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Re: 360 Magnum vs 383... What would make more power?
[Re: JohnRR]
#1393708
02/27/13 01:54 AM
02/27/13 01:54 AM
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Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
64Post
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Quote:
I have a 383 that is about 12.4 compression ... to get it , I had to increase the stroke to 3.9 , cut the heads down to 84 cc from 90 and put a 10 cc dome on the piston.
Damn, great minds think alike. Those are the exact specs on my rotating assembly.
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Re: 360 Magnum vs 383... What would make more power?
[Re: 64Post]
#1393709
02/27/13 02:44 AM
02/27/13 02:44 AM
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Joined: Jun 2006
Posts: 5,159
CT
GTX MATT
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I will say 383 because I am a big block guy. You can probably score used bolt on parts for it cheaper too. I see low deck aluminum intakes for 75 bucks all the time. Cheap summit cams, used cams, and cams people didn't decide to run.
I've never owned a 383 myself. I've been really unimpressed by some, and really really impressed by others. Make sure its got gear and its tuned well and it'll scream.
And you'll have to deal with selling the 383.
Now I need to pin those needles, got to feel that heat
Hear my motor screamin while I'm tearin up the street
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Re: 360 Magnum vs 383... What would make more power?
[Re: 74yellowduster]
#1393711
02/27/13 07:09 AM
02/27/13 07:09 AM
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Posts: 4,862
the frozen wastes...
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ok for cheap then, just get the solid .528 cam for the 383 & e85 quickfuel carb have the heads milled to get you to 12:1 or so (iron heads, alum could go to 13:1) run a 180 deg thermostat
you will probably want to run an elec fuel pump with return style regulator/bypass if you go E85
on straight pump gas, ok yeah the 360magnum might have an edge. just watch when you buy one though make sure the exhaust valve seats are not all cracked up. if it came out of a pickup, rode real hard they probably are.
We dont have E85 here anyways... so moot point.
I was looking for one from a van preferably. Really, from what i've seen there are enough to choose from around here i can probably find a nice one without too much effort.
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Re: 360 Magnum vs 383... What would make more power?
[Re: pnypwr]
#1393712
02/27/13 07:13 AM
02/27/13 07:13 AM
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keep the trans in mind...all things equal unless this is a hypothetical situation if you have a big block and are thinking of changing to a small block...everythings different...that can get expensive. as for power id go with the 383 they make gobs of torque, rev to the moon, you could find a set of closed chamber heads put bigger valves in them some mild porting and make a low budget screamer. I had a 440 with 67 lopo closed chamber with a valve job and bigger valves, stock short block a used fireball cam and iron sixpack and it put 400hp and 550 ft lbs to the pavement with a real conservative tune had 2500 into the whole deal with the sixpack 1200 into the engine and most of that was the headwork
All i'd be missing is mounts (cheap) and a SB bellhousing (just sold one, dammit!). I think the only real expense would be a set ov GOOD headers for a small block... but for now it'd be manifolds or shorties if need be.
Oh, and my 383 already has 516's, and i have another really nice set ov 516's kicking around as well. Was thinking down the road a bit having them shaved pretty hard and doing some minor porting with some 1.81" exhaust valves.
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Re: 360 Magnum vs 383... What would make more power?
[Re: GODSCOUNTRY340]
#1393713
02/27/13 07:15 AM
02/27/13 07:15 AM
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With the bore of a 383 (4.25) you can go with a lot bigger valves than you'd ever get into a 360's bore (4.00).
Yes, but also keep in mind the 360 Magnum crate with its 380HP made more HP than the 360 LA crate with 360HP it replaced... and it has smaller valves too. This is where old school meets new school, and kinda the point in this whole thread... does the modern technology make up for good ol' cubes and big everything.
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Re: 360 Magnum vs 383... What would make more power?
[Re: 70Cuda383]
#1393714
02/27/13 07:30 AM
02/27/13 07:30 AM
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ok for cheap then, just get the solid .528 cam for the 383 & e85 quickfuel carb have the heads milled to get you to 12:1 or so (iron heads, alum could go to 13:1) run a 180 deg thermostat
Do you have any idea hom much would have to come off a set of heads to get his low compression 383 , he's lucky if it's 8:1 on its RATED 9.2 compression.
I just ran some numbers , the pistons in his engine are probably .080 in the hole , if this is the case he would have to have a head with a 46cc chamber to get 12.0 in a 383.
If his heads are 84cc he would have to cut .190 off them to get the chamber down to 46 cc.
It's a nice thought but not something doable with his low budget build with parts he has laying around .
there were different 383's some 10:1 some 9.5:1 some 8.5:1 etc.
you're talking advertised numbers I take it? what 383 was ACTUALLY a 10:1 compression?
the magnum will be about 9.0 compression with the stock heads and stock head gaskets. a .030 cut on the heads and a felpro 1008 gasket gets you 9.5 compression with the dished factory pistons. I actually measured mine while I had it open and I'm at 9.5 compression, assuming things like a 58cc head was actually 62 before being cut, and as accurately as I could measure the edge of the dished piston in relation to the deck at TDC.
anyway, budget minded, I still give the nod to the 383. a good intake, carb, cam, headers, and you have a 400-425hp motor on 89 octane gas. the magnum will cost a bit more money to get over 400 hp out of it.
Yeah... i looked and looked and looked for a 68-69 383 4bbl-ONLY engine to get that extra compression, but i found nothing but cores and junk. Try to find a nice running 383 Magnum or 4bbl engine that doesn't need a rebuild... I actually found one last year... but a flipper got to it 10 minutes before i did.
The minor mods you mention on the Magnum are something else i'm considering, down the line... so its good to know i could actually make some compression without rebuilding the engine.
In my shop i have:
- a good running 67 383 2bbl long block
- Holley Street Dominator intake (ported)
- Holley 800DP and a Holley 670 Street Dominator carb
- Hedman shorty BB headers
- deeper sump oil pan, windage tray
- aluminum water pump and housing
- MSD pro billet distributor
- a nice set o 516 heads and some new 1.81" exhaust valves to put together and port (later)
- cool valve covers
- piles ov the little stuff, all for lowdeck big blocks
- enough 3" mandrel pipe to dual-exhaust a school bus.
I have only to buy the Hughes Whiplash cam (that i am 100% sold on) and i'll have a pretty killer little combo i think.
Hell... i even have a Weiand 2x4 tunnel ram in the pile too... bought when the plan was different...
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Re: 360 Magnum vs 383... What would make more power?
[Re: feets]
#1393715
02/27/13 07:35 AM
02/27/13 07:35 AM
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Which transmission and converter do you have on hand? If it's B/RB stuff you'd be money ahead to stick with the 383.
4-speed from a 70 340 Cuda. I have every big block piece needed save the actual clutch disc (have that too, but the shipper sent me an 18-spline one instead).
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A mild 383 and 5.9 Magnum are going to be very close in power. For some reason the 5.9 has always been a gas hog. 
Yeah, so the story goes, but i've always wondered if that was because the trucks they came in were underpowered and flogged all the more for it. EVERY time i see/hear a V8 Ram go by its being flogged. My friend used to get single-digit MPG with his 5.9L 4x4 Ram.
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Re: 360 Magnum vs 383... What would make more power?
[Re: DPelletier]
#1393716
02/27/13 07:39 AM
02/27/13 07:39 AM
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anyway, budget minded, I still give the nod to the 383. a good intake, carb, cam, headers, and you have a 400-425hp motor on 89 octane gas. the magnum will cost a bit more money to get over 400 hp out of it.
...and I think the weight difference is overrated; once you put on headers and an aluminum intake, the 383 isn't that heavy. A mini starter, alum water pump, etc. and it gets lighter yet. You could always go with a set of alum eddy's or stealths in the future too. I would bet that a 383 with all the alum goodies is as light as a stock LA setup.
Dave
Yeah... i have all that stuff, but wont be getting aluminum heads again, ever. Not unless BC ceases being the most expensive place on Earth anytime soon.... I'd never buy Edelbrock or Stealth heads though... i'd scour the Earth for a set ov used Stage 6's or B1BS's first.
As for the weight, thats true, but at the same time... i can start buying aluminum parts for the small block too... I'll already have the manifold.
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Re: 360 Magnum vs 383... What would make more power?
[Re: RUNCHARGER]
#1393717
02/27/13 07:45 AM
02/27/13 07:45 AM
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Both engines can be made to run, I like the combustion chambers and roller cam in the magnum, I like the big bore and ease of working on the 383. I would base my choice on transmission needs. If you want something with more than 3 gears auto or 4 gears manual it will be much cheaper and easier to go the Magnum route with the factory available overdrives for it.
Sheldon
Yeah... i've always been a big block guy too. I cant think ov a simpler engine to own or at least work on. Never been into the small blocks at all.
But i also like the modern efficiency... and if both engines make 380HP but the Magnum does it on less gas i'll go that way and not look back. I dont need more than 400HP right now... i can win plenty ov races with that. I also like the SOUND ov the Magnums... they have a definitive howl that older engines just dont have. They sound like a new engine. I really like that.
Confused about the OD thing though... i thought it was just as expensive to put a 5-speed behind a small block than a big block? I dont want a NV truck tranny. Am i forgetting something? An OD stick IS part ov the long range plan.
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Re: 360 Magnum vs 383... What would make more power?
[Re: DaytonaTurbo]
#1393718
02/27/13 07:47 AM
02/27/13 07:47 AM
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Talking unrebuilt short blocks here, the 360 magnum wins hands down. A 40 year old cast ringed 383 that lived under a carb all its life versus a moly ringed 360 that lived under a clean running efi system. If you've ever taken apart a high miles carb engine versus a high miles efi engine, it's a night and day difference. The 360 will have better ring seal, cleaner pistons and valves and be easier to get a decent compression ratio out of on a budget. As much as I like big blocks, you almost can't find a good running good condition unrebuilt stocker anymore.
I DO have a nice 383... got lucky. But now you're making the new stuff sound even better to me. Didn't know all that stuff. Hmmm...
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Re: 360 Magnum vs 383... What would make more power?
[Re: Pale_Roader]
#1393720
02/27/13 10:34 AM
02/27/13 10:34 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Quote:
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Both engines can be made to run, I like the combustion chambers and roller cam in the magnum, I like the big bore and ease of working on the 383. I would base my choice on transmission needs. If you want something with more than 3 gears auto or 4 gears manual it will be much cheaper and easier to go the Magnum route with the factory available overdrives for it.
Sheldon
Yeah... i've always been a big block guy too. I cant think ov a simpler engine to own or at least work on. Never been into the small blocks at all.
But i also like the modern efficiency... and if both engines make 380HP but the Magnum does it on less gas i'll go that way and not look back. I dont need more than 400HP right now... i can win plenty ov races with that. I also like the SOUND ov the Magnums... they have a definitive howl that older engines just dont have. They sound like a new engine. I really like that.
Confused about the OD thing though... i thought it was just as expensive to put a 5-speed behind a small block than a big block? I dont want a NV truck tranny. Am i forgetting something? An OD stick IS part ov the long range plan.
well, a manual tranny, get a 3.9L dakota AX15 bellhousing, and I believe a supra R154 tranny bolts up to it, if you're looking to low-buck it...
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2017 Grand Cherokee Overland
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Re: 360 Magnum vs 383... What would make more power?
[Re: patrick]
#1393721
02/27/13 12:19 PM
02/27/13 12:19 PM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
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I know you said you don't want the NV trans...mine held just fine with at least 400 ft lbs of torque at the crank...with street tires. I know a guy who's got his reg cab dakota into the 13s on slicks with a supercharged 318 and an NV3500.
if you keep your build mild, the 3500 will work ok.
or, you can source the Supra trans, those are much beefier than the NV3500, and some guys have put them behind their small blocks with the AX-15 bell housing.
but in general, yea, if you go with a TKO or a T-56, it's the same cost regardless of if you go small block or big block, the only part that's different between the 2 is the bell housing and possibly the flywheel depending on how your engine is balanced.
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