Intake Runner volumes
 

I know alot of you probably have seen this article from AFR's website, but maybe some havent. Either way, I find the results kind of interesting. I see alot of guys suggest that if you go outside the norm, say too big on intake runner size, the engine combo will be a "Turd, lazy, pig, wont get out of its way, or simply a piece of crap".

In this test, they had a 496ci, with a solid roller camshaft as the test mule. The power band they measured, was 3500-6500rpm. Kind of relevant to a high performance offshore boat power band. I find it interesting, that a huge 360cc runner head, like the trick flow, or 355 edelbrock, smokes the 325cc stock head, in average torque. and about the same or better than the avg torque of the smaller dart 308cc runner. Maybe these numbers are lies , as we know magazine articles may not always be 100% truthful, or accurate. I know that if someone here, recommonded a 335cc port on a 496ci, they'd be kicked right in the ball bag thru the keyboard, let alone a 360cc runner head, and pretty much told the engine probably won't even get the boat on plane do to the lack of torque . Any thoughts on this article and the results?


GM rectangle ports
Peak Power- 630 @ 6,600 rpm
Peak Torque- 577 lb-ft @ 5,300 rpm
Avg HP (3,500-6,500)-532.4
Avg TQ (3,500-6,500)- 560.5 lb-
TQ @ 4,000 RPM - 562.7lb-ft

Summit/Dart 308 Iron Eagle
Peak Power- 688 hp @ 6,600 rpm
Peak Torque- 607 lb-ft @ 5,400 rpm
Ave HP (3,500-6,500)-555.5
Ave TQ (3,500-6,500)-582.1
TQ @ 4,000 RPM-563.3 lb-ft

Pro Comp 360cc
Peak Power- 690 hp @ 6,300 rpm
Peak Torque- 600 lb-ft @ 5,500 rpm
Ave HP (3,500-6,500)-554.2 hp
Ave TQ (3,500-6,500)- 581 lb-ft
Tq @ 4,000 RPM-568.3 lb-ft

Trick Flow 360cc
Peak Power- 691 hp @ 6,400 rpm
Peak Torque- 603 lb-ft @ 5,400 rpm
Ave HP (3,500-6,500)-555.3
Ave TQ (3,500-6,500)- 581.9 lb-ft
TQ @ 4,000 RPM-562.3 lb-ft

Brodix 332 CNC ovals
Peak Power- 705 hp @ 6,400 rpm
Peak Torque- 624 lb-ft @ 5,200 rpm
Ave HP (3,500-6,500)-574.6
Ave TQ (3,500-6,500)- 602.7 lb-ft
TQ @ 4,000 RPM-585.7 lb-ft

Dart 335 CNC
Peak Power- 717 hp @ 6,500 rpm
Peak Torque- 619 lb-ft @ 5,600 rpm
Ave HP (3,500-6,500)-568.0
Ave TQ (3,500-6,500)-594.3 lb-ft
TQ @ 4,000 RPM-572.5 lb-ft

Edelbrock CNC 355cc
Peak Power- 723 hp @ 6,500 rpm
Peak Torque- 627 lb-ft @ 5,600 rpm
Ave HP (3,500-6,500)-573.5 hp
Ave TQ (3,500-6,500)- 599.9 lb-ft
TQ @ 4,000 RPM-574.0 lb-ft

AFR CNC 300cc
Peak Power- 729 hp @ 6,500 rpm
Peak Torque- 639 lb-ft @ 5,400 rpm
Avg HP (3,500-6,500)-584.1
Avg TQ (3,500-6,500)-611.4 lb-ft
TQ @ 4,000 rpm-587.0 lb-ft

http://www.superchevy.com/how-to/pro...ut-the-o-vs-r/

Interesting data

but the smallest head made the most power and the gm head did the worst.

I believe the afr had a 110cc chamber, and the dart a 121cc chamber, so it had a little help from some extra compression, to make that extra 12hp and 20ft lbs.

If one was to put say, the dart 335, afr 300, brodix 332, or 355 edelbrock (all the cnc ported heads), headed setups in a boat, how much mph difference would we see ?

Or, we might say the 308 dart would be a better fit for a 496 because of the runner size. Obviosuly though, the 335 dart, flows a bunch better, and is making a fair amount more HP, and torque. On this dyno test, looks like the 335 would be a better choice (disregarding cost obviously).

I'm glad you posted this. I've always stayed on the small side with any of the boat engines I've built. Personally I don't see any need for more than 265-280 oval port on a 454-468, 310 max on a 496-509, 315-330 on 540-565
And so on. At least for the marine apps running under 6k

I will give up a little top end for throttle response any day.

Say What!? More compression = More Power? You don't say
What's the first thing you learn in any introductory statistics class?...
Another apples to oranges comparison from a magazine.

Also does this seems like a very happy dyno?
Comp Cams 300BR-14 offered 0.652 lift, a 255/262 duration split and 114-degree LSA (not that aggressive of a cam)
630HP on Stock GM rectangular port heads @ 10:1

I've been looking around lately myself. Going with 320 pro filers and have valako work his magic with them. He said when he's done they'll be a little under 330 and that for my 565's. Not sure if he's gonna wedge them or not. Regardless I've always been a dart guy however the cnc 315 afr' pull some awesome flow numbers out of the box.

Personally I was thinking 335 runners for my 565's but Jim talked me out of them. Buying the pro filers through him.

I'd love to make some hefty bets with the majority of these if not all who are advertising x for their hp, torque, etc. I see sales/ads for 496's making over 700 hp on pump gas. Wtf. Really. Guess I have to go back to school.

Did I miss somewhere if these were out of the box or completely tricked out heads. 100 hp bolt on head. Don't think so. I've spent a lot of time in the dyno room and there is no way.

She told me port size doesn't matter...its all about the flow.....