New Magnum replacement head nearly as good as MP R/T

[Jesse Lackman]

Flow with used stock 1.92/1.625 Magnum valves, no porting or blending, factory valve job.


0.200 128.4 120.1 94%
0.300 189.9 155.7 82%
0.350 213.2
0.400 238.1 176.9 74%
0.450 244.7
0.500 241.4 181.8 75%
0.550 239.7
0.600 238.1 184.2 77%

If there is interest an aluminum one is a possibility. It would easily be as good as the Edelbrock Magnum probably closer to the MP R/T. I've been talking to the guys at RHS and will relay any interest in the aluminum one. It might even be possible to get the aluminum head machined for LA style intakes.

Try to buy the MP R/T machined for old style intakes right now, can you? Does MP have any R/Ts in stock right now?

But, again, if anyone is looking for new iron Magnum heads these really are the only heads to consider. They are around $300 bare.

I'm going to talk to Don at FBO and see if we can set up to sell these heads through the FBO dealer network.

[rumblefish360]

I'd like to see a R/T flowed on the same bench in the same way that was done. Otherwise, it's just flow bench racing.
The numbers look very good. Great pic by the way.

[Jesse Lackman]

Originally Posted by rumblefish360

I'd like to see a R/T flowed on the same bench in the same way that was done. Otherwise, it's just flow bench racing.
The numbers look very good. Great pic by the way.

Well this is a unported 1.92/1.625 Magnum '671 with a good valve job on the same flow bench.

0.200 130.0 107.0 82%
0.250 0.0
0.300 182.0 152.0 84%
0.350 202.0 0%
0.400 218.0 174.0 80%
0.450 218.0 178.0 82%
0.500 219.0 180.0 82%
0.550 219.0 180.0 82%
0.600 220.0 182.0 83%


I've seen data that shows the early ProTopline 318A head flowing 2-10 cfm better on the intake when compared to a MP 2.02 R/T on the same bench. The current head is different than the 318A head, the ports are supposed to be the same though. I have some of the 318A heads here but never flowed them.

[perfmachst]

hello, which type of flow bench was this done on?? what test pressure??the flow bench a laminar flow or a pressure drop style?? the numbers seem very high? just asking

[Jesse Lackman]

SF110 corrected to 28"

Do you think the stock Magnum numbers are high? It did have a hp valve job and back cut intake.

[perfmachst]

hello, yes very high. just food for thought!

[Jesse Lackman]

So what have you seen for stock Magnum flow?

I have seen stock Magnum numbers from others that is pretty close to what this bench shows.

[rumblefish360]

Thanks. I also agree with perfmachst. It looks more like a light porting job all over. Thats why I asked about other heads. 240 cfm is pretty hefty for a stock head.
I am not call you a liar or suggesting otherwise. The numbers just seem high. That head is not known for such flow. (If I have the right head in mind.)
However, the price tag on the head is right and the flow numbers I remember from the past were even good then. It's still a steal of a deal.

[Jesse Lackman]

By "that head" which do you mean?

The 318A or the C360HPST?

As I have been saying they are different heads. As cast the C360HPST intake ports are about 10cc larger than the '671 Magnum so it *is* like it they have had a "light porting job all over".

The flow bench is not known to be a happy one, and the numbers I have seen for stock Magnums are in line with other flow benches. The port we tested on the C360HPST may have been a happy port though.

The '671 Magnum head flow numbers were for a restricted race head, no porting allowed, it had a highly developed multi angle valve job so it may be a bit higher flow than a stock valve job Magnum head but still it is within 5cfm of what some other benches show.

My work with the C360HPST heads stopped when ProTopline went out of business, what would have been the point? But now, they are available again.

[fastback340]

Jesse, Your stock Magnum 671s look pretty close to what I've seen.

[rumblefish360]

Jesse

Head pictured vs. Magnum R/T head.

I also was not aware of so many head castings of the Magnum. I have not keep up it seems. To busy pushing kids on swings.

As cast the C360HPST intake ports are about 10cc larger than the '671 Magnum so it *is* like it they have had a "light porting job all over".

Cool.
Would the '671 be a 318 head or just a general casting used all over?

[Jesse Lackman]

The 53006671 Magnum heads I have worked with have come off 318 engines but that's not saying they were never put on 360s. The '671 head has larger ports than the '466 head. I don't think that is the casting Mopar Performance sold, I think the one they sold had the smaller ports like the '466 head. There is one other casting number for factory Magnum heads which I have never worked with. So in total there were three factory Magnum castings. There have been two Protopline castings (C318A and C360HPST) and now one RHS casting (C360A)

[Jesse Lackman]

Originally Posted by fastback340

Jesse, Your stock Magnum 671s look pretty close to what I've seen.

thanks, I didn't think the '671 numbers were too out of whack...

[rumblefish360]

Thanks for the lesson Jesse. Mucho thanks.

[HankL]

Those of you who have flow benched stock Magnum cylinder heads - have you found that the intake port on any one of the four different combustion chambers has a tendency to flow better than the other three as cast?

For example, does the rear most cylinder (#7 or #8) on the head 'usually' flow better as cast than the others.

Or do the outside cylinders 'usually' flow better than the two inner cylinders.

Is there any trend?
{I mean before hand porting is done}

Along the same lines, do any of the chambers 'usually' CC a little more/less out of the box than the other chambers?

Is there a trend in combustion chamber size as rough cast?

[HankL]

Any guesses?

Since the right hand of the cylinder head is identical to the left side,
I suspect the question is whether intake port number 1
flows a little less than intake port number 2?

If the intake ports flow about the same,
would anyone care to guess about whether the exhaust ports flow differently?

If the exhaust ports flow about the same,
would the Magnum-style cast iron exhaust manifold
affect things.

Would exhaust port number one have the best flow
into the exhaust manifold because nothing is in front of it?

Would the centered exhaust ports 2 & 3
either create a hot spot in the head,
or flow differently so close together?

Would the backmost cylinder exhaust port flow worse
into the exhaust manifold because 3 cylinders are dumping in
front of it?

From looking at several sparkplug changeouts,
it looks like the back cylinders 7 & 8
always have 'whiter' ceramic noses on the sparkplug than the rest.
I have wondered whether this is due to a coolant flow hotspot at the rear of the block, or perhaps due to those back intake ports flowing more air and having a leaner A/F ratio?

[rumblefish360]

Hank, you pose some real good questions here. Since I never had a chance to run my engines on a dyno, the questions of hot spots could possibly be answered when you look how a engine operates.
The "Whiter" plugs could be because there (5&7) fireing right next to each other. Single plane intakes not adjusted for proper fuel flow can show a cyl. run lean.
The 2 exhaust ports together have a potentail of running hot. Exhaust temp probes could answer that one. But I do not ever remember reading big differences in heat when they were used and reported.

The only other thing I can add is casting a head is not a perfect process. So some variations are bound to occur. But like your question , how much?

[Jesse Lackman]

You can control coolant flow to the head with the openings in the head gasket.

More information on the 360HPST, a potential modified version;

http://www.moparchat.com/forums/showthread.php?t=94491

If there is enough demand this head is a possibility.

[rumblefish360]

Jesse , forgot to say thanks for the pics and numbers in the post.

[Jesse Lackman]

Finally some results with these heads.

408 based on Magnum block

-RHS 360HPST iron heads, 2.02/1.60

-Hughes 236/242 @ .050 Hyd roller .557/.521 lift 112 LSA installed at 110

-stock Magnum hydraulic lifters

-Dove/Racer brown rockers 1.6 intake 1.5 exhaust

-Performer RPM Air Gap

-Holley 870 Street Avenger

-1 5/8 x 2 3/4 dyno headers

-91 octane pump gas

-12.5 manifold vacuum @ 950 RPM

-398 CTQ @ 2000 RPM

-542 CTQ peak @ 4300 RPM

-520 CHP peak @ 5900 RPM

-500 CTQ from 3200 to 5200 RPM

No time to try any tricks, would have made more upper RPM HP with an open spacer but customer did not have the room to use one.

[peg leg]

Mopar 5007950 "Mopar R/T" heads. They are available with the LA style intake bolt pattern which of course is angled into the head. They are 2.02/1.65 valved, and have no protrusions into the exhaust stream (AKA big lumps of iron in the ports corners and no air injection bosses). I think they are the best iron head you can get for a small block, IMHO. The ports look like they should flow really well. These heads are heavy around the exhaust side, and will use most headers. The valve gear is magnum style, oil through the pushrods, and like roller cams.
Ron

[Jesse Lackman]

Are the LA R/T heads actually available?

Hughes Engines has information that shows the EQ 318A head to be better than the 2.02/1.625 MP R/T.

http://www.hughesengines.com/partDet...678&eTypeID=10

The RHS 360HPST is as good as the EQ318A, better in some areas I think.

[franklin]

i would love these heads with cast in rocker pedestals,please.

[dust]

Originally Posted by Jesse Lackman

Finally some results with these heads.

408 based on Magnum block

-RHS 360HPST iron heads, 2.02/1.60

-Hughes 236/242 @ .050 Hyd roller .557/.521 lift 112 LSA installed at 110

-stock Magnum hydraulic lifters

-Dove/Racer brown rockers 1.6 intake 1.5 exhaust

-Performer RPM Air Gap

-Holley 870 Street Avenger

-1 5/8 x 2 3/4 dyno headers

-91 octane pump gas

-12.5 manifold vacuum @ 950 RPM

-398 CTQ @ 2000 RPM

-542 CTQ peak @ 4300 RPM

-520 CHP peak @ 5900 RPM

-500 CTQ from 3200 to 5200 RPM

No time to try any tricks, would have made more upper RPM HP with an open spacer but customer did not have the room to use one.

What's the compression ratio of this entine. Do you think you'll see higher numbers with a Holley DP or Demon?

[greasydonkey]

where can you get them, and has any endurance testing been done on them?