Cheap ways of Increasing gas mileage and power - Chevy 454 (smog controlled)

[Madathlon]

Okay Friends, I have a California Smog controlled 454 (Yuk) and leaving the state for ever and will NEVER smog it. So what are a few Cheap things I can do to improve the gas mileage and power?

Things that you know 100% that will work. None of this gimmick add-on like a tornado. But real things.

And lucky me, I have the OEM Vac gauge (Fuel economy gauge)

At this moment I can not afford a new 3in exhaust system. BUT I'm tempted to mod a few cats.. (Broom stick mod) if I can get them off.....

[M & J]

Search fuel economy 454 or similar. Lengthy discussions and several topics.

[Froggy1936]

Modifying a catalyitic convertor is highly not reccomended as you will not improve anything and if it is a honneycomb type it will prove to be very difficult to destroy the honneycomb and the housing may not survive ! Flow will not be increased ! If it is a bed type( Beads laying in the bottom )you are also wasteing your time Any improvement to be made are on engine controls Or a complete exaust syestem replace (Banks syestem)  Frank

[Madathlon]

I did search the threads and 99% of what I found related to changing major parts out, IE Carbs, Exhaust, and intakes, While all are good there out of my current budget. I'm looking for the small stuff that can be done on the cheap.

And thanks Foggy for saving me the time of punching out the cats. I have been looking into exhaust dumps but not to sure if there safe on a RV.

[DaveVA78Chieftain]

Hmm, I didn't think they even started installing CATs in medium duty chassis' like these until late 80's or maybe 1990 when GM went to TBI on the P30 chassis. 

[bluebird]

I did search the threads and 99% of what I found related to changing major parts out, IE Carbs, Exhaust, and intakes, While all are good there out of my current budget. I'm looking for the small stuff that can be done on the cheap.

Good luck getting good gas mileage from a carbureted  class A with any motor.

I had a 80 Itasca with a 454/ 400 combo a few years ago. Ran like a top, too, but only 4 to 6 mpg is all I could get out of it, unless you want to run around 50 mph. Taking the cats off won't do a thing but make the exhaust stink.

The PO of my coach put duel exhaust on it with pipes all the way out the back. I doubt it did a thing for mpg but it did sound good. I don't know what the horse power was for these coachs, but would be surprised if it was much over 220. Gota remember when these coachs were designed the federal speed limit was 55 mph.

I don't believe there is a cheap way to increase the mpg very much, if at all. Build an engine with more horse power and use taller gears would help some, but not feasible for most. Look at all the new cars today, they have increased the compression ratio, hp, and get better mpg, because they just have to run just a bit over idle now a days.

My Challenger does over double what my Itasca did in mpg, but it cost me $10,000 to move up. A guy can buy a lot of gas for 10 grand.   

[pvoth1111]

Good gas mileage in a motor home....vw westy camper van....

I think it costs a dollar a mile to move the coach.....period
Drive it sane and all is well....when we first started out we pushed too hard and it just stressed me out...
On the highway 55-60 MPH....lock the cruise and just chill when you get tired find a rv park and chill....six hours of driving and I am beat.

And remember torque gets you going and HP keeps you there.
The best thing you can do is reduce drag and make the ol Rat motor breath better....an engine is an air pump and nothing more....make it easier to breath and exhale while reducing drag and it is all is good.

It sucks that these huge engines make maybe 200 hp....in sock trim....as I said improve air flow...and give the timing a little advance and make sure carb and ignitions system are all in good working order and roller down the road....still at a dollar a mile.

[Oz]

Bottom line, if you read the other topics on improving gas mileage and power, you already found that there is no such thing as a "cheap" way to significantly improve either, and definitely not both, other than keeping your engine properly maintained and tuned.  I can't say if removing the emissions stuff helps or not as mine only had the little PCV(EGR)(?) valve and "cookie jar" gas breather so, maybe removing the emissions additions will help, maybe it won't. 

What do you think, moto-pros?   Will removing the mass of emissions additions help or not?

There is only one way proven, "cheap" way improve mileage and... it's free... adjust your driving habits to maximize economy.  Slow take-offs and keep speed at or under 55 on the highway.  Optimum economy speed is actually considerably lower.

This is arguably the most asked question.  That's why I got this for everyone.  It's about as comprehensive as it gets, yet written for the backyard mechanic.  It's a totally overlooked resource dedicated to RV performance and mileage:

http://www.classicwinnebagos.com/forum/index.php?action=store;sa=view;id=184

More air in + more air out = more power and economy, basically.  Of course this is based on a correct fuel/air mixture.  You can't just add a lot of air in and out without getting lean in the fuel mix.  K&N filters and the same type of different brand have always been a staple for helping the motor breathe in without messing up the balance.  And, they're not really "cheap" but, they definitely are on the cheap end of what the other modifications cost.

Rhat vacuum gauge you have for economy?  It's your best friend and it does tell the truth.

[Madathlon]

Ya, I do plan on the double nickle speed limits. and a lot of drafting hehe. and also keeping the tire pressure right. Then there also finding some way to get fresh colder air in from outside some how. and changing the single snorkel air box to a dual intake set up.

And I hope to pick up a dry Nos set for those long steep mountain roads. Sadly tho you cant buy them here in California (What I'm told by local speed shops who have no clue about the other side of NOS)

I gone thru all the bearings and replaced all the old tires.

[Oz]

My '74 Indians (Dodge 440) had dual snorkels.  Prior to selling, I had a project to document but never did.  I cut the snorkel ends and secured automotive, flex air intake tubing (the rectangular kind) on them and ran them over the top of the motor and used louvred ducts cut into the forward, flexible engine shroud (which goes around the radiator).  This created a CAI (Cold Air Intake) system which can sell for a couple hundred dollars for a single, commerically produced automotive style.  Cost was about $30. 

I used the louvered intake covers (backed with used window screen) to keep rain and bugs from getting in.  Did it help?  I don't really know.  I did take it for a few short romps and it did seem to have more pep.  I had to sell the RV almost right after I did the mod but, I had a CIA on my PT Cruiser and it definitely gave it a noticeably better throttle response and maybe just a tad better mileage, maybe 1 mpg, but that's on a 4 cylinder car, not an 8 cylinder land-yacht.

Anyway, these snorkels were OEM and even had a picture and partnumber of the original, skirted thermostat on them.  They came off 750cfm Thermaquads and went on 750cfm Edelbrocks.  So, if the top of your carb (quadrajet?) is the same diameter - one of these air cleaners would work.  Whether or not you have the space and ability to run the tubes to the front of your RV, I don't know.  They are pretty shallow and I had to custom match a K&N filter to them.  I don't know if the Chevy air cleaner is taller but, if it is, all the better.  And if you can find one with dual snorkels, even with round ones, it's completely doable, if you have the room over the motor and directly to the front.  (Don't go down under a bumper or something like that - bad idea.  Another member did that and proved the point.)

[Madathlon]

I had thought about the dryer ducts but feared they melt. Once the rains stops I will look into going thru the rubber flap above the radiator

[Oz]

Metal dryer ducts, the kind which are angled down would work too.  I used the plastic kind and I heat melted the louvres open and angled slightly downward.

[Madathlon]

Humm, food for thought. I know from working on my old trucks and boats that colder air means more power. Its all down to if there is room enough. I have used dryer ducts before and made my own double snorkel air cleaner.

Now if only the weather would break

[ibdilbert01]

Modifying a catalyitic convertor is highly not reccomended as you will not improve anything and if it is a honneycomb type it will prove to be very difficult to destroy the honneycomb and the housing may not survive ! Flow will not be increased !

Unless its clogged, in that place it needs replaced anyhow.  That being said, I had a cat clog up on a crown vic.  I didn't have a lot of money so I just worked the inside over with a crow bar tapping it with a hammer until I got it all out.   Ended up putting another 100k miles on it like that.

[Oz]

... I can't say if removing the emissions stuff helps or not as mine only had the little PCV(EGR)(?) valve and "cookie jar" gas breather so, maybe removing the emissions additions will help, maybe it won't. 

What do you think, moto-pros?   Will removing the mass of emissions additions help or not? 

[Stripe]

Look at this and go from there...   
http://www.classicwinnebagos.com/forum/index.php?action=mgallery;sa=item;id=1120

Fredric

[ClydesdaleKevin]

You can get double snorkel setups for the 454 from Summit Racing.  Prices ranged from 150 bucks to 400 bucks last time I checked.

Big old waste of money if you ask me when it comes to the 454 and a big heavy motorhome.

Bottom line is that unless you do a complete engine rebuild and mod, you just aren't going to get a whole lot of power out of these things...you'll never be able to accelerate up a 7% grade and reach the top at 90mph... :)rotflmao

Seriously, the book Mark mentioned is invaluable, and worth the whole 7 bucks in the club store.

As far as gas mileage goes, driving habits will make the biggest impact.  Keep it at or below 55, stay in the slow lane, take back roads when you can and go 40-45.  We get a pretty solid 8mpg at 55...and darn close to 10mpg at 40 if its an open back road without lights and traffic.  That is with a 35 foot rig, compartments full, and towing a Jeep.  By the way, if I push it at 65, my gas mileage drops to less than 6mpg!

Kev

[Madathlon]

ClydesdaleKevin

You can get double snorkel setups for the 454 from Summit Racing.  Prices ranged from 150 bucks to 400 bucks last time I checked.
>I can make one much cheaper<

Big old waste of money if you ask me when it comes to the 454 and a big heavy motorhome.
>Saving money is never a waste of time<

Bottom line is that unless you do a complete engine rebuild and mod, you just aren't going to get a whole lot of power out of these things...you'll never be able to accelerate up a 7% grade and reach the top at 90mph... :)rotflmao
>90mph! No this is not want I am looking for<

Seriously, the book Mark mentioned is invaluable, and worth the whole 7 bucks in the club store. 
>Great I do plan on getting it.<

As far as gas mileage goes, driving habits will make the biggest impact.  Keep it at or below 55, stay in the slow lane, take back roads when you can and go 40-45.  We get a pretty solid 8mpg at 55...and darn close to 10mpg at 40 if its an open back road without lights and traffic.  That is with a 35 foot rig, compartments full, and towing a Jeep.  By the way, if I push it at 65, my gas mileage drops to less than 6mpg!
>Yes I do plan on sticking to 55 to 60mph, besides being a good safe speed I can also draft Semi rigs<

[RockwoodMike]

My John Deere chassis motorhome has the Ford 460..I did do all the expensive stuff..Banks exhaust..MSD ignition..I installed a midrange RV cam designed for 1500 to 3500 rpm

I rebuilt the heads because it had so many broken off stud bolts, that I couldn't install the headers..rebuilt the carb..Installed scorpion roller rockers..The thing has gobs of power..merging onto the freeway is a breeze and it weighs at 14000 lbs with nothing on board!!..Before I did all that..just a touch over 6 mpg.. now..just a touch over 7..You just really can't increase millage and cruise the freeway at a decent speed (60 for me)..

The next thing I want to do is get the cruise control working again..maybe that will help some

Mike

[bluebird]

Mike, I can better the cruise control by 1 or 2 mpg with my foot. I used to try using the cruise but noticed on most uphill climbs the cruise just almost floors the throttle. On my currant coach, it unlocks the converter and down shifts to 3rd gear, significant decrease in mpg. I just keep a steady throttle, and let the coach slow some.

[Lefty]

The best thing you can do, and it's fairly cheap... is make sure the engine is in a top state of tune.

New plugs, gapped properly, and excellent quality. I prefer NGK personally, but nothing wrong with AC Delco's either (but be sure to check them at the store for loose porcelain at the base... that's a known problem with AC Delco's)
Platinum or multi gap plugs are only beneficial if the regular plugs are having trouble burning all the fuel in the cyl. In my experience they didn't give any difference in power or economy vs the original style plugs.

A premium quality Cap/Rotor combo. Echlin Gold is an excellent brand... as is MSD  Both have solid brass contacts, as well as a being made from a better grade of plastic than the standard el cheapo brands. Which will help them carry more current with less arc'ing.
A better HEI Coil will improve performance at the upper rpm range, improve overall mileage by burning the fuel better, and will usually result in faster starts and a smoother idle. Both Accell and MSD make excellent HEI coils that put out around 50k volts vs the original 35k
A good set of 8mm wires, equipped with High heat boots and heat shields (The fabric type are available from NAPA in pairs), to carry your new higher output voltage from your HEI to the plugs.
Buy an assortment of different diameter vacuum tubing... about 25-30' of each size to start.. and replace every single vacuum line on your engine one by one... This one thing will likely result in the best improvement in mileage and drivability.. as well as how smoothly the engine runs, over any other single change. You'd be amazed at how much a difference it can make. Rubber hoses are only good for about 5yrs. Most RV's here are approaching the 30yr mark.. and often are still running the original vacuum hoses. All the tiny leaks from all those hoses add up big time.
Check the timing, as well as make sure the dist. advance is working properly. Often the advance weights will get stuck, or the springs get weak. Either can result in a big loss in power due to a non-functioning advance.
Check the pre-heat damper assembly on the passenger side exhaust. If it sticks in the closed position it can restrict the exhaust flow.
Check your tire pressures... Under inflating can result in increased tire wear or excess heat.. causing tire failure. Also, under inflation increases rolling resistance, reducing fuel economy.
Grease your front wheel bearings, prop shaft U-joints, and check the rear end gear oil level. All can affect rolling resistance.
Check your fan clutch. If a fan clutch is not dis-engaging properly at highway speeds it can greatly reduce power and fuel mileage. Typically fan clutches should be replaced at around 50k miles... as the viscus fluid does lose viscocity over a period of time.. this is absolutely normal.
If your RV has O2 Sensors.. They should be replaced every 50k-60k miles. They are subject to high heat and carbon buildup... and do lose the ability to quickly sense changes in the air/fuel mix over time.

As for removing the smog pump, smog tubes, EGR valve, etc... You can remove the pump, get a shorter belt to bypass it (use string tied around everything routed like you want.. and subtract 1/2" to allow for the automatic tensioner) , then make a plate to go over the hole on the intake after removing the EGR. And install flare tube male plugs in the exhaust manifold where the original A.I.R. tubes were.
Whether it will help or not, or if it may result in drivability problems (usually knocking, pinging, and detonation problems) I can't tell. The problem is, Stock smog heads don't do very well when you remove/bypass all the emission stuff. They usually result in excessive combustion chamber temps, as well as very poor fuel burn characteristics. They actually need the additional fresh air from the smog pump and EGR to help keep the temperatures in check and prevent detonation. Most people who remove the smog stuff, also switch out the heads for an older non-smog , non-EGR style head. And also switch the camshaft for one with more lift/duration. Especially a dual profile cam that has more lift and duration on the exaust than the intake is especially effective on the 454 for maximum torque.

[ClydesdaleKevin]

LOL!  If you plan on driving 55-60, good luck drafting the semis...those guys drive FAST nowadays!  At 55mph on the highway they pass me like I'm standing still...with a big old wind push that scares the heck outta the wifey.


Kev

[Oz]

RE:  buying a dual snorkel air cleaner housing from Summit ->I can make one much cheaper<

I have to agree with that one.  You can get complete CIA set-ups too with dual snorkels but... they don't come anywhere close to the pre-requisite of "cheap" (unless you happen to be Donal Trump).

If you can make one - that's about the cheapest there is.  For someone who might not be able or wanting to do that, I think you'd be able to find one in a junkard pretty cheap.

[Madathlon]

LOL!  If you plan on driving 55-60, good luck drafting the semis...those guys drive FAST nowadays!  At 55mph on the highway they pass me like I'm standing still...with a big old wind push that scares the heck outta the wifey.


Kev

I dont know about out of California, but around here the highways are think with CHP and they loving nailing speeders in big rigs, So most around here tend to keep it around 60.

[Madathlon]

And thanks for the tips Im_Still-Lefty, Thats a will do and makes a lot of good sense