454 engine improvements for better mileage

[Brian P]

For what it's worth (ignoring power enrichment, which may or may not tilt the scales) an engine is more efficient at WOT than at any part throttle %, due to reduced pumping losses. This is the physics behind cylinder deactivation, small engines with turbos and Hypermilers who accelerate at WOT from very low to low/medium RPM and then coast.

Wide-open throttle but at whatever revs correspond to the power demand and with the torque converter locked so that it doesn't throw it all away as slippage.

My van has a modern engine and relatively modern automatic transmission. If an uphill starts getting steeper it will stay in top gear (6th) with the torque converter locked until full throttle in 6th with the converter locked doesn't deliver enough power, then it starts downshifting until it finds one that does deliver enough power. The torque converter is always locked in 6th and most of the time in 4th or 5th.

[garym]

Thanks for all the replies.At this point I am considering the COMP CAMS 11-238-3 cam with 218 int & 224 ex @.050 lift .504 int .510 ex 110 lobe sep.I was in hope that I could use the valve springs that are on the 454 motor now but in the Comp Cams catalog the stock valve springs can not be used and recommend the 911-16 valve springs.Also I assume I will have to get the spring spacers for the exhaust valves to replace the spring rotaters on the exhaust valves?The p/n4779-8 is for the spring spacers and I assume I will need just the 8 spacers for the exhaust.I have not taken the valve covers off as of yet but just trying to get an idea as to what to buy to hopefully get a little bit better mileage and driveability. THANKS garym

[ptuomov]

In terms of piston friction losses, here’s what Mahle’s experiments show move the needle the most:

Installation clearance
Piston skirt stiffness
Piston skirt roughness
Top ring width and tangential force
Piston pin offset
Piston profile
Tangential force oil ring
Piston skirt coating
Piston skirt area
Piston pin coating

For an 4-liter eight cylinder engine, looser installation clearances would be worth almost 3kW at 4000rpm. The cost is greater oil consumption.

[MadBill]

Assuming that list is in descending order of effect, a few surprises. (to me anyway..)

[ptuomov]

Assuming that list is in descending order of effect, a few surprises. (to me anyway..)

Here’s the summary graphic:

9B5D43D7-01D5-4868-BF76-53962CE3A2C6.jpeg

[MadBill]

An eye-opener; I would have guessed way less for skirt stiffness and roughness and more for skirt coating and oil ring.

[ptuomov]

There's an earlier edition of the book available on the web:

https://www.fsb.unizg.hr/miv/MSUI/KonMo ... r-2012.pdf

Chapter 7.3.3 starting on page 151. One interesting finding is that "spintron" style piston friction experiments give basically very misleading results about piston friction. The fired operation friction results can be very different, and obviously the more relevant for a running engine. The results are for a 2L turbo diesel, but qualitatively should carry over to gasoline engines for friction results.

"For low loads, the oil viscosity is the dominant influence factor. The piston installation clearance,
however, is the most significant design measure. The effects of skirt roughness, piston
pin offset, tangential load of the oil ring, and measures for the top ring are considered to be
about equal."

"In the high-load range, the oil viscosity loses significance. Installation clearance, however, is
still the most critical design parameter here. Optimization measures on the top ring and the
skirt surface also increase in significance at higher loads."

[Newold1]

Wear lighter shoes and not heavy boots when you drive so you wont be pressing so hard on that GAS PEDAL!

[Belgian1979]

Install a small block.

[mtmvette]

Use the smaller cam. Question answered.

[JoePorting]

I'd start with the ignition system and electrical system. Make sure both are in top condition.

[cjperformance]

What is the most common/average rpm range you use for cruise and heavy towing?

Do you know the compression ratio of your engine?

Exhaust length can be a killer in some of the long wheel base trucks with the exhaust extending right out the back. A system diameter that suits the hp range becomes restrictive over a long length and on the flipside a diameter too big is just lazy and restrictive due to long pipe with low velocity.
Get the exhaust diameter from collectors back right for the hp in your most used range, they may be smaller than you think, then use a chambered style muffler before the tailpipes then after a couple of feet step the pipe size up, or better still for this application step up a couple sizes and into a single tailpipe. We're not making a "max rpm" system here but a system to suit your average rpm/hp usage.
I always do tow/torque/low average hp use exhaust systems differently than hp orientated stuff.
And do not use a 4 into 1 paralell collector of for eg 3" then stepped down to say 2.5" for this type of use. Go for 4 into 1 with a choke which them steps up to system size or at least comes straight down to system size, or go for tri-y pipes which would be my chioce here. Im not sure what you have available?, but if going for off the shelf stuff chase down some pipes with small primaries.

I would most likely use a 650 carb rather than 750 here , for the hp you will be making a 750 will do nothing to help your cruise economy and probably nothing *once we know your average rpm use* for pulling either. I agree with the edelbrock carb choice, id also go for the new annular booster 650 version. Ive only used 1 so far (lots of reg booster eddys) but i really like them.

Dont go for too much exhaust duration on a wide lsa as you don't need that exhaust valve opening too early and wasting some leftover cylinder pressure that can still be used as tq, but you do want enough exhaust gas left later in the cycle to give you plenty of exhaust velocity to allow the short overlap period to work for you in your used rpm area. The big durarion exhaust will max rpm better but thats not what you need for this type of use.

[rfoll]

I would be willing to bet that a well prepared 400 small block would be a big improvement over the stock 454. Also, I have never heard of anyone using the Edelbrock or an AFB and getting better gas mileage unless the existing carb is messed up. You stock carb, likely one of the 800 cfm units, will be better if you tune it.