What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Which aluminum head would be best? PG 4 questions about RHS

broncoman6524

broncoman6524

1/2 ton status
Joined
Oct 31, 2005
Posts
2,469
Reaction score
2
Location
chuluota Fl
I'm planning on purchasing heads for my 383. When I finish rebuilding it the specs will be as follows:

3.75 stroke.
4.030 bore
These are the pistons
http://store.summitracing.com/partdetail.asp?part=TRW-8KH860CP30
I have not made a final choice on a camshaft yet, the lift will be anywhere from 480-510, with a 260/270 ish duration


I'm thinking 64cc chambers, 195cc runners, 2.02 and 1.94 valves with CNC runners atleast.

I have been looking at AFR heads, but when I was talking to one of the mechanics at work he said they always like Brodix heads.

Anybody have any input?

Chris
 
Last edited:
AFR's are the best aluminum head out there. They outflow every other head on the market. If this is for a truck you want the 180cc intake runners, this build excellent low end velocity which will make TONS of torque at lower RPM's. The larger the intak runner is the higher the RPM the power will be made. I currently am running a 350 chevy with 180cc AFR's and people swear i have a built 454 in my rig.

BTW, the AFR's are now all 100% CNC ported in every location (intake runners, exhaust runners, and chambers). They all alsol feature undercut stems on the stainless valves. They will cost you about 1485.00 a set.
 
AFR are the best but why do you want aluminum heads?
Cast iron will make just as much or more power than alu and are better for a truck IMHO.
If you are drag racing or something like that, where weight is a critical issue. Then alu heads are good. But on a 5K+ ton brick. They are just expensive ornaments.
Cheaper to go with performance cast iron and have the same flow/ power for way less $$$$ spent
 
only aluminum heads i've ever had, was a set of trick flows twisted wedge heads, making a difference is an understatement! i like how the valves are rearranged, putting intake valve more in the center of the combustion chamber!
 
blazin_blazer said:
only aluminum heads i've ever had, was a set of trick flows twisted wedge heads, making a difference is an understatement! i like how the valves are rearranged, putting intake valve more in the center of the combustion chamber!
Click to expand...

That valve arrangement on the chevy TFS heads is why they are no longer made that way for a chevy. That design ate intake valve guides in less than 1K miles.
 
good to know 4x4high....i guess it was a good thing i sold that vehicle about a month after i got thru ''sprucing it up''!
 
I think there are a set of those at the Machine shop, Weird valve design Correct? Where the intake valves are more straight?


The reason for Aluminum heads is my Compression ratio. With my currect pistons and 64cc heads, its 9.6, the pistons I'm planning would bring it to 10.4


From my understanding anything above 10.0 will cause detonation issues on iron heads. I forgot who said it, but in another thread someone said this was not always the case.

If that is true...please make that more clear to me.
 
I was going for the higher ratio. Thats why I was planning for new pistons. I currently run 76cc heads. (882 casting)

I was also looking for the 195s because the motor is going into my blazer, which sees mud. Which means it get tached up, and stays there. I figured I would sacrafice a little lower RPM power, to make more power at 3K+
 
bigger cc heads will flow more air if you haven't bought the pistons yet get a higher comp set that will be less with higher cc head is not just look into a 70 cc instead of a 64 cc
 
I have not bought anything yet. Have my gamr plan, Still working it through. haha, Lot of money, want to do it Right. And only once.
 
broncoman6524 said:
From my understanding anything above 10.0 will cause detonation issues on iron heads. I forgot who said it, but in another thread someone said this was not always the case.

If that is true...please make that more clear to me.
Click to expand...


That was me I suspect. Compression, fuel, chamber design, material, all play into propensity to detonate.

I know my DD motor is at 10:1 (Hyundai) and 87 octane is the recommended fuel, I'd guarantee the heads are AL.

There are probably three advantages to AL heads: Weight, ease of repair, and MAYBE ease of porting, which might shave cost a bit over iron. I don't port heads for a living, so no idea, but AL would seem to be easier to work with. Weight helps, but as mentioned, saving 50lbs in a 5000lb+ vehicle is going to take a LOT of driving to make up for. :)

AL LOSES power over iron heads, which is why the increased compression is possible....they shed heat so fast/much vs. iron that they don't detonate as easily. Problem is, heat=power, so the hotter you can keep the cylinder (without causing other problems) the better. The higher compression with AL simply offsets the loss of power due to heat loss.

Numerous magazine articles have tested this over the years, and the difference in power is negligible, as long as compression is bumped up to compensate. Otherwise, the AL heads lose power-wise, all else being equal.

So in other words, identical iron heads at 9:1 (and of course no figures are hard and fast, too many variables) are going to make just as much power as AL heads at 10:1.

Increases in power production from compression alone is one of the smallest gains you will see when compared to larger bores, efficiency improvements, etc. If you could go from 8:1 to 15:1 the power difference would be pretty significant, however 8:1 to 9:1 alone isn't going to make a big difference.

Smaller modern chambers and flat top pistons are where it's at for power/efficiency.
 
That makes sense, and yes it was you I was implying about. I have always been told that Chevrolet were the ones for the 10.0 rule, because of design of the chambers.

Now I'm completely torn on which route to go. haha
 
The first question is what kind of gas do you want to buy/run. A 383 is a torque motor for the most part until you spend lots of bucks to make it spin fast. If you plan on any street driving then run an iron head and keep the compression down.
 
 
NOTHING (ok, almost nothing) will outflow an AFR head. If you think you ever want to build this engine with more power then you should definately choose the AFR heads. Cast iron heads don't even begin to compare to aluminum as far as flow.
 
That's true. My dad was talking to me about this, and was suggesting that I get Vortec heads. From my understanding aside from the Combustion chamber size, they flow just a little better than the heads I have now.
 
broncoman6524 said:
That's true. My dad was talking to me about this, and was suggesting that I get Vortec heads. From my understanding aside from the Combustion chamber size, they flow just a little better than the heads I have now.
Click to expand...

They also crack VERY easily. I'm an automotive machinist and every set of vortecs that come into my shop have at least one if not both heads cracked. They do flow excellent for an out of the box cast iron head but i would never run a set just because of the knowledge i have of them.
 
You must log in or register to reply here.

Latest Posts

Top Bottom