Iron VS Aluminum heads
02-19-2016 | 06:05 PM
#211
Platinum Member
Joined: Apr 2005
Posts: 2,150
Likes: 15
From: Northport N.Y.
Too many generalizations and assumptions regarding port volume and head performance. Head performance comes form flow and velocity. They have to work together. The velocity factor comes form the minimum cross sectional area of the port and on a conventional BB Chevy head this area is usually just past the push rod "pinch". Mean flow numbers are what they are, and the smaller the cross section, the more velocity the port will have. Old school BB Chev heads like the OEM rectangle ports and older Brodix and Canfield heads that were designed after that have a lot of volume in the front of the port with large minimum cross sections ( big rectangle port) but have relatively small bowls. Then you can look at something like a Dart or AFR and you see the port is a lot smaller in the front with smaller minimum cross section and more of the volume is in the bowl, after the short turn. You can have three different 320cc cylinder heads and have three completely different velocity profiles and three completely different power potentials. I just finished a set of AFR 315's and did a 2.300 intake valve upgrade with a lot of bowl and short turn work. I didn't change the minimum cross section at all because it's already a little on the big side for what i want but the work increased the airflow significantly, so now the velocity will be closer to where I want it through the minimum. These heads are probably in the 325cc range now, bit with the small cross section of the 315 and they will out flow the 335 cnc. My guess is (without measuring them) the EQ heads are probably relatively small in the front and will work fine on a 500+ci engine with the right cam. They're not ideal, but for the price could be made to work real well. I wouldn't lose a minute's sleep over using them.
Here's the 315's I'm doing. I'm leaving the burr finish.
My office...
For those interested in numbers:
Flow: (4.50 bore, 2.125" pipe on ex)
right / left / ex
.2 165.5 / 164.2 / 120.8
.3 249.2 / 245.6 / 204.4
.4 306.9 / 300.5 / 249.7
.5 351.7 / 344.7 / 277.3
.6 382.9 / 364.2 / 290.2
.7 398.1 / 382.9 / 302.7
.8 404.2 / 394.6 / 313.4
.9 411.0 / 401.9 / 318.2
1.0 412.1 / 405.6 / 321.7
Right port on 4.60 bore (just for reference to AFR's numbers)
.2 166.0
.3 250.7
.4 312.4
.5 357.0
.6 389.3
.7 403.0
.8 406.2
.9 412.8
1.0 415.4
Here's the 315's I'm doing. I'm leaving the burr finish.
My office...
For those interested in numbers:
Flow: (4.50 bore, 2.125" pipe on ex)
right / left / ex
.2 165.5 / 164.2 / 120.8
.3 249.2 / 245.6 / 204.4
.4 306.9 / 300.5 / 249.7
.5 351.7 / 344.7 / 277.3
.6 382.9 / 364.2 / 290.2
.7 398.1 / 382.9 / 302.7
.8 404.2 / 394.6 / 313.4
.9 411.0 / 401.9 / 318.2
1.0 412.1 / 405.6 / 321.7
Right port on 4.60 bore (just for reference to AFR's numbers)
.2 166.0
.3 250.7
.4 312.4
.5 357.0
.6 389.3
.7 403.0
.8 406.2
.9 412.8
1.0 415.4
02-21-2016 | 10:40 PM
#212
Thread Starter
Registered
Joined: Jul 2004
Posts: 11,332
Likes: 73
From: chicago
I've read a lot of those posts as well, some good data. Articfriends has a ton of time on MPI's and seems to be the most knowledgeable with it from a home grown perspective.
I'm focused on my specific build though and those with specific hands-on experience with my setup. Thanks anyway for the info.
I'm focused on my specific build though and those with specific hands-on experience with my setup. Thanks anyway for the info.
02-22-2016 | 12:57 PM
#213
Frank's Marine Service
Joined: Sep 2002
Posts: 11,959
Likes: 142
From: Elkton, MD
Frank, why don't we stop playing games. You are here to #1, basically look for a combination you could copy, for your own engine build, and #2, asking questions to myself and others, to play your agenda over on boatfreaks with the others. You have alot of ballz to criticize my advice, the guy who's wanting to dismiss a cylinder head on a build over 12cc of port volume, with no discussion of any other parameters of the cylinder head (which foxwell clearly explained here), and dismissing another cylinder head over 7cc worth of chamber volume (because its been CNC ported). Maybe you are unfamiliar with something called milling a cylinder head. But, I suppose for a guy who is looking to "copy" someone elses build, and stick to what he can "bolt on", I am not surprised. You're posts clearly show you have minimal understanding of engine design, and the fact you are playing games acting nice over here, and a wise azz over there, show your true colors. Please don't give me the bullchit of saying "thanks anyway for the info".
I put my post up over there because I was interested in hearing FACTS based on EXPERIENCE, not a debate over what you may think will work sitting behind your keyboard. You're exactly right, I was looking for a proven combination and I was not looking to reinvent the wheel. Not having worked with the MPI before, I'm not going to pretend to be an expert and come up with a package for someone. If YOU had in fact put together a package like the one I'm doing, I think you would have shared your experience but from what I gather, you never have. When you don't have experience with something, I don't suggest pretending to be an expert on it. By sitting here and insinuating I don't know anything about engine design is quite funny because you have limited expertise in that area as well. Neither of us are engine builders or designers.
The funny part in all this is after all said and done the owner has purchased the EQ heads and decoded tp go in that direction due to price point. That had absolutely nothing to do with your input as much as I'm sure you would like to think it did.
I believe you have had an issue with me since I questioned your friends water plumbing technique on Facebook a few months ago. During that exchange you wanted to argue with me over instant message so I agreed to disagree and move on. I still wouldn't plumb an engine with the water going through the exhaust manifolds before entering the engine unless maybe it was in frigid waters of Novascotia. Ever since then, it seems there's always been an issue. Quite honestly, I don't have an issue with you. You seem to have one with me so don't get upset when I react.
Have a nice day!
02-22-2016 | 02:39 PM
#214
Thread Starter
Registered
Joined: Jul 2004
Posts: 11,332
Likes: 73
From: chicago
Yea, looks like you guys have quite the group of engine builders over there in that forum.
This was MY thread, in which you asked for input several times. If you dont like me, or anyone else here, i have a pretty good idea on what you can do with your questions.
Have a good day!!
This was MY thread, in which you asked for input several times. If you dont like me, or anyone else here, i have a pretty good idea on what you can do with your questions.
Have a good day!!
02-22-2016 | 04:33 PM
#215
Banned
Joined: Oct 2015
Posts: 277
Likes: 1
I've never used a set of the 332 ovals.
02-23-2016 | 05:05 PM
#217
Platinum Member
Joined: May 2012
Posts: 11,425
Likes: 3,953
From: Midwest & T-Rock
I really don't think that's bad at all, they do look nice, its all about the improvement over stock to me, bang for the buck spent = hp gained
02-23-2016 | 05:16 PM
#218
Registered
Joined: Apr 2004
Posts: 1,268
Likes: 239
From: Michigan
Best investment I ever made in context of over all performance gains! DO NOT under estimate what a professional and I do mean PROFESSIONAL cyl head man can do to enhance your engines power output! Just some real world input from a hobby boater,
