Those of you that have spoke to me and used me for cams will udoubtly have had me explain I/E ratio. The ratio between Intake and Exhaust flow numbers can tell you if your engine is cammed properly.
Some heads have high I/E ratio, 75% and some have low, 62%. Neither number is wrong or right but both take a different camshaft. If you have an AFR headed engine that runs good and your buddy builds the same engine and puts a set of Brodix on it, please don't recommend your camshaft to him. Both engines can be made to make about the same power, but it will take a totally different camshaft.
I've had the privledge to work with a gentleman that has used 3 different cams that have had the duration split increase each time. These heads had been worked on and the IE ratio was not that good so it took quite a bit of split to help the engine. Finding 61HP in a combo I think is a nice gain.
This is the fourth year I have run a 540 (.060 underbore 555) in a big car with the Brodix BB2 extra heads. First year was heads out of box with SR comp cams 254/260 at .050 .660/.660 lift. World Merlin intake and 1050 dominator. Ran ok but throttle response sucked and was done at 6100 rpm. 750hp/732 torque. Ran 11.16 and a torque monster on street when it grunted and hit.
Second year ran a 950 hp with an adaptor and the car ran great for street and picked up to about 10.70 in quarter.
Third year went 282/292 at .050 cam and ported heads. Ran 10.1 or a little qucker but engine went flat hp for 800 rpm at 6500 rpm. Ran better with dominator for mph but 950hp was faster out of hole. 805 horsepower.
Chris Straub ciphered out a cam this year with 22 degrees split at .050. Gained 61 hp on dyno, nice powerband. 866 horepower. Yet to take it down the strip.
In conclusion the BB2 heads need cam with I/E split out of box or ported. Holley 950 hp or other 4150 style carb will work better for you on the street. That big a motor doesn't care if you put a single plane intake on it. The biggest headers I have run are 2", they have been fine. Hooker comps. ''
If the engine requires more duration a tell tale sign is that it will hit a wall on power at a given rpm range. What I mean is the engine will get to an rpm point and from there make about the same power for 400 or 600 rpm more. This tells you the engine is "smothering". The power will be within 4 to 6 hp in this range and bounce up and down.
If your on the dyno and want to help it. Pull the covers and adjust the lash on the exhaust by tightening it. I recommend only up to .004" unless you consult your cam company. The engine will respond to this my making more power since you gave it more duration on the exhaust.
Variables are CID and RPM but a good rule of thumb for most street engines is if the I/E ratio is 75% you need a single pattern cam at .050". If for every % below that you need about 1.5 degrees of split favoring the exhaust. For every % above that you need to add 1.5 Degrees to the intake.
Some heads have high I/E ratio, 75% and some have low, 62%. Neither number is wrong or right but both take a different camshaft. If you have an AFR headed engine that runs good and your buddy builds the same engine and puts a set of Brodix on it, please don't recommend your camshaft to him. Both engines can be made to make about the same power, but it will take a totally different camshaft.
I've had the privledge to work with a gentleman that has used 3 different cams that have had the duration split increase each time. These heads had been worked on and the IE ratio was not that good so it took quite a bit of split to help the engine. Finding 61HP in a combo I think is a nice gain.
This is the fourth year I have run a 540 (.060 underbore 555) in a big car with the Brodix BB2 extra heads. First year was heads out of box with SR comp cams 254/260 at .050 .660/.660 lift. World Merlin intake and 1050 dominator. Ran ok but throttle response sucked and was done at 6100 rpm. 750hp/732 torque. Ran 11.16 and a torque monster on street when it grunted and hit.
Second year ran a 950 hp with an adaptor and the car ran great for street and picked up to about 10.70 in quarter.
Third year went 282/292 at .050 cam and ported heads. Ran 10.1 or a little qucker but engine went flat hp for 800 rpm at 6500 rpm. Ran better with dominator for mph but 950hp was faster out of hole. 805 horsepower.
Chris Straub ciphered out a cam this year with 22 degrees split at .050. Gained 61 hp on dyno, nice powerband. 866 horepower. Yet to take it down the strip.
In conclusion the BB2 heads need cam with I/E split out of box or ported. Holley 950 hp or other 4150 style carb will work better for you on the street. That big a motor doesn't care if you put a single plane intake on it. The biggest headers I have run are 2", they have been fine. Hooker comps. ''
If the engine requires more duration a tell tale sign is that it will hit a wall on power at a given rpm range. What I mean is the engine will get to an rpm point and from there make about the same power for 400 or 600 rpm more. This tells you the engine is "smothering". The power will be within 4 to 6 hp in this range and bounce up and down.
If your on the dyno and want to help it. Pull the covers and adjust the lash on the exhaust by tightening it. I recommend only up to .004" unless you consult your cam company. The engine will respond to this my making more power since you gave it more duration on the exhaust.
Variables are CID and RPM but a good rule of thumb for most street engines is if the I/E ratio is 75% you need a single pattern cam at .050". If for every % below that you need about 1.5 degrees of split favoring the exhaust. For every % above that you need to add 1.5 Degrees to the intake.
