BIG DUKE VS BIG BRODIE

[jrthone]

BATTLE OF THE BRODIX

If a Big Duke can flow 440cfm @ 0.800"out of the box and a Big Brodie(say BP BB3 Xtra-O etc) can flow [email protected]" with ease with still lots of room to go further. Why go to the expense of 18-12 degree heads

[cboggs]

because a well ported big duke will flow more then that, ..

BUT, it's not all just flow, .. the raised runner of the big duke allows
better delivery to the valve, better fuel delivery into the chamber, .
and well ported will flow well over 500 cfm.

typically a spread port head like the big duke will make at least 60 hp
more then a conventional head, ..

other consideration is average power not just peak, .. average power is
what really makes et and fast cars on the track, not just peak power.

Curtis

[jrthone]

But a well ported BP BB3xtra-O will flow more than 500cfm as well. Is it really worth the expense in say a 1200hp big block.Maybe up around the higer mark but surly there nothing wrong with running the BP BB3 XtraOs on a 1200hp Big Block.

[jrthone]

Im only arguing this point because racers on a budget need somthing good to work with especially with 600+cubes. Is it really that bad to run BB3 xtras?????

[cboggs]

But a well ported BP BB3xtra-O will flow more than 500cfm as well. Is it really worth the expense in say a 1200hp big block.Maybe up around the higer mark but surly there nothing wrong with running the BP BB3 XtraOs on a 1200hp Big Block.

I don't know who told you a bb3 will flow more then 500 cfm, but that is total BS, .
460 maybe 465 cfm max on an honest bench, . .. plus the head is too small
for a large cube engine.
Can't get the area for a 600" engine out of an oval port conventional head , ..

If you're on a budget yes it's a fine head but won't make 1200 hp.
There's a hand full of good conventional heads for a 600" engine.
Dart's big M is a 410 cc port conventional and when well ported with a big
valve will flow over 470, .. and has made great power for years.
We do a large port version of the Victor that flows over 470.
BMF has a 400 cc head that will make good power with some work.

Keep in mind peak flow isn't the only thing that makes power.


Curtis

[wltrb]

I remember a guy who had a dragster with a Sonny's motor in it with Dart bigm's, .. and a single 4, .. ran 6.80's back in the early 90's, ..

w

[jrthone]

So if they come out of the box flowing 461cfm.You are telling me you cant get another 39cfm out of them.

[bbchevy]

Budget???
Can we switch Budgets?You will have more in your Heads then i will have i my Whole Long Block!
My Opinion,if your after 1200HP and worried about your Budget?Then somethings is Wat Wrong withe Picture?
If Curtis tells you a Quarter is only Worth a Dime?LISTEN to HIM!He will Explain WHY...................?
Later
G 8)

[hammertime]

But a well ported BP BB3xtra-O will flow more than 500cfm as well. Is it really worth the expense in say a 1200hp big block.Maybe up around the higer mark but surly there nothing wrong with running the BP BB3 XtraOs on a 1200hp Big Block.

I don't know who told you a bb3 will flow more then 500 cfm, but that is total BS, .
460 maybe 465 cfm max on an honest bench, . .. plus the head is too small
for a large cube engine.
Can't get the area for a 600" engine out of an oval port conventional head , ..

If you're on a budget yes it's a fine head but won't make 1200 hp.
There's a hand full of good conventional heads for a 600" engine.
Dart's big M is a 410 cc port conventional and when well ported with a big
valve will flow over 470, .. and has made great power for years.
We do a large port version of the Victor that flows over 470.
BMF has a 400 cc head that will make good power with some work.

Keep in mind peak flow isn't the only thing that makes power.


Curtis

No doubt Curtis is right never seen a bb3 oval over 500 or even close to it, a brodix big duke IMO is awesome head.

[cboggs]

jrthone,

I think you're missing the point, .. more flow doesn't mean more power, ..
it's just not that simple.
If it was we could just put a 2.8" valve in a 600cc port and flow 1000 cfm, ..
but we both know that wouldn't work.

We have to consider air speed BEFORE the mass airflow volume or CFM.
If you don't have proper airspeeds you will never fill the cylinder over 100%
that is necessary to make the power levels we are discussing.

Exit speed of the intake charge out of the valve and into the chamber is one of
THE most important design issues to making good power.
Slow, sluggish air speed and power drops off fast.

So, .. this being said there is actually a fine balance between the mass flow or
CFM of a head designed for an application, .. and the airspeed or velocity that
head is designed to produce.

Big holes make big cfm numbers that look good in magazine ads but don't
run well on the race track. So that being said, yes I could likely make a -3 flow
another 39cfm, .. and it likely wouldn't run worth a crap on a typical bracket engine.

Case in point, .. I know of a head that was advertised at over 500 cfm, ..
and actually did it on a good bench, .. and makes less power then my standard
RFD / Victor or an out of the box -3, .. by a bunch.

David, .. I love the 1803 big duke, .. damn nice head.

Curtis

[michael1]

I have a brand new pair of pb1802 heads, what needs to be done to make these work on a 632 with 2 1150 dominators with 10.5-1 compression in a 3400 drag radial car. Thanks

[cboggs]

I have a brand new pair of pb1802 heads, what needs to be done to make these work on a 632 with 2 1150 dominators with 10.5-1 compression in a 3400 drag radial car. Thanks

why is the compression so low?

if the 1802's are just out of the box, .. some porting and a proper valve job
will wake them up.

Curtis

[michael1]

I'm building it for the pump gas drags, will this combo work? Do you think this is to much head? How much would you charge, they are bare heads.

[cboggs]

I'm building it for the pump gas drags, will this combo work? Do you think this is to much head? How much would you charge, they are bare heads.

it'll work for the pump gas drags, .. but I'd rather use an oval port
head like the Brodix 1803 or the new RFD / Edelbrock Big Victor.

Big heads and sheet metal intakes with two carbs aren't very
good on pump gas, .. it'll take some heavy engine building skills to make it work.

Curtis

[michael1]

I had to go with these heads bacause I have had the intake and carbs for a while now so I figured it would be cheaper to just use it. I only need to get about 950-1050 hp on motor to compete. I also plan on putting nos on it. If I send you the heads how much would you charge me to make them work including all parts. I will also send you the intake so you can port match it too. Thanks

[Pwmax]

My advice, would be to skip the twin dominators, and sheet metal manifold, for that combo. YOu will be WAAAY more happy with a single carb on the new Edelbrock Spread port manifold. We had a guy that bought a used sheet metal intake, that physicaly bolted to some Big Chief heads, on a 598 I did over the winter, and, the single carb, on the Edelbrock intake made more power!!. Old "mystery" sheet metal intakes, built by who knows, don;t gaurentee more power because its made from shert metal, and looks really trick. Typicaly, they are made to "tune" a narrow window of a power band, and will look bad if that window isn;t utilized, because the engine wasn;t run up that high in RPM.

Besides, 2 dominators for the cruise, could be a TOTAL nightmare. But, 1000hp, is doable on 92 with the right combo

Frank
Advanced Performance
www.get-ap.com

[michael1]

It is a Dart spread port tunnel ram intake and Dart said for my specific combo they think that this intake would work better then a sheet metal intake. Do you think this is true? Also the intake has never been ported so the runner volume should not be to much, does that sound right?

[TheRabbit]

We have to consider air speed BEFORE the mass airflow volume or CFM.
If you don't have proper airspeeds you will never fill the cylinder over 100%

Exit speed of the intake charge out of the valve and into the chamber is one of
THE most important design issues to making good power.
Slow, sluggish air speed and power drops off fast.

Curtis

This also leads to the discussion of size and type of headers / collectors???
Curtis where do you decide to go up to 2 1/2" and/ or 5" collectors?
and what effect does length of tubes have??
Maybe you should write a book! I"LL BE GLAD TO PUBLISH IT FOR YOU!! :wink: :!:
THANX again!!

[cboggs]

Maybe you should write a book! I"LL BE GLAD TO PUBLISH IT FOR YOU!! :wink: :!:
THANX again!!

I'll consider writing a book, .. what type of publishing deal are we talking?

C

[supergass]

Curtis,
I just bought a set of the 365cc oval Brodix heads for a 565. Dod you like these heads over a head like the 355 cnc Dart?? Can I angle mill these down to 110cc chambers without sticking the valve out ?? I havent seen mine yet.

Chris Carlile

[hammertime]

Curtis,
I just bought a set of the 365cc oval Brodix heads for a 565. Dod you like these heads over a head like the 355 cnc Dart?? Can I angle mill these down to 110cc chambers without sticking the valve out ?? I havent seen mine yet.

Chris Carlile

I am sure they are the 3x's better head then the darts out of box for sure, which I am sure Curtis will agree.