LA 360 or Magnum 5.9

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ir3333 said:
You would have to do quite a bit to a 318 to get 350 hp.
even with new heads,cam,intake and higher compression pistons the small bore would still probably struggle to match and early stock 340 at 275 hp.
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If you build a 318 and 340 to the same specs. There gonna make about the same hp. The bore size isn't gonna restrict the air flow overly compared to a 340 especially under 450hp. A 4" bore is considered the standard small bock bore a rebuilt 318 is only 0.030" to 0.060" under.

The only difference is the 318 powerband will be 200-300 rpm higher and make 20-30 lbs-ft less which can be made up by going one gear set lower.

Saying that if you only looking for 320-350 hp. The 300hp create engine is a stock long block 5.9 with 4bbl and headers and said to make 320hp and any cam and hit 350 hp at least.
 
have a look at Comp Cams own dyno sheet.
This is on a stout 350 (i know SBC) with Dart heads
only 342 hp

COMP Cams® - Xtreme Energy 268 Hydraulic Flat Tappet Camshaft, Part # 12-242-2 Dyno Sheet copy.jpg
 
IIRC, the Dart S/R heads are like well prepped heads. Not like ported stock. There a good head.
 
I guess it depends on your definition of easy?
I think the 318 would fall noticeably short of 350hp, but a .040 over 360 with an XE 268, 9.25:1 comp and x heads might hit 350 hp.
Notice that cam peaks at 5000 rpm in the 3.5" stroke chevy.A 340 may hit it's peak at 200 or 300 rpm higher with the 3.31 stroke.
....where are you AJ?
 
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I'm always guessing
I try not to use absolutes like "will do",
preferring might do, could do, should do, Probably, possibly, maybe,
cuz then it's not as embarrassing when I'm wrong,lol.

I try to mix it up so you guys don't notice.
A very long time ago, in the beginning, I said I was one of those arm-chair whatever you call'ems. That hasn't changed.
But I'm pretty good with a calculator.
I used to have a Desk-Top Dyno, back in 99, but it lied all the time. Then all the new heads and stuff came out, and it got even worse. I couldn't figure out if the program lied or internet junkies made stuff up. So I just started guessing.
One thing's for sure;there are a buncha guys on FABO, that seem to really know their chit. And the one thing I know for sure is, I wouldn't want to piss 'em off.So when a thread shows up and some of the big guns show up, I stand back and Ziiiip it.
And another thing I have recently come to believe is Hydraulic rollers ain't for me.
And I hate green peppers on pizzas
 
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I am in total agreement with you.There are a lot of guys on here that know their stuff and have the hands on experience to back it up.I just try to look at things logically.
I love responses that say this is what i did or used...and this is what i found!
 
ir3333 said:
I guess it depends on your definition of easy?
I think the 318 would fall noticeably short of 350hp, but a .040 over 360 with an XE 268, 9.25:1 comp and x heads might hit 350 hp.
Notice that cam peaks at 5000 rpm in the 3.5" stroke chevy.A 340 may hit it's peak at 200 or 300 rpm higher with the 3.31 stroke.
....where are you AJ?
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Why do you think a 318 will fall short ?
318 340 350 360 etc.. are an engines static size non running. Just a measure of all the bores add together. But a running engine is dynamic in size depends on rpm.

Well assume all these engine similar in friction efficiency and VE.

That 350 peaks at 5000 rpm so 350 x 5000 equals 1,750,000. An engine only has a intake stroke every other rotation. So you got to divide by 2. Which equals 875,000 cubic inches per minute. Thats the real size here. Now thats a rather large and useless number. So turn it into cubic feet per minute or cfm. So you'd divide by 1728 to get the number or divide the original 1,750,000 by 3456 for simplicity sake which we know as the what people try to use as the carb formula.

Which would be 350 x 5000 / 3456 = 506 cfm. So that engine pulls about 506 cubic feet per minute depending on VE. So since these engine are similar in efficiency it takes about 506 cfm to make 342 hp. A 318 at 5500 rpm would pull 506 cfm. And same with 340 @ 5147 rpm and 360 @ 4867 rpm. At these rpms these 4 engines are the same size. Same potential.
 
ir3333 said:
I am in total agreement with you.There are a lot of guys on here that know their stuff and have the hands on experience to back it up.I just try to look at things logically.
I love responses that say this is what i did or used...and this is what i found!
Click to expand...
Yeah , I try to limit my responses to that kind of thing, but sometimes I get carried away and the post gets a little "wordy"
 
273 said:
Why do you think a 318 will fall short ?
318 340 350 360 etc.. are an engines static size non running. Just a measure of all the bores add together. But a running engine is dynamic in size depends on rpm.

Well assume all these engine similar in friction efficiency and VE.

That 350 peaks at 5000 rpm so 350 x 5000 equals 1,750,000. An engine only has a intake stroke every other rotation. So you got to divide by 2. Which equals 875,000 cubic inches per minute. Thats the real size here. Now thats a rather large and useless number. So turn it into cubic feet per minute or cfm. So you'd divide by 1728 to get the number or divide the original 1,750,000 by 3456 for simplicity sake which we know as the what people try to use as the carb formula.

Which would be 350 x 5000 / 3456 = 506 cfm. So that engine pulls about 506 cubic feet per minute depending on VE. So since these engine are similar in efficiency it takes about 506 cfm to make 342 hp. A 318 at 5500 rpm would pull 506 cfm. And same with 340 @ 5147 rpm and 360 @ 4867 rpm. At these rpms these 4 engines are the same size. Same potential.
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Same potential, but IMO different applications. And sooner or later the smaller engines will blow up,trying to keep up with the bigger ones, or will cost a fortune to survive. And the higher you spin 'em the softer the bottom gets.
One thing I can say with absolute surety is that I ,that's me personally,wouldn't spend a nickle on a smaller than 360 engine, for a street A-body, and someday I'd sure like to stick one in a lightweight-A . The 360 just hits more targets, more of the time with less sacrifices made.

Nice math
 
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I just want to build something I can cruise that has a good lopey idle that will occasionally eat up a camaro and mustang here and there. I got my current 318 I could result or I got a chance to do a magnum but I'll be honest as I am limited on funds,
 
You've already got the 318. I'd rebuild that motor. With the right parts, 325 will be easy. Plus there will be NO worries as to what will transfer over and what will not.
 
harrisonm said:
You've already got the 318. I'd rebuild that motor. With the right parts, 325 will be easy. Plus there will be NO worries as to what will transfer over and what will not.
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How would I go about getting that kind of power from a baby 318. I hear 360 heads kill compression. Best piston I found is a kb167. Stroker to 390 will be too pricey. 302 heads are scarce like a unicorn.
 
The 5.9 Magnum is a no brainer as far as finding one in good condition. The LA engines are just getting harder to find without needing a complete and total rebuild with all the expensive stuff like seats and guides, boring and new pistons.
 
texas360 said:
I just want to build something I can cruise that has a good lopey idle that will occasionally eat up a camaro and mustang here and there. I got my current 318 I could result or I got a chance to do a magnum but I'll be honest as I am limited on funds,
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Id go with a running 5.9 magnum just add some headers and 4bbl and you hit your minimum of 320 hp add cam later and hit 350 hp plus.
 
AJ/FormS said:
Same potential, but IMO different applications. And sooner or later the smaller engines will blow up,trying to keep up with the bigger ones, or will cost a fortune to survive. And the higher you spin 'em the softer the bottom gets.
One thing I can say with absolute surety is that I ,that's me personally,wouldn't spend a nickle on a smaller than 360 engine, for a street A-body, and someday I'd sure like to stick one in a lightweight-A . The 360 just hits more targets, more of the time with less sacrifices made.

Nice math
Click to expand...

I agree 360 has all the advantages especially on the street. But I was just trying to correct the thinking somehow 318 cant make similar hp with the similar parts. Of course your gonna have to turn the powerband up about 600 rpm and at least 2 steps lower gear and about 600 rpm more stalll and a ruffer idle than a 360 . For some those are disadvantages their willing to live with and others not. I figure if your will to gear it
(small displacement) build it if not go bigger or except lesser performance for the same dime.
 
texas360 said:
You know around town. Get. On some back roads. Do some repaving,, get on hwy and chill at 70.
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Oh, OK
Here on the prairies cruising has a different meaning,. A cruise is a 4-hour ride to nowhere that includes a lunchbreak somewhere.
It has to have long abandoned blacktop stretches, some twists and turns, some valleys and hills,blind turns, abandoned towns,and you know; there's no cops anywhere except in the place you left behind.
 
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273 said:
I agree 360 has all the advantages especially on the street. But I was just trying to correct the thinking somehow 318 cant make similar hp with the similar parts. Of course your gonna have to turn the powerband up about 600 rpm and at least 2 steps lower gear and about 600 rpm more stalll and a ruffer idle than a 360 . For some those are disadvantages their willing to live with and others not. I figure if your will to gear it
(small displacement) build it if not go bigger or except lesser performance for the same dime.
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How about a streeter with lotsa gears, overdrive, a clutch, and and a stout 360 ? I know, I know, overkill. I buy my tires in bulk.
 
I'll be installing a sure grip and 3.23 in my 8.25 also once I figure that out. Never set up a rear end.
 
texas360 said:
How would I go about getting that kind of power from a baby 318. I hear 360 heads kill compression. Best piston I found is a kb167. Stroker to 390 will be too pricey. 302 heads are scarce like a unicorn.
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While the larger chamber head does kill some compression it has been proven in a few venues, here included that you should take flow over compression every time. There is more loser in flow than compression.

Search posts by member IQ52.

I have a set of bare 302’s doing nothing.
There still greasy and unchecked.

AJ/FormS said:
Same potential, but IMO different applications. And sooner or later the smaller engines will blow up,trying to keep up with the bigger ones, or will cost a fortune to survive. And the higher you spin 'em the softer the bottom gets.
One thing I can say with absolute surety is that I ,that's me personally,wouldn't spend a nickle on a smaller than 360 engine, for a street A-body, and someday I'd sure like to stick one in a lightweight-A . The 360 just hits more targets, more of the time with less sacrifices made.

Nice math
Click to expand...
Agreed. But at this level, your not worried about burning out a 318. Even at 400hp, or 480 hp. And that’s because we your seldom living at 4500+ rpm.

My last 360 was north of 475hp and it is and will be fine. Until I live at that rpm for that magic hp level. Visiting once in a while won’t wreck the engine anytime soon.
 
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