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3 inch stroke motor project, rod ratio, and mpg

32K views 184 replies 21 participants last post by  4 Jaw Chuck 
#1 ·
my name is Austin, and this is my first real post on here. I hope it doesn't make you guys think I am nuts or have a screw loose. Any ways I have a couple of questions that you guys can help with. I have acquired for a song 2 283 motors, a 327 small journal motor and a 307 from craigslist. These things go super cheap here in Louisville and I know why. It's because everybody wants big cubes to get the power way down low in the rpm range. Anyways, I have been reading about how all the people on here are very much against using these motors in a full size car, and I dont mean in drag racing, but even just a daily driver. I don't mind that I wont win any land speed records thats not what Im looking to do. I just want to get better fuel economy, I cant afford the gas. So here are my questions: #1 If I get 6 inch rods and mate them to stock 350 chevy pistons in that 327 block and hook them to the 283 crank, would that work? #2 Compression height calculator shows about .040 higher in the bore with them, but dropping from a 3.48 stroke of a 350 to a 3 inch stroke is gonna lose alot of compression so is +040 closer to the heads too much? #3 In my mind, rod ratio increases dwell time at tdc so I can run less ignition advance and still burn all the fuel and the same with compression ratio up to a point correct? I would like 11:1 static compression, I think if I watch how much ignition timing I am running it will get better gas mileage especially since I have a huge radiator to keep the heads cool. #4 If nobody thinks a 3 inch stroke is good enough to be in a heavy car then why did gm put them in the 1957 chevy and lots of other heavy vehicles like trucks studebakers and checker taxi cabs until 1968? #5 According to wiki the 327 was the most powerful small block combo ever made until the LS6 in 2001. Even the paltry 307 managed 200 hp (149 kW) SAE gross at 4600 rpm and 300 lb�ft (407 N�m) of torque at 2400 rpm. http://en.wikipedia.org/wiki/Chevrolet_small-block_engine The question is, with the short deck height of the small block, is any more stroke than 3.25" really helping peak power at all, and is more stroke actually hurting fuel economy do to rod ratio? The main question is will 350 pistons work in my 327 with 6 inch rods and 283 crank. Thank you for reading, Austin
 
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#77 · (Edited)
Dirty Biker said:
my name is Austin, and this is my first real post on here. I hope it doesn't make you guys think I am nuts or have a screw loose. Any ways I have a couple of questions that you guys can help with. I have acquired for a song 2 283 motors, a 327 small journal motor and a 307 from craigslist. These things go super cheap here in Louisville and I know why. It's because everybody wants big cubes to get the power way down low in the rpm range. Anyways, I have been reading about how all the people on here are very much against using these motors in a full size car, and I dont mean in drag racing, but even just a daily driver. I don't mind that I wont win any land speed records thats not what Im looking to do. I just want to get better fuel economy, I cant afford the gas. So here are my questions: #1 If I get 6 inch rods and mate them to stock 350 chevy pistons in that 327 block and hook them to the 283 crank, would that work? #2 Compression height calculator shows about .040 higher in the bore with them, but dropping from a 3.48 stroke of a 350 to a 3 inch stroke is gonna lose alot of compression so is +040 closer to the heads too much? #3 In my mind, rod ratio increases dwell time at tdc so I can run less ignition advance and still burn all the fuel and the same with compression ratio up to a point correct? I would like 11:1 static compression, I think if I watch how much ignition timing I am running it will get better gas mileage especially since I have a huge radiator to keep the heads cool. #4 If nobody thinks a 3 inch stroke is good enough to be in a heavy car then why did gm put them in the 1957 chevy and lots of other heavy vehicles like trucks studebakers and checker taxi cabs until 1968? #5 According to wiki the 327 was the most powerful small block combo ever made until the LS6 in 2001. Even the paltry 307 managed 200 hp (149 kW) SAE gross at 4600 rpm and 300 lb�ft (407 N�m) of torque at 2400 rpm. http://en.wikipedia.org/wiki/Chevrolet_small-block_engine The question is, with the short deck height of the small block, is any more stroke than 3.25" really helping peak power at all, and is more stroke actually hurting fuel economy do to rod ratio? The main question is will 350 pistons work in my 327 with 6 inch rods and 283 crank. Thank you for reading, Austin
In 1957 there weren't any interstate highways other than a few Turnpikes like the Pennsylvania and Ohio. The average speed on two lanes while posted 55 or 60 was closer to 45-50 if that as you moved from town to town and stoplight to stoplight. So bigger engines just weren't required and actually considered dangerous by the manufacturers themselves. All that got lost in the 1960's, especially as the interstates spread across the land making sustained high speed travel possible. Technically there were significant problems, these cars rolled on bias ply tires and stopped with 4 wheel drum brakes, most likely unassisted. Power assist brakes and steering were extra cost options that most vehicles didn't have. Same for air conditioning, even in the desert southwest where I grew up, it was very, very rare especially on cars other than Caddies, Lincolns, and Imperials. So much of the car just wasn't designed for sustained high speed travel and the power extraction for accessories was a lot less so huge engines just weren't needed and the perception of performance was a lot lower. The adults of the era grew up with flat head engines, cotton cord tires, and in some cases mechanically (cable like your emergency brake, but this was the service system for each wheel) applied drum brakes. How bad were drum brakes even with assisted hydraulics the original GTO could not be emergency stopped from its top speed with the 389 V8. At the other extreme neither could the Ford Falcon with it's tiny I6. Add to that tire failure was common, with blowouts even with rayon that came between cotton and nylon cords time wise. Tires also formed bubbles in the side wall where the bond between the cords failed allowing air leaked thru the cord structure but not yet thru the outer layer of rubber. So these things would develop large bubbles or bulges usually in the sidewall but also in the tread. The technology of highways and auto systems started to come fast in the mid 60's with nylon cord tires, bias belted tires, and disk brakes. Little things like man-made rubber began to replace leather for seals doing a much better job of keeping wheel bearing grease in place as well as sealing up engines, transmissions and differentials which tended to gush oil on the roadway and certainly parking places. Wheel bearing failure was very common, you had to be careful to pack those bearings at least once a year, and if you missed the schedule you could count on their failure in the not too distant future. These technical improvements that came in the very late 1950s thru the 1960s made the muscle car era possible. In 1957 getting and engine to 100,000 miles was an amazing event, most engines of the era would see a valve job around 50,000 and rings at 70,000 and be junked by 100,000. Tune ups to replace plugs, points, and condenser were something done about twice a year; with a point adjustment monthly, regapping and cleaning the plugs every-other month and a chassis lube about every 1000 miles, especially those new fangled ball joints. That's the reason why there was a gas station or garage on every corner and the average guy had to become car savvy because it took a lot of continuous work to keep 'em running.

The preceding era up thru the late 50's was an era of technical problems people don't even think about today, let alone know about, unless you lived during those times.


Bogie.
 
#78 ·
Dirty Biker said:
Also you said:
"People who talk about torque don't realize what actually moves the car- power."

You mean like horsepower? No offense Turbolover, but I think you have that backwards.
No, I don't have it backwards, but MOST people do. Power is what counts, but you need the gearing to use it. Even the OEMs realized that which is wh you could get a S10 with a 2.2L with 4.10 gears or a 4.3L with 3.23's. Ford did the same thing.
 
#79 ·
turbolover said:
No, I don't have it backwards, but MOST people do. Power is what counts, but you need the gearing to use it. Even the OEMs realized that which is wh you could get a S10 with a 2.2L with 4.10 gears or a 4.3L with 3.23's. Ford did the same thing.
I would agree with that, its pretty hard to describe an object moving from one place to another with a number that only describes torque!

K
 
#80 ·
mileage

I've been thinking of building a 267, good blueprint n balance work, good quench, small RV cam, cleaned up ports, keep the small valves, TPI, 700 r4, Think I might get 26mpg in a Studebaker lark, and have reasonable power. Maybe 23 in a 90s half ton?
I never got excellent mileage with the 3" stroke.
 
#81 · (Edited)
Dirty Biker said:
I agree with the turbo diesel 100% Turbolover, thats what Im working towards. you said: "smaller bores allow for better air, fuel and ignition control, but the 283 will have a higher percentage of parasitic losses." Parasitic losses from what out of curiousity? Theres alot of factors involved, sure, but in stock form in your thoughts, which is a 400? more of a really efficient engine with low peak power or a really powerful but inefficient engine? What about the 283? In my mind they are kinda opposite right? How many ft/lbs of torque and how many horse power does a stock 400 make out of curiosity? Wiki says 265 horses, but doesnt mention torque or what rpm, it has to be pretty high I would think tho.

Just so we can fairly compare apples to apples here: This is the best one I could think of here-
I would think it would be like comparing a 267 to a chevy 265. A 265 has bigger bore shorter stroke, 3.75 bore and 3 inch stroke right? A 267 has small bore long stroke 3.5 inch bore and 3.48 stroke. Gm stopped making them both but for the sake of comparison.. Now there were no emmissions control in 1955-56 so we do not really know if the 265 would have passed or not in 1982.. but the 267 was phased out after the 1982 model year due to inability to conform to emission standards. Whats that mean? Unburned fuel coming out the tail pipe? Any ways, which one would make more low end power? My guess is the 265 torque peak would begin alot earlier in the rpm range, but the 265 would produce more total torque but do it later in the powerband. Now with the right cam and heads and no smog pumps and no catalytic converters who knows maybe the 267 could be a real thumper compared to a 265 but I kinda doubt it. Which one would be the best in my van going down the road at 4100 rpms? I dunno for sure because I didnt try yet but my money is on the 265 tho. If I can build the Chev 302 and get 336 hp@5500 rpm, 360 ft-lbs @4500 rpm I think that would be plenty. (Taken from http://www.hotrodders.com/forum/267-small-block-chevy-2817.html)

I love that article that cobalt posted on the 350 that gm shoulda made, it puts off 400 ft/lb of torque at 2400 rpm and probably lower, the scale doesnt start until 2400. That would be plenty for an rv! With that kind of torque it is not just a race car motor at all. Could be a great truck motor. I wish I had a 400 block and a buncha 100$ dollar bills, I might try that build up.

My point is, how much torque in ft/lbs do you guys think I need to drive a 7 ton motor home down the road? 300ft/lb enough? Wiki says 307 makes that. I could build a 307 or 327. Or do I need 400? How many ft/lb does my bone stock 454 make(so I have a reference)? Can't be much more than 400 can it? Keep in mind I have 5.13 gears and my 454 seems way ridiculously overpowered for a motorhome. Even with all my tools in my van, I can out accelerate my moms 1999 iron duke s10 when its empty up till about 40 mph, and the s10 runs just fine. I am not kidding at all. That first gear is low, the thing jumps when I hit the gas for such a big heavy thing..
If the 454 has any balls it will have near 500ftlbs+ in the high 2000 rpm range.

You shouldent be complaining about getting 9 with a 454 that runs 4000+ on the highway, my truck has a 360, 3spd and 3.55 tires, runs at 2000 at 60 and gets 13 in the summer, 6 in the winter.
 
#82 ·
Okay, here's the thing; You have to determine exactly what you want in a car.
You have said that you want a small block cruiser.

My advise; Find a few friends, guys that have engine/car combos that are similar to what you want, and talk them into taking you for a ride. Ask lots of After you do this, you may have a different opinion.

The SBC is a great motor with a wide range of options, you can make it do almost anything... however, honestly, (assuming that you are on a budget) if gas mileage and power/cost is what you want, you'll do much better with a low mileage modern chevy motor, from a wrecker.

Next factors will be gearing, transmission, and where you drive, highway/city/cross-town traffic.

My 2 cents; For fuel economy and torque, I'd do a 383 small block with a dual plenum low rise manifold, non-ported, but port matched, aluminum heads, cold air intake, long tube small diameter headers. Run a 650 cfm edelbrock/carter carb. vac secondairies.

On my very heavy 'stang, with a 434cu BBF I get 11.5 mpg city and 17mpg highway (spirited canyon carving, and taking advantage of the abilities of the engine)

Good luck
 
#84 ·
cobalt327 said:
Yeah, not quite- the "cruiser" is a 14,000 pound step van. W/a 5.13:1 rear gear. Has 283/307 parts to build an engine from. Wants long rods, and for it to rev (remember the 5.13:1 gears). And to get better mileage than the current 454. No OD allowed.
and it sounds like he's on a tight budget too- just to make it challenging...

For me next act I shall walk on water.




Just get an OD trans and go from there. It'll never get spectacular milage. If you get it to 12 mpg be thrilled.
 
#85 ·
After reading all these posts, i really think you will be a lot better off going the diesel route.
If it was me I would go to a Cummins 6bt.,about 200 adv horsepower at 2600 r.p.m. try to find one and trans from an old school bus.
Another good diesel is an international D.T. 466
The Cummins 6b.t.a. on a marine app. is rated at about 400 h.p.,but that has a salt water cooled intercooler and you would have problems with the cooling system.
 
#86 ·
topwrench said:
After reading all these posts, i really think you will be a lot better off going the diesel route.
If it was me I would go to a Cummins 6bt.,about 200 adv horsepower at 2600 r.p.m. try to find one and trans from an old school bus.
Another good diesel is an international D.T. 466
The Cummins 6b.t.a. on a marine app. is rated at about 400 h.p.,but that has a salt water cooled intercooler and you would have problems with the cooling system.

(I missed the 14,000 part)
I agree, get a diesel (maybe a used one) a small block is a waste of time. You need cubes (cubic inches) and torque to tow or move a heavy vehicle.

Your question, is like asking; How do I get good gas mileage in a winnebago.
A: You don't
 
#87 · (Edited)
@Ripped: Yes I agree, I think a diesel would be by far the best too. I realize that I am never going to get good mileage with a rv.

@topwrench I think I could get a DT360 or a DT466 by buying a whole school bus on ebay, cheaper than buying just the motor. The motors alone are very expensive but the whole schoolbuses can go pretty cheap surprisingly. Depressing tho, the thought of ripping one out of a perfectly cool schoolbus tho dang it. My girlfriend really wants one... She has alot of stuff and it would be a welcome addition of space, plus she is a tattoo artist and a painter, so she likes the idea of all the windows... My van is made for security, with alarm system and just the way it is made, which I like. Also I can fit in a parking space, and I look like a work truck. We can sleep in a parking lot and nobody nobody knows its really hippy van command central. We try that stuff in a scool bus and get hassled by the man 15 minutes into it sending our dusty butts packing. Plus we are hippies so they are going to wanna search for marijuana and alll that crap. I'm going to get her a scool bus tho one day.. maybe. I would have to get a custom driveshaft made tho wouldn't I tho to run DT360 in my van? That can't be cheap. I like the idea of 700 ft/lb of torque or more and I could run on bio diesel. Convert my trailer into a little refinery..

Another option might be a gm 6.2l v8 diesel would bolt right in tho and the been selling them pretty cheap pulled from humvees as military surplus since they are all switching to super expensive duramax. But my old ladies mom has a van that she paid over 6000$ for several years ago for her flea market booth she has. She only got part of a season out of it and it died. It has been sitting for four years behind her house ever since. I about have her talked into trading me since our vans are the same ex snap-on tool truck style step van. Hers might not run but it is alot nicer than mine. Chrome wheels, big lift gate on the back I could use as a back porch and as a stage to play guitar and sing. Even has a Honda liquid cooled propane power rv generator that can put off 220 for welding... My onan is just 110volt and I still need to fix it even. And it has the 6.2 liter diesel. I just need to get her to trade me for this 454 gas hog that runs great but no lift gate and no good genset. She will trade tho I'm pretty sure.

@turbolover yeah if I get 12 mpg in this thing it would be great especially since that would be a 33% increase over 9mpg

@ripped I dont see how a 383 would really be any different than what I have now, except it would be wimpy compared to the mighty awe and splendor of the 454. Might do worse on gas if what you guys are telling me is true about bigger is better. I was wanting to try something completely the other opposite end of the scale. I like the 500lb/ft of torque right off idle, don't get me wrong, but at a stop light but if I just floor it at a when it turns green 400 lbs of tools and stuff on shelves go flying back to the back of the van. Kinda overkill. 500 ft/lb of torque is nice on a mountain side, unfortunatly I don't thing it has that much torque at 3500 rpm or more. It always wants to settle back down to 40 mph on a big hill no matter if you floor it or stay in the idle circuit, because the torque peak is in the wrong place for the gearing I have and the speed I want right?

It has been suggested in some things I read that a motor achieves its peak volumetric efficiency at the rpm it puts out the most torque, I can try to find where I read that if you want. Peak volumetric efficiency equals better gas mileage right? So if I can live with 350 ft/lb of torque, I can get better gas mileage if I can build a motor that makes the peak torque at the rpm range that I drive alot. 4000rpms. To do that I could get a cam and headers for my 454 that made the power at 4000 rpm, or I could get a stock 283 chevy and try it out!! Torque peak 4000 rpms in stock form!! Well as soon as I had completed that thought, motors fell in my lap from the universe.. 2 283s, one runs, a 307 and a 327. Of course i am going to try to make a legendary obscure old 302chevy I kinda have to... I really always wanted to anyways. Why not right? Who cares if it doesn't work? I'll still have a cool engine on a run stand! Maybe you guys are just jelous...

Really tho, the 307 crank in the 350 with 327 pistons would be a better ticket for this big beast if I insist on doing this because of the extra grunt. You all are all right about that. There I said it... But only because a 327 is a bit stronger than a 283 and can still turn 4000 rpm comfortably and in the torque peak with mild cam and vortec heads.

This is just an experiment tho people, I wanna see what happens with the other extreme end of the scale compared to a 454 in a big truck! I don't think anybody has really ever tried it because it is so ludacris. You guys probably are right that it won't be worth a crap in town and only would run right at 75 mph on the expressway but I think I better just try it and find out anyway just to make sure... Cheapest way to do it is just stick the running 283 in here one day and see what it feels like, then I will have a ballpark idea on if it will work at all or not. 302 would be just like an overgrown 283 right?

@ tiretracks: Thanks for the info on the 454, I didn't know a stock 454 had all that manly beefy torque. 500 ft/lb sounds pretty impressive. I feel a little proud of having a 454 now.




@duntov That's awesome man, building a 267 might be fun, or even a 288... yeah thats right... 400 crank in a 267 block... Undersquare!! That would be great, use the stock 400 rods too, put in a super low rpm rv cam and see if it will idle at 50 rpms. I would love to see it, that sounds like something I might try if i had the parts, Might get good mileage too if you had nice tall gears!

@turbolover, I think my moms 99 s10 with the 4 banger musta got the wrong rear end gears mixed up at the factory or something... To me it doesnt have enough low end torque to use overdrive unless I am going better than 80mph. Its a real dog.

@old bogie: man thats an interesting read there Thanks! Before I got the 283s, I cam very very close to buying a good running pontiac 287 with tranny on craigslist for 300 bucks. Oh how I wanted it so, a big old pontiac motor with only 287 cubes and a extra super great rod ratio! Those motors are famous, they even put them in big GMC trucks at one time! I was afraid I would have trouble getting it to fit and hooking the driveshaft up to it. I could have simply gotten a bop to chevy v8 bellhousing adapter tho I think and made it work. I chickened out, chevy parts are cheaper.. Big ole 400 pontiac block with a 287 crank could squeeze some big ole long rods with that kind of deck height... Mhhh.. oh crap there I go again..


Ok in summary, motor get best efficiency and gas mileage at the onset of the torque peak unless I am wrong, so it is ok to run at 4000 rpms if that is where the motor is made to run and get power.

Unless I am wrong and tell me if I am, a 300 cube motor spinning at 2000rpm only can pump half as much air/fuel mixture as a 600 cube motor at 2000 rpm. Right so far?

ok so
Double the rpms means double the pumping volume of air and fuel right? So a 300 cube motor can pump twice as much air/fuel at 4000 rpm than it did at 2000rpm. Right still?

and so

a 300 cubic inch motor at 4000 rpms can potentailly pump the same amount of air and gas as a 600 cubic inch motor spinning at only 2000 rpms. Right?

Now there is the whole crank arm lever effect and that the bigger piston has more pontental pressure exerted on the crank thing on the 600 cube motor. But the smaller 300 cube motor has twice as many smaller pulses of energy transmitted in the same duration of time. And wouldn't that make up for alot of an advantage of some crank arm leverage factor? Like that 350 that chevy shoulda built article, 398 ft/lb at 2400 rpms with a 3.25 inch stroke crank. Now we could compare that to a 700 cubic inch motor making 398 ft/lb at 1200 rpms. Sounds about right to me...

That makes a 302 motor not seem like such a bad idea. At least to me anyway. I could build a 604 cubic inch motor, spend lots of money on it, spend lots of money on the overdrive tranny, and on new rear end gears, and hopefully get the headers to fit in that tight motor area, not to mention adding another 500 lbs of weight, and finally get to cruise in style at 2000 rpms and holy mother mary... if I ever did step on the gas, look out! A real beast for sure! The gas stations would really love me then as I'm afraid I would never be able to keep my foot out of it. Or.....now get this.. I got an idea..... Wait for it..... (drum roll please)..... I could just take the 150$ running 283 that I already have from craigslist and stick it in there and see what happens. Did that help you guys understand why it kinda makes sense especially for me on a budget with a baby and baby mamma to care for and my own mom have financial troubles and me with not much income? You guys wanna sponsor me, Ill build any motor you want I promise...
 
#88 · (Edited)
Fuel mileage. How about a volkswagen rabbit diesel. 50 = mpg. It will run on corn oil heating oil peanut oil, bio fuel, diesel fuel . I have seen them go 300,000 miles before they start to get worn to the point that they dont start well and smoke to much because of tired rings. You can convert it to french fry grease burner pretty easy too.Keep it simple
 
#89 ·
latech said:
Fuel mileage. How about a volkswagen rabbit diesel. 50 = mpg. It will run on corn oil heating oil peanut oil, bio fuel, diesel fuel . I have seen them go 300,000 miles before they start to get worn to the point that they dont start well and smoke to much because of tired rings. You can convert it to french fry grease burner pretty easy too.

I tried livng in a vw rabbit before. It sucks. Sits very low to the ground loaded with tools and a few passengers and the dog too, not to mention its a real dog on hills pulling my trailer. And parts are very expensive. I like it when a new starter is 35 dollars and they have them on the shelf at napa, also they are really a very delicate car, I tore mine up off roading at the rainbow gathering trying to get back to the highway. No my friend, I need comercial grade. And hope everyday that it's just enough.
 
#90 ·
I would then opt for the dt 360 or dt 466 in my step van and do a french fry grease conversion. Or learn how to cook the glycerin out to make bio fuel.I have talked to quite a few truckers who have run it as there companies ( short haul) have it and they sat it runs better , cleaner and has more power than regular diesel fuel. Now aint that a kick in the pants? Way better for the environment and you can sell it if you make enough.
 
#92 ·
This thread is intreage in the making and I like it, I won't pretend to have read each and every detail,,, DB one thing is for sure IMHO you are certainly a creative sort and can also fat finger in a really good bit of info and thought as others can. Its great to read and learn.

This is just an experiment tho people, I wanna see what happens with the other extreme end of the scale compared to a 454 in a big truck!
I get ya here thats what I mean by intreage,,,something not yet tried or proven, hot rodding has no bounds, first time in 14000 lb van but what the heck.

500 ft/lb of torque is nice on a mountain side,
This may be were the little V8 leaves you literally hanging, All the inertia is handled better by the 1500 rpm 454,,, the 302 may not spin at all just a notion:embarrass

All in all if you can't build your dream, Diesel man Diesel,,,my 2 cents
 
#94 ·
The diesel will live a lot longer than the 454 in any heavy application like this.
A lot longer. 454 is a great motor but makes lots of heat and when you need it the diesel will give better power in the mountains and will probably give better mileage too.
 
#95 ·
"But the smaller 300 cube motor has twice as many smaller pulses of energy transmitted in the same duration of time. And wouldn't that make up for alot of an advantage of some crank arm leverage factor?"

NO, the only substitute for cubic inches is cubic money.

You are intensionally ignoring pumping loses and internal drag from bearing speed, lifter drag and compressing the springs twice as much, ALONG WITH turning the trans and rear end 2X AND those pumping loses. You'll also need to change pulley sizes to slow down the accessories or replace regularly.

Going to a large bore/short stroke compounds the pumping loses and throws efficiency out the window for 2 reasons:

the power-stroke piston must overcome the next compression piston which is traveling into a burning air/fuel charge , approx. 450psi X the surface of the piston face. Bigger pistons = bigger face = bigger loses x 2X rpm.

the larger pistons make for a larger quench area, where unburned hydrocarbons and CO are produced, quickly dropping efficiency and increasing emissions.
 
#96 · (Edited)
oldBodyman said:
"Going to a large bore/short stroke compounds the pumping loses and throws efficiency out the window for 2 reasons:

the power-stroke piston must overcome the next compression piston which is traveling into a burning air/fuel charge , approx. 450psi X the surface of the piston face. Bigger pistons = bigger face = bigger loses x 2X rpm.

the larger pistons make for a larger quench area, where unburned hydrocarbons and CO are produced, quickly dropping efficiency and increasing emissions.
what about the short stroke allows longer rod, in this case 2.08:1 r/r giving more dwell, more time at or near tdc making more time for the flame front to move across the piston?

and "The power stroke piston must overcome the next compression piston" But part of that force it must overcome is caused by ignition advance isn't it? Shouldn't I require less total spark advance say than a 383? Or to any short rod motor because of less dwell time at tdc? I would think that is a contributing factor, giving some measure of advantage in favor of the shorter stroke/longer rod.

I really want a diesel and I agree its the best way for sure, do you guys know much about the 6.2 liter diesels? You can put a turbo from a 6.5 one and I understand A turbo helps fuel mileage on a diesel doesn't it?
On ebay I noticed the pistons and rings and bearings are very cheap if I needed some. Mechanical injection, means I could run straight veggie oil too right? Get this though, according to wiki it produces

Specifications
Engine RPO Codes: LH6 ('C' series, with EGR) and LL4 ('J' series)
Displacement: 6.2L / 379 cu in
Bore x Stroke: 3.98 × 3.80 in (101 × 97 mm)
Block / Head: Cast iron / Cast iron
Aspiration: Natural
Valvetrain: OHV 2-V
Compression: 21.5:1
Injection: Indirect
Horsepower / Torque (at start): 130 hp (97 kW) @ 3,600 rpm / 240 lb·ft (325 N·m) @ 2,000 rpm
Horsepower / Torque (at final): 143 hp (107 kW) @ 3,600 rpm / 257 lb·ft (348 N·m) @ 2,000 rpm
Horsepower / Torque (army): 165 hp (123 kW) @ 3,600 rpm / 330 lb·ft (447 N·m) @ 2,100 rpm
Max RPMs: 3,600
Idle RPMs: 650 + or - 25


only thing is that seems like it would need more power than that. Is that going to be enouh? I mean I guess that is enough if it comes with them from the factory but jeez... the School bus diesel would be the best huh, The dt360 does better, makes 210 horses according to this I found and the 466, 250. Thats better than the 6.2 liter at least. If I could shoe horn me a cummins 671 two stroke diesel and be done with it that would be something to brag about there..... gobs of torque and have a nice sound. I could pull a BIG lawnmower trailer too heh. That much torque would let me spin a tire if I tried I betcha.. I could run thunder valley dragway(I wonder what class that would be?). My dad drove a semi when I was a kid and he said the old freightliner would easliy spin the tires on dry pavement without even trying whith no trailer hooked up.
 
#97 · (Edited)
Wow man dirty biker, you wrote a book that time, I was gonna quote it but it was just too long.
I suggested a 6bt because I think it would fit your app. better than a 466,I really would rather not even talk about 6.2 really not a good thing for you,please dont ask whats wrong,just take my word for it.
Dt 466 would be a big problem to put in that van.
And as for the man looking for weed in a school bus......You know dirty biker,and speaking from personal experience again....I really wondered what exactly it was you had been smoking....Just kidding...no no, wait maybe not..
Anyway I just ran my 355 long rod motor down the road, put it through all five gears on Al. sr.91. last speed I remember looking at on the speedo was 65 and that was in 2nd.gear,Had plenty of power well below 5500, but Ill tell you what man , when it hit 5501 it lit the tires up,you know someone said on another post long rods were ok above 5500.
Hey if you need any help setting up that diesel,thats what I do for a living.
Right in the middle of double overhauls on MTU 16V2000s right now.I dont think you'll wanna put one of these in that van,I dont know....may be interesting to see that.
Dude, take my word for it,dont get into the 6.2 deal,you'll ragret it!!
And by the way,a well read guy like you should know,Cummins didnt make 6-71,Detroit Diesel did...71 series were 1-71 2-71 3-71 4-71 6-71 8n12-71 and in detroit diesel 2 cycle dying days and when Penske owned it they made a 24-71(2 12-71 blocks bolted together...Big time nightmare!!!)
Do not go the 2 stroke route either,engs.r just too big n heavy and fuel mil will be crap..
 
#98 ·
Custom10 said:
something not yet tried or proven, hot rodding has no bounds, first time in 14000 lb van but what the heck.

All in all if you can't build your dream, Diesel man Diesel,,,my 2 cents
So far no gas engine can match a diesel for efficiency. Early cars, which were heavy, started out with small bore/long stroke, and the engineers have been working back to that formula for a decade. I think the 283/302 type ratio was part marketing and grew out of the perception that it made more power because the big bore small stroke was a drag car philosophy since the 1940s. Gas was 17 cents a gallon when I was in high school, higher octane too.

There are guys my age and older still today, who will tell you with a strait face that a 327 is faster than a 350 because of the shorter stroke. According to that the 383 would be a real dog. And I'm sure that perception was perpetuated by the change in the way HP was rated just after the end of the 327. And of course Ralph Nader came along about the same time.

Lots of reasons why long stroke is cheaper to run; can't deny the math. I build small blocks, but drive Isuzu diesel daily because it saves me enough in fuel cost to buy a set of aluminum heads two or three times a year. There is plainly a lot more units of energy in a gallon of #2 oil than in a gallon of gasoline, that's mostly why, but research will yield that most diesels are also under square.
There is probably an engineer somewhere who if you told him you were going to spin up a 302 to pull a load more efficiently////he would just walk over to your desk and stick his pointer in your eye. :nono: :spank: :smash: :boxing:


I was bored :D Duntov :D
 
#99 ·
detroit diesel I knew that, I musta been thinking about cummins turbo at the same time as I was typing, theres a bell housing adapter on destroked.com

I was being silly anyways, I wouldnt want that heavy of an engine. The old van needs new springs and airbags now anyways, they hold air but the springs are sagging. But what about this: I bet my girls moms van with the 6.2 has a lower rear end ratio, so maybe I should put the 350 from my suburban in this van before I trade her which lightens the front end fixing the spring sag, then just use the 454 in that van with the lower ratio.. it won't matter that it doesn't have overdrive then. I don't know the ratio of hers yet, theres a tag on the back hopefully but everybody wins, she gets a better motor for spinning 4000 rpm and will still have enough power because she wont load it down like me, and I get a newer van with a liftgate and a big block that runs good. But if I could get that 6.2 running with one simple fix, I might have to try it.
 
#100 ·
Duntov said:
So far no gas engine can match a diesel for efficiency. Early cars, which were heavy, started out with small bore/long stroke, and the engineers have been working back to that formula for a decade. I think the 283/302 type ratio was part marketing and grew out of the perception that it made more power because the big bore small stroke was a drag car philosophy since the 1940s. Gas was 17 cents a gallon when I was in high school, higher octane too.

There are guys my age and older still today, who will tell you with a strait face that a 327 is faster than a 350 because of the shorter stroke. According to that the 383 would be a real dog. And I'm sure that perception was perpetuated by the change in the way HP was rated just after the end of the 327. And of course Ralph Nader came along about the same time.

Lots of reasons why long stroke is cheaper to run; can't deny the math. I build small blocks, but drive Isuzu diesel daily because it saves me enough in fuel cost to buy a set of aluminum heads two or three times a year. There is plainly a lot more units of energy in a gallon of #2 oil than in a gallon of gasoline, that's mostly why, but research will yield that most diesels are also under square.
There is probably an engineer somewhere who if you told him you were going to spin up a 302 to pull a load more efficiently////he would just walk over to your desk and stick his pointer in your eye. :nono: :spank: :smash: :boxing:


I was bored :D Duntov :D


One thing tho long stroke motors like the 383 still have to spin up pretty high to get the huge power numbers but with that long stroke the extra stress of slinging all that weight around means you have to get really good parts that cost alot. Not as important for my project already has a forged crank and the cheapie 6.25 rods I want will be stronger than stock so I will be golden, I wouldn't need a super quick ranp cam and roller like the 383 would need either.
But diesel, is the way to go if I could.
 
#101 ·
Go diesel

Dirty Biker said:
One thing tho long stroke motors like the 383 still have to spin up pretty high to get the huge power numbers but with that long stroke the extra stress of slinging all that weight around means you have to get really good parts that cost alot. Not as important for my project already has a forged crank and the cheapie 6.25 rods I want will be stronger than stock so I will be golden, I wouldn't need a super quick ranp cam and roller like the 383 would need either.
But diesel, is the way to go if I could.
Diesel is the way to go, but I would think a 383 built right would produce more than enough torque @ 2700 or even less rpm to gear for 65 mph.. If you are looking for numbers look at torque only which would occur early on a 383. Horsepower usually cost fuel.

Just go diesel.....12 14 mpg would be about the best I would expect on the loaded van.
I did get 16 with a similar load with a 334, (stroked 305) but the right diesel might get 18/19 @55mph
 
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