89WS-6

I was wondering if you could get 40 mpg out of a sbc V8 in our beloved thirdgen cars. Here is my idea. What kind of gas mileage do you think it could hit?

305 TPI with T-56 and 2.73 in rear!!!
Maybe some roller rockers, K&N, but not cold air, maybe a borla muffler, hi-flow cat, probably some 225/60 tires, a little less weight maybe, no wing.

What do yall think? Could it hit 40mpg, or maybe more. Has anyone seen 40mog or more in their car, but not necessarily had this setup. Thanks guys.

TekViper

i dont think its possible without making the engine run like a 4 banger and driving it extremely easy. even then it might be difficult to do. maybe have two computer setups that u could easily change? extremely gas efficient but slow during the week, but on the weekend you could flip a switch to use another setup ?

89WS-6

Well thats a good point, but I would have to disagree, I read a while back on this site, a couple of people that hit 30 mpg in their 305 TBI 5 speeds. So I figured if you built a car to run on the highway at like 1200 rpm's (T-56 mated to 2.73) and did the other things I mentioned, then it might be possible. Thanks for rersponding though.

firedawg225

i had about that combo and i only get around 30 on the higway if i'm lucky thats with cruse on. and thats with a 700r4

Soft Taco2

its very possible, just put the smallest injectors you can find, and lower your fuel pressure alot. It will probably put you at around 50hp, but im sure you could make 40mpg.

89WS-6

Thats cool, well I might do this in the future, because my mom wants a toyota prius, and we all know how illegal that is. So I told her I bet we could get 40 mpg, and then turn around and spank some things as well. :d Hee hee, well see what happens. I used the third gen equations and figured out with normal tires, you could be at 1300 rpm's on the highway with a T-56 and 2.73. :d That is insane. I mean thats loads better than my already considered low 2000 on the highway. Anyways, thanks guys.

92 zzz28

I used to get about 30 mpg with my 305 TPI and 5spd combo. The only mods to it were free mods with the exception of a straight pipe in place of the cat. I had some lame *** exhaust on it when I bought the car, no muffler; but it did sound pretty throaty.

I don't think you are going to get that kinda gas mileage out of a V8. I don't think it is impossible, just not very likely. Right now I would be happy with 18mpg...

Vader

I would guess that the right combination of weight shaving, tires, gears, and tuning would make a peak mileage of 40 possible. I'd also think that tuning and adjusting for a sustained 40 MPG under driving conditions would require a lot of effort and modification.

If my memory is any good at all, I believe Glenn91L98GTA was getting a sustained 30 MPG in highway driving on his ThirdGen with a fairly stock setup and a lot of PROM tuning. You may be able to substantiate that with a search.

FruityOne

I dunno about 40mpg, but 30mpg is entirely possibly. Last friday 9d1burd and I drove out to indiana to meet with a few people. While it was about 120 miles of highway and about 40 miles of residential driving I still managed a respectable 25mpg. Not bad I'd say. I still have other issues to work out, but I'm sure I could improve that to about 28mpg with some prom tuning.

Jim85IROC

iTrader: (2)

Just keep in mind that 2.73s and a .5 overdrive gear (t56) won't do you any good if your motor can't push the car with such a small mechanical advantage. Even my Vette isn't really all that useful under ~55 in 6th gear with the 3.54 gears. I can go down under 50, but you've got to put your foot into it for it to have the power to keep going, so you're not getting any kind of milage benefit.

I would suspect that the only way a relatively stock 305 is going to work well with a T56 and 2.73s would be near the peak torque range, i.e. over 3,000 rpm. I'm too lazy to do the gear calculations, but I suspect that there's nowhere in the country where those speeds will be legal.

Viprklr

iTrader: (5)

Jim85IROC pm or email me. your mailbox is full.

My90Iroc

I agree totally, there's no way you're gonna be able to drive a car at 1300 rpm and like it (unless you convert to a diesel motor of course ). My T5 with 3.08's doesn't even like 5th gear until about 60. I'm willing to say going for 40mpg will not be at all worth the effort, besides your sig. say there's a 388 vortec stroker soon to come, focus on that

Kingtal0n

There are a million gazillion things that affect fuel economy, and even if every single one was absolutelly perfect and with everything absolutelly TUNED and SETUP For Fuel economy on the highway, it would still be hard to say.

weight and BSFC (engine efficiency) have a lot more to do with fuel economy than RPMS On the highway. also, the amount of force it taking to keep the car moving is a big factor too (wind resistance, tire pressure, bearing conditions etc...)

an engine that cruises in its peak torque area will have the best BSFC i am told by crossfire, and having that at a very low RPM can mean cruising with a very fuel efficient gearing setup.

Dropping the car and shaving doorhandles and mirrors can help.
Weight is a huge issue. if you can shave 500 or more Lbs you can not only make the car faster it will get much better fuel economy.

HP output is directly related to fuel consumption. the less HP your motor has to make to keep the car moving the less fuel it will use.
Having valve timing / spark timing events tuned PERFECTLY to completelly burn and USE the entire air/fuel mixture will help alot too.

having perfect fuel atomazation (HIGH PSI / Small Injectors / High vacuum) will help a ton too.

Ive been trying to squeek 20 MPG out of my blown / TBI camaro. its not easy. i started around 12 MPG and im up to 19 now, im shooting for 25 if i can. playing with the timing and a/f ratio and swapping a more mild cam got me from 12 to 19 as it is. I suspect i may need to change tire diameter a bit to bring the motor down and cool the inlet charge and run the motor a bit cooler so i can use more timing / less fuel. working on it....

and all of this is just a longer version of what VADER already said.

92blue

iTrader: (1)

I got 31 mpg over a two hour road trip when I had 2.73s with my 6 spd. I had cruise control on most of the way at about 65 mph. The car would not accelerate for ****, but it could hold its speed. Funny enough, in the city I would get about 11 to 12 mpg. Now with 3.73s, I am getting 12 to 13 mpg in the city. I have no clue about the highway, I haven't had to do any long distance driving so that I can get an accurate mpg measure. I can actually pass a car in 6th now without having to downshift.

SSC

250 inline, in perfect tune, with the correct componets behind it could get fairly close to 32 in city if you granny it. Who's going to pop an inline infront of thier 6 speed to test it?

Ive seen some setups on SUV's where people put lawn mower carbs inline and claim 60MPG.

92 zzz28

I bet your highway mileage will stay about the same, depending on what rpm range you cruise in. If you go a little slower and stay in the same range as before your gear swap, you should be the same. If you go higher you may lose a point or two, no biggie though. I wish I had a 6spd. That comes later...

8Mike9

That's about as relevant as saying a Civic get 42 on the highway or a Metro 50.

Ace_Murdock

what about going into the computer and sequentially shutting off injectors while you are cruising. kinda like the displacement on demand crap that are on some of those new fangled prototype engines. you cant really shut down the valves and keep them closed, but you can cut off the flow of fuel to the cylinders.

if you do this, just make sure to cycle through the cylinders so that some dont get cold, you don't want a cold cylinder.

now if you really wanted to get deep into thermodynamic processes and zee otto cycle.....

i am reading a book called "introduction to internal combustion engines". in it they talk about the really gigantic ship engines being really efficient because A) they have a really long stroke and slow rpms that allow for a more complete combustion process. B) the increase in size of an engine can increase the efficiency of it because of lower heat losses through the block and heads; and mechanical losses in the bearings and rings.

it is odd, but to get more efficiency you want to have as much heat in the combustion chamber before the spark happens. the more heat, the more work that the cylinder can do. Increasing compression ratio also makes the engine more efficient. infact you can calculate the thermodynamic efficiency of an engine based solely on the compression ratio.

why not try coating the piston faces and combustion chambers with ceramic coatings. can tuned headers like those on snowmobiles that have the expansion chambers on them help in this application? i would also have to say get roller bearings on the camshaft, and put roller bearings on all of the journal bearings in the engine. polish the livin' daylights out of everything that contacts the incoming air charge and exhaust.

will an ingnition upgrade help?

i betcha there is more,
just my .02

andrew

92 zzz28

What's odd about that. Heat is precisely what makes an engine work. When approx. 2/3 of the heat produced by an engines is lost through the exhaust and disapation, it is odd that we as consumers still rely so heavily on it for basic transportation. Internal combustion engines are horribly inefficient by design. Engineers and designers do what they can and we in the aftermarket and tuning world also do what we can to make them more efficient. Unfortunatley, until someone can make the engine run at more than a 1/3 thermal efficiency we will have to be happy with whatever we can squeeze out of them. I think I read that book you mentioned, very good read if I recall correctly.

Kingtal0n

but heat can also damage engine parts. once you get so hot bad things start to happen.

if you keep the thing cold as crap and rely heavilly on just cylinder pressure (which is what we are after to make torque anyways) then you can get more power out of the motor. but that doesnt mean its getting better fuel economy. it just means it puts more to wheels.

so there are good and bads about both sides when dealing with temps. in an engine.

89WS-6

You are exactly correct about that. I mean internl combustion engines are incrediblly interesting, and also, are getting more and more advanced as days go by, but it still sits that they are pretty inefficient. Kinda sucks.

DartByU

Anyone read about the ceramic engines being developed? The blocks are made of ceramic material. But I'm sure it will be awhile before we see these in production, I pulled this off another site:

A new ceramic material has recently become available. The material is silicon in the form of Si2.Silicon is one of the most abundant elements on earth. Silicon technology has already come of age: the material is used in glass, transistors, turbine blades. It is ideal for internal combustion engines because:
• it does not melt easily even at high temperature
• it has a low friction coefficient
• it has a low expansion coefficient
• it has low thermal conductivity
• it is extremely hard
• it is relatively light
• it does not corrode

These properties, although desired for an engine, mean that the material is difficult to work with.

Si2 is similar in appearance to the ferrite known by electronic engineers for making transformers. When it has been worked into an engine block it is dark-gray with a surface that feels as smooth as wet soap to the touch.
The (patented) process of working the extremely hard material is similar to that of making a ferrite transformer. Si2 powder is compressed at high pressure, sintered and cured. This is the time-consuming part of the manufacture, although not very labour-intensive.
The engine block is bored with a vibrating diamond drill: also a patented process. This takes all of 15 seconds, which compares well with working a metal engine block. The accuracy of the drilling process is 2 micron, the free play between piston and cylinder is the same size. This means that piston rings are unnecessary and indeed unwanted, and new piston shapes can be tried.

Some properties of the ceramic engine:
• no lubrication
• no cooling
• +150 % more power
• neglegible wear and tear
• -75% lower fuel consumption
• no pollution
• -50% less weight for same physical size (which means -80% for same power output)

Incredible? Let's put it into words.
We have an engine here that has 2.5 times the power of a metal engine of the same size using 1/4 of the fuel. It never uses oil or water and will run almost forever without servicing.
During its lifetime it will cause no pollution except minimal CO2 emission: nitrous oxide and other polutants are not measurable.
To top it all the engine reaches operating temperature in seconds after startup, again minimizing transient polllution.

With these characteristics it must be very expensive, right?

Cost As silicon is abundant, the basic material cost is low.
Working the material is more expensive than working metal. Instead of melting and casting a process of pressurising powder, sintering and curing is used, which takes time.
After that, boring and finishing is easier and faster for the ceramic engine than for a metal one.
For the final finished product the ceramic engine has the advantage again as there are no radiator, fans, pipes and pumps to be installed.
The result?
An engine that is 25% cheaper to manufacture than a metal engine of the same size with 60% less power.
Note however that the price of the engine is only the minor part of a car price: an advanced engine like that of a BMW328 costs about $1500 ...

Status: A batch of 10 ceramic engines of 1 liter (61 cubic inch), 400 kW (500 horses) capacity has been running a traffic simulation test program, including (German) highway driving at full speed for 10 hours.
The longest-running engine is now going for 20,000 hours without signs of wear and tear. This translates to about 2,000,000 km ( 1,200,000 miles) of average driving without servicing.

92 zzz28

Ceramic materials will do wonders for internal combustion engines. I for one would love more efficiency, better mileage, and virtually no wear and tear in an engine. Top that off with little to no maintainence and how do you lose. Well, the aftermarket parts suppliers may not like it to much, but the consumers will love it. I wonder though how long it would be before we start to see ceramic engines in readily available cars.

Ace_Murdock

what i meant about being "odd" was about them mentioning of cold air intakes and then the whole having as high of a temperature as possible before ignition, that is all i meant.

yes Kingalon you bring up a very good point. on paper you can "design" a "perfect" engine running 1,000,000 to 1 compression, runs at 5,000 degrees. on paper it is possible, but i cant think of too many materials that can handle these loads, well maybe nonobtanium.

you have to remember that engineers can design the best damn engine in the world....in a test chamber. now the problem is not with the design but how do you mass produce this engine in such a way that it is cheap and very little scrap. you can have the best design but if it is too expensive, the bean counters up top will tell you to find another way to save a nickel or two. now a nickel may not seem like a whole lot, but if you look at the production scale...a nickel a car for, well, a lot of cars can add up.

now the problem with GM is that it is run by Accountants. Dodge is primarily run by Engineers, could this explain some of their financial problems in the past?

why didn't chevy run with nice high quality forged pistons instead of the cast ones......cost. same with the powder metalurgy connecting rods. and the same goes for the cranks. that is why stock sucks. GM also has to contend with the tree huggin hippies, EPA, CARB, legislation and whatnot, not only do engineers have to design an engine that can meet standards but can be mass produced. Engineering is tough, and not everybody can do it.

there are engines out there that run something like 5 Mw generators that can get close to 60% efficiency, don't quote me on that. but of course these generators will have turbochargers on them using up excess heat in the exhaust.

the internal combustion engine is an extremely good design. in the bottom rotating assembly how many moving parts are there? the fact of the good design also comes through with the fact that no incredibly major improvements have been made to the basic design (connecting rod, crankshaft and piston). those three things are in every four stroke engine (rotary excluded of course). I mean what basic types of heat engines can you choose from, not too many.

Vader

The ultimate driving machine will have a servomotor at each wheel, acting as both an acceleration and braking device. Acceleration will be instantaneous, with up to 600% rated torque at 0 RPM, and speed limits that are incredibly high. Braking will be a regenerative process that will recharge the electrical system. The servomotors will also be controlled for adaptive traction control, steering assist without the need for a pump (by speeding or slowing opposing wheels for steering assist) and antilock/antiskid stopping by regulation of the braking effect and applicatrion of traction of various wheels. Those same servomotors are available today from Kollmorgen, Fanuc, Reliance, and several other common manufacturers. The big hangup is the power supply, since batteries are so heavy. If anyone has seen GM's latest development project, they aren't too far away on that one, either. Our quaint little piston engines are destined to become relics in the near future, and won't stand a chance against these technologically superior and more efficient systems. GM showed off their running prototype abput two months ago.

Ace_Murdock

yeah i remember seeing that concept car in a magazine somewhere.

the problem is the whole needing electricity. Given the time batterys will definately be able to hold enough charge. there is a demand for it.

now the problem isn't quite with the batterys in my view. the problem is where will you get the electricity to charge up those batterys with? I honestly don't think we have the nessesary infrastructure for every citizen to own an electric car. think about it, if you are going to charge up a high capacity battery you need alot of electricity. now it is okay when just one person does it, but what happens when a couple of thousand people charge their cars at the same time. in the summer cities already have rolling black outs because their power network cannot supply the demand of airconditioning. can you imagine the needed increase in nuclear power plants and power lines? i sure cant.

i think the solution is a hybrid vehicle. the motors on each wheel is an excellent idea. i think the better power source would be a turbine engine coupled to a generator. turbine engines are great for making power at a constant RPM, and they are very efficient. we dont' see them in cars today because they don't like to have their RPMs changed for nessesary driving conditions.

what else is nice about turbines is that they can practically run on almost any fuel. i betcha if there was a turbine large enough, i mean really gigantic, it could burn imports as its fuel. maybe not imports, but definately R i c e as in the food, even corn kernels. make the turbine big enough you could throw trees into it, well maybe you would want to pulverize them first. you could run the turbines off of methane created from decomposing waste in our sewers, infact there are powerplants out there that do that.

tubines that big wouldn't fit on cars. tubines still require fuel to run. as we all know fossil fuels are a non-renewable resource, and we are running out. the solution is to find ways to make fuel renewable. we already can do this. corn when distilled will make moonshine and ethyl alcohol which already is in most of our gasolines. i think we could easily grow enough corn to sustain our needs. If we cant, there is another crop that can produce a bio-diesel, hemp. yes hemp can grown and distilled then easily pumped into a diesel powered car. I believe you can do this with few if any modifacations to the engine. I remember reading a story about this.

what is nice about keeping a liquid fuel source is that we already have a supply system that would not have to be altered to meet the demand created. if we go to electricity billions if not trillions of dollars must be spent on making a supply system. this means everything from powerplants down to the wiring in our houses will need to be made much much larger. there is a lot of stuff that needs to be done before electricty can be the only power source in cars.

yes vader, piston engines will probably soon be replaced by something. i still think piston engined cars will still be zooming around our streets for quite some time, A) because of the phase in time and B) for a long time there will be true hot rodders out there modifying small block chevys probably for another couple of decades. and there will still be guys with ******s out driving around in third-gens

later

andrew

Jokerman

Well 40mpg maybe, maybe not, 35 could probably be reached without sacrificeing power and with out anything radical just some creative prom tuning, a good tune up, weight savings some careful gear and tire selection and a good light foot and you could be there. I mean my Rs gets around 26mpg running between 70-105mph on the drive from home to chicago (420 mile trip) so i think a bit slower and such and you could get 35, maybe more.

BluEyes

they're not prototypes - Mercedes and GM are producing them for the '03 or '04 year.
Actually, they're going BACK into production. GM first tried it in the early 80's, and it failed miserably back then - probably bad electronics and stuff. Thesedays, with the all the advances in computers and electromics, they should work great.

I wonder if you could do what you describe with shutting off injectors though? Probably use circutry similar to the 'soft touch' rev limiters that randomly shut off spark to one cylinder to keep the RPM under the limit, but use it on the injectors. It just might work...
I wonder if it would cause engine vibration, though?

Also, it's not odd that we use cold air intakes when heat is power. Because it's the change in temp that makes power. Take in cold air, and you have more air molecules in the cylinder. Compress them (higher CR possible with cold air intake) and then burn the gas and really heat them up, and more air molecules expand to a greater final volume than if we had hot air intake, thus more pressure on the piston.

Jproz1167

iTrader: (3)

Hoist up some sails, that should do the trick. and imagine cruise by a tornado and you could dust off anything

Ace_Murdock

you just turn off the injectors in the proper timing. so that the engine will still run smoothly. i think you could fire every third cylinder and keep a relatively smooth running engine and still be able to easily cycle through the cylinders, every third will automatically do this.

normal ====> 1-2-3-4-5-6-7-8
every third==> 1-4-7-2-5-8-3-6-1....and so on and so on

pump up your tires too. replace your wheel bearings. make sure the brakes are not dragging. get lighter wheels and tires, isn't rotational mass a 4th power type physics problem?

92blue

iTrader: (1)

I think I read some where in an old post that Cadillac produced a system that ran on 4 cylinders under 1/3 throttle, 6 up to 2/3 throttle, and on all 8 past 2/3 throttle. Or atleast something along those lines, I don't know the specifics. I believe this was sometime around the 80s. I do remember that it was only in production for one year, as the system failed miserably.

92 zzz28

It sounds like a good idea to turn off injectors to help achieve gas mileage while cruising. I am curious how though. How can an individual injector be shut off in a batch fire system? I don't know...

Doward

It can't. It'd have to be a SFI setup.

You want 40mpg? Get a Civic.

You want fun? Drop in a 383.

You want a combo of the two? Get a turbo 4 or 6 cylinder.

Turbo only uses more fuel when you drop the hammer. Cruising, you're running normal 4 or 6 cylinder economy.

FruityOne

Vader, I remember doing research into this topic for an automotive class in high school. Problem then was the same as it is now. No real, economical way to meet the energy demand. Infrastruction problems, as well as the weight of the batteries to contend with.

I'm really looking forward to the day when hydrogen, and propane fuel cells become cost effective solutions to our transporation woes.

I recently read an article that focused on propane fuel cells, and how they were making good strides with them. Stuff like this has been around for a while though. The shuttle uses a fuel cell similar to this. It seperates water into O2 and Hydrogen, the by product gets turned back into water that they use for drinking. It also helps to supply power to the onboard electronics.

BTW, who's up for chasing a short in the shuttles systems..^_^

Ace_Murdock

if i remeber right, fuel cells dont really get good efficiency at splitting. and if i remember correctly you need energy to split the fuel into o2 and h2.

if i were a betting man, i think i would place money on finding ways to come up with bio-fuels. i think we have the resources to do so right now, there is just no demand for it right now.

what else is nice about finding a way to make bio-fuel is that you could probably come up with a formula that can fuel existing cars. if that is possible people can still drive around with their existing cars. it is a win win situation

i remember hearing stories of distilleries around my house making 3,000 gallons of moonshine a day during prohibition. and those were just in one barn.

now if everybody didn't drive those damn suv's and trucks

BluEyes

ah, but you could, just not through the ECU. Each injector has a seperate set of wires running to it, right? Just rig up something (you'd have to be good at electronics and stuff here) that takes a feed from the tach, and controlls an interrupt relay (the relay would have to break the circuit when voltage is applied) or something that is wired to each injector. Then just send voltage to the proper relay at the proper time. Just because the ECU sends a 'fire' command to each bank at a time, doesn't mean each injector has to revieve that command

As for Caddy - yes, they did that in the early 80's. It sucked back then. (see my earlier post) I believe besides shutting down the injector, they also rigged a switch in the oil passageway to collapse the lifters (special lifters to collapse fully) to the cylinders that were being shut down.

92 zzz28

I thought of that too, it just seems to me that there is a lot of room for error. However, if set up properly and used at the right times, I think the person would see a noticable improvement in highway gas mileage.

BluEyes

yeah, it would be tough - you'd have to get it all timed right with the distributor I guess.
Probably more trouble than it's worth!

Now, maybe shut down one bank, and run only four cylinders? On a carb'd car, you could make a way to block off one side of the dual plane intake?

92 zzz28

I just had a revelation. We should all drive Honda Insights to get around to work and just running errands. That way there will be plenty of gas for our "toy" cars. Then none of have to worry about only getting 12 mpg and running out of gas on long stretch of highway!!!

82camaro

Shuting off the fuel to an injector isn't going to help. Why? The other cylinders still have to 'drag' that cylinder along. Without holding the valves open on the compression stroke, the other cylinders will compress the air in that cylinder for no reason--wasting energy. All of that is the opposite of efficiency. You need to run the engine as lean as possible at cruise rpm and that rpm needs to be at the highest vacuum possible. Back in the day, some cars used to have 'ecomony' guages--basicly a vacuum guage. For peak mileage you had to stay in the 'green'. 40mpg v8, sure it can be done. Probably need to be a really small version of the LS1, eco cam, and lean running(custom chip). Not what I would call a powerhouse.

rx7speed

even the rotary hasn't had too many changes (excluding renesis) major changes involve apex seals (your piston rings) and location of intake ports, as well as an oil seal fix.

thats about it for some of the major ones
but it lacks thermoefficiency that a piston motor has.
surface to volume ratio on a rotary motor is horrible plus you tend to get a little more blowby into the next combustion chamber or down into where the eccentric shaft (your crank shaft) sits.....

though if I remember right the motor is very good at limiting pumping loss through the system. unlike your piston motor there is no valves to get in the way, no major bends to get around, no humps where the valve enters the head, and with the constant rotating motion of the combustion chamber I would think it would induce a lot of turb inside there to produce a nice flame front.... but still you would have issues with blowby and thermoefficiency

Morley

What you are asking should be quite possible to achieve. Back in the late 80's early 90's Carcraft ran a competition called "Street Car Shootout" where you applied to be in it and were invited to bring your car and compete. There were several catagories, the 1/4 mile run, handling, ride and drive and show and shine to name a few. In one year a guy entered with an 89 T/A, he took the 1/4 mile, handling, show and shine and the ride and drive. In the ride and drive he got a whopping 35 MPG from a car that ran 12's the day before in the 1/4.
Careful selection of parts and meticulous prom tuning should get you there or very close to 40 mpg, that and keeping your foot out of it while driving.

BluEyes

but, then once the air in the cylinder is compressed, it will exert an equal downward force on the piston during the ignition stroke - just like how the forces from valvesprings all cancel out. Energy put into compressing the spring are returned when the spring is released.
The OEM's are doing the same - when the cylinder is shut down, both valves are closed, and the air within is just compressed and expanded in a continual cycle.