360 Heads 450 HorsePower Recommendation

[dust]

Im looking for a recomendation for which heads i should go with on my 360 build up.
Is my HP estimate realalistic for this shortblock?
Do you recommend any other heads that are not listed but within about $1400?

My base engine / Application:
amount for heads: $1400(pair, about)
NEW 360 Mopar Magnum 9.5 compression ratio short block
Putting into a Duster as a street / strip project, hoping to get about 420-450 hp out of the motor
I will be doing some of freeway driving, about 50 miles a week and will need to run on only pump gas

My options are
Magnum R/T heads from Mopar assembled
Magnum Eddy's assembled
-if you recommend the Eddy's, please recommend rockers, i have read that they use chevy rockers.
OEM Magnums from Mopar(possibly port with money saved)
other???

i also know a guy who will port (stage 1) heads for me for:
Iron 650$
Alum 450$

thanks

[Mopar4LIF]

Yes, the edelbrock magnum heads can use chevy rocker arms.

[dwc43]

Use the edel heads for lighter weight. You'll need more compression though. Aluminum heads need 1 point higher cr over a cast head. 420 to 450 is easy. We get that out of the old stock X,J, and U 2.02 valved heads. Only reason I suggested edel over the older heads is for the weight savings. Rule of thumb isa 100 lbs is worth a .1 on the strip.

[dust]

Originally Posted by dwc43

Use the edel heads for lighter weight. You'll need more compression though. Aluminum heads need 1 point higher cr over a cast head. 420 to 450 is easy. We get that out of the old stock X,J, and U 2.02 valved heads. Only reason I suggested edel over the older heads is for the weight savings. Rule of thumb isa 100 lbs is worth a .1 on the strip.

Thanks for your replies!

1 point? do you recommend i go with the 10.5 CR Short block then? i thought that 10.5 was pushing it for pump gas.

how do edel heads compare to mag RT heads for performance? i know that the weight diff is on edel's side but what if edel was made of iron? which would you recommend then?

as for the chevy rockers, do i just look for small block chevy rockers then, can i use Mopar rockers or are they completly different? (knows little about chevy heads).

[dwc43]

I'd still pick the edel heads over the magnums. And yes, go with the 10.5 cause the aluminum heads dissapate heat at a more rapid rate, so detonation is not as big a problem with higher cr's. Use the Mopar rockers or get a set of Harland Sharp aluminum roller rockers. These are the best adn it's waht we use in our race engines.

[dust]

Originally Posted by dwc43

I'd still pick the edel heads over the magnums. And yes, go with the 10.5 cause the aluminum heads dissapate heat at a more rapid rate, so detonation is not as big a problem with higher cr's. Use the Mopar rockers or get a set of Harland Sharp aluminum roller rockers. These are the best adn it's waht we use in our race engines.

10.5 seems alittle high for Calif. pump gas, what what compression ratio should i worry about ping and such?

[dwc43]

Originally Posted by dst

10.5 seems alittle high for Calif. pump gas, what what compression ratio should i worry about ping and such?

That's about as far as you can go with pump gas and aluminum heads.

[TK]

Originally Posted by dwc43

I'd still pick the edel heads over the magnums. And yes, go with the 10.5 cause the aluminum heads dissapate heat at a more rapid rate, so detonation is not as big a problem with higher cr's. Use the Mopar rockers or get a set of Harland Sharp aluminum roller rockers. These are the best adn it's waht we use in our race engines.

cant beat the harland sharps, they're expensive, but worth it

[sanborn]

Your horsepower requirements make it easy to achieve with several different cylinder head combinations. The rule of thumb you should be looking for is about 220 CFM of head flow at about .600" lift. That will give you about 440 HP. Because of heat loss, the aluminum head needs to flow a little more- about 230 CFM.

I know a lot of Mopar guys shy away from them, but W2s would be my choice---especially since the older heads show up on the used market. Flow would not be a problem, the basic design is superior to any stock type head, including Edelbrock. But, they require different intakes, rockers, headers, etc. It would be real easy to build a very streetable 480-500HP engine with W2s.

My next choice would be the Edelbrocks(or Brodix either). Both use GM rockers, both need to oil through the pushrods, which will require AMC type rockers, hollow pushrods. "Out of the Box" they should get you real close to 440-450HP.

[dust]

Originally Posted by sanborn

I know a lot of Mopar guys shy away from them, but W2s would be my choice---especially since the older heads show up on the used market. Flow would not be a problem, the basic design is superior to any stock type head, including Edelbrock. But, they require different intakes, rockers, headers, etc. It would be real easy to build a very streetable 480-500HP engine with W2s.

Thanks for the techincal info!

The guys at the local Dodge dealership are telling me that Mag RT heads are basicly W2 heads with squared ports, they also use stock exhaust and intake ports. would'nt this make the RT heads better for a street application? i hav'nt found much info on the RT heads but the guys at the dealership say they are great and offer better perf. than Edel.
"you lose all the heat with alum. heads" - dealership guy

sounds like with increased compression the heat loss is not much of an issue then?

[dwc43]

The edels will be better over the R/T heads. There trying to sell ya something. With the increased compression you'll make more power alone. The weight savings really helps too.

[norcalcuda]

HI DST, I have a couple of questions, and recomendations, about your buildup. On the W2's, iron, open chamber, no quench, 9.0to1 tops. Also, what cam? Does the MOPAR 360 shortblock have a 'zero deck'? And last, but not least, your 'guy' who will port your heads?, if he doesn't have any real head porting experience (dyno results!), skip it. Pretty ports ain't worth s--t I'm open to criticism guys, whaddya think?

[norcalcuda]

P.S. It's not like a few tenths less compression is gonna kill 40 hp. ( hot calif. summer nights at the cruise-in, sittin in traffic...........OH S--T! Im overheatin! Quik!, find a place to pull over.............) just a thought.

[dwc43]

If you get your set up right, it wont over heat. I've never seen an overheating problem that could not be solved. Yet.

[DartGT66]

How deep in the bore is the pistons in the MP 360 short blocks? I mean, will you get a good quench distance with one? AS fara as I calculated for the higher CR LA short block, the pistons will be about .040" below the deck at TDC. I think that's too much.

[sanborn]

Personally, I don't have any experience with RT heads. Go to the dealer, look in their spec book---see what the flow is. That gives you a starting point for evaluation. Or better yet if you could get your hands on a head, have it flowed.

[dust]

Originally Posted by norcalcuda

HI DST, I have a couple of questions, and recomendations, about your buildup. On the W2's, iron, open chamber, no quench, 9.0to1 tops. Also, what cam? Does the MOPAR 360 shortblock have a 'zero deck'? And last, but not least, your 'guy' who will port your heads?, if he doesn't have any real head porting experience (dyno results!), skip it. Pretty ports ain't worth s--t I'm open to criticism guys, whaddya think?

I did'nt see "zero deck" but this is what i found:
"a 0.020 in. overbore block that has been shallow cut to true-up the deck surfaces for optimum head-gasket sealing."

The Cam:
"The camshaft is a hydraulic roller type with 0.501 in. of intake lift and 0.513 in. of exhaust lift. Intake duration is 288 degrees; exhaust, 292 degrees."

this info from summit website under Mopar 360 magnum short blocks

i think i'll go to the dealer and ask them for flow numbers on the RT heads, then i'll compare them to edel flow numbers i think i have seen in a recent Mopar Mucle magazine. (next week)

the guy who will be doing the port work does have alot of experiance, he does alot of head work for a guy i work with (engine builder) and im supposidly getting a good deal through him. since i hav'nt decided which heads to get, i hav'nt researched into this guy yet. yes, i dont know his name.
im still debating whether porting Edel heads would be nesc. how much power would i gain with a stage 1 port, worth 450 bucks? the guys at the dealership are saying that porting RT heads would free up about 40-50hp.

[dust]

Originally Posted by norcalcuda

P.S. It's not like a few tenths less compression is gonna kill 40 hp. ( hot calif. summer nights at the cruise-in, sittin in traffic...........OH S--T! Im overheatin! Quik!, find a place to pull over.............) just a thought.

What would happen if i did go with 9.5 or 10.0 instead of 10.5 CR? would normal driving be effected? is it just X amouth of HP and Torque loss?

my cooling system is excellent now(oversized rad), im not worried about that much.

[rumblefish360]

Heres some good info from Hughes engines on head porting. They go over the Edel. and Magnum heads. http://hughesengines.com/
The 10.5-1 engine should run fine on 91 octane. Because aluminum disapates heat so fast, it is very similar to a 9.5-1 iron headed engine.
The cam also plays a part in this. Being it has some size to it on a tighter than stock centerline, the cam bleeds off some compression.

1pt of comp. will vary on the build of the engine. More the merry so long as theres octane to feed it. Theres not a huge loss.

Another thing about the Edel heads that I have noticed. You will not need to run alot of advance on the distrib because of the nice chamber shape and quench you'll get with the heads. This feature reduces the amount of octane needed.
If you had an open chambered head like an "X" or "J", there would be more need to advance the timing.

Ethier head will do but you must know what ratio you'll end up with when you apply the head to the engine.
The R/T's have merrit and would not overlook there potential.

[dwc43]

Originally Posted by dst

What would happen if i did go with 9.5 or 10.0 instead of 10.5 CR? would normal driving be effected? is it just X amouth of HP and Torque loss?

my cooling system is excellent now(oversized rad), im not worried about that much.

You'll loose quite a bit of hp over it. I'd get it is close to 10.5 as you can to get the max out of it. Cooling should not be a problem.

[TK]

where i come from, higher compression means cooler engine, not hotter

[dust]

Originally Posted by rumblefish360

Ethier head will do but you must know what ratio you'll end up with when you apply the head to the engine.
The R/T's have merrit and would not overlook there potential.

found a compression ratio calculator at
http://www.bgsoflex.com/cr.html

With Mopar Mag 360 10.5 shorblock and Edel heads

Input Parameters Are the Following:

* Cylinder head Volume (CC) = 58.00
* Piston Top Volume (CC) = 10.50
* Cylinder Bore (Inches) = 4.0
* Cylinder Stroke (Inches) = 3.58
* Deck Height (Inches) = 0.030 <---???
* Head Gasket Thickness (Inches) = 0.041

Computation Results:
# Computed Compression Ratio is 9.9 to 1

Deck height was default .030, is this near correct?
do you see any other questionable numbers?
im thinking that 9.5 - 10.5 CR would be best for my application, something that will be driven often. sound about right to you?

[rumblefish360]

The deck height is were the piston sits. As in how far down from the top of the cyl. block. Or how far down the hole it sits. This must be known.
Is it near correct? Probably not.

My MoPar 10-1 short block is suposed to be a zero deck shortblock. If your choice is the 10.5-1, I can only assume it is also a zero deck piston. I went to the calc and rentered the numbers with a zero deck piston. The ratio came to 12.1-1.

I question cyl. head gasket thickness. If the .041 is what the manufacture says it is, then OK. If it is a .039 thick gasket, the raio increases .01

I don't know how far down the hole the piston sits in the 9.5-1 short block. Look into it.

[dust]

Originally Posted by rumblefish360

The deck height is were the piston sits. As in how far down from the top of the cyl. block. Or how far down the hole it sits. This must be known.
Is it near correct? Probably not.

My MoPar 10-1 short block is suposed to be a zero deck shortblock. If your choice is the 10.5-1, I can only assume it is also a zero deck piston. I went to the calc and rentered the numbers with a zero deck piston. The ratio came to 12.1-1.

I question cyl. head gasket thickness. If the .041 is what the manufacture says it is, then OK. If it is a .039 thick gasket, the raio increases .01

I don't know how far down the hole the piston sits in the 9.5-1 short block. Look into it.

Thanks for the info!

I found that the four 360 shortblocks have a deck height of 9.56". Can this help with finding the deck height of the 10.5 or 9.5 CR shortblock? If not ill just go to the dealer next week and ask.
source: https://www.jimsautoparts.com/mopar_...ce_engines.htm

The gasket thickness is between .040 and .042 for Mopar Head gaskets
source:http://store.summitracing.com/ (long url, search for mopar head gasket)

If your calculation is correct and i'll end up with 12.1 CR, would'nt that mean that pump gas would not be enough?

[rumblefish360]

I found that the four 360 shortblocks have a deck height of 9.56". Can this help with finding the deck height of the 10.5 or 9.5 CR shortblock?

No. Thats the blocks deck height. There looking for the piston info. How much clearance there is until the piston is flush with the deck. If the piston pops up above the deck, then it would be called positive deck height and expressed with a + is front of the value.

You need to findout the piston specs or simply where it sits in the hole.

[70AARCuda]

To find the deck height on the pistons..you will need to fine TDC. Once the piston is brought to TDC....you will need a dial indictator and some type of bridge that will hold the dial indictator.... There you will measure how far down the pistons are in the cylinder...

[norcalcuda]

Hi dst, Lots of good info from the guy's here, but, maybe we're jumping ahead a bit on the 'tech info' for you. A 'zero deck' means the pistons, at TDC (Top Dead Center, the highest point the pistons reach in they're stroke) would be flush with the top of the block. A 'Positive Deck', (pistons above the deck surface) and 'Negative deck' ( pistons below deck) are the other two dimensions. Then, the 'quench' distance ( the distance between the top of the piston, and the cylinder head ) should be no more than .040" (fourty thousandths of an inch). This 'quench' number can be adjusted with the head gasket thickness. Hope this helps! Jump in guys with any other comments or criticism.......... MOPARS Rule the Universe! C-YA!

[dust]

Originally Posted by norcalcuda

Hi dst, Lots of good info from the guy's here, but, maybe we're jumping ahead a bit on the 'tech info' for you. A 'zero deck' means the pistons, at TDC (Top Dead Center, the highest point the pistons reach in they're stroke) would be flush with the top of the block. A 'Positive Deck', (pistons above the deck surface) and 'Negative deck' ( pistons below deck) are the other two dimensions. Then, the 'quench' distance ( the distance between the top of the piston, and the cylinder head ) should be no more than .040" (fourty thousandths of an inch). This 'quench' number can be adjusted with the head gasket thickness. Hope this helps! Jump in guys with any other comments or criticism.......... MOPARS Rule the Universe! C-YA!

Thanks for the information! im learning alot here. this week im going to go to the dodge dealer ship and get some numbers for CR calculations, when i get those calculations im going to post them here with any additional questions i have. hopefully i'll have a engine part combination ready to post and get opinions of.

[torsionbar340]

just use a good set of rollor rockers,whatever you do DO NOT use chev rockers on a mopar with your budget you may need to buy good second hand

Originally Posted by dst

Im looking for a recomendation for which heads i should go with on my 360 build up.
Is my HP estimate realalistic for this shortblock?
Do you recommend any other heads that are not listed but within about $1400?

My base engine / Application:
amount for heads: $1400(pair, about)
NEW 360 Mopar Magnum 9.5 compression ratio short block
Putting into a Duster as a street / strip project, hoping to get about 420-450 hp out of the motor
I will be doing some of freeway driving, about 50 miles a week and will need to run on only pump gas

My options are
Magnum R/T heads from Mopar assembled
Magnum Eddy's assembled
-if you recommend the Eddy's, please recommend rockers, i have read that they use chevy rockers.
OEM Magnums from Mopar(possibly port with money saved)
other???

i also know a guy who will port (stage 1) heads for me for:
Iron 650$
Alum 450$

thanks

[DAHEMIKOTA]

According to the spec sheet issued to the AMA by Chrysler Corp. The specs on a 1976 360 4-V Hi-Perf engine are: Cylinder head volume: 68.9-71.9 cc, Compressed head gasket thickness: .032-.035", Deck clearance (pisto below block) .077". Minimum combustion chamber volume: 99.95 cc. Dan