Factory Magnum Heads

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Booby, Those older magnum crate motors arent anything special either. Just a nice Hy roller cam 230/[email protected] and a single plane M1 intake. The heads have different springs but other wise are stock and the short block is same as a production truck motor but with upgraded speed Pro pistons.

Nice motors, But not fancy and hardly worth the $5000, all though the newest version does have the magnum R/T heads
 
I agree on the price tag on some things sold these days. However, it is at least brand spankin new stuff your getting. I liked it better when the price tag was in the mid to low 4's. LOL and time goes on.

Like I said earlier, about the heads, the ported units above should help further wake up a create engine. Hummmmmmmmmm Might have to ship BJR a FUBAR'ed create shortblock.
 
Rob, They use to be just over $4000 but now with the R/T heads they are over 5gs
 
AdamR said:
Rob, They use to be just over $4000 but now with the R/T heads they are over 5gs
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Go back even further they used to be about $3400 with the 300HP version being $3100 and I think I recall seeing the 300 HP version advertised once for under $3 grand. Can't understand how MP can jack the price up so much in such a short time unless they are trying to force everyone to purchase a new generation hemi.
 
Good information BJR. I remember seeing an article somewhere by Steve Dulcich saying that he got 300 cfm out of an R/T magnum head IIRC. I thought that number was optimistic, now I know for sure.
 
The R/T heads share very little port and combustion chamber wise with the production Magnums.
 
dgc333 said:
The orignal magnum crate motors came with stock magnum heads. The 380 HP verison of the 360 will dyno consitently in the 410 HP range.
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A engine that would dyno at 410 would only put about 325-330 HP to the tires. The numbers that I came up with would dyno somewhere around 485-490 HP by the flow #'s. Of course you would have to have a good cam and intake like the crate engines, not saying those exact ones but something similar.
 
needsaresto said:
BJR,thanks for the info. How much do you think the intake could be made to flow? And if I dont have a large overlap cam will this improve or eliminate the lean condition?

Im going to slap the mags on a 318 and will be building a very streetable,hi torque, good mileage motor for a 4000 lb car with 2:94 gears. I planned on a small cam under .450 like an xe262. The heads are fresh and have brand new stock springs, and stock 1.6 ratio magnum valve gear. I will port them with the template kit from mopar. Shooting for about 9.5:1 but may need to get K.B pistons so 10:1 with them.With that small of a cam I may not bother porting. Was thinking of that in case of a cam upgrade
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The less the overlap the better Tq, and cylinder pressure you'll have. And yes it will stop the leaning out of the engine. I think that with more work I really believe that they could be made to get somewhere around 260-270 but this would take a good bit of work. I'll keep playing until theres no head left to port. The key to porting is to get as much air flow and keep the port as small as possiable so velocity will stay up. I guess I should have cc'd the port after I went through each stage just to see how large the port was really getting. I may have more time to play with them this week, we'll have to wait and see.
 
AdamR said:
The T?T heads share very little port and combustion chamber wise with the production Magnums. The R/Ts have a lot in common with the W2s.
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R/T Magnums and W-2s are entirely different animals. Rocker shafts with offset rocker arms vs. stud mounted rockers. Different combustion chambers. Oval intake ports vs. rectangular. Entirely different exhaust ports:

W2.jpg


RT.jpg
 
so are these the things you would do to the magnum heads to make it perform best?? what about porting the bowls? or is that bowl blending...what would you do to the heads.. and what kind of valves would you use? so on
 
Great job Bobby!! Glad to see what these heads actually do in stock and modified form. I've read so much controversial info on them I didn't know what I could believe. Thanks for sharing your results.
 
Here are some port molds I made of stock magnum heads. I also cut a head up to see how far I could port plus how big of a valve I could fit. The intake shows how restrictive the pushrod area is on the magnum head. The exhaust has a bump on the roof which seems to pinch the port.
I also made molds of w2 heads. I don't have any pics of those, but it is easy to see why w2s flow so well.

Magnum Ex1.jpg


Magnum Ex2.jpg


Magnum Ex3.jpg


Magnum In1.jpg


Magnum In2.jpg


Magnum In3.jpg


Magnum In4.jpg
 
Well I finally got around to opening up the head for 2.055 valve and reflowed the head and this is what it did.

.100 78
.200 119
.300 182
.400 215
.500 239
.600 238

This is a good bit less than what the head did with the stock size valve in it, I thought that maybe it was the bench so I flowed a MP head that I flowed before and it flowed like it should have, so the larger valve hurt the flow and slowed down the port velocity a good bit.
This is what it flowed with the 1.92 valve.

.100 84
.200 139
.300 201
.400 231
.500 246
.600 252

This just goes to show that bigger isn't always better.
 
Don't know if any one saw the write up on the small block dyno shoot out in Mopar Muscle. This is an annual dyno shot out the magazine does, this year it was sb limited to 410 cid and 93 octane. As with past shoot outs it's power/cost combination that wins the shoot out. After market parts extract a points penalty so they need to make enough power to offset the penalty.

This year almost all the competitors stuck with factory heads (Indy cylinder head won with magnum R/T heads). They all but Indy used factory magnum heads, no X, J, O, U or 308 heads. All these guys made in excess of 500+, had to be a reason they chose the magnum head.
 
dg,
Did they say what they had in the heads for valves? Because from what I've found they may have went the wrong way on them.

IMO I would gasket match and bowl blend the heads and leave it at that, use stock size valves and do some machining on them. Port the exhaust, but this isn't totally necessary as 70% exh. flow is all that really is needed to make the engine perform, and less on the street. So IMO I would use these heads if the engine already had them, as the cost to swap them over may not be worth the gain that you may want or get.

These heads don't respond like the older LA heads do when opened up for larger valves. Sure most all heads will lose some flow in the low lifts when a larger valve is installed but the high lifts should be better, and in this case it was worse. Larger valves only gain about 5% in the upper lifts and lose this in the lower lifts so use the valve size for the amount of cam used. Upper lifts being .600 and up. As can be seen in the flow #'s that at .500 they get to be about even. From .100 to .500 it's the valve job that makes the port work and is the most important, after .500 the port itself takes over and the valve job becomes less effective. In the case of the 2.055 valve the chamber and the cylinder becomes the restriction. Even if the chamber is relieved the cylinder wont be, so the need to do this may be hurting the flow some as the air flow would be running into the cylinder wall.

So in my overall opinion on this casting, if the R/T is better then this may be the way to go but if it isn't then give me old iron. This head was worse than a 587 head with minor work done and a smaller valve. And only even to a 576 head out of the box.

This is what the head flowed with a 2.02 untouched,

.100 79
.200 132
.300 198
.400 225
.500 224
.600 224

So as we can see the magnum head is suffering a good bit due to the port shape and cross sectional area. So being that the CSA is small the smaller valve works better and thus would be the best choice.
 
Didn't mention the valves but Indy completely ground out the pushrod pinch and pressed in a brass tube on the R/T heads they used. They were not allowed to build up the ports with epoxy.
 
Memory fails, but, aren't the R/T heads 2.02 OOTB?
 
R/T heads come with either 1.92 or 2.02 intakes both use the same 1.62 exhaust as standard magnum heads.
 
If the R/T heads have 2.02 valves then the port I'm sure is different or it doesnt seem feasiable to me to put them in. It sure didnt help here on the std. magnum head.
 
the flow numbers are horrible, use them for paper weights
 
Does anyone have an idea why on the intake side they put that bump in the port?? Whats that for? Also besides the stud rocker arms would the TBI heads be better than magnum heads as they still have the swirlport also?? From what i've got with this people should keep the heads the same and spend the money to convert magnums to the LA heads if the la's flow better than the magnums anyways. Can you do flow numbers on the TBI swirlports as a comparison?
 
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