laszlo01

Just purchased boat and am Looking at two different types of heads for a pair of hp 500's with 450 hrs, any comments on the dart pro-1 310 or the AFR 315 heads, which one would yield the best set up to have a solid 600 hp on stock 500 hp's ? trying to achieve a solid 85 mph on a 34 vyper. Boat has had some top end work done but has stock heads and the hours indicate a top end rebuild anyway so i figure i would change out the top end except the intake and carb, I.E cam lifters rockers and heads. Allready has EMI-512 manifolds with silent choice. Thinking of this route since i got a lot of feedback against the supercharger way.

articfriends

iTrader: (1)

The afr315 heads out flow the dart 310's by 10% on the intake and 20% on the exhaust,more importantly they have a nice intake to exhaust ratio of around 75%.You would have to spend big bucks on professional porting to get the darts to match and even then they still might not. For more info check out the headflow data base:http://users.erols.com/srweiss/tablehdc.htm#BBChevy
Rmbuilder (aka bob madera) is a dealer for afr heads and can get you the best pricing and has good availability on the afr's,you can reach him at 585-654-8583. He has also profiled cams that work VERY well on motors with afr heads that will still idle good and have a REAl marine power band with torque and hp where you can actually use it,Smitty

KAAMA

iTrader: (1)

I prefer naturally aspirated engines too and they're a little easier to detect when something starts going wrong vs supercharged engines---they definately make power, but have more moving parts, require more maintenance, more stress on parts, and they're prone to breaking drives a little easier.

Are you looking at both Dart and AFR in the CNC'd mode? I have had both heads...first the non-ported Dart 310's, but then had JimV fully port them. Then a few years later I bought some AFR 315, cnc ported heads which I now have on my 565cid naturally aspirated engines.

About a week ago I was by myself out on Lake Michigan in my boat testing some new props and ran into a friend of mine who owns a 32' Active Thunder just like mine---same hull. He has a pair of 557cid super charged engines with Dart Pro-1 heads (don't know what size) that supposedly make 810hp on the dyno vs my little naturally apirated 565cid wimp engines that don't make any power. I have even seen the dyno sheets of his engines built by Ultra Tech in Indiana.

Anyway, I guess he suddenly decided he wanted to go to guns with me, so we got it on and he could not pull me in acceleration (from about 3500rpm) and once we got up to the top he couldn't pull me there either! There ARE variables, but neither of us was able to out do the other, but as close as we are in cubic inches for the least dollar$ spent, and the speed he is running I am sure he is the winner there! He mentioned to me he's gonna pull the engines and have bigger cams installed---it never ends! None the less, I think he was a little surprised I could hang right there with him and I'm very pleased with how my little hog runs.

I guess what is really surprising is when a bass fishing boat, or the Sea Doos the have these days comes by you at speed---now THAT is painful!!! Anyway, have fun with your project.

rv

Kaama,
Didn't you have some flow data you posted before on OSO for your Pro1's before/after Jim finished with them. It would be interesting to see that.

Rick

SB

iTrader: (1)

Dart and AFR make some killer heads...no doubt.

Either would be a terrific choice.

Do we go with Tony or Richard ? Hmmmm. As a human I'm partial, and in an application like this I'm a little more partial to AFR.

CONDOR24

do any of you guys have an opinion on, or have tried the eldelbrock rpm aluminum heads, i saw them in a summitt racing catalog and they have a" marine" version with hardened valves and anti corrosive coating. i also have an hp500 i was considering porting the stock iron heads or going aluminum, just trying to research where to spend the $ for best results

KAAMA

iTrader: (1)

Okay yall, here are some flow number comparisons as RV has requested I post. JimV fully ported the Darts Pro-1's 310's and installed some larger 2.30" intake valves---this also included one of JimV's chamber port jobs which provides even more power. The AFR 315's were CNC ported with a smaller 2.25" intake valve. Flow numbers are from JimV's Super 600 Flo Bench @28" of water. WITHOUT 6" pipe.

Dart 310cc Pro-1with 2.30" intk valve
Intk Ext
.2 149 130
.3 225 171
.4 295 206
.5 348 256
.6 380 286
1397 1049 (total cfm)

AFR 315cc as is out of the box with 2.25" intk valve and best flowing Ferrea exhaust valve that you can get from AFR with this head
Intk Ext
.2 164 140
.3 243 193
.4 306 232
.5 357 250
.6 380 254
1421 1069 (total cfm)

We wanted to improve the flow numbers from .500"-.600" lift on the exhaust side of the AFR's-----so, I gave JimV the nod and he went in and did a little hand massaging of the exhaust ports so, here's what we got...

AFR 315 w/JimV exhaust port hand massage WITHOUT 6" pipe!
.2 146
.3 201
.4 246
.5 268
.6 279
1141 (total cfm)

Okay, we all know that AFR advertises their exhaust flow numbers WITH a 6" PIPE! So, I have listed results below...

AFR 315cc JimV exhaust mods WITH 6" pipe
.2 146
.3 213
.4 263
.5 290
.6 320
1232 (total cfm)

My cams have a lift that sits somewhere between .600" and .650" lift and the flow numbers on the AFR exhaust port with JimV mods and a 6" pipe is 327cfm.

So you can see the AFR's didn't quite flow as they are advertised out of the box...but I am sure air density and barometric pressure, etc, etc, may have something to do with that...not sure. However, you can see that the AFR 315's still out flowed the Dart 310 Pro-1's...even with larger intk valves and one of JimV's chamber port jobs. Then the AFR's got even better on the exhaust side with JimV's massaging. Now that's the last time I am gonna splain it to yall!

articfriends

iTrader: (1)

Kaama,how did the exhaust ports flow BEFORE the porting with a extension tube on them? Smitty

WAGS382

I am a proud owner of two sets of 305 cc AFR's with cnc'd chambers.
They are on my HP 500 carb motors in a 382 Fastech. The only parts that are not original HP 500 are the heads, custom cams, lifters and push rods.
These motors made 620 HP @ 5500 rpm and have a strong Idle.
This is with the original 800 cfm Holley's and gil exhaust.
I have 280 hrs on these motors with no problems. The boat picked up a solid 8 mph on the top end with this upgrade, now running 82 mph.
As smitty said call Rmbuilder (aka bob madera) for all your valve train and afr's, He knows marine engines and how to get a 600+ HP 502.
Jeff

KAAMA

iTrader: (1)

Here you go Smitty...

AFR 315cc (as is) out of the box WITH 6" pipe on JimV's flow bench

.2 146
.3 206
.4 251
.5 280
.6 287
1170 (total cfm)

So, there looks to be a 62cfm difference between out of the box vs the same port with the JimV mods.

Also, at .650" lift it is 291cfm