Beak Boater

Changing to Aluminum heads, on a 5800-6000 rpm, pair of motors. Have had some conversations about intake runner CC's. Anyone else running this combination, what size runner are you using??

Turbojack

I am running a 540 with procharger stage 4. In talking to david at AFR he said I should not go any bigger that 335cc's in a boat. I should be getting heads any day now. They had a 8 week backlog.

Beak Boater

Thanks for the response Turbo Jack. I talked with Mark at AFR and he recommended the 315 CC Intake runner CNC'd. He said that he wouldn't go any bigger or the throttle response would be soft, or not as crisp. Originally talked with Dustin and he recommended the Dart Pro 1 head with the 335 cc intake runner CNC'd. I was just trying to get some different opinions. The AFR heads flowed better than the Dart heads at every lift up to .600 and had a smaller intake runner. Was really looking at mid-lift comparisons since the camshaft will not have any more than .632 gross lift.

jdnca1

I run fully ported and polished Dart 360's (flow about 420) on a natural 632 with a fairly nasty solid roller. Throttle response is unbelievable through out the the band and TQ is sick in the mid range (820 ft/# @5200) NET lift is .710. If you're looking for MAX responsiveness then smaller is better, but why not have say 95% of the responsiveness and another 50hp? A 315 head is way too small for a blown 540" motor turning 6000 rpm in my opinion.

Beak Boater

JDNCA 1 Thanks for the info. Thats why I keep asking the question. Everyone has their own opionion. When I talked to Dart they agreed with Dustin about using a 335 cc runner. When comparing the Dart with AFR head the AFR head is flowing the same or better up to .600 with a smaller runner. That is why I ask the question what advantage is a bigger runner if the airflow is almost the same?

paradigm shift

I have to agree with jdnca1 on ports. I would think that with a blower you are going to have more than enough torgue. Port size is not as important as flow you are correct. Just make sure they are using the same test procedures when they state what the flow is for a given port size though.

KAAMA

iTrader: (1)

What size head would you guys think would work well on a naturally aspirated 598 cubic inch engine using a hydraulic roller/single carb set-up?

jdnca1

Kamma;

I would look hard at the Dart 355 Pro 1's. These heads wern't available when I did my motor, but I hear they flow almost as much as heavily worked 360's right out of the box. Remember big motors need lots of air...what rpm do you plan to turn?

Beak;

I would PM JimV for his comments. With the caveaut I'm far from an engineer and don't know much about blower motors, I believe it comes down to "volume" and flow to the motor. With forced induction there is the potential for more of each. When I did my motor Dart specifically recommended the 360's I think it depends on who you get on the phone as well. Originally they said to use the Big "M"'s, but I thought that was overkill for a 6200 rpm motor....now if we talk 8000 thats another story.

Strip Poker 388

iTrader: (6)

one thing you might think about throttle responce like on my blower motor did not use anthing below 3000rpm ,usally went from idle to 3000rpmjust to get on plane then throttle responce between 3000 and up ,usally your tatal advance is already maxed at 3000 or below and i think the bigger runner you want notice any diff from 3000 on. if its a blown motor ,tourq will make up throttle responce when in boost.on a blown motor the smaller runner will give more boost #s which is restriction and heat.

bobby daniels

FOR SURE ROB !!!!!!!!!!!!