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  #121 (permalink)  
Old 08-23-2010, 02:42 PM
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Nobody is deliberately setting out to knock you down, just trying to get you to understand you are assigning great significance to something(rod/stroke ratio in this case) that is actually down in the 1% area of significance of things to plan a build.

To Wit: You could build a 5.7" rod 302 and a 6.25" rod 302 and there won't be in the area of 10 hp difference between them,... you are not going to find some earthshattering revelation and instantly rewrite Sir Henri Ricardo's internal combustion theory.

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  #122 (permalink)  
Old 08-23-2010, 02:44 PM
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Most of the time I don't get along with them because they're counter productive. I do get along with a few but as time goes by they have "grown up" as I call it.

As far as the sbc vs bbc everything is different. The cam journal size has moe of an effect than rod ratio and you probably never considered it. Or the heads, oiling cooling, etc.

Rod ratio is near the bottom of the list of things that matter and its the only thing on your list... I'm just trying to save you from spending your money on something that will not produce.
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  #123 (permalink)  
Old 08-23-2010, 03:03 PM
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You are right ericnova there might not be that much diff between stock rod 302 and a long rod one. I just think that since it would cost about the same either way, I would just go ahead use the lighter pistons and longer rods and see how it does, and write about it on here and on youtube and stuff. I doubt many people have ever even tried it. Maybe some people wanted to try it but they probably got talked out of it and made fun of so they gave up and just built a 383 like most everybody else does. I don't want to be one of those people tho.

Check this out: a 267 sbc bored out 60 over with a 400 crank in it would equal 299 cubic inches. There would be a big difference between a 302 and a 299 tho. I would guess twice the power from the 302 as the 299 using similar grade parts.
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  #124 (permalink)  
Old 08-23-2010, 03:08 PM
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Quote:
Originally Posted by Dirty Biker
The theoretical 380 cube motor I was just posting about could be easy to build, and be very durable...
Dang, wish I would've thought of that.

Post #52:

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OR if you'd have said a BBC-based engine built on a 454 or 502 Gen 6 foundation, using a 3" stroke and 7.4L heads. This would give a displacement of 340 or 382 ci respectively, and could at least get the truck down the road.
Similar displacement, but from a shorter stroke/larger bore combo. At least yours can be built from OEM parts- even if they're not very common.
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  #125 (permalink)  
Old 08-23-2010, 03:15 PM
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yeah theres a 348 crank on ebay now, 350 bucks. Been on there since spring. http://cgi.ebay.com/ebaymotors/1958-...ts_Accessories
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  #126 (permalink)  
Old 08-23-2010, 03:17 PM
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Quote:
Originally Posted by Dirty Biker

Check this out: a 267 sbc bored out 60 over with a 400 crank in it would equal 299 cubic inches. There would be a big difference between a 302 and a 299 tho. I would guess twice the power from the 302 as the 299 using similar grade parts.
You're correct here, the 299 from the 267 block will be a dog, but not do to stroke differences or rod length differences. The 267 has a tiny 3.5" bore, there is no way to put a head on it that will breathe well enough to make power, compared to the 4" bore of the 302 allowing a foctory performance head or a race head.

Still has nothing to do with rod/stroke ratio. As far as the 302 , performance, and being different... that is fine. But the same money put into a 383 and put in the same vehicle will smoke you. Just a cold hard fact

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  #127 (permalink)  
Old 08-23-2010, 03:45 PM
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"But the same money put into a 383 and put in the same vehicle will smoke you." Just a cold hard fact." Maybe, maybe not. According to this, there is at least one 302 powered 3000lb chevy nova that runs in the high 9's. As far as cheaper goes well I think I could build a pretty wicked 302 for less than 1000 dollars total, thanks in part to old used craigslist parts that nobody seems to see much value in. I dunno what kinda 383 I could cobble together for that little but I wouldn't be surprised if the 302 could give it a pretty good run for its money. And get better mileage around town... :p
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  #128 (permalink)  
Old 08-23-2010, 04:01 PM
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To run 9.9 ET w/3000 lbs, one calculator (Wallace) says:

Your HP computed from your vehicle ET is 549.98 rear wheel HP and 611.09 flywheel HP.

@ 3200 lbs (w/driver?): 586.64 rear wheel HP and 651.83 flywheel HP
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  #129 (permalink)  
Old 08-23-2010, 04:11 PM
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Quote:
Originally Posted by Dirty Biker
"But the same money put into a 383 and put in the same vehicle will smoke you." Just a cold hard fact." Maybe, maybe not.
There is no "maybe not" a 383 will walk all over a 302 unless you have serious suspension issues which prevent the 383 from putting the power to the ground.

BTW as already indicated none of your build prove anything regarding rod ratio.

The easiest/cheapest way to build an engine with only a differing rod ratio is to build a 350 with a 400 rod and a 327 piston and then a 350 with a 6.125" rod and a piston for a 6" rod 383. You would have to cut the deck but by using different head gaskets you could even keep the same quench distance milling a set of heads would allow you to keep the same compression too. you would have one engine with a 1.6 rod ratio and one with a 1.76 rod ratio.

Even then your engine would not prove anything until multiple heads, cams, intakes, headers, etc. were tested on both engines. Otherwise it would only provide results for one application, not enough enough to develop a theory. By the time you finish this testing your dyno time bill would be more than most of us put into our cars in a year.

Or you could do some research into rod ratio and the affects it has (and related mathematical evidence to support the affects- but I'm afraid that it wouldn't support your longer rod ambitions as a 302 would need a shorter rod to get the peak average airspeed in the port high enough for a good torque result...

That's another reason hippies bother me- they think they're special. Well, they are special, just like everyone else, but when it comes to engine design I would leave it to the professionals. They've spent more time researching engine design parameters than you have probably spent driving a car- something to consider.
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  #130 (permalink)  
Old 08-23-2010, 04:19 PM
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Quote:
Originally Posted by Dirty Biker
"But the same money put into a 383 and put in the same vehicle will smoke you." Just a cold hard fact." Maybe, maybe not. According to this, there is at least one 302 powered 3000lb chevy nova that runs in the high 9's. As far as cheaper goes well I think I could build a pretty wicked 302 for less than 1000 dollars total, thanks in part to old used craigslist parts that nobody seems to see much value in. I dunno what kinda 383 I could cobble together for that little but I wouldn't be surprised if the 302 could give it a pretty good run for its money. And get better mileage around town... :p
So do it, bring us that $1000, Craiglist sourced 302 and show us how it is done. $1000 won't even cover the machine work and small parts like rings bearings and pistons, and you still don't have heads that will do the job.

You example 302 engine in the high nines was admitted to be very built up, tunnel ram and such, and from experience I would say there are very few stock parts in it. Likely crank and block at best, and maybe only the block, and maybe not even that, as there were no real specs given in that link.
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  #131 (permalink)  
Old 08-23-2010, 05:13 PM
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Quote:
Originally Posted by cobalt327
To run 9.9 ET w/3000 lbs, one calculator (Wallace) says:

Your HP computed from your vehicle ET is 549.98 rear wheel HP and 611.09 flywheel HP.

@ 3200 lbs (w/driver?): 586.64 rear wheel HP and 651.83 flywheel HP

That is amazing you can get that kinda power from a 302, Two horsepower per cubic inch naturally aspirated is pretty friggin good!

I wonder how hard it is to get 766 horsepower out of a 383...

turbolover: The difference between 1.6 rod ratio and a 1.76 ratio is too small to really make much difference I agree with you so theres probably not much point in doing that on a 350 chevy except maybe to get lighter pistons. It would be hard to find a motor to test the ratio up to 1.9:1. One way to test might be a 327, with 302 pistons and 400 rods for 1.7:1. then again with 6.25 rods and those same pistons for the 383 with 6 inch rods for 1.92:1. That might be better but 1.7:1 rod ratio still pretty darned high compared to a 383 with 400 or 5.7" rods.

The same factor that causes the velocity to be slower on long rod also helps keep it from forming eddi currents in the intake at high rpm, like a short rod motor does. Also the longer rod motor with the right cam can still have decent torque for low rpm cruising, then when you want to burn more gas and get more power just drop down a gear or two, double the rpm, and air fuel that it can breath. But most the time when you do not need that much power (like 90% of the time) you are running around with a smaller motor burning less gas.

Here is a cool 302 build that got in the high 400s hp with only a two barrel carb before they fixed the linkage. http://superchevy.automotive.com/999...dyno-test.html

It ends up with 458 ft/lb of torque at 5600 rpm and 534 horses at 6700rpm. The guy who ran high 9s in a 3,000lbs Nova says he hit the trap at 9,500rpm, which is about 40% more rpm than the 534 horse 302 got at 6700 rpm. If the 9500 rpm car could turn that extra 40% more air/fuel its pumping thru there into hp, that would be about 750 horsepower. Naturally aspirated. But then that is insano tho for sure all high dollar parts.
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  #132 (permalink)  
Old 08-23-2010, 06:09 PM
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  #133 (permalink)  
Old 08-23-2010, 07:08 PM
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So what are you going after rod ratio or short stroke or small displacement?
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  #134 (permalink)  
Old 08-23-2010, 07:34 PM
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So what are you going after rod ratio or short stroke or small displacement?
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  #135 (permalink)  
Old 08-23-2010, 07:50 PM
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all over the place?

I didn't know any of that. Build a couple of "W" motors a hundred years ago but forgot what I ever knew, and haven't built a big block of any kind for a long time now.
Will give you this... destroking does make whatever heads you have bigger than they were....not gonna match a diesel though
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