Re: AFR heads: Anyone else interested in buying?
 

Articfriends/Smitty,

I have heard from several engine builders that an engine with a supercharger usually needs or will allow for a larger cc runner sized head just by the mere air volume that a supercharger puts through an engine.

I bought my 357cc AFR cnc ported heads as USED because I got a half way decent deal on them. Yes, a 335cc head would work great on my engines. I'm sure there are exceptions to the rule as this can get to be very controversial and create a lot of arguement, but I have asked about 4 professional marine engine builders all with several years of experience if a 357cc runner sized head is too large for a naturally aspirated 565 cubic inch engine for a marine application in the 3000-5800rpm range---they all said "no". I only have a 32' boat---it isn't real heavy---maybe 8000lbs or so. It is true that torque is the name of the game for a marine engine, but with my boat I don't need a ton of torque to get it moving. I believe that one of the factors in choosing a specific size head will depend on how heavy your boat is. There is a member on OSO by the name of "Bad to the Bone". He has a 35' Cig Awesome---VERY HEAVY boat---probably 11,000-12,000lbs! He built a pair of naturally aspirated 540 inch engines with GM ported rectangle heads on it. He bought some 315cc AFR cnc ported heads and a maybe a cam change and he said the difference was like night and day---he was very happy. If he had superchargers on it then he would probably get more favorable results with some 335cc heads vs the 315's. Yes, torque is good, and I want the boat to have good throttle response, but I would think that you'd want the engine to breath a little and move some air too. Besides, I don't exactly need Bravo drive killing torque.

The trouble is that there are 1001 different combinations and all of us has an opinion, therefore with a supercharger on a 540 inch engine (if it was me) I would lean towards the 335cc head. But what do I know? I am just an exterminator---I only kill bugs for a living, so I will probably get some rebuttal on this post, but that is kinda what this forum is for.

Anyway, I wish you the best in your decisions as you journey on your endeavor for torque and horsepower. Have fun! :D

Re: AFR heads: Anyone else interested in buying?
 

Kaama,maybe i'll run into you at hardy pond.I want to upgrade my heads,i just don't want to lose midrange,it's a toss up!We all know what its like to spend all winter redoing something and not get the exact results you want. Good luck on your motors too,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Arcticfriends,
I have a polished Procharger box with a dual carb setup that I would be interested in selling. If interested shoot me an email and I will give you my number so we can talk. I would like to sell the box, carbs, and intake. This setup came with my M-4, so it should work well for your application. I ran it with 13 lbs of boost.

Re: AFR heads: Anyone else interested in buying?
 

Smitty,
For your combo, you are missing about a 100HP/150#/ft of torque somewhere. I have missed all this time you are positive manifold pressure. . .sorry. In this case a 320 to 335cc runner head would be fine on a blower engine. I would suspect camshaft is not in sync with the rest of your combo and is fighting the induction system. Based on the ratio of the intake flow to exhaust that you posted. The cam should have about a 12 to 14 degree split favoring the exhaut. Based on the the CID and rpm range. . . now is when I will get called NUTS. . .cam duration at .050" shoud be about 226/238 for a max rpm of around 5500. Lift would be greater then what you have. I think you got the parts you need to make some power, they just need a little tweaking.

Chris

Re: AFR heads: Anyone else interested in buying?
 

Hey Smitty:

The heads and/or the Merc intake must be the problem; you were at least 100 ft-lbs short when you were running 9-10 psi boost. With a single plane intake and ported GM heads we see 800 ft-lbs @ 5500 RPM with 8.5-9 psi on 500 CID.

Why don't you buy the Holley EFI universal kit? You already have the computer, wiring harness and injectors. All you need is the manifold with fuel rails and a throttle body. You really only need the 1000 CFM throttle body but you could use the Dominator flange intake and the 2000 CFM throttle body.

Of course, this would now fit a supercooler under the hatch. :rolleyes:

Chris:

I agree with keeping the cam small, especially for a centrifugal blower. And I wouldn't be afraid to use the 315 CNC heads. This would make great torque down low without boost, then let the supercharger do the work on the top end. Midrange will be awesome.

Re: AFR heads: Anyone else interested in buying?
 

Chris, Most fellas usually like large cams, but I sure don't think you're "nuts"----I agree with you! Unlike most guys, I kinda like the idea of using a smaller cam as well. In fact, more and more I try to get away with using the smallest camshaft allowable.

Re: AFR heads: Anyone else interested in buying?
 

Chris, Most fellas usually like large cams, but I sure don't think you're "nuts"----I agree with you! Unlike most guys, I kinda like the idea of using a smaller cam as well. In fact, more and more I try to get away with using the smallest camshaft allowable.

Re: AFR heads: Anyone else interested in buying?
 

Chris,my cam is a cam motion hyd roller,.228 deg at .050 intake,236 ex,.593 lift intake,.612 lift ex 110 intake centerline,118 ex centerline.
Tomcat,the 695 ft lbs torque and 630 hp was at 5psi boost w/4 degrees less ign timing on dyno,the boat with motor in it exactly that way off dyno was 3 mph SLOWER than my old 502 w/stock merc cam but all the other topend components i'm currently running. After turning IGNITION timing up 4 degrees and upping boost to around 9 i picked up roughly 8 mph. To gain 8 mph i'm guesing the torque and hp to be around 800 ft lbs and 725 hp but its only a guess.Are you saying if i didn't run the merc manifold/efi i could pick up another 100 ft lbs or am i in the ballpark of what it should be making? The motor just started burning a few puffs of oil on startup so i'm thinking the guides are getting worn,so i'm planing on freshening the motor and figured it would be a good time to optimize the topend (higher flowing heads w/better i/e ratio). Also like we were talking about on a thread a few months ago i just got some real nice bourdon tube vacuum /pressure gauges and i'm going to rig them temporarily on my boat this weekend and post a thread showing inlet press vs outlet press vs intake manifold press w/aw504 intercooler on my boat,ive always wondered where the pressure really was and where the drop will be,Smitty

Re: AFR heads: Anyone else interested in buying?
 

Arcticfriends,
I have a polished Procharger box with a dual carb setup that I would be interested in selling. If interested shoot me an email and I will give you my number so we can talk. I would like to sell the box, carbs, and intake as a package and give you a deal on all of it. This setup came with my M-4, so it should work well for your application. I ran it with 13 lbs of boost.

Re: AFR heads: Anyone else interested in buying?
 

:rolleyes: