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  #136 (permalink)  
Old 08-23-2010, 07:08 PM
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Quote:
Originally Posted by turbolover
So what are you going after rod ratio or short stroke or small displacement?
All three at the same time, so when I am cruising around slowly and don't need a large amount of power the smaller displacement may help get a little better gas mileage. Then when I do need extra power, that short stroke will help me spin my motor up faster. Then the long rod ratio might help my parts last longer hopefully. I speculate the increase in tdc piston dwell time by the longer rod will help to burn the fuel more completely, maybe helping the gas mileage a bit further and reduced side loading could help cut down on friction, as well as the smaller main bearing journals of the 283. Those are all small things I agree, but they would have to add up to something measurable I would think.

I added the cost of the parts up, it will cost more than I thought. I think could do it for less than 1000, but only barely and I would have to use the stock rods and stock heads and stock 302 pistons. I think I could do it with 1500$ tho, with the 150$ 062 vortec heads on CL, and a 200 used edelbrock air gap manifold from ebay, and 300 for the 6.25 rods from ebay, and 200-300 for high compression pistons. Ideally would want a custom ground cam and solid lifters but a hyd rv cam or any short duration cam with decent lift and plenty lobe sepparation might work ok. I have a good running 283 tho, if it seems ok on the compression gauge I am just going to try that first. It would be pretty close to what I may expect from a 302. A 327 could maybe be an option, I bet I would feel a pretty big difference over the 283 especially in this van.

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  #137 (permalink)  
Old 08-23-2010, 07:21 PM
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Originally Posted by turbolover
"So what are you going after rod ratio or short stroke or small displacement?"

having a great rod ratio pretty much dictates that my engine must have a short stroke and hence a small displacement, Unless I built a 427 tall deck, or the 380 ci destroker 454 with "W" 348 crank
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  #138 (permalink)  
Old 08-23-2010, 07:22 PM
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I keep double posting on accident and cant delete the extra post sry
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  #139 (permalink)  
Old 08-23-2010, 08:39 PM
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You are forgetting parasitic losses an the advantages of a smaller bore and the disadvantages of a longer rod. Its not so cut and dry.
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  #140 (permalink)  
Old 08-23-2010, 09:47 PM
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Quote:
Originally Posted by turbolover
You are forgetting parasitic losses an the advantages of a smaller bore and the disadvantages of a longer rod. Its not so cut and dry.

That is because I do not believe there is any advantage to a motor of the same displacement with a smaller bore. Do you mean pumping losses instead of parasitic losses of a long rod? Like due to less intake velocity at low rpm? I don't think that is going to be an issue with stock heads and a one barrel. Smaller intake intake runners increase intake velocity. I actually used a one barrel carb on my suburban with a 350 for a long time and it worked just fine. I could hardly tell the difference between that and the quadrajet. Didn't get much better gas mileage than the four barrel but I could tune it without changing jets and it ran really smooth with it on there. It would idle as smooth as a fuel injected motor does, no joke. I have an original 50s model fish carburetor that I love very much.

Here is a little bit of info on them

http://www.youtube.com/watch?v=CsQIsLCYiAI

http://www.roaring-twenties.com/the_fish_carburetor.htm
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  #141 (permalink)  
Old 08-23-2010, 10:43 PM
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Bored

Hey Turbolover

Following any other interesting threads? Been a while since there was one I could get into.
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  #142 (permalink)  
Old 08-23-2010, 11:29 PM
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Not a thread but an interesting article, http://www.superchevy.com/technical/...lley_carb.html

It makes me want to just put the 350 in my big van tho due to that torque I could potentially get with headers and a cam. 390 ft/lb I think it said, still a far cry from the 500 lb I apperently already have now with 454 tho.. I am going to miss this motor if I change it I am sure...
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  #143 (permalink)  
Old 08-24-2010, 07:33 AM
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Quote:
Originally Posted by Dirty Biker
That is because I do not believe there is any advantage to a motor of the same displacement with a smaller bore.
regardless of your beliefs there are reasons for smaller bores.

And I meant parasitic losses, your pumping losses are only a very small part of the engines power that is consumed before it makes it to the rear wheels. Gross assumptions are often what causes design failure. I believe there was a little bridge collapse that happened not too long ago over some "minor" assumptions. They're still paying for that one and people are still dead as a result of those assumptions.

That is an extreme case but it goes to show you that refusing to consider all aspects will bite you in the a55.
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  #144 (permalink)  
Old 08-24-2010, 09:59 AM
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Quote:
Originally Posted by turbolover
regardless of your beliefs there are reasons for smaller bores.
so would you tell me any of those reasons, without being vague, why a non emmisions, high compression 267 chevy would be in anyway at all better on gas at 4000 rpm than a similar 265 chevy please? Bigger bore, same ci 265 can have bigger valves and lower friction losses due to the reduced distance travelled during each engine rotation and lower crank stress due to the lower peak piston speed relative to engine speed.

From what I have learned just from reading online (and I realize you can't believe everything you read) is that smaller bores a given displacement would be to make the torque at a lower rpm at the cost of less peak power. And you said power moves a car, not torque. Smaller bores/long stroke go great in a John Deere tractor or something right? But if I need to move 7 tons up a mountain and that 267 just won't do it in high gear, will I still be able to just drop down into second gear and scream up the mountain at 6500 rpm making oodles of power with the 267?

here is one I read before turbolover, tell me if these guys are wrong and why please, http://findarticles.com/p/articles/m...g=content;col1
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Old 08-24-2010, 10:20 AM
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your article is on racing engines, not engines that are driven every day. You really need to learn to stop picking and choosing what you want to read.

I have a feeling most of what you read has probably given you the information you need to better understand your faulty reasoning- you just seem to have an ability to over look it.

BTW the great majority of your losses do not come from your stroke, I don't know why you think that is so critical.
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  #146 (permalink)  
Old 08-24-2010, 10:46 AM
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*facepalm*

long stroke is great for torque, it lets an engine pull in more air/fuel, but will fall on its face at higher rpm since it physically will not move fast enough.

Short stroke will fall on its face at low rpm because it cant get the volume of air/fuel that a longer stroke will, but due to lighter parts, shorter distance to move it will reach a higher rpm.

You said that a small bore/long stroke is good for a john deer tractor, but not for moving a large load?! I dont know about other farmers...but our tractors pull stuff that is mind blowing! If you need to MOVE something, heavy, a long stroke will give you the torque to do it!

You're thinking about this all wrong, but i doubt we can sway you differently.

Yes, when your "miracle engine" gets a load on it, you could downshift, and get up whatever your going over...a speedbump? but downshifting possibly would kill your mpg dilly your going after.

And! a crank out of a 265/283 is a CAST crank...i ran one last year in a roundie-round car...it broke. so turning high rpm, above 5500...your punching disaster in the face...and disaster is a HUGE, steroid popping body builder...that has a short temper and will hit back...hard.

ALSO! High RPM engines wear more! There is a reason why I have to replace the rings/bearing once a season in my 355 race engine, cause its constantly turning 7500+ rpm. There used to be a graph or book that showed reasonable time between rebuilds compared to rpm...im not taking the time to find it.

So, by the time you build this engine, you said $1500 at least. You could either...

1. change gear in the rear of this van, its not THAT hard! quit being lazy...
2. put a 9 inch ford under this van, so changing gear would be even easier!
3. get a salvage yard 700r4, and bolt it right in! AROUND 300-500 BUCKS.
4. buy an econo-box kind of car...
5. buy 1500 cheeseburgers from Mc donolds...man them things are awesome!
6. fuel inject the 454...

See! 6 things that will yield MORE results than what your trying to do!

Your theory is going and building an engine that is made to run at 4100 rpm, the rpm that the 454 turns at highway speed. Why not just OD the van, lower rear end gear, and get EVEN BETTER mpg than this engine you want to build?! *slaps forehead* i dont get it!

...and i lost my train of thought...so ya!
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  #147 (permalink)  
Old 08-24-2010, 10:48 AM
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and even if you go from 12 mpg (guessing on milage) to 16-18 mpg...thats not a lot of savings! its gonna take YEARS to even pay off building this engine! AHH!
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  #148 (permalink)  
Old 08-24-2010, 11:06 AM
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Quote:
Originally Posted by turbolover
your article is on racing engines, not engines that are driven every day. You really need to learn to stop picking and choosing what you want to read.

I have a feeling most of what you read has probably given you the information you need to better understand your faulty reasoning- you just seem to have an ability to over look it.

BTW the great majority of your losses do not come from your stroke, I don't know why you think that is so critical.

That article was just something I found quickly on bore/stroke. Your'e right, I might have taken more time to cite a better example knowing that you will look for fault in it. I try to read everything I can find on this subject (that I find so interesting), but some of the things I agree with and some of the things I tend to disagree with. Right again. I guess everybody does that to some extent tho?

If two engines of the same size displacement are compared, the only difference being stroke bore ratio and for the sake of this one point lets say they have the same rod ratio even, whatever you think is average say 1.7:1, but otherwise identical in every way, same deck height, same heads, same advance curve same everything right? Now lets say that 4200 rpm is the rpm range that the engine will spend 80% of its time. Which would have the widest power band? Which would give the most torque over the widest rpm range? Which would give the greatest peak torque? Which would make more horsepower? Which would give the best gas mileage? Which would last longer at endurance runs at 4200 rpm for days on end? Which motor will have the highest volumetric efficiency? Thank you turbolover, I always love your critical mind, share with me some insights, thoughts, and experiences.. I want to hear them.
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  #149 (permalink)  
Old 08-24-2010, 11:12 AM
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but if they both are being tested at 4200 rpm...whats the point of knowing which one has the broadest power/torque band?
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  #150 (permalink)  
Old 08-24-2010, 11:26 AM
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Quote:
Originally Posted by BigRoy1978
and even if you go from 12 mpg (guessing on milage) to 16-18 mpg...thats not a lot of savings! its gonna take YEARS to even pay off building this engine! AHH!

Ah but it helps, while it may seem like not that much, (I get about 8 miles per gallon actually) to go from 8 mpg to 12 mpg is 33% more gas mileage. 33% less I have to spend. If I spend 100 a week on gas, 5200 a year, it would only be $66 dollars a week at 12mpg or about $3450. That is 1750 dollars, about what I predict I could build it with using used vortec heads and manifold and the parts I got from craigslist but new pistons flat tappet solid lifter cam and high compression pistons. However, I have a 283 that doesn't need rebuilt yet that I plan to try in here first before building a better one. I got it for 160$ and helped the guy pull it out of his truck.

Gonna cost me 93 dollars to go 300 miles down to tennesee @8 mpg, if i got 12mpg it would only cost $62. That is 30 dollars, a case of beer and a pizza!!!!
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