Iron VS Aluminum heads
02-18-2016 | 08:28 AM
#181
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From: chicago
After doing a lot of research I think I'm leaning away from the EQ heads for this build and I'll state the reasons why.
First, it has nothing to do with the quality of the head. From what I'm reading and hearing they're a good head.
However, I don't think the head is going to meet the needs of my build primarily because the intake runner is too large (320 cc). I'm building a 509" MPI engine and there is a lot of restriction in the throttle body and more importantly the intake manifold. With a 320 CC intake running, it's probably going to have most of it's power gains above 5000 rpms and this engine is going to be a 5200+/- engine.
EQ also makes a replacement GM head but looking at the spec sheet, there's no real advantage (in my opinion) of going with that head because it doesn't have a rolled valve angle, raised exhaust port, upgraded valve seats or bronze guides for example. So even though it's cheaper, it doesn't meet my needs.
I feel that I need to put a head on this package which has a smaller intake runner such as the Edlebrock Performer RPM, Victor Jr, AFR 290 or largest port being the Dart Iron Eagle 308 CNC.
First, it has nothing to do with the quality of the head. From what I'm reading and hearing they're a good head.
However, I don't think the head is going to meet the needs of my build primarily because the intake runner is too large (320 cc). I'm building a 509" MPI engine and there is a lot of restriction in the throttle body and more importantly the intake manifold. With a 320 CC intake running, it's probably going to have most of it's power gains above 5000 rpms and this engine is going to be a 5200+/- engine.
EQ also makes a replacement GM head but looking at the spec sheet, there's no real advantage (in my opinion) of going with that head because it doesn't have a rolled valve angle, raised exhaust port, upgraded valve seats or bronze guides for example. So even though it's cheaper, it doesn't meet my needs.
I feel that I need to put a head on this package which has a smaller intake runner such as the Edlebrock Performer RPM, Victor Jr, AFR 290 or largest port being the Dart Iron Eagle 308 CNC.
Big ports dont necessarily mean poor airspeed, and small ports dont necessarily mean better airspeed.
I know of a builder who recently did a pair of 525 merc upgrades. 525 has edelbrock rectangles, which arent big flowing heads, and have a 315cc port, made 650 plus ft lbs of torque, and around 590ish hp at 5300.
Id be hard pressed to believe, that the EQ head, with its good airflow, good wet flow characteristics, would perform any less than those edelbrock stock exhaust port location heads .
The afr 290 is a sweet head, but whats the price difference ?
02-18-2016 | 08:31 AM
#183
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From: chicago
Ive seen where guys go in and port heads , and gain power afterwords. If properly done. This sometimes involves doing some bowl blending, thinning of guide bosses, and other cleanup. The material removed that increased flow, also increased the actual volume of the port. But the engine made more power and torque from better low lift and mid lift airflow and cylinder filling.
Pour an intake runner on most of these heads, esp ones that have had some cleaning up, and compare the actual cc's, of both ports, to the advertised port volume. You may be surprised.
Pour an intake runner on most of these heads, esp ones that have had some cleaning up, and compare the actual cc's, of both ports, to the advertised port volume. You may be surprised.
02-18-2016 | 08:37 AM
#184
Frank's Marine Service
Joined: Sep 2002
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From: Elkton, MD
The intake runner/plenum is going to be modified but not the TB on this build unless the owner wants to invest in it.
02-18-2016 | 08:41 AM
#185
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
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From: Elkton, MD
There's no data out there that I can find supporting running the EQ heads on a 502/509 MPI build. I have to put my name on these and I'm not going to take a chance with an unknown combo. They may very well be a good choice, I'm just not willing to take the chance without hard data for this exact combo. If it were my own, I might take a chance but not with someone else.
Just my opinion, but i wouldnt write a head off simply on port volume. If the part is designed properly, it will have better airspeed and flow. The stock merc head has similar volume, however, the overall flow and port speed is lacking. Hence why if you were to swap that merc head, out for even a 335cnc afr head, you will still likely see more torque and power across the board from better cylinder filling.
Big ports dont necessarily mean poor airspeed, and small ports dont necessarily mean better airspeed.
I know of a builder who recently did a pair of 525 merc upgrades. 525 has edelbrock rectangles, which arent big flowing heads, and have a 315cc port, made 650 plus ft lbs of torque, and around 590ish hp at 5300.
Id be hard pressed to believe, that the EQ head, with its good airflow, good wet flow characteristics, would perform any less than those edelbrock stock exhaust port location heads .
The afr 290 is a sweet head, but whats the price difference ?
Big ports dont necessarily mean poor airspeed, and small ports dont necessarily mean better airspeed.
I know of a builder who recently did a pair of 525 merc upgrades. 525 has edelbrock rectangles, which arent big flowing heads, and have a 315cc port, made 650 plus ft lbs of torque, and around 590ish hp at 5300.
Id be hard pressed to believe, that the EQ head, with its good airflow, good wet flow characteristics, would perform any less than those edelbrock stock exhaust port location heads .
The afr 290 is a sweet head, but whats the price difference ?
02-18-2016 | 08:48 AM
#186
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
[ATTACH=CONFIG]551227[/ATTACH][ATTACH=CONFIG]551228[/ATTACH]
02-18-2016 | 08:58 AM
#187
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From: Hemlock, MI
Buddy of mine is doing a stock headed/fairly stock intake build 502mpi and is expecting about the same 500-525 hp result. You should see 525 easily in the iron eagles and some intake massaging easily. If not 550
02-18-2016 | 09:29 AM
#188
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From: On A Dirt Floor
With the intake being such a choke point, even if mildy worked on, I would think the larger runner heads (320) which include OEM would not be a 'good' choice. I would think the Iron Eagle 308's would be the better choice here.
A lot of thinking huh ?
BTW: Speaking of 'smaller heads' On the net , Saw a few AFR 300 's (roval) go nuts on power. One 460cid and one 555. 460 had 11.1 compression and went to 800hp. I believe the 555 went 850.
BTW#2 Panther: I would strive for a little better transition into the top of those MPI runners than what is shown in the pic. At the min, round over that center divider. Remeember, air has mass, and when it goes into those runners as in the pic, air will try to flow towards the center of the runner (again, at the runner) and effectively make that section of the runner act if it was narrower.
A lot of thinking huh ?
BTW: Speaking of 'smaller heads' On the net , Saw a few AFR 300 's (roval) go nuts on power. One 460cid and one 555. 460 had 11.1 compression and went to 800hp. I believe the 555 went 850.
BTW#2 Panther: I would strive for a little better transition into the top of those MPI runners than what is shown in the pic. At the min, round over that center divider. Remeember, air has mass, and when it goes into those runners as in the pic, air will try to flow towards the center of the runner (again, at the runner) and effectively make that section of the runner act if it was narrower.
02-18-2016 | 09:55 AM
#189
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
BTW#2 Panther: I would strive for a little better transition into the top of those MPI runners than what is shown in the pic. At the min, round over that center divider. Remeember, air has mass, and when it goes into those runners as in the pic, air will try to flow towards the center of the runner (again, at the runner) and effectively make that section of the runner act if it was narrower.
02-18-2016 | 09:56 AM
#190
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
Also, Dart now has a CNC 308 which I think is a good choice over the regular 308.
