Intake Runner volumes
04-02-2016, 12:57 AM
#12
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Everyone want more top speed, till there` s a head thread, then everyone wants a small head for down low tq. 
I don`t get this automotive off idle acceleration mindset.
This guy need lots of TQ down low that I can understand.
None of those heads give up anything worth talking about to consider a small head over a future proof larger one
I don`t get this automotive off idle acceleration mindset.
This guy need lots of TQ down low that I can understand.
None of those heads give up anything worth talking about to consider a small head over a future proof larger one
Last edited by ICDEDPPL; 04-02-2016 at 12:59 AM.
04-02-2016, 01:41 AM
#13
Here's something ya'll might find interesting reading....some stuff I have witnessed myself----I know of 3 different BBC engines with the exact same Cubic Inches (500+cid) dyno tested on the same dyno over the past year all destined for offshore applications.....a Roots 14-71, an M4 Pro-Charger and a Whipple 8.3L/510. All 3 engines were built with solid roller cams and inter coolers.
I do not have the liberty to give detailed specifics because these engines belong to customers of my builder.
The Roots 14-71 engine was destined for an offshore racing application and had the largest cam of the 3 engines, but the heads are some older aluminum designs with porting and the same size as the M4 Pro-Charger heads. The M4 Pro-Charger engine's cam was about 3* duration larger on a 112* LSA compared to the Whipple engine's 114* LSA "tight lash" cam.----therefore, the Whipple engine has the smaller/milder cam design.
All 3 engines made peak HP and TQ within about 10hp. The Intake runners of the heads of the M4 Pro-Charger engine were about 20cc larger than the Whipple's engine's heads. Both heads were a late design cnc ported head design of the same manufacturer---with the same exhaust port size/design and same size valves. The Roots engine heads were the same size as the M4 Pro-Charger's heads, but different manufacturer/design.
The M4 Pro-Charger engine was very impressive...it had the lowest Intake Air Temps between the 3 engines. However, it took 9 lbs of boost to make the same peak HP as the Whipple engine.....The Whipple engine only took 7.5 lbs of boost to make the same HP....and the Whipple did it at a 300rpm lower rpm rate compared to the M4 Pro-Charger engine. Both engines were timed at 32*. The Roots 14-71 engine made peak power with about 11.5-12 lbs of boost with the same peak RPM as the M4 Pro-Charger. I don't remember what the timing was for the Roots engine, but being that it was built as a racing engine destined for offshore racing with the heads that the customer had at the time, then I am sure the timing was set a little higher.
This is just my own observation/opinion...but I thought it is/was a very interesting comparison and from some of what I have heard in the past about the Pro-Chargers, I thought the M4 Pro-Charger would have kicked a little more arss in the HP per RPM per pound of boost, etc, department....and I am sure it would have kept going, but at the sacrifice of higher RPM.
Even though the Intake Air Temps of the M4 Pro-Charger were cooler than the Whipple, and the Whipple cooler than the Roots---the Whipple after a long pull on the dyno with a hard pull at the end, you could lay your bare hands on the surface of the blower case of the Whipple and it would be COLD to the touch....unlike a Roots. I thought that was very impressive.
I understand every engine is different and you can argue the finer details if you want, but the smaller intake runner CC sized heads of the Whipple engine beat the larger 20cc sized heads of the M4 Pro-Charger plus with the slightly larger 3* cam and tighter LSA...at least in this reference.
I do not have the liberty to give detailed specifics because these engines belong to customers of my builder.
The Roots 14-71 engine was destined for an offshore racing application and had the largest cam of the 3 engines, but the heads are some older aluminum designs with porting and the same size as the M4 Pro-Charger heads. The M4 Pro-Charger engine's cam was about 3* duration larger on a 112* LSA compared to the Whipple engine's 114* LSA "tight lash" cam.----therefore, the Whipple engine has the smaller/milder cam design.
All 3 engines made peak HP and TQ within about 10hp. The Intake runners of the heads of the M4 Pro-Charger engine were about 20cc larger than the Whipple's engine's heads. Both heads were a late design cnc ported head design of the same manufacturer---with the same exhaust port size/design and same size valves. The Roots engine heads were the same size as the M4 Pro-Charger's heads, but different manufacturer/design.
The M4 Pro-Charger engine was very impressive...it had the lowest Intake Air Temps between the 3 engines. However, it took 9 lbs of boost to make the same peak HP as the Whipple engine.....The Whipple engine only took 7.5 lbs of boost to make the same HP....and the Whipple did it at a 300rpm lower rpm rate compared to the M4 Pro-Charger engine. Both engines were timed at 32*. The Roots 14-71 engine made peak power with about 11.5-12 lbs of boost with the same peak RPM as the M4 Pro-Charger. I don't remember what the timing was for the Roots engine, but being that it was built as a racing engine destined for offshore racing with the heads that the customer had at the time, then I am sure the timing was set a little higher.
This is just my own observation/opinion...but I thought it is/was a very interesting comparison and from some of what I have heard in the past about the Pro-Chargers, I thought the M4 Pro-Charger would have kicked a little more arss in the HP per RPM per pound of boost, etc, department....and I am sure it would have kept going, but at the sacrifice of higher RPM.
Even though the Intake Air Temps of the M4 Pro-Charger were cooler than the Whipple, and the Whipple cooler than the Roots---the Whipple after a long pull on the dyno with a hard pull at the end, you could lay your bare hands on the surface of the blower case of the Whipple and it would be COLD to the touch....unlike a Roots. I thought that was very impressive.
I understand every engine is different and you can argue the finer details if you want, but the smaller intake runner CC sized heads of the Whipple engine beat the larger 20cc sized heads of the M4 Pro-Charger plus with the slightly larger 3* cam and tighter LSA...at least in this reference.
Last edited by KAAMA; 04-02-2016 at 01:45 AM.
04-02-2016, 07:19 AM
#14
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I absolutely can't stand head tests that have very varied combustion chamber sizes. Difference between a 9:1-10:1 BBC can be huge !
Seems every BBC head test in the mags does this.
More than a few 30-33ft twin engine boats out there running over 90mph with 496's and AFR 315-325's.
Raising a port lengthens it. This makes for a larger measured CC runner. So, this is not always a good indicator of performance.
Seems every BBC head test in the mags does this.
More than a few 30-33ft twin engine boats out there running over 90mph with 496's and AFR 315-325's.
Raising a port lengthens it. This makes for a larger measured CC runner. So, this is not always a good indicator of performance.
04-02-2016, 07:45 AM
#16
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Absolutely but example I would bet anything if you took my 496 with 10.5:1, 244/248-647/637 on a 111 and dart intake with pro one 310's and dynoed with stock gm heads I'm not gonna drop 100 hp. That's all I'm trying to say. Especially with that cam. Like rookie said its not that Big of a cam. Gm heads are taking a nap anything over .600 lift.
04-02-2016, 07:49 AM
#17
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Knowing how my little 265 AFR's preformed, which is certainly a small port, high velocity design. I was so happy with those that I’m going with the new AFR 300 oval for my current engines. As for runner size- I'm really confused as why someone would want to use a large runner head when a small runner will perform the same or even outperform its bigger brother. If you can get high velocity AND high flow why would you not pick the head that does both?
Below is a flow chart of the different heads in this comparison. Even compared to the Dart 335 CNC or the big Trick Flow 360, the AFR 300 is the better flowing head.
Lift AFR 300........DART 335...........Trick Flow 360
.20 165..................121........................15 1
.30 240..................203........................22 7
.40 296..................276........................28 3
.50 340..................322........................32 5
.60 378..................365........................36 2
.70 388..................395........................38 2
Yes- the numbers above came from different shops, so yes this is not exactly apples to apples. What these numbers do show, is that the old thought of bigger is better is not true. The numbers above show this as well as the dyno results. 35cc is a lot bigger and in this case flows LESS until .70, and none of us on here are running a cam big enough to take advantage of any increase at that lift. And why anyone would ever want to put a 335 cc head on a 496 is beyond me, let alone a 360 cc, especially given the choices we now have with some of the new AFR designs. Another very important difference is that the mid-flow numbers on the smaller head are substantially better, resulting in better filling of the cylinder.
Now a comment that KAAMA made, that I also experienced on my AFR 265 engine. Again not apples to apples, but that engine would pull so much air thought the carb I would get serious condensation on the carb. While my current 454’s are running GM heads and HP500 carbs vs Holley HP 950 on the afr engine, I’ve never seen a drop of condensation on the current carbs and they are never cold to the touch after a hard run. I’m not saying that runner size is what caused this, but both engines are running similar cams, and similarly sized carbs, so the heads are the one big difference between the two.
This is an interesting comparison that super chevy did, and IMO proves that fact that there is more to making power than slapping a large head on an engine.
Below is a flow chart of the different heads in this comparison. Even compared to the Dart 335 CNC or the big Trick Flow 360, the AFR 300 is the better flowing head.
Lift AFR 300........DART 335...........Trick Flow 360
.20 165..................121........................15 1
.30 240..................203........................22 7
.40 296..................276........................28 3
.50 340..................322........................32 5
.60 378..................365........................36 2
.70 388..................395........................38 2
Yes- the numbers above came from different shops, so yes this is not exactly apples to apples. What these numbers do show, is that the old thought of bigger is better is not true. The numbers above show this as well as the dyno results. 35cc is a lot bigger and in this case flows LESS until .70, and none of us on here are running a cam big enough to take advantage of any increase at that lift. And why anyone would ever want to put a 335 cc head on a 496 is beyond me, let alone a 360 cc, especially given the choices we now have with some of the new AFR designs. Another very important difference is that the mid-flow numbers on the smaller head are substantially better, resulting in better filling of the cylinder.
Now a comment that KAAMA made, that I also experienced on my AFR 265 engine. Again not apples to apples, but that engine would pull so much air thought the carb I would get serious condensation on the carb. While my current 454’s are running GM heads and HP500 carbs vs Holley HP 950 on the afr engine, I’ve never seen a drop of condensation on the current carbs and they are never cold to the touch after a hard run. I’m not saying that runner size is what caused this, but both engines are running similar cams, and similarly sized carbs, so the heads are the one big difference between the two.
This is an interesting comparison that super chevy did, and IMO proves that fact that there is more to making power than slapping a large head on an engine.
04-02-2016, 07:53 AM
#18
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iTrader: (7)
I absolutely can't stand head tests that have very varied combustion chamber sizes. Difference between a 9:1-10:1 BBC can be huge !
Seems every BBC head test in the mags does this.
More than a few 30-33ft twin engine boats out there running over 90mph with 496's and AFR 315-325's.
Raising a port lengthens it. This makes for a larger measured CC runner. So, this is not always a good indicator of performance.
Seems every BBC head test in the mags does this.
More than a few 30-33ft twin engine boats out there running over 90mph with 496's and AFR 315-325's.
Raising a port lengthens it. This makes for a larger measured CC runner. So, this is not always a good indicator of performance.
That would be on a snowmobile here in nw mi today. Snowing again.
04-02-2016, 08:03 AM
#20
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iTrader: (4)
I did a cam swap and head change and I netted 8-9 mph. I don't think you could go wrong with any of the top 4 heads in this test. Flow bench and dyno racing at it's best! The true dyno is the boats performance or the track.
