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300hp magnum crate 360 convert to 380hp?
#653937
03/28/10 06:43 PM
03/28/10 06:43 PM
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Joined: Jan 2003
Posts: 1,271
eastern long island,NY
JeepJimmy
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,271
eastern long island,NY
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has anyone converted the magnum 300hp 360 MP crate motor to the 380 hp model. from what i can find its only the cam and to a single plane intake. any ideas??
70 duster 360magnum, 1975 jeep j-10.
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: JeepJimmy]
#653938
03/28/10 08:21 PM
03/28/10 08:21 PM
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Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
Rapid340
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top fuel
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Posts: 2,091
oberlin, Ohio
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Are the pistons/compression the same?
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: chache876]
#653941
03/29/10 12:05 AM
03/29/10 12:05 AM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
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Posts: 12,419
Kalispell Mt.
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The pistons are different and slightly higher compression, the 380 HP motor I saw come appart had pistons with 2 valve releifs instead of the soap dish production pistons and 300hp pistons. They were below deck but I don't know how much but they would give a slightly higher compression.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: HotRodDave]
#653942
03/29/10 12:16 AM
03/29/10 12:16 AM
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Joined: Feb 2004
Posts: 4,501
Gainesville,FL
goldmember
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Gainesville,FL
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Quote:
The pistons are different and slightly higher compression, the 380 HP motor I saw come appart had pistons with 2 valve releifs instead of the soap dish production pistons and 300hp pistons. They were below deck but I don't know how much but they would give a slightly higher compression. [/quote 
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: DaytonaTurbo]
#653944
03/29/10 09:54 AM
03/29/10 09:54 AM
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Joined: Jan 2003
Posts: 17,841
S.E. Michigan
ZIPPY
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S.E. Michigan
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Change the cam, springs, retainers, and intake and you're done.
Here's the evolution of those two engine programs:
300 and 380 initially came with a stock long block right from the Saltillo Mexico engine line. Both had stock magnum heads. 380 got the cam, springs and retainers changed....300 did not.
Then MP ran Chrysler completely out of OE magnum heads, the OE supplier wasn't interested in making them anymore, and it probably would have cost 500k or more to modify the tools to fit a different foundry line.....So, enter the R/T heads and plan B:
320 and 390 had R/T heads and started out with stock Saltillo shortblocks.
That worked fine for awhile, but it wasn't long before MP ran Chrysler completely out of new OE shortblocks...and it was time for plan C:
They both got .020 over reman shortblocks with FM hypereutectic pistons, R/T heads, and otherwise the same specs as before.
380 had a stock piston.
390 in it's final, .020 over form had a better piston with a couple vavle reliefs.
390 in it's very first form had a stock piston.
Rich H.
Esse Quam Videri
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: JeepJimmy]
#653945
03/29/10 06:13 PM
03/29/10 06:13 PM
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Joined: Jan 2003
Posts: 1,271
eastern long island,NY
JeepJimmy
OP
pro stock
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OP
pro stock
Joined: Jan 2003
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eastern long island,NY
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Thanks Zippy, i could not get a correct answer from anyone. trying to find a PN breakdown of the motors. i know i saw one years ago.. Wonder how it will work keeping the dual plane. its not a drag car.
70 duster 360magnum, 1975 jeep j-10.
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: ZIPPY]
#653946
03/29/10 08:00 PM
03/29/10 08:00 PM
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Joined: Aug 2006
Posts: 1,609
Southern Cal
Noblewk
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top fuel
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Southern Cal
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Quote:
Change the cam, springs, retainers, and intake and you're done.
Here's the evolution of those two engine programs:
300 and 380 initially came with a stock long block right from the Saltillo Mexico engine line. Both had stock magnum heads. 380 got the cam, springs and retainers changed....300 did not.
Then MP ran Chrysler completely out of OE magnum heads, the OE supplier wasn't interested in making them anymore, and it probably would have cost 500k or more to modify the tools to fit a different foundry line.....So, enter the R/T heads and plan B:
320 and 390 had R/T heads and started out with stock Saltillo shortblocks.
That worked fine for awhile, but it wasn't long before MP ran Chrysler completely out of new OE shortblocks...and it was time for plan C:
They both got .020 over reman shortblocks with FM hypereutectic pistons, R/T heads, and otherwise the same specs as before.
380 had a stock piston.
390 in it's final, .020 over form had a better piston with a couple vavle reliefs.
390 in it's very first form had a stock piston.
Plan D. While making the 402 stroker the R/T heads were adapted to "Big valve" heads. The remainer of the R/T "Big Valve" heads were used in the last production run. All crates were put together my Cummins. You will find a Cummins Date tag/Serial# on the blocks "pass side on the Bell mount"
66 Dart GT, 402 11.18:109 Best
63 1/2 Galaxie 500XL 406 4Speed 13.20:103 Best
2000 Ram
2005 Durango Hemi.
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: ZIPPY]
#653948
03/29/10 09:48 PM
03/29/10 09:48 PM
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Joined: Oct 2009
Posts: 87
Bama
BigDawg72
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Bama
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Zippy... Thanks for a very informative post! To the OP, I am using the Professional Products Airgap RPM knockoff in my build and was told by someone knowledgeable on the magnum engines that it should produce more HP than the Mopar M1 single plane intake. They stated that the M1 wasn't a great intake.  If my Flamethrower distributor would hurry up and get here I would fire mine up and have some real feedback on the combo. It does make me feel confident that my 400-425 HP goal is attainable since the same cam was/is used on the 380, 390, and 435 horse crate engines. I know it's all in the heads, but I hope to see the high side of 400 with my slightly cleaned up plain magnums. Maybe I' m too optimistic...
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: HotRodDave]
#653950
03/29/10 11:52 PM
03/29/10 11:52 PM
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Joined: Feb 2004
Posts: 4,501
Gainesville,FL
goldmember
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Gainesville,FL
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Quote:
Quote:
Quote:
The pistons are different and slightly higher compression, the 380 HP motor I saw come appart had pistons with 2 valve releifs instead of the soap dish production pistons and 300hp pistons. They were below deck but I don't know how much but they would give a slightly higher compression. [/quote
Thanks for the aditional insight there, very helpful 
I was picturing you looking at the valve reliefs and doing the math in your head,then the distance down by eyeball and more speculating. Thats real helpful! 
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: goldmember]
#653951
03/30/10 07:03 AM
03/30/10 07:03 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
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Posts: 16,123
Grand Haven, MI
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upgrading a 300HP mag motor for a street car, I think I'd use a cam like a hughes 1828, not something as big duration wise as the 380 horse motor. Zippy, I thought the 300HP motors got the upgraded springs, too.
the dual plane isn't a bad piece, it's on par with a stock LA 4bbl intake. an edelbrock air gap would probably be worth an additional 15-20 HP...
the M1 single plane is a good intake, probably makes about the same or a touch more HP as the air gap, but like most single planes, is probably down 15-20 lb ft of midrange torque over the air gap or the dual plane....
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: BigDawg72]
#653952
03/30/10 08:59 AM
03/30/10 08:59 AM
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Joined: Mar 2003
Posts: 571
Beaverton, OR, USA
Alikazam
super gas
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super gas
Joined: Mar 2003
Posts: 571
Beaverton, OR, USA
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Quote:
Zippy... Thanks for a very informative post!
To the OP, I am using the Professional Products Airgap RPM knockoff in my build and was told by someone knowledgeable on the magnum engines that it should produce more HP than the Mopar M1 single plane intake. They stated that the M1 wasn't a great intake.
If my Flamethrower distributor would hurry up and get here I would fire mine up and have some real feedback on the combo. It does make me feel confident that my 400-425 HP goal is attainable since the same cam was/is used on the 380, 390, and 435 horse crate engines. I know it's all in the heads, but I hope to see the high side of 400 with my slightly cleaned up plain magnums. Maybe I' m too optimistic...
My 360 is putting down 340 whp on a dynojet chassis dyno, so with 20% drive train loss comes right at 425 hp (727 transmission, ford 9" rearend). I run Edelbrock heads (not ported, out of the box), RPM Air-Gap, 10.2:1 compression ratio, holley 750 VS carb, headers and dual 2.5" exhaust, and a crane retro-fit roller cam (112 lsa, 107 installed, 230/238 @ .050, .528/.538 lift). If your combo is close to this you should be able to see similar numbers I'd think 
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: ZIPPY]
#653954
03/30/10 10:10 AM
03/30/10 10:10 AM
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Joined: Aug 2006
Posts: 1,609
Southern Cal
Noblewk
top fuel
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Southern Cal
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The plan D had to do with the "Big Valve" R/T heads on the last group of 360/390 crates. The earlier versions of the combo received the standard R/T head combination.
66 Dart GT, 402 11.18:109 Best
63 1/2 Galaxie 500XL 406 4Speed 13.20:103 Best
2000 Ram
2005 Durango Hemi.
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Re: 300hp magnum crate 360 convert to 380hp?
[Re: ZIPPY]
#653956
03/30/10 12:29 PM
03/30/10 12:29 PM
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Joined: Sep 2009
Posts: 186
Kansas, USA
Venomvpr900
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Kansas, USA
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Quote:
There is a new low cost 4" stroke, reman-style, magnum head MP crate engine hopefully coming online this summer. I'm not going to post the part number until it's been activated, however the directional MSRP is currently $5419 so that's a good sign. Given the pieces in it, it should run as hard (or better) than the older version.
That would be better then the $10,000 they have the 405hp 360 listed for. What a rip 
1987 D-100 SWB, 390hp/360ci Mopar Performance Crate, Built 998 trans, 9.25 axle with sure-grip and 3.92's - 3960#'s with driver
13.83 @ 96.36 1.98 60 ft
2003 Dodge Ram 2500 HD 5.7ltr HEMI!!!
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