I need some advice on intake port size for my .030 over 427. The motor is in the planing stages so the specifics aren't set in stone yet,
but I will be running a Tremec TKO 5spd. Currently I have a set of Brodix BB-1 OEFI "oval port" heads with 258cc intake port and .600 raised exhaust port. I talked with Brodix tech and he said with full port job intake flow numbers would jump up about 18% from 275cfm to 325cfm at max lift. In stalk form the exhaust flow to intake flow ratio is about 82% Then he offered me their new "Race Rite" oval ports. Intake size jumps up to 271cc and max flow increases to 342cfm and exhaust ports are in stock location. On these heads the exhaust flow to intake flow ratio is only about 69%. He seemed to have the "bigger is better" mentality and said that they would run better than the heads I have now. This could be true but I wanted to run it by you guy first.

So here is the question. Which head would run better? The 258cc intake port head, which is more efficient and has a raised exhaust port.
Or the bigger 271cc head with standard exhaust port. It is less efficient but it has more max flow. Also how would the exhaust port location effect performance? Would the higher velocity of the intake charge on the smaller head be more desirable compared to the more total cfm provided by the larger head? Here are some links to Brodix for more flow info.
Brodix BB-1 OEFI (http://www.brodix.com/onlinecatalog/page1-2/page1-2.html) Brodix RR BB-O (http://www.brodix.com/race_rite.site/rr_bb_o.html)
I know these are a lot of questions but I know you guys have will have some good input! Thanks in advance. graemlins/beers.gif

Really need a little more info like what cam, CR, gears ect...and intended use to make a good recommendation. You may want the 271c heads anyway since the 258cc heads have raised exhaust ports and make header fitment a PAIN

I'd move away from the raised exhaust port heads if I were you. You don't mention your car in your post, but be aware you're probably looking at having custom headers built for about $1K total to run the those heads in a Chevelle. Stock location exhaust ports are a GOOD THING in a Chevelle. BB headers are tight in a Chevelle to begin with. I'd strongly recommend you move to those heads if possible, sell those others to a boat guy or something. The full port and headers are going to run you $2K or more anyway.

Tom

b64

A intake to exhaust flow ratio is not a determining factor for a heads efficiency.

I wouldn't worry about the split because you can easily get a custom cam to make up for the difference. Pro stock heads shoot for approx 66 percent. Sonny leonard gets as much as intake flow as possible and then uses his exhaust system and cam to get it out.

I would be more concerned with header fitment like the other guys mentioned. I know one guy bought a offthe shelf header and modified only a couple of tubes to fit better.

I havent tried the raised ports in a chevelle but apparently some of the guys have.

Todd

I'd say go with the BB-O's. If you compare the flow charts, the BB-O's flow much better on the intake, and still flow better on the exhaust side even with the stock location ports. They may only have a 69% I/E ratio, but that definatly wont hurt your combo. A nice dual pattern cam would work great with it.

The other head you might consider is the Dart Oval Aluminum. They have very large chambers at 123cc, 2.25/1.88 valves and 265 cc ports. Almost surely they have raised exhaust ports, but they flow 311/241@.600 with a 4.25" bore fixture.

What are a set of bare and complete Race Rite's going for?

Originally posted by 71454Chevelle:
What are a set of bare and complete Race Rite's going for? Darren,
If you send me an email I can probably save you a few dollars on the Brodix Race Rites ;)

Thanks for the input guys!!
The car is a 64 and will be a dual purpose car used for canyon carving and 11 second (hopefully) 1/4 mile blasts. Right now my 12 bolt has 3:31's and tires are 25.7" tall. With the Tremec's .68 over drive I think I will jump up to 3:73's or 4:11's. CR will be in the range of 10.5 - 11.0. As far as porting and polishing I was going to do myself. I've got a junk set of aluminum heads to practice on. If I don't feel like the results are satisfactory I will leave it to the professionals because I don't want to eat a $2K mistake!! The cam I haven't nailed down yet. So any recommendations in that area would be helpful also. I am leaning towards a roller, solid or hydraulic I haven't decided yet. For specs I'm in the general area of 254* intake 260* exhaust duration at .050" and .660" intake and .667" exhaust lift with an approximate LSA of 110. These were Comp Cams recommendations.
It seems that the raised exhaust port is probably the biggest deciding factor between the two heads.
So if I ran the raised exhaust port heads in my '64 I would have to have a set of custom headers?

71454Chevelle, the "Race Rites" are going for $1895 complete
graemlins/beers.gif

Bryce

Bryce,
You have mail!

If you considering the new BB-O's also give somethought to having Brodix CNC port the chambers ..... and I can say from experience that fellow TC member Mike Lewis will give you excellent service and competitive pricing on these heads ...... nice to support TC members when we can. BTW the quality of these heads is outstanding compared to some other brands

Originally posted by CDN SS:
If you considering the new BB-O's also give somethought to having Brodix CNC port the chambers ..... and I can say from experience that fellow TC member Mike Lewis will give you excellent service and competitive pricing on these heads ...... nice to support TC members when we can. BTW the quality of these heads is outstanding compared to some other brands Thanks Bill graemlins/beers.gif