Are any of you considering building an "efficent" hot-rod?

That can't be true , there is friction loss / valve area / heat loss and many other factors that go into producing ponys.

 

Also, a 280HP engine moving an object that's 1 ton will use less fuel than one moving a 2 ton object...

 

Fresh469,

Henry Ford messed with a 5 cylinder engine as well- he was pretty tight-lipped about his experiments (hated to be embarrassed).

 

Ah yes, GM's Beemer 6 ripoff.

 

Ever driven an Audi 5? Ag-Ri-Cultural

 

Tell you what- I would have loved to see Henry's "X-4" get a little more R&D- would look great on the front of a Morgan 3 Wheeler type!

I have some pics at work- will try to post them in the morning (if prepping the 5th graders for commencement doesn't get in the way)

 

Dude yer graduating thats too cool

 

The key here is your last sentence, but the specific fuel (based on heat output) to produce X amount of HP is the MINIMUM - less efficient engines may require MORE than this amount to produce the same HP.

This is part of the above. It is true that a specific quantity of fuel has a specific amount of energy that can be transformed into heat and then into HP - there is a minimum amount of fuel required to generate a specific HP. However, most engines are not 100% efficient, so between engines producing the same amount of HP, some use less fuel than others to get there.

It depends. If it moves it at the same speed and is on a level surface in un-accellerated steady-state speed, it takes a specific HP to move a specific weight a specific speed. So you're doing apples & oranges. If you use ALL 280HP to move your 1 ton object and ALL 280HP to move your 2 ton object, you will use the same amount of fuel - the difference will be the speed you move them.

 

these modern engines are much more efficient at getting every bit of horsepower out of what fuel is being used. older engines tend to send more unburnt fuel out the tailpipe. thats fuel not being made into horsepower and like throwing money out the window. also you forget that a modern 6 cyl pushing the same horsepower is probably lighter,and won't have as much mass in the rotating assembly, bigger engines do take more fuel to produce the same horsepower. it's just physics. the smaller engines are just under a lot more stress. with modern fuel injection and computer control,this keeps them from falling apart.

 

Maybe the place to look for inspiration is 1950's sports racing cars. There was a whole class of 750-1000cc cars that looked really cool and went pretty quick. There were a whole group of American Hot Rod guys that took on the expensive European cars and often beat them. I would think that aerodynamics are very important to gas milage and those 50's racers were very aerodynamic and look great too. Not Traditional Hot Rods but I believe we could get some good ideas from looking at what those guys were doing back then and apply some of it to our cars.

 

Just to compare new and old technology, we race a Vintage Modifieds on oval tracks here and it costs roughly $10,000 to build up and old 250 I6 just to get 300 hp on the dyno. Now we are limited to a single carb aluminum intake but we have spent years perfecting to head porting. So a stock 4.2 at 280 hp could easily be bumped with a little experimenting. And as far as an I6 at 280hp and a V8 at 280hp using the same amount of fuel I would disagree. Any smaller or larger engine could be better than it's comparison, it all depends on it's efficiency.

 

Don't tell my wife and kids

Flat Ernie,

I stand corrected! Please forgive me- I'm a music teacher; we only get to count to 4, and then start all over again!

 

I am just wondering what will happen to all these 2mpg hot rods, when fuel gets to 10+$'s per gallon. Museum parkers I guess?

 

1986-7 Oldsmobile Aerotech

1988 Oldsmobile Aerotech

The 1988 Oldsmobile Aerotech, an experimental high-speed vehicle incorporating the latest in performance technology, was driven by three-time Indy 500 winner A.J. Foyt to a world closed-course speed record of 257mph (413 km/h). It was powered by a specially-prepared turbo-charged version of the Quad 4 engine. The Aerotech body was designed by GM Design staff and is one of the sleekest vehicles yet developed for a GM car division. The design of the Aerotech includes the capability of adjusting underbody sections to control the distribution of downforce, front to rear.

uh... that'd work... and i'll take the moon discs too!

 

I suspect they will still be driven. Maybe not as often, but they will be driven.

 

Theyll probably convert to Alcohol (so they can distill it themselves for something less than $4.00/ gallon) so it can be a 3/4 - 1 MPG rod.

 

Ok, some engines are more efficient than others (i.e., get more horsepower out of a given amount of gas, or to rephrase, use less energy in converting gas to usable energy) so, I'll ask again:

Is an overhead cam engine more efficient that an in-block?

Are twin cams more efficient that single cams?

Given equal displacement, is an engine with fewer cylinders more efficient than one with more? (that appears to have been answered to the affirmative)

Are higher compression engines more efficient than lower?

Are there any other characteristics that make an engine more efficient?

Thanks,

gary

 

ok, to the best of my understanding here are the problems with running a lean mixture: harder to ignite, burns hot enough to destroy internals, and less power. now, looking at some of the old aircraft racing engines you see water injection a lot--cools the charge to make it denser and also cools the engine. theoretically speaking, one could design an carb that would deliver from one half water and the other half fuel. at idle a lean mixture with high water content, tromp on it and water cuts out then dumps fuel, cruising it backs off of the fuel (then runs enough fuel to maintain speed but a lot of water). im thinking something for a test bed--moderate compression (9:1), beastly ignition setup, then four barrel to twin 2 barrel conversion (one fuel, one water). as for linkage setup... havent quite figured that part out yet... thoughts?

 

To answer part of your question it would come down to friction loss. there is also the issue of lifters at RPM with push rods . At 4000 RPM push rods might not make alot of difference. At 8000 RPM that config probably does not keep up so overhead cams are needed. Mind you i'm no expert but if the valves are controled by the cam why not have it by the valves rather then inblock? Either you use push rods or a chain/belt . You have rotating mass with a chain so there is loss there but valves dont close or operate at hi speed with the in motor cam. I think it depends on the application and what type of power your looking for. Brute HP derived from RPM or bottom end torque for plowing fields. Honda with its variable adjusting valve timing is the answer to both so in some ways you can say there is such thing as a free lunch. I would think it has to be more efficent if everyone is doing it.That tech must have been proven on the race track. I would say Higher compression engines are more efficient then one with lower compression . Here is why i think that .... Going back to the old air cooled 2 strokes say a 350cc of old compared to a more modern 350cc liquid colled , the newer ones make much much more power, Why? the tolerences atr closer due to the constant tempature of the engine. Colser tolerences mean more compression due to a tighter piston. Now one can say they are more efficient due to the heat loss , and that would also be true so you get better preformance all around. If you have a 350 ci V8 that makes 250 HP and 350 ci V8 that makes 300 HP due to higher compression it will preform better. Say it takes 250 HP to get the car / truck whatever to go 60 MPH in 10 seconds , well you would be full throtle using all the power at hand , compart that to the 300 HP car / truck [ all things being equil ] you use less throttle to get the same car / truck to the same speed in the same amount of time.

Look at the hot rod methods of produsing power . all help effenciency. closer tolerences / hi compression / rocker rollers to reduse friction / light weight rods/ pistons to reduce reciprocating mass [creating more PRMs making that pump more fuel / air therefore more HP ] anything you can do to lighted the moving parts and reduce friction will make more preformance.

I read alot of bike stuff and the HP gains overlap to any cumbustion engine , Every year the 600 cc bikes get stronger , to where you think they can't get more power from the same displacement, but they do. They test and test and find ways to reduce fristion bu removing a baring or some small minute way of finding 1 more pony. Smaller / lighter flywheel , a lighter gearbox or a way for polish the gears so they spin more free. Its a whole packedge when thinking making a vehicle more efficient , the entire driveline is in question because its getting power to the wheels .. Every moving part robs power . Wheel barings , U joints/ Lighter wheels and tires , an altenator . If it spins its making you slower. You will gain power and MPG to the wheels if you 1 reduce friction [ lighter oil . gear oil. rear end oil. Repack your wheel barings . Make sure your breaks arent touching the disc. Just think combination when thinking effiency. Wax your car, that alone will make it slip through the air better. Lighten everything. If your going to fab a part for a hot rod , make it out of alunimum. LOL i laugh to myself when i see the billet hating going on here cause the guys back in the day werent stupid , if they had CnC machines they for damn sure would have had billet everything on thier speed machines.
Swap that cast intake for an alunimum one , there goes the weight of a passenger practicly your carying around constantly. Alunimum wheels is probably the best thing you can do to help MPG .. 1 lb off the wheels is = to 4 off the chassis. Someone mentioned swiss cheeseing every thing .. good idea long as you do it and not compromising safty. In bike racing they cut the break discs to a minimum to reduce rotating mass or carbon discs if the rules allow. You have to not only think how can i make my engine work better but where else can make savings.

Rant over LOL .. Please keep in mind im no expert about engines you need to look no further then the race track and follow what they do to make the car / bike more effecient. Change your air filter !

 

After taking my 225ci slant-6 powered Essex for it's first decent highway run last week, it got 24 mpg (imperial). Not too bad for an engine that's been sitting for 20 years. Should be interesting what a decent tune-up will net it for both power and economy.

 

likes these guys says, making a car/ engine lighter gets u halfway there, reducing friction is probably the other half if you're not going to put the parts into an aerodynamic body shape. these modern all aluminum engines are the way to go, if u hate 4 cyl then ford has a new 3.5 v6 that makes 260 hp. personally, i don't have anything against the new 4 cyls - the ford zetec makes 165 hp when mildly tuned, and most of the dohc cam 4s sound great with the right exhaust system

 

Thanks for the reply. I don't have a problem with 4 cylinder engines. I've got 2 Turbo Coupe engines, 2 Chevy II engines, and 3 Pontiac 195 slant 4's sitting in the shed. Of the 3 types it would appear that the Ford would be more efficient, though not as good as something later.

I'll have to think about buying something vs using what I've got.

gary

*******

Wanted: blower manifold for Pontiac 195 slant 4 (not destined for a fuel efficient hot rod)

 

Yes, it's the whole package, a more stramlined rod would be better, lighter is better, lower the rolling resistance as much as you can, minimize drivetrain losses as much as possible. Gear the car to turn the engine within it's designed speed range. Don't gear it too low, or too high (cause it won't be economical with the power enrichment on). Then there's the engine.

More compression helps (to a point) not because of the effort to compress, but because of the amount you are able to expand the combustion volume to recover the power (before the exhaust vavle opens, 'dynamic expansion' for lack of a better term).

Reduced crevice volume helps (the nooks and crannies that the A/F can hide in and burn after you want it to). So use the smallest bore head gasket that won't overhang the bore (or the chamfer at the top). Moving the top ring further up the piston helps that too. Of course the further you move that up the more fragile the top ring land is, and "chunks 'o ring land" bouncing around in the cylinder are bad.

The so caled 'fast burn' chambers help, getting the mixture to be more homogenious is a good thing (both cylinder to cylinder and within each cylinder).

Reducing frictional losses helps, the newer, thinner and lower tension ring packages help, various coatings can help, tighter oil clearances so you can get away with the lightest synthetic oils, using the lowest possible volume oil pump that will do the job.

There are many more I am sure I am forgetting, but I believe the point I am after here is made. If you wish to find a used engine for an 'Eco Rod' these are helpfull.

If you wanted to build an engine, you reach a point of diminishing returns very quickly, how much fuel do you have to save before the custom pistons, custom gaskets, coatings, special cylinder head(s), etc would pay for themselves. If you were trying to achive really high mileage on the road some of these things are desireable, others make the engine fragile and tempramental (in a bad way).

 

ol' harley had it all figured out and gas turbine powered too.

 

BUT, There was not one piece of the entire engine that came from Oldsmobile in the the final version of the engine!!!!
Gemini EFI

 

As much as I'd love a V8 in my rod which will eventually get built I don't think there's any way I'd be able to afford to run it over here, the price at the pump goes up every time I fill up and it's expensive to run an efficient 1.4L car!
i was thinking maybe a 4 banger ford (Of which there are plenty in the UK) but just try to hide it, maybe keep the engine cover on, you can still get good power out of them but they don't sound as good.

 

I have always wondered about that (the running joke here was the paint on the block was the factory color, and that was the 'production base').

So not even the Rocketparts beefed up block or the crank forging blank or anything?

 

Wow. I was in my late teens when that car was all over the magazines. As my memory recalls, they sure made it sound like the car was powered by the same engine as the street cars. Smells of deception to me.

 

Not to totally change the subject, but is it inevitable that any conversation we have about about fuel efficiency and small motors always leads back to more hp? Sure, most tales end up going that way eventually, but.... I'm REALLY interested in a light car, no more than 200 factory stock / torquey horse power, trannys with a LOT of overdrive and having that in a drive-train package that is small and ultra-light weight, too. Gary

 

I want to build a hot rod motor that runs on manure. Then when I need a fill up I can just come to this thread