tried it and it worked.

 

I have experimented with water and water methanol injection on my diesel too.
I took my home made kit off my diesel last winter to keep it from freezing and make some upgrades. I will probably put the old water injection from the diesel water injection on my big block.
I don't think the gas engine will need as much was as the diesel.

 

Since I have been a gearhead / Sparkie since the 60's . View some on ground fun of the times to date . I'll add as I find the 2017 E-drives
Sloth , it will be a fun ride

 

Man it took a while but I finally got that engine in. Now just have to make it run.

 

My cold weather ops package already installed is, windshield washer fluid warmer, front windshield wiper area deicer grid, I repaired the rear defrost grid, 5,500w hot water heater element coolant heater.
What's new on the engine, two 120v 600w block heaters one on each side, a port in the oil pan to install a hot water heater element to warm the oil.
Lastly a 30 plate heat exchanger for coolant to oil.
That HX will bring the oil up to operating temperature a lot faster and keep it there, decreasing engine wear, giving cleaner oil and increasing fuel economy. Got the idea from the big Detroits I worked on for the HX.
Figured out the hot water element coolant heater in Maine, I wanted to do double block heaters but couldn't and that was plan b.

 

I once built a 460 Ford for a pick up. Used 429 heads, called Lunati and told them what I wanted to do and had them grind a cam that ended up just a bit more aggressive than an RV cam, roller lifters, stud girdles, port matched stock intake, Holley 600 with 68 and 74 jets, Mallory magneto, dry sump oil pan, and under drive pulleys. Went from 91 rear wheel horsepower to 318 on the dyno. The biggest gain was 14 mpg to 21 on the highway with cruise on and A/C off. It also went from 10.51 to 8.13 in the 1/8. I sold the truck in 98 and the guy still uses it as a daily driver.