360 TrueStreet Magnum Build

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RAMM

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Its been awhile since I've posted anything useful or remotely interesting. I recently acquired a 360 Magnum core that once resided in a Jeep Grand Cherokee, at least that's what the guy I bought it from told me. I never say no to a 360 core if its the right price and not too far gone. So after sitting on it awhile trying to figure out what to do with it I've finally settled on a plan.

The plan is to build a really nice mild street engine on a fairly tight budget using as many of the OEM parts as possible. The goals are maximum bang for the buck on Canadian pump gas whether it is 87-91 octane also keeping an eye toward excellent street manners (driveability) . I would rate this one as 99.5% street .5% strip. Truthfully I don't know what to expect as far as HP production goes but I feel 360-380hp and a ton of off idle and midrange torque is fair to expect.

Parts: '99? 360 Magnum block
360 Magnum crank
360 Magnum rods prepped w/ARP bolts
Mahle-Clevite Magnum replacement pistons .020"
CCCN New Magnum replacement castings-ported OEM valves
OEM Magnum rocker gear/pushrods/new Melling roller lifters
Lunati Hyd-Roller #20200715 http://www.lunatipower.com/Product.aspx?id=1549&gid=360
1 5/8" headers w/Magnaflow mufflers
Professional Products Crosswind intake
QuickFuel 600 Vaccuum Slayer carb


Specs: 363.5 cubic inches
9.0 comp
hydraulic roller cam
dual plane

I know this sounds really boring but I am honestly intrigued with the sum of these parts.

Here's a shot of the block being rough honed. J.Rob

View attachment 360 006.jpg
 
This pic displays the .003"-.005" wear in the cylinder nicely. As you can see the block has been roto-blasted and decked at this point. Only .005" was removed in order to achieve a new,flat fresh surface. J.Rob

View attachment 360 007.jpg
 
After the cylinders are rough honed to within .003" on go the torque plates. J.Rob
 

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These are the prepped rods and OEM replacement pistons in .020" J.Rob
 

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Nice, I love the build since there are tons of these 360 blocks out there. Sounds like this will be like the 380 hp crate engine, but less $$.

Will be watching.
 
Keith Mopar said:
Nice, I love the build since there are tons of these 360 blocks out there. Sounds like this will be like the 380 hp crate engine, but less $$.

Will be watching.
Click to expand...

Yes that is kind of what I am aiming at although it will have a lot less camshaft so it should be very easy to live with.

I didn't want to get into using expensive forged pistons or aftermarket rods because I don't plan on balancing this engine. J.Rob
 
Keith Mopar said:
Sounds like this will be like the 380 hp crate engine, but less $$.

Will be watching.
Click to expand...

Are you sure you weren't a fly on the dyno cell wall?

I was able to complete this build and do some preliminary testing. Suffice it to say I did not quite reach 380hp.

All testing was done with a 600 cfm QFT vac sec because it is reliable and the biggest carb I have under 950 cfm right now. Esso 91 was used because that is what I had in the tank. I am confident this will make as much power on 87 . At no time or timing setting was the engine hard to start or shut off.

I wound up with 371-374 hp @ 5100-5200 rpm on pull 4 through 9. I only pulled to 5500 rpm where it was down about 1-2 hp from peak. What is really nice is the 428 ft/lbs @ 3900 rpm. I started the testing at 3250 rpm where 423.8 ft/lbs was observed. Idle vaccum was a steady and smooth 15-16" @ 750-800 rpm. Total timing was wound up at 37-38 total likely due to the low compression and no real quench to speak of. A half inch spacer hurt power everywhere. I was hoping to see 380 hp show up but not without putting more time than I have into this build. I feel that a 750 dbl or even a 650 dbl would likely crest the 380 hp mark and then some. Manifold vacuum was registering 1.1-1.3" in the upper third of the pull indicating the carb is on the small side and presenting a restriction. It is extremely responsive-I pulled it once as low as 2500 where 376 ft/lbs was available.

All in all I am quite pleased. It has stock valvetrain except for the springs,stock replacement pistons, stock rods (ARP bolts), crankshaft, dual plane manifold, and mild Lunati hydro roller. It almost matches the output of a Mopar 380 hp 360 crate but with FAR better manners/driveability and on cheap fuel and likely a bunch cheaper to acquire as well. J.Rob

View attachment TSMagnumdynosheet.jpg
 
Here's a screen shot of the vitals at idle. J.Rob

Video to follow.
 

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Man that's as close to 380 as it gets, an easy build to duplicate.
thanks for the build info RAMM.
 
fratzog lover said:
What roller cam does the 380hp have in it? Was just wondering that today for a future build. Anyone know?
Click to expand...

Here is a link http://www.moparmusclemagazine.com/techarticles/engine/mopp_0303_360_crate_engine_buildup/

It states 288/292 duration but I am unsure of the LSA. I have worked on a couple of cars with this crate and with the big cam and big single plane they couldn't get out of their own way. They need a lot of gear for any kind of performance. This cam is definitely more for strip use. J.rob
 
Sweet engine on a budget.
If you put a smaller cam in the same engine, for a truck that just was used for towing, max rpm 4000 what would you expect for torque?
Say for instance a cam that would pull clean from 500 rpm to 3500.
 
What a nice build J.rob. Super nice torque curve & that power with a 213* cam is sweet. :thumbrig:
 
Now you got me thinking of pulling a junkyard magnum that is just a shortblock and doing this to it for my truck and pulling all the stuff off my 318LA that it would need.

what'd you do to the heads? I'm sorry I am a complete noob here. I don't understand how one would port valves. Could you explain a lil? could it be done at home?
 
Read Mopar Action. They are currently doing a Magnum low buck buildup that might help with ideas. it's been progressing for the last few issues (and the current one) and they sell back issues.
Seems like the Enginequest iron head is the best thing going for Magnum builders who don't want to go aluminum or really hi buck.
Hope this helps I'll be watching since this idea has merit for me too! Good luck!
 
PanGasket said:
Now you got me thinking of pulling a junkyard magnum that is just a shortblock and doing this to it for my truck and pulling all the stuff off my 318LA that it would need.

what'd you do to the heads? I'm sorry I am a complete noob here. I don't understand how one would port valves. Could you explain a lil? could it be done at home?
Click to expand...

Here's the thread with the actual heads in use--http://www.forabodiesonly.com/mopar/showthread.php?t=257491

It could be done at home but you need to verify them on the flowbench to monitor your progress. J.Rob
 
OldmanRick said:
What a nice build J.rob. Super nice torque curve & that power with a 213* cam is sweet. :thumbrig:
Click to expand...

Thanks OldmanRick. The engine would truly be at home in the vast majority of street bound Mopars with highway gearing and stock converters. J.Rob
 
sireland67 said:
Sweet engine on a budget.
If you put a smaller cam in the same engine, for a truck that just was used for towing, max rpm 4000 what would you expect for torque?
Say for instance a cam that would pull clean from 500 rpm to 3500.
Click to expand...

I wouldn't expect anymore torque to show up--I would just expect it to be shifted lower in the RPM's. A slower more conservative timing curve may be required though. J.Rob
 
You can see here how it closely resembles a stock rebuild. J.Rob
 

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Too bad you couldn't run it with stock cast exhaust and a 500 2bbl for us roundy round guys. We are all about a flat torque curve expecially in the 2500 to 6000 rpm range.
 
mod5v said:
Too bad you couldn't run it with stock cast exhaust and a 500 2bbl for us roundy round guys. We are all about a flat torque curve expecially in the 2500 to 6000 rpm range.
Click to expand...

You should shoot me a PM.
 
With some head porting you probably could hit 400 hp and still have a pretty tame running engine.
So when they say those 380 hp create engine really make 400 - 420 hp must be true.
 
The create engines have routinely dyno'd at 410+ every time. Do keep in mind that they have a 9.0-1 comp ratio and stock Magnum heads minus the springs to work with the cam. It is a really nice platform to go from.

Now think what the head could be with a capable porter and a slight milling. A few guys here were/are running them in Dusters to low 12's with the create engine OOTB and 11's when the car is put on a weight loose program.
 
273 said:
With some head porting you probably could hit 400 hp and still have a pretty tame running engine.
So when they say those 380 hp create engine really make 400 - 420 hp must be true.
Click to expand...

These heads are ported. This engine is about as tame as it gets. J.Rob
 
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