Accorrding to afr, their comp ported heads have the hioghest flow #'s arnd. Esp. On the exhaust side.

We also have lloyd elliot and advanced induction, but their numbers (on the exh. Side) aren't as high.

What gives?

 

Mine flow almost identical and I'm using C&C ported brodix heads.

 

Apples to oranges. Besides, flow numbers do not always = HP.

 

AFR usually uses a larger bore than you can get in an LT1 and they use a pipe on the exhaust port, both inflate flow numbers which again do not equal performance anyway. Great for sales though.

 

Also, the flow is less when they mill the heads to make the chambers smaller for your NA engine.

Doesn't mean they are bad heads at all, just that the numbers they show probably won't be the numbers your application sees.

 

ok. That's interesting.
Def not apples to apples comparison if le's and ai's numbers are based on a real lt1 intake and headers

 

Before I had my Brodix heads, I had some Dart Pro 1's ported by Lloyd that flow almost exactly the same as the Brodix's but with a little bigger intake cc.

 

When someone is flowing a head as just a test rather than a marketing trick they use nothing on the exhaust side, and on the intake side I think some clay or acrylic plate with a 1/2" radius is considered standard, but again companies will play games to inflate flow numbers for sales.

Look for a car you would like to copy and copy it.

You worry about flow numbers and such and you will endup with a bench racer's dream but frustrated over a car that doesn't actually perform well for what you have into it.

There are literally examples out there of heads/cam,nitrous cars being just as fast at heads/cam PLUS 500lbs heavier cars.

In that case which setup would you rather copy.

There are still occasional advanced on the LT1 but they are small incremental gains by guys who have been at it for awhile.

The best thing the new guys can do for themselves is to pick one of the proven recipes and copy it.

 

Is there another explaination why you wouldn't flow the exhaust with a pipe ? I see this mentioned occasionally like it's a guarded professional secret. The heads on my car have a pipe connected to them... wouldn't you want to replicate the port as it is when in use ?

 

I am sure professionals use it for a reason, they test lots of things they don't publish BUT they post with pipe numbers for marketing. Pipe size and length affect things making apples to apples hard, even though one bench to another isn't really apples to apples either.

Until fairly recently AFR was publishing all it's LT1 flow number on a 4.125 bore, even the 4.060bore they use now is VERY rare.

Ask yourself why don't they publish number at the 4.030 bore that is far and away the most likely overbore? It is not a huge difference but it shows a trend of doing what it takes to inflate numbers.