Author Topic: 360 Magnum - EFI vs Carb  (Read 4793 times)

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Offline mjhallas

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360 Magnum - EFI vs Carb
« on: February 24, 2010, 02:59:34 PM »
I was going through some old threads and found this one about what makes the 360 Magnum 300 HP crate motor.

"Mag engine as is, stock injected, is 230hp. By simply placing a dual plane M1 carb intake on top (using stock truck mag roller cam/long block) hp bumps up to 300, and is what the mopar performance "300hp crate motor" is. A stock truck engine with a carb on top."

Where does the extra seventy horsepower come from? How came this be- I always believed the Efi to be far more efficient than a carburetor. No cam change, head work ect.....???

Junkyards are selling these 360 mag's for around $300-500 depending on the mileage. The M-1 intake goes for around $300, add in the install cost's like a new torque converter or flywheel, Thats a budget friendly power upgrade.

Offline s ǝoɾ

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Re: 360 Magnum - EFI vs Carb
« Reply #1 on: February 24, 2010, 03:40:54 PM »
Probably comes from the timing control or higher flow through throttlebody, or a combination of the 2.

EFI could be more efficient and usually is. Stock pcm limits timing a little bit so you can pull a 7000lb load up a 6% grade on 87 octane w/o pinging.

It also comes from the fact the crate motor is dyno'ed using the old SAE gross standards, where they use long tube headers, no drive accessories, and no air cleaner. Hell I don't think they even dyno with a water pump, let alone a engine fan. Usually no belt period, and just use a universal electric pump to make dyno work easier.

The production magnum is destined for regular production vehicles and is dyno'ed as would be installed in production vehicle. Stock manifolds (may even include cat and y pipe) stock air box, engine fan, alt, ps pump, any other accessories.

That is where the other part of the hp went. Crate engine uses the muscle car standard. Muscle car standard produced over inflated exaggerated numbers.
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Offline Elwenil

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Re: 360 Magnum - EFI vs Carb
« Reply #2 on: February 24, 2010, 03:53:35 PM »
Keep in mind that all the 360 Magnum crate engines seem to dyno a bit over their rated horsepower so even the advertised rating is a little conservative.  While EFI may be a more fine tuned system of fuel delivery and timing management, it probably is also tweaked a bit to keep the engine running safely through the warranty period at least.  Add to that the parasitic losses of accessories, emissions and restrictive exhaust and that's probably a good 70 HP right there.
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Offline mjhallas

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Re: 360 Magnum - EFI vs Carb
« Reply #3 on: February 25, 2010, 01:54:20 PM »
Still, that's pretty good for swap material. Can anyone say how the stock EFI cam works with a carb?
Right now I'm running two LA 360's, One bracket motor with Eddy heads (11.00 to11.30 ave.) and one with Mag heads. I don't know their HP ratings other than a SWAG. What got me looking into these is
I just got my wife an 86 Ramcharger with NP435/241 for Valentines Day. The motor was kept by the seller, so for this replacement project I want to use a 360 Magnum. The one feature I like is the factory roller cam. Albeit some what more pricey to replace a roller, today's oil getting less friendly to flat tappet cams. Plus the manufacturing clearances are certainly better than they where in the seventies maybe giving a little more longevity.

Offline s ǝoɾ

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Re: 360 Magnum - EFI vs Carb
« Reply #4 on: February 25, 2010, 02:03:48 PM »
For a driver I would just keep the efi on there. If you needed to gain the power back, you can always port the throttle and trim back the runner length some other day.
Avoid replacing any part that you have not proven to be faulty through extensive testing.

Offline trojmn

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Re: 360 Magnum - EFI vs Carb
« Reply #5 on: February 26, 2010, 09:02:36 AM »

Where does the extra seventy horsepower come from? How came this be- I always believed the Efi to be far more efficient than a carburetor. No cam change, head work ect.....???


yep the MP 300HP mag engine is EXACTLY a stock MPFI motor.
it comes from accessory losses, headers, open exhaust, in other words basically net v gross ratings.

Troj

Offline trojmn

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Re: 360 Magnum - EFI vs Carb
« Reply #6 on: February 26, 2010, 09:08:10 AM »
I just got my wife an 86 Ramcharger with NP435/241 for Valentines Day.

 ;D awesome.   Now THAT is sign of a committed relationship!

Offline chrysler300le

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Re: 360 Magnum - EFI vs Carb
« Reply #7 on: February 26, 2010, 11:58:06 PM »
As said before the difference is the gross HP vs net HP rating.
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Offline mjhallas

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Re: 360 Magnum - EFI vs Carb
« Reply #8 on: February 28, 2010, 12:11:56 PM »
;D awesome.   Now THAT is sign of a committed relationship!
Now I just have to make it run like a new truck.

Offline blueduster

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Re: 360 Magnum - EFI vs Carb
« Reply #9 on: March 3, 2010, 01:46:44 AM »
the barrel intake sucks beyond 2500 rpm. ditching that by itself to a dual plane like the M1 is 30HP. headers and net vs gross is the rest of the difference as the guys said. with the right intake, efi is hands down better. check out hughes' efi eddy rpm air-gap, especially if you modify the engine any. it is what i'm using when i get the fuel system up to par. for now i'm using my M1 dp and a eddy 1406 600cfm. don't need a 750 in a mild 360, especially in a truck. no 6500 rpm shifts at the track but mid range is supposed to be awesome. a tech i worked with has this hughes intake on his 1999 dakota r/t and his 1995 1500 4x4, he can't stop raving about it.

http://www.hughesengines.com/Index/products.php?partid=24773
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