Understanding headflow numbers??

[DerrickfromNC1]

I was comparing the flow numbers between the DRD L6 and the CB Perf wedgeports, both are within $50.00 of each but one is using at 25" of water and the other is at 28". Which is the better head....what other factors should be considered?

DRD L6. $849.99 at .550" lift flow at 203.9 @ 28" of water

CB Perf wedgeport at .550" lift flow at 198 @ 25" of water

Both are intake rates at one given lift an the wedgeports is a 44mm intake verse a 42mm intake for the L6.

Thanks

[mark tucker]

there is a conversion for that. Ill see if I can find my superflow manual for it.

[mark tucker]

that was an easy find.the conversion factor for those flows are
have flow @ 25" x1.06 =28"flow witch would be 209.88 cfm.
And if you want the other way around it would be,
have flow at 28"x.945 =25" flow ## witch would be 192.68 cfm.
that make it hard to compare heads because some times the flow rate isant stated.it make it easy to "fudge"on the ###'s but still be accurate.if you cant make them flow as much as somebody elses just flow them at a higher flow rate(test pressure)and then you have more.but not realy, but some heads need to be flowed at a defferent rate.but I doubt there is a vw head out there that does.possiably the new cb elemnators.(on a small flow bench that cant pull enough air to reach the 25" test pressure you would use the next lower test pressure that will work&then convert it.if the flow bench cant pull enough to reach the 25"the head is flowing better than the head that reaches the 25"and that is a good thing.
as for the heads I would use the cb heads as they flow more,but pull them appart,do a valve job(lightly do the seats)and any clean up work needed in the seat bowel aera. but depending on how big your motor is you may need to see what the runner cc's are on the heads. the cb mini wedge port has a smaller runner than the wedgeport but still flows more than the drd head you listed.and it has the 42 mm intake valve also. do your home work. under 2200 cc runner size can be importaint on a street car.my 2028 had a slight sag in power midrange,hopefuly the taller better desigined big beef cb intakes will elimnate it.my 2332 with the same cam,cb tall intakes &lower cr had no problem at all.

[Pat D]

[vince1]

Any good pics of those heads Pat? We only see a "crappy" pic

I wish you made some cool pics like on the wedges and mini wedges product pages.

Would you install those on a big bus engine? (like a 2332 with cam like a FK44 and Magna F/S FI and crank trigger kit)
_________________
my French blog https://vwpanelvan.wordpress.com/

Click here for my full pix detailed 2165 engine build with beehive valvetrain.

Sorry for my poor English, I'm a French guy ...

[craigman]

Max head flow #'s don't mean $hit...
Are you going to drive your car around at 7K rpm all the time? If you are, then max #'s might mean something.
It's all about port velocity...
Don't know about the DRD heads, but most CB heads are based on their own head castings. Not stock casting like most heads out there.

[RockCrusher]

I won't say flow numbers are not important for performance but no one talks about them with respect to why they may or may not be important at different times for different applications. There is much more interest now in port volume which is correct thinking for sure but you should see that a port with the same flow numbers at full lift have fatter flow numbers in the low to mid lift region that a higher volume port. That is a winner of a head. At very low lift, just off the seat, you will see that the numbers change very little from head to head for a given valve size because it's ruled by the valve seat prep. In a street engine that is throttled a lot those mid/low to mid lift numbers are the key to sharp throttle response and good economy with power and torque right here and right now.

When you move into the higher sustained RPM's the mid numbers are less important than the total flow and volume as the flow regime has changed and the timing events, on a relative scale, have become much shorter due to RPM and the effect of piston movement becomes more influential than in a lower RPM street engine. What I'm talking about is relative piston velocity vs time allotted to get the air in the cylinder. Piston velocities are rising while time is shrinking so the pressure drop thru the port is rising. Raw volume becomes more important in this region and also why cam timing has to increase as has always been understood. In this situation VE can go very high with careful intake setup.

Don't bother to point out some of the issues I purposely left out to try to keep this simple. It's almost impossible to put into 2 dimensional words something happening dynamically in 3 dimensions. It would take pages and pages and be more confusing than enlightening.

RC
_________________
[email protected] Please use email for all general inquiries.

I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly.

[mark tucker]

[Pat D]

The super pro is a smaller port than the wedgeport. It flows from 3-8 cfm more starting at .300 lift than the wedgeport. The port volume is 6cc less then the wedgeport. Any time you can achieve more flow with a smaller port, you have a more efficient better performing head. The decrease in port volume increased port velocity by about 30 ft per/sec. A win win situation. Flow numbers are just as important as velocity numbers. They need to go hand in hand with eachother. Too much air speed= sonic choke. Sonic Choke is directly related too the Cross section of the port. There is no way too fix it other than making the crossection bigger. You have too lower the air speed.
Not enough air speed or too large of a port = port will not recover at lower rpm's and will have poor performace.
The Super pro is a great head for the money.

[modok]

All the newer CB heads, the super-pro, the mini wedge and los panchito

Look friggin awesome

Headflow at 25" is hp potential, choose the one that fits your goals and the rest of your engine

[ralf]

and this is why... some.. will say only the flow bench can tell (if ur doing it right or wrong.. or its the only way? LOL)

but airspeed, and depression says alot more than flow..

just like a dyno ...peak numbers open eyes, but e.t. and our lap times differ greatly on how the "curve" on the dyno is...

plotting numbers by cfm ' cb's have fat curves that lets u use all of the heads potential


looks like the new offerings from CB are like wat modok says, AWESOME!

now i wonder how my friend's 2176 would run with the super pro when it already has good top end with the cnc wedge's


_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

[Hotrodvw]

I was just looking at the super pros. They look really good! Very attractive for my up and coming head purchase.
_________________
'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

[MURZI]

[mark tucker]

I think they have cnc ported intakes for all thier stuff,get the tall big beef intakes there about the best intake out there,nice &slim helps keep velostcity up ,not just a set of flanges with a big hole leading to a small hole.I have them on both of my motors.+they look good.(wish they would widen them up a bit),but plenty of room for just about any size &shape port you might want or have.

[wicked1lbc]

I've been saving for about a month for the SuperPro's and talking with Pat about my 2276T I'm Building. (Hoping for about 275ish HP low-boost street/daily driver... impossible??? ... we'll see i guess) Got the cam he recommended and finally was about to call this a.m. to order the heads with the valve spring upgrades and to my dismay... CB is closed on Monday's FML...LOL...
_________________
http://www.facebook.com/pages/Vintage-VDubz/158714140852567
64 Bug -- http://www.thesamba.com/vw/forum/viewtopic.php?t=446680
2276cc Turbo
Freeway Flyer Tranny
Matte Black with Spikes

[RockCrusher]

[wicked1lbc]

[mark tucker]

I did not like the .082 in mine, with 33x19.5 street tires,to much between 3&4 for around town(rpm drop in 4th to low and 3rd to high, well not to high but more than I want around town.but the 093 was much better so it dont take much,and I did not notice any thing on the highway just cruzze at 75-80 and dont worry about it.

[wicked1lbc]

[wicked1lbc]