RLW

Jim V,
So what would be a good "Marine Head" for a N/A 496 Stroker to a 502-509 inch motor?
Is there one particular head that would be good for this range of size engines or is it more specific on displacement?
5500 max rpm and around 9:1 - 9.5:1 Compression ratio.
Thanks for any reply.
Russ

Madmax

Edelbrock marine oval ports? Anybody like those???? 1400 bucks from summit hard anodized with inconel exhaust valves.........

What's your verdict on them Jim? I haven't heard anybody that uses them......

S4Hadi

I was hoping that this would have been a simple head & cam swap etc. with a proven reliable kit.

Thanks for the input, as I kind of knew that this would be too good to be true. It usually is.

Any proven bolt on kits out there for a MAG 502 MPI? Motor runs great, I do not want something that needs to be dialed in with trial and error.

Thanks,

Jamal

KAAMA

iTrader: (1)

If anyone has dyno tested the AFR 315 CNC'd heads or flowed them on a flow bench please post it here for us---thanks!

RLW

http://www.chevyhiperformance.com/techarticles/41598/

Monty

KAAMA,

I'll have flow bench results with AFR 315 CNC ported heads within the next week or two. I ordered my heads bare because I prefer Del West valves over Manley, or whatever else AFR uses, and I'm just waiting on the valves to be back cut. Should be done anyday now.

Both 540's will be dyno'd within the next month with AFR 315's, Crane 741, Holley 850, etc. The last component I need to order is the intakes, and that decision is partially based upon some hatch clearance measurements I'm waiting on from Doug1. It's either Victor Jr's or Airgaps. I'll probably end up with the Airgaps cause I've got a tight fit and I don't think I can squeeze the Victor Jr's in.

KAAMA

iTrader: (1)

RLW, thanks but that website is limited in the castings they use and I could find any test data on the AFR 315 CNC head.

Monty, I've been waiting so much in anticipation by chewing on my finger nails that they're begining to look like I've been using a chain saw on them! The suspense is driving me crazy!

Tinkerer

Monty---Why are you using the Crane 741 instead of the 771 ???
Crane recommends the 771 for 540 and bigger cubes.

rpm

Monty, I don't believe an 850 is enough carb for ported heads on a 540. Look at the bsfc and A/F ratios on one of ours with a 1050.

Rod

Monty

Rod,

I hear what you're saying about using a Dominator, I briefly considered it, but I'm building my 540's to maximize mid-range power and torque and the 850's were a better fit, I beleive. Those BSFC numbers and A/F numbers don't look that bad. Generally, .50 - .55 bsfc is what can be expected from most engines NA engines. Obviously, highly tuned racing engines or forced induction engines will have different results/requirements. Most NA engines generally make best torque(max VE) at around 11.8 - 12.2 A/F ratio, and best power in the 12.8 -13.0 range.

With 540 ci it's not too hard to build more power and torque than the TRS drives can reliably handle, especially with good heads. There's always the tendency to go big when it comes to choosing heads, cams, intakes, etc but I've always focused on desinging the engine for it's realistic application. If I had #3A drives or better, beleive me, the engine's would be alot more impressive.

I'm not building the engine's for maximum power or rpm. My goal is only about 600-625hp. RPM will be limited to ~5500 for the sake of reliablity, throttle response, area under the curve, ease of maintanance, and compatibility with what the drives can handle.

(540 x 5500)/3456 = 860cfm @ 100% VE

My engine's will probably average 85-90%, so even at 90% VE, the engine's will only require 773cfm at 5500 rpm. Even at 6000 rpm, with 90% VE they only require 844cfm. Obviously, the carbs will be maxed out, but at anything less than max rpm, the result will be very good throttle response due to the strong venturi signal.


As for using the 741 cam vs. the 771 cam, Again I just felt it was a better fit for my intended rpm range and 9.0 compression ratio. I actually debated between the 731 and 741. While the 741 is generally recommend for 454-502 ci engines up to 6000rpm, it's also recommended that dry headers and a 10.0+ compression ratio be used. While my displacement is about 10% larger, I'm only running 9.0 compression and wet Stainless Marine manifolds up to ~ 5500 rpm. The duration fits my rpm range, and the lift and lobe intensity is such that they won't beat up valve springs or require alot of valve spring pressure. I don't want to worry about changing springs and lifters every year.