How fast can you go with a Magnum? Who has the quickest setup?

[MRGTX]

So it seems like a set of heads, cam/valve springs and the right intake can pretty easily get you into the 12s but how far can you go with this platform?

From what I gather, the LA 360 has some advantages at the higher end over the 5.9 and I assume that the same applies to the 318/5.2. Have you found that to be the case?

Who has built a beast out of one of these motors? How did it go compared to other builds? Which bottlenecks show up first? At what level do you need to get into the bottom end of the engine?

Alternatively, who is planning on building a monster and what's your plan for getting there?

 

[CUDA69]

If money isn't an issue, wouldn't the block be the limiting factor? 550 HP or so, some of the strokers make that.

 

[rumblefish360]

So it seems like a set of heads, cam/valve springs and the right intake can pretty easily get you into the 12s but how far can you go with this platform?

Minus oiling mods I'd say 6500 rpm's for safe operation. Head port flow limits. Valve train instability issues with extreme lift and rpm. Actual displacement limitations. (HP per CID.)
AKA, total HP per CID & also total engine, weight, drivetrain & chassis combo issues. The amount of power that can be built into the stock (or create) engines is limited. But that is the question now isn't it?

I don't think going into the 11's or less is a huge issues as it isn't the engine that has the only burden. But it has the highest hurdle to overcome.

Are we sticking with the OE heads & pistons or moving away from them?

From what I gather, the LA 360 has some advantages at the higher end over the 5.9 and I assume that the same applies to the 318/5.2. Have you found that to be the case?

I think there is an advantage to the earlier rocker arm set up. Stock head vs stock head, the LA ports out better from what I have been reading.

Also, if I have this right, there are only 2 aftermarket heads for the Magnum. 1 iron, 1 aluminum. There pretty limited vs. all out race heads.

Who has built a beast out of one of these motors? How did it go compared to other builds? Which bottlenecks show up first? At what level do you need to get into the bottom end of the engine?

1st 2 questions I can not answer.
The first bottle neck the Magnum engine faces is ether the heads port flow or the OE low compression ratio.
You'll need to get into the bottom end when cam specs exceed the stock pistons ability to handle ether the long duration holding the valves open or the lift limitations of the OE piston.

I do not know where this happens.

Alternatively, who is planning on building a monster and what's your plan for getting there?

Pipe dreams count?!?!
LOL!

I plan on use of a Magnum block but not the heads.

 

[TrailBeast]

I think you are right on the biggest limitation being head flow.
Engine quest says it's pointless to do anything beyond a cleanup and smooth of their Mag heads due to them already being about as high flowing as possible right out of the box. (better than OTTB Edlebrocks they say)
The EQ head with the 1.92 valves and .512 lift flow right about 230cfm, and with a few bolt on's the 5.9 can easily go over 400hp with a stock bottom end.
Mine was rated at about 420 with the cam EQ heads 1 5/8 long tube headers and 1.92 valves.

 

[MRGTX]

So... lots of good thoughts and suggestions in your post, @rumblefish360 but I just chopped and reorganized a few pieces to hopefully narrow some questions down.

..
The first bottle neck the Magnum engine faces is ether the heads port flow or the OE low compression ratio.
...
I plan on use of a Magnum block but not the heads.
...
Also, if I have this right, there are only 2 aftermarket heads for the Magnum. 1 iron, 1 aluminum. There pretty limited vs. all out race heads...

So if I understand correctly, stock heads have limitations on lift, valvetrain stability and compression, don't respond well to porting, have low compression...

So aftermarket heads are kind of a must-do, correct?
But...there are only two options; EQ and Edelbrock....right?
EQ:
JEGS EngineQuest Mopar Magnum Cylinder Heads | JEGS
Edelbrock:
https://www.summitracing.com/search...9l-360/engine-family/mopar-small-block-magnum

So which ones are you going with?

You'll need to get into the bottom end when cam specs exceed the stock pistons ability to handle ether the long duration holding the valves open or the lift limitations of the OE piston.

Has this been explored? Are there piston/cam combinations that have worked for folks?

 

[jos51700]

I'd say limit this to aluminum heads because every car needs aluminum in it.

Edit: corrected 'grass' to 'heads'. F'en autocorrect

 

[rumblefish360]

So... lots of good thoughts and suggestions in your post, @rumblefish360 but I just chopped and reorganized a few pieces to hopefully narrow some questions down.

OK cool!

So if I understand correctly, stock heads have limitations on lift, valvetrain stability and compression, don't respond well to porting, have low compression...

Limitations not in compression or how well they port out. But yes. Limitations in compression and how well they port out as well as how stable the valve train is and it's max lift is.
OK, I think I may have confused you there.

The stock, as delivered head can only accept so much lift. What lift I don't know and how far it can go is up to the valve, spring and machine work by the machinist. This issue is with all stock, as delivered heads.

They have rocker stability issues. (High lift and RPM) There fix is a girdle, just like a Chevy. You can even use Chevy rocker arms in a Magnum head.

Porting. All heads have limitations on there metal available to port out. The Magnum head does OK on porting. The more you can port the head (for more air flow) the more power you can make.
Do a comparison of ported heads.

Compression is not an issue. But fuel is. That is if you don't want to run E85 but just gasoline in the street. The small chamber helps make high compression.
You build the engine with a desired ratio. How close you get to that is your choice in the challenge.

So aftermarket heads are kind of a must-do, correct?
But...there are only two options; EQ and Edelbrock....right?

Yes and no.
How fast do you want to go?
Very fast? Will stock heads get you there? Probably not.
As far as actual "Magnum" heads and gear goes, as far as I know, there are only 2 heads currently being made that are "Magnum" heads.

So which ones are you going with?

W5 & W2. Oil through pushrod LA heads on the Magnum block.

Has this been explored? Are there piston/cam combinations that have worked for folks?

There are a couple of guys running all Magnum engines. And a few good magazine write ups.

What is your goal? E.T. or dynoed HP number? What car are you using? Is it track only? % of street & track?

With some of the posted/listed flow rates of ported Edelbrock Magnum styled heads, making 600 NA or better HP is possible by the numbers. If your car is a dedicated track car, a severe car lightening program can have the car running quite quick.

 

[rumblefish360]

I'd say limit this to aluminum heads because every car needs aluminum in it.

Unless a rule dictates a iron head, or the choice of iron on the end user is wanted for a reason, then I have to agree. Lighter the better, more the merry.

 

[TrailBeast]

OK cool!


Limitations not in compression or how well they port out. But yes. Limitations in compression and how well they port out as well as how stable the valve train is and it's max lift is.
OK, I think I may have confused you there.

The stock, as delivered head can only accept so much lift. What lift I don't know and how far it can go is up to the valve, spring and machine work by the machinist. This issue is with all stock, as delivered heads.

They have rocker stability issues. (High lift and RPM) There fix is a girdle, just like a Chevy. You can even use Chevy rocker arms in a Magnum head.

Porting. All heads have limitations on there metal available to port out. The Magnum head does OK on porting. The more you can port the head (for more air flow) the more power you can make.
Do a comparison of ported heads.

Compression is not an issue. But fuel is. That is if you don't want to run E85 but just gasoline in the street. The small chamber helps make high compression.
You build the engine with a desired ratio. How close you get to that is your choice in the challenge.


Yes and no.
How fast do you want to go?
Very fast? Will stock heads get you there? Probably not.
As far as actual "Magnum" heads and gear goes, as far as I know, there are only 2 heads currently being made that are "Magnum" heads.

W5 & W2. Oil through pushrod LA heads on the Magnum block.


There are a couple of guys running all Magnum engines. And a few good magazine write ups.

What is your goal? E.T. or dynoed HP number? What car are you using? Is it track only? % of street & track?

With some of the posted/listed flow rates of ported Edelbrock Magnum styled heads, making 600 NA or better HP is possible by the numbers. If your car is a dedicated track car, a severe car lightening program can have the car running quite quick.

IIRC the OOTB EQ heads are limited to about .500 or a hair more at the valve because of stem length and guide height.
Using the Hughes retainers gets you close to .550 and cutting the guides with longer valve stems can get it up there pretty good on lift.
I didn't want to have to get longer valves or have the guides cut for a daily driver, so using the Hughes springs, retainers and locks was fine for the .512 lift using the OE Magnum 1.6 rockers.
I remember the OOTB lift limit being so close to the lift of the cam I used that I wasn't comfortable with it without the Hughes stuff for a little more clearance.
The OE EQ heads have a 63cc closed chamber, 170cc runners and spec out at about 9.1:1 on compression.
As close as I remember anyway.

 

[rumblefish360]

Right! Very good. At 170cc, it is equal to the Edelbrock head, cc wise. So next issue on a daily driver is the ability to flow well at low lifts. More the merry!

I don't know who does what on valve jobs for the best low lift flow rates. But the valve job is (IIRC) responsible for lifts up to .400. Maybe .450. After the .400-.450 lift it becomes more of the bowl area (under the valve) that becomes more responsible for more flow.
9.0-1 is IMO excellent for street use and premium pump gas.

 

[Shainesboostin]

I have a 5.9, hitting with a decent shot of Nitrous. The heads are the issue. You can do a decent piston, eq heads, and some spray it'll run great.

 

[MRGTX]

So this is mostly encouraging stuff, guys.
The info is greatly appreciated...if it weren't for folks like you on this forum, my Magnum would still be on a stand in the garage.

IIRC, the factory fuel injection is a performance bottleneck, correct?

Have people had good luck with aftermarket EFI like the Holley Sniper, etc?

 

[rumblefish360]

Yes and No.

The bottle neck IMO starts with the intake manifold. Then, the throttle body. I could have it reversed. The computer Chyrsler uses isn't street user friendly. Or, in other words, you have to know a person to reflash it. The injectors have limitations. I do not know where that is. There rated at xx pounds. You have to know where xx pounds will show it's hp ceiling.
I don't know where you want to go with this build.

FWIW, A MP - M1-single plane just hit the classifieds for $275, used, glass beaded. That intake is best used at 4,000 plus RPM for the strip. Otherwise, hughesengines has a RPM with FI abilities due to the cast in FI bosses.

No aftermarket EFI experiance here.

 

[MRGTX]

Yes and No.

The bottle neck IMO starts with the intake manifold. Then, the throttle body. I could have it reversed. The computer Chyrsler uses isn't street user friendly. Or, in other words, you have to know a person to reflash it. The injectors have limitations. I do not know where that is. There rated at xx pounds. You have to know where xx pounds will show it's hp ceiling.
I don't know where you want to go with this build.

FWIW, A MP - M1-single plane just hit the classifieds for $275, used, glass beaded. That intake is best used at 4,000 plus RPM for the strip. Otherwise, hughesengines has a RPM with FI abilities due to the cast in FI bosses.

No aftermarket EFI experiance here.

Good info there. Thanks again!

I'm currently running a Mopar M2 dual plane and a 650 carb so my motor is a clean slate when it comes to fuel injection...but it sounds like a factory system wouldn't be worth the trouble.

I'm going to check out that Hughes Engines piece! That sounds interesting...

I'm just looking to wake up this lazy motor but I don't have a final vision in mind for a power level. I tend to find that a powerful but still balance and well matched set-up to be the most fun. I admire and respect the guys who build for the drags too but that's not my goal.

Assuming I can keep the weight down, a fully braced up, Abody with suspension upgrades, a manual transmission, good tires and 450ish hp V8 might just peg the fun-meter for me.

Again, the info is hugely appreciated.

 

[rumblefish360]

I don't know how capable the M-1 dual plane is. Yes, it is an aluminum version of the OE part, but what it takes to ring 450hp out of it and 360 cubes is a route that can vary a bit depending on the rest of the induction side.

You made a mention of it in the Duster with perhaps the OE fuel injection. I know of only 2 kits that will use fuel injection and the Hughes is one. A while back there was a similar set up with the MO single plane that was used. *I think* Mancini sold it. Someone with better grey matter material will have to find that for us right now.

Food for thought.....

Despite the constant ragging on the OE heads cracking (overrated concern) the OE head does power the create engine (360/380hp) to over 400hp via of the testimony of several dyno reports. FWIW, I normally have seen 415/420hp.

Would porting the heads add that extra 30/40hp? Probably so. I don't think you would have to go that far in porting ether. Someone that knows the MP head and the valve seat technical end with a bowl hogged out should be enough.
(IMO anyways)

The OE head maybe a $$$ cheaper option than the EQ head. Which is a very nice head.

What does the rest of the drivetrain consist of? Trans, rear & gears?

 

[blk00rt]

if you can find a set of RT heads true RT heads not just ones from a dakota RT, you can get them to go over .550 lift. Mine are set up for about .600 lift on them. Also computers can be reprogrammed to your set up. That is if you are still using the JTEC computer. If so there are companies like SCT that allows you to send programs to your computer. If so the major programmer out there right now is Ryan. Stock blocks I believe the limit is somewhere around 600-700 hp with superchargers..some are getting higher with turbos. if you are staying N/A and keeping the magnum intake bolt pattern, look for the mopar performance 2bbl intake. It was one of the better intakes for the magnum engines. As far as TB's go look at F&b throttle bodies, they are good. I run a magnum 408 in my dakota with a good shot of nitrous, all from a reprogrammed factory computer..

 

[Abodybomber]

Send OU812 a P.M.,or RAMM or IQ52. All are excellence in Magnum head porting. OU812 has a basic 360 Magnum build,in Mopar Muscle last month.

 

[Bobzilla]

The R/T cast iron heads from Mopar have been out of production for a while and are not worth looking for since they are really no better than currently available EQ heads. The R/T heads, EQ heads, and factory original magnum heads all have very similar lift limitations. They all require cutting down the guides for sufficient clearance and none suffer any negative results from this cutting down of the guides. Also, since it comes up occasionally, I just recently measured clearances on a 1999 magnum 360 with original stock pistons, heads, and valves. No modifications were performed at all except installation of Hughes cam SER1418ALM-10 and their retainers and locks. I used light checking springs for this and found right at .550" test lift the intake retainers contact the factory style valve stem seals. The exhaust retainer contacted the seal at .540" test lift. This is why the old 380hp crate motors had odd cam specs; Mopar never shortened the guides, they just installed a cam that fit the clearance. I had the guides machined down .100" on my heads to fix that clearance, then tested valve to piston clearance with the Hughes cam. Intake valve to piston clearance measures.090" with zero valve lash and no head gasket installed. The exhaust valve to piston clearance measures .200" with zero lash and no head gasket installed. Since everyone uses different head gasket thicknesses during assembly, I gave the measurements without gaskets installed. Once the guides are cut down for lift clearance and retainer to guide clearance, the main limiting factors on the magnum engines are the narrow ports at the pushrod pinch area, and that goes for all available versions in cast iron. However, as many guys and shops have already proven, well sorted parts combinations easily provide enough power to find the limitations of the factory block, usually well past the 500hp mark. There is no need to second-guess a magnum setup for a strong street or bracket engine.