What heads would you use?
 

I am building a mild 509ci BBC. I'd like to get 500-525 HP. The bottom end, basically a 502/415 GENVI motor bored .030. Plan on using a 525 camshaft. What heads would you use? Manufacturer, cc, etc., etc.

Hate to say it but yes cost is a factor:angry-smiley-038: But I'm willing to spend extra $$ for quality.:boat:

Will be put in a 1999 '25ft. Active Thunder Tantrum:D

The peanut port cast head is the head for you. It will make outstanding torque from 2000rpm right up through 3500rpm, right where you need it. The only other option might be AFRs, I've heard tale of folks doing well with those too. :p

BT :cool-smiley-011:

:cool-smiley-027:
Not much top end, though. I'm deliberating the same question -
-I have 4 peanuts and 4 rectangles and 2 x 468ci in a 28' Checkmate.
-I have two Wieand open plenum and two original dual plane HP aluminum intake manifolds.
-I have two Q-Jets and two 1050 Dominators.

I plan to use the rectangles, the original HP aluminum intakes, and the Q-Jets for economy running and will swap out to Wieand and dominators for high speed running. While I know the head runners are oversize for a 468 until about 3500 rpm, I'm buliding to 6500 WOT. We'll see how much of a dog she is coming out of the hole and I may reverse the rect port decision...but that's my plan for now.:evilb:

Sshh, don't tell raddiction that, I can't have him rompin past me laughing his ars off :angry-smiley-038:

My setup is similar to yours NW but my cid is 470. Rect port heads, dart sp intakes last year with 800dp. Runs pretty strong and I have been happy with them. Couple years back I ran same edelbrock alum rect port heads with dp performer intakes. She ran better then. I actually lost 2mph going with the single plane. Now I am going with small blowers and dominator carbs. If I go back to n/a it would be with the dp peformer intakes. I have 2 blue hp 500 takeoff carbs to sell (800dp) if you are interested. I would definately dump the qjets and I have spent a lot time an money trying to make they work, they just can't match the holley.

Based on your rpm goal, single plane is a no brainer and I think the dominators a good starting point.

BT :cool-smiley-011:

Afr 315 cnc but get a custom cam. The 525 cam is actually a little big for that combination. 550 hp with excellent drivability will be easy with that. Dammit Donna was logged on, Ian

If you are saving money and only want 525 HP I would use the Dart Iron Eagles 308 cc 1600.00- 1700.00 complete with inconel valves.

Aren't the Edelbrock marine heads about that same price? They seem like a deal for an assembled aluminum head with inconel valves- what's the catch?

AFR 315cc CNC Ported,Hard Anodized water jackets, Inconl upgrade, that should do it. PM me for a price.

The Edelbrock marine heads don't have springs, retainers, etc. They still seem like a pretty good deal. How much are you leaving on the table for a nild 500" motor compareed to AFR's

Stay with a large oval port. No need to go more than a 290cc, but don't go less than around 270.
GM and Edelbrock make a 290, Dart makes some great pieces too.
A 100cc or so, combustion chamber would give you around 9.5:1 with a flat top as long as you were alittle less than .020 in the hole.

my .02
DAVE

Rect vs. Peanut
 

BT -
Agreed about the Q-Jets and Holleys, but $$ are tight and I have other priorities right now. (However, if you're only looking for a wink and a slap on the a$$, PM me). Take a look at what I started with...
What cam are you running? I'm probaby blowing bubbles thinking I can have both ends of the spectrum with the rect heads, but I have my eye set on the CC XM284HR as soon as I can afford the $2k upgrade.
I have the original 454 7.4l GM cams and a couple of CC 286H I want to check out.The 286, although flat tappet, will give me an idea of the trade-off between bottom end torque and WOT with the rect heads.
My blocks are with Active Performance for machining now..I plan on some lightweight 9.5:1 domes with H-Beams so I'm hoping the increased compression will overcome some of the low end "bog".:boat:

I run the comp cams cb xm 278h-12 cams. Flat tappet you know. Approx 9.5:1 compression. They run real strong up to 5400 or so. Bravo drives won't last going too high rpm wise. You should consider that NW.

Where you at Raddiction?

The recommendation on the Bravo Drives is the best bit of info on this thread. Watch your Torque and RPM. As for the heads, AFR for sure if you can afford them. Matched with a good intake and custom cam. A custom cam is NOT that much more then what you can purchase from Summit. Dump the Qjets and pick a good mechanical 4150 Holley HP. Now if the AFR's are out of price range, the Edelbrock large oval marine heads are a good second choice. Yeah, 1540.00 does not include the guides, springs, etc. But you can complete them with YOUR choice of products and be under 2K. Not bad for alum large ovals.

I have done something very close to this motor project, made 550HP/600TQ at 5400 with less CI and a stinking Air Gap dual plane intake. Did not spend a bundle getting it either.

Second best recommendation (IMHO):
Custom CAM by RMbuilder
Carb calibrated by Nickerson

Other than the weight I think the Dart's make more power.

Agreed

Thanks for the info guys......keep it comin'!!:D:cool-smiley-011:

Hey Tyler, do you mean these heads?
http://www.sonnysracing.com/products...portheads.html


Ok, fun stuff put aside, you and Mr. Gellner have tons of experience in the marine performance arena. How would you score a Dart Iron Eagle vs. an AFR counterpart? I.E. similar runner and cc volume.

Good question Rotax.....Dean/Tyler what are your thoughts.:cool-smiley-011:

Heres a little more to think about.....


Can the 502 MAG/MPI injection setup support the HP I'm looking for?

R Addiction, there is a local guy in Thordale, Pa. that could hook you up with some BAD heads. I hear he does some BAD work!!:cool-smiley-027:

Calling him tomorrow....

I bought a set of the Dart Iron Eagles. Disapointed in the quality. Sharp edges in the bowl area leading onto the ports. Flow might be better than stock, but still not that great. The Pro one's would better.

I personally like the Dart components. They flow better across the range. AFR flow numbers are inflated . I have personally flow tested many sets of heads on our 600 Superflow , and the number do not jive to what they really are. If your looking at price the Dart Iron Eagles are no doubt the way to go. They also have an alum. version which is 310 runner. Everyone has their preference. I also sell and use alot of Brodix Heads. Depending on application, one of these two companies will have a perfect match for what your looking to do. As we all know here, it's knowing what combinations work the best that will make the difference between bolting on 40 horsepower or gaining 100 HP.

WOW Mike.....is that you? Here on OSO!! :D

Yes, but the computer will need reflashing.

sorry to butt in but what are the specs o the 525 cam is it a roller or flat tappet thanks Randy

:boat: sure is

We used RHS heads on my 454 MAG MPI build up. With these and a Tyler Crockett camshaft, we mad 501hp & 535 lb*ft torque at really nice rpm numbers. The set was about $2200.00 complete with inconnel valves and all.

AFR 315 are great heads I just did a pair of 509s for a customer and made 615 hp on 9.4 - 1 comp and had no problem running pump gas. The dart pro 1 heads are also very good but I wouldn't waste any of your money on Edelbrock heads.

Would the AFR ported 315 work well on a 598 at 5600 rpm? It looks like it will flow enough in the .6 to .65 lift range.

I bet it would work great I wa using a cam with .625 lift and it made peak hp at 5650 rpm

I was readin along thinkin DAYUM this lady knows her **** :D

Thanks Randy. Now that's what I call priceless information.
Speaking strickly heads, I am so tired of hearing HP this, Torque this. All are meaningless. Put the head on a Flow Bench and read the results. Sure would be nice to have an across the board (manufacturer of BBC head wise) comparison of first cast iron heads, then aluminum heads. Each classed in their respective valve and runner sizes. Sorta like a Consumer Reports of BBC marine heads.

flow results
 

Do internet search cyl head flow test, its an AFR site has flow test of 16 heads alum and cast , same bench and test equiptment found it one day playing. hope it helps Randy

I remember asking RMBuilder the same question a year or two ago---he said it was somewhere between 5000-5500rpm, but I cannot remember the exact RPM he stated before the intake air flow would go into turbulence for an engine that size (598cid) with the AFR 315 CNC ported heads. Even so, 315cc's would be cutting it a little too close for me. I would opt for the next size up from there---the AFR 335 CNC ported head for 598 cubes. Perhaps someone else can chime in, but I would still put a call into RMBuilder/Bob Madara of Marine Kinetics and see what he says.

Ok....new scenario.....I have the chance to purchase a 530 HP motor complete, with 140-150 hours from a very reliable source. HP500 injection setup, remapped ECM. Dyno sheets show 531 HP. Is a volvo setup, my next question is are the wiring harnesses compatible?

I may end up keeping the 509 bottom end and doing another motor, possibly for a car or truck. Decisions Decisions!! Thanks for all the info.:D

Is it factory stock? You would need to go through the top end mininally. Hopefully this would be equipt with the eickert headers. If not, I don't see much benefit over building what you have.

another thing to keep in mind with the dart heads are you need to get longer bolts to secure to the block as i learned with my motors

It doesn't have Eickerts on it Dave. Imco powerflow. The person who has the motor is very knowledgeable and a trusted friend. But I am still looking into building up the 509 if $$ allows.:D

the 500 dpx volvo motors had the same cannon plug connector as the mercruiser ones if that is the motor you are looking at