large port bowtie vortec

[zums]

anyone have a stock out of box flow curve for the 225cc head from 2011 i can compare too, thanks

[cspeier]

Zums, did you find anything from the return of the sample?

[zums]

hey chad, getting this black box dialed into the bench, seems the cal drifted from a year ago, im gonna try to call you later today, thanks- tom

[T-flow]

I have done those heads, several different ones. It's killing me that I cant find the flow numbers in my book.....
But I think the Big Bowtie's were 2.0" In. - 1.50" Ex. 230ish cfm outta the box. But this is out of my head.
They will go 260+ish ported, with chamber work and so on. They are a great street head.


T-flow

[tt 383]

I think 230's is low. That sounds more like the 206cc version. I seem to recall advertising being in the 265-280 range for the 225cc .......

[Orr89rocz]

I've seen this posted.
http://www.castheads.com/factory_chevy_ ... bowtie.php

185cc small port flows 234/164 but that doesnt seem like much more than a stock 170 truck vortec head?

225 cc large port is said to flow 266/164.

[T-flow]

Yes, you guy's are correct. I found some notes but not the finished flow sheet(s). 256@.625"(contact retainer to guide)4.040 bore. Rough'd in port 278.3@.625"(contact retainer to guide) we cut the guide down for clearance and roller springs, custom Bret Bauer cam .660" lift IN.
Regular vortec head, 216.6@.600" , 256.1@.600" ported(2009, notes 4.040 bore)


T-flow

[zums]

so no one came across the magic large port that gm claimed 279-280 out of the box, i get 267 max on my bench, heavy duty advertising huh, thanks for the replys

[stockcar5]

so no one came across the magic large port that gm claimed 279-280 out of the box, i get 267 max on my bench, heavy duty advertising huh, thanks for the replys

dont kid yourself. those head make killer power.

[CNC BLOCKS]

so no one came across the magic large port that gm claimed 279-280 out of the box, i get 267 max on my bench, heavy duty advertising huh, thanks for the replys

dont kid yourself. those head make killer power.

There is quanity of flow

There is quality of flow

Those heads a quality of flow and my best circle track engines have been with those heads.

Years ago Tom Vigue and myself built a 358 solid flat tappet 11:01 two barrel made 531 on the dyno and was a bear to drive on the track.

[zums]

i dont kid myself and the bench dosent lie, curious as to how gm came up with those #s

[raynorshine]

i dont kid myself and the bench dosent lie, curious as to how gm came up with those #s

267+5%=280.35

so less than 5%

many advertise errors of 10% or more.....why so tough on GM

[tt 383]

Could depend on the bore fixture size. Most seem to use a 4.125 but some are 4.06-4.00..... RHS uses a 4.20 on some small block flow numbers.

[raceman14]

I am with 383 on the deal on Vortec flow. If you use Amenduri flow tubes on the exhaust and almost any intake radius you can pick-up as much as 5%.

As you are experienced I am sure you know most folks flow at 28" these days and many of us old timers flow at 25" as that was the original reference number in most of the Superflow owners manuals. That difference in itself is almost 7%.

If you de-shroud the intake a little in the combustion chamber, and take the VJ up to 52.5* you will see a decent bump in CFM but an even better jump in HP.

Those heads also react well to a rich burn, retarded timing set-up as they are so efficient with the combustion chamber. I start at 25* and move on up on timing until acceleration rate slows down.