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what heads are the best

8K views 48 replies 16 participants last post by  culprit294 
#1 ·
ok
I'm building a 572 bbc 8 to 1 pistons
solid roller 758 lift 114 lobe separation.
I want to buy a set of heads but before I do I thought
I would get some opinions . I called brodix and ask what
their thoughts were. they said to use bb3 xtras.
I know there are alot of knowledge on this forum .
any help out there
this motor is going in my hydro
thanks
 
#3 ·
ok
I'm building a 572 bbc 8 to 1 pistons
solid roller 758 lift 114 lobe separation.
I want to buy a set of heads but before I do I thought
I would get some opinions . I called brodix and ask what
their thoughts were. they said to use bb3 xtras.
I know there are alot of knowledge on this forum .
any help out there
this motor is going in my hydro
thanks
Is this a N/A motor, If so why the low CR? You could go 10.5:1 cr on pump gas, also you need your heads flow #'s before you pick a cam, you'll get better results that way. If you give alot more info about your motor, boat and intended use that would help alot.:)
 
#5 · (Edited)
Sounds like a blower motor. 8 to 1, 114 lsa.
No duration numbers on the cam.
No mention of the inductrion system
I'm thinking one its 650 on a dual plane so 049's with over sized valves should be perfect.:)sphss

Thats all the info you gave Brodix and they were ableto tell you BB3xtra. There went the very last bit of respect I had for Bordix. Which wasn't much to start with.



 
#9 ·
I'm so lost I don't know where to begin. How do you know what your compression ration is if you don't know what CC your chambers are.

Do you know what you want your compression to be. Do you know the dish size of the pistons you have and the distance in or out of the hole?
Have you bought any of this stuff, or is the stuff you want to buy.



 
#11 ·
X2 He's brought up all excellent point of info any good builder would ask :)

I always like to know the application it will be used in

What type of boat, size, drive, gears,exhaust and intake, prop and weight

After picking the right comb parts. Just like buying a good suit

the final fitting starts :)hand
 
#12 ·
Bb3 xtra

ok
I'm building a 572 bbc 8 to 1 pistons
solid roller 758 lift 114 lobe separation.
I want to buy a set of heads but before I do I thought
I would get some opinions . I called brodix and ask what
their thoughts were. they said to use bb3 xtras.
I know there are alot of knowledge on this forum .
any help out there
this motor is going in my hydro
thanks
I ran a set of cnc bb3 xtras on my 572 last summer. They were 355/119s. Compression was 10.4, cam was .714I, .690E. Any way the motor made 837 at 6300 without a perfect tune. I know this may not have much to do with your blower motor but they made good power on my 572. Brodix also stated that they were borderline of being too big for my 572 at 6300.
 
#13 · (Edited)
I ran a set of cnc bb3 xtras on my 572 last summer. They were 355/119s. Compression was 10.4, cam was .714I, .690E. Any way the motor made 837 at 6300 without a perfect tune. I know this may not have much to do with your blower motor but they made good power on my 572. Brodix also stated that they were borderline of being too big for my 572 at 6300.
This why I hate Brodix heads. Everything I look at says the 3xtra cnc is a 366 cc intake. What can be really confusing is when the CCs are less on the cnc heads than the as casts. Like the 2xtra as cast is 365, but the cnc is 355:)sphss
Not counting the fact that each series head requires its own dedictaed shaft rocker stands.

Jungledave, are you sure yours are 3s or that the CCs are 355?



 
#14 ·
The first flag is the 8-71 on 572 inches. Going to take some decent over drive with a real good set of heads and a cam of that size. Did a dumb test one time and found it took about 3.0 lbs to break even on a 9.1 555 incher with a 10-71. Sounds like this will be pump gas. Its probably going to need 9-11lbs of shitty air with the 8-71 to make 950 hp. That spinnin the 8 pretty hard
 
#17 ·
machineHead, I completely agree he is has to spin the hell out of that 8 to cover the heads and cam. But oon this "dumb" test you did. Did you obtain the 3psi with the throttle, or with pulleys at wot.
I'm not sure I understand what you guys are saying. If I read it right, you're saying an 8 is to small to build boost on a 572 with good heads/cam? Or that it took 3 lbs boost to cover the losses from the blower? Or something else entirely.... Care to elaborate?
 
#15 ·
machineHead, I completely agree he is has to spin the hell out of that 8 to cover the heads and cam. But oon this "dumb" test you did. Did you obtain the 3psi with the throttle, or with pulleys at wot.



 
#18 · (Edited)
David, it is going to be hard to built enough boost with a 8-71 on that motor to justify the cam shaft. If you match the cam to a set of heads, it should have more boost than he can easily make with the 8. If from the beginning you knew you were going to run a 8-71, you would choose a smaller cam and there fore a smaller set of heads. Basically, the blower will have a hard time delievering enough air for that cam along with the heads that cam wants.

I not really sure what Machinehead was trying convey with the 3lb thing, or how he even limited the boost to 3lbs. With the throttle? or with pulleys?



 
#20 ·
I know on Nelson's 509, his (fresh) 1071 was working to make 15# @ 6000rpm. I can't imagine what the air temps will be with an 871 trying to make 10# on a 572, especially if you put stoopid big heads on it like some mentioned above.
I certainly don't claim to be a blower expert but based on what you guys say, I'm guessing a gas blower must be a lot looser than one for alcohol. On my 565, I run a similar cam (a bit less lift), 10.5:1 CR, a decent set of heads (probably "stoopid big" by some estimations;)) and can build over 5 lbs boost at 4% under. The same basic motor/blower combo as mine made 12-14 lbs at around 25% over. Don't remember exactly as they were on the dyno just after me and I didn't keep track of all the changes they made.
 
#21 · (Edited)
David, its not just boost pressure here. If he is running pump, he can hit a boost number o 7-8 relatively easy.
Bu yo can't compare his deal with yours for a couple of reasons. If this is a lake/rier deal, it will be a slug anytime its not in boost. You could care less, your never running it at anythig less than hammered. You are at full boost from the hit. Also, your running alky. Think about the amount of fuel you have in the port along with the air. As far as the air is concerned, the port shrank by that amount. and its more than you might think. FC Pilot has a post in Info's air flow and a butt load of boost. But Funny heads are HUGE, and only spin 8500 and are boost limited. It because of the amount of fuel in the Funny's port. I also wonder what he redline of your deal is compared to what the OP i willing to spin his.

There really isn't enough info here to make a call. But it has a cam like a race motor, he has been recommented heads for a race motor. You can assume alot from the post, dry headers(hopefully) v-drive, properly geared and prop.

But like Big Steve said, whats the usage, is it a race motor, or is it a lake/river deal on pump? is it inner cooled? carb size?
Comparing your drag deal to a river boat, unless strictly for banzi runs, somewhat misses the mark.

If its a race deal, he needs more compression, or more blower. He would, as you said, have to spin 25%+ over. More like 30 on a unstripped stage 1 BDS. Thats a little faster than I would care to spin a gas blower, specially if it isn't inner cooled. And if it is, he just sped the blower up another 2-5% to get the boost back.

the whole deal needs why more info.



 
#28 ·
The brodix is a killer head and you can't break them with a hammer. And they offer more choices for more engine than damn near anybody. And if your familar with their labeling and series designations, they probably make sense to you. But like you making a simple mistake ID ing the head as a different size, its easy to do. I would need a system flow chart to keep it all straight. I am better with them now than I was just a year ago. Its why I caught your little oopsie. But its still mind numbing to me.

They are one tuff casting and from what I understand, great customer support. Specially if you wound one and need it repaired.



 
#30 ·
Oh yeah, thats more than believable. You would have gotten a little more HP with a blower sized to deliever 3 lbs. But your right. You have to pay the piper before you see any increase in power. Its why I will never run a blower motor in the 300 mi enduro again. It used to much gas just cruising at 4000 Rs and not really making all that much more HP at part throttle than I could get with an N/A, and with much better fuel milage. Blowers, specially larger ones, are not the answer for boats that spend alot of time cruising. Great way to make power if your looking for the max HP at a lower RPM, @WOT. But the part throttle HP verses fuel usage will make you cry.

Your findings just drive home what we have said here over and over. Never underestimate the amount of power it takes to drive that thing. That belt is that big for a reason.



 
#32 ·
Lets say IAT is the governor. And a 8-71 will make 840 HP @ 220F. And a 10-71 910HP and a 14-71 960HP. Boost level is irrelevant. Engine size is moot. How much good air will a blower make. Ever wonder why a pump gas blower motor will make 240BMEP and survive and a NA will hurt itself at 200. Oh, to answer the OP question, any head you can afford. The blower is the limiter.
 
#33 · (Edited)
Oh, to answer the OP question, any head you can afford. The blower is the limiter.
Yeah, that claim just keeps poping up. The user name changes, but the claim reamins the same. Its all in the boost. A 049 oval port will make the same power as a set of 357 AFRS on a 572 spinning 7000Rs with the blower spinning with the same drive ratio:)sphss Sure it will. Same goes for the cam. No sense camming for more head than you have.



 
#36 · (Edited)
Go back and read it again Bob. I didn't say the BMFs were over the top. I said OK maybe BMFs. They make some killer stuff all the way down to 310 cc intakes bsaed off Canfield castings.:)devil If I wasn't runnign AFRs, I would be running BMFs. In fact my newest set of heads, yet to be run, are Canfields set worked by you know who. :D
What was over the top was his link to the CFE's. Even though they are the same company, kind of like saying SRP and JE.
Exactly which of these CFE's would you suggest for the OPs application:D

LINK:CFE HEADS



 
#42 ·
Exactly which of these CFE's would you suggest for the OPs application:D

LINK:CFE HEADS
dunno that i'd suggest cfe's. probly 049s with mild porting...;)


If they're the Canfield BMF's keep an eye out for cracking.
my bmf's are just fine, thanks. especially compared to the profilers that lasted only 6 years before blowing out the whole side...
 
#45 ·
I understand that the castings are dedicated for CNC process, and have ports no bigger than you thumb. I question how much material is added to the "outside" of the port that allows him to push them out that far. There are definitly multiple castings. Becuase when I picked up my heads from Steel, they sets he had just purchased, and has since sold were totally different castings than mine. Very noticably so. They appeared at first glance, that they would allow for the intake port to be raised, or ported higher. The enitre inside portion of the rocker area was higher and appeared beefier than on mine.

But if Canfield didn't supply extra material to the jacket side of the port, and make the "finished" port wall thick enough to be cut to a 385, or high enough, that they start cracking around the spring seats, thats another story. You can only push a casting so far. You can only push the entire design layout so far. There is a reason the Dart Big Ms conventional heads require offset rockers.



 
#46 ·
The old Canfield CNC castings were a different casting all togehter, not just a different intake port. I know Terry (new owner of Canfield BBC Heads) was in contact with Foltz regarding upgrading the new castings to help remedy some of the cracking issues, but not sure where that has gone. The new Canfield will be a clean sheet build using the CNC castings with upgraded water jackets and a completely re-designed port and chamber configuration. Someday.;)
Old Profilers had issuse, but that was a long time ago.
 
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